Patent ID: 12259427

It will be appreciated that any of the variations, aspects, features, and options described in view of the systems apply equally to the methods and vice versa. It will also be clear that any one or more of the above variations, aspects, features, and options can be combined.

DETAILED DESCRIPTION

Disclosed herein are thermal heads and corresponding test systems for independently controlling a plurality of zones (e.g., one or more components) while testing one or more devices under test. In some embodiments, a thermal head comprises a plurality of adapters, one or more heaters, and one or more thermal controllers for independently controlling temperatures of the components. For example, two components may have different set point temperatures. The thermal controllers may control the temperatures of the two components independently such that thermal control of one component does not affect the thermal control of the other component. At a given time, a first heater (thermally coupled to the first component) may be heating the first component, while the temperature of the second component may remain the same. In some embodiments, the thermal control is by way of one or more cold plates, and the thermal head comprises one or more cold plates. As one non-limiting example, at a given time, a first component is being cooled by a cold plate, whereas the second component is not. As yet another example, a third component may not be thermally coupled to a heater and/or cold plate. Embodiments of the disclosure include independent control of one or more forces using one or more force mechanisms. Embodiments of the disclosure further include methods for operation thereof.

The following description is presented to enable a person of ordinary skill in the art to make and use various embodiments. Descriptions of specific devices, techniques, and applications are provided only as examples. These examples are being provided solely to add context and aid in the understanding of the described examples. It will thus be apparent to a person of ordinary skill in the art that the described examples may be practiced without some or all of the specific details. Other applications are possible, such that the following examples should not be taken as limiting. Various modifications in the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described herein and shown, but are to be accorded the scope consistent with the claims.

Various techniques and process flow steps will be described in detail with reference to examples as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects and/or features described or referenced herein. It will be apparent, however, to a person of ordinary skill in the art, that one or more aspects and/or features described or referenced herein may be practiced without some or all of these specific details. In other instances, well-known process steps and/or structures have not been described in detail in order to not obscure some of the aspects and/or features described or referenced herein.

In the following description of examples, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the disclosed examples.

The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combination of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that the term “same,” when used in this specification, refers to the stated feature as being identical or within a certain range (e.g., 1%, 5%, etc.) from identical.

Some of the devices may comprise a plurality of zones, where each zone may comprise one or more components (e.g., IC chips in a package or functional blocks in a chip).FIG.1Aillustrates a top view of an example chip comprising a plurality of zones. Device100may comprise zones117A,117B,117C,117D,119A,119B, and119C. For example, a complex SOC device may comprise a plurality of graphic processing unit (GPU) cores, a plurality of central processing unit (CPU) cores, and various interfaces and other functions, where zones119A,119B, and119C may be high-power zones (e.g., comprising GPU and/or CPU cores), and zones117A,117B,117C, and117D may be low-power zones (e.g., comprising memory, transceivers, etc.). A zone may comprise one or more components. In some embodiments, at least two zones of a device may dissipate different amounts of power while under testing conditions due to different functions of and/or tests being performed on the zones. It may be beneficial to keep the temperature of one or more zones constant and at one or more set point temperatures (or within a given range) while the device is being tested.

A zone may comprise one or more components, such as zone117A comprising one component, and zone119C comprising at least two components. One or more components may be part of a single device (as shown in the figure), or alternatively, part of a plurality of devices under test (not shown in the figure).

FIG.1Billustrates a block diagram of an example test system, according to some embodiments. Test system190may comprise a thermal head150, a controller158, a socket121, and a tester141. The thermal head150may be configured to thermally control the device under test100. The thermal head150may comprise one or more of: an adapter130, a heater156, a cold plate162, or a force mechanism132. The adapter130may be configured to allow thermal energy to transfer to and/or from thermally-coupled components. For example, the adapter130may allow thermal energy (e.g., heat) to transfer from the heater156located on the bottom side of the adapter130to the cold plate162located on the top side of the adapter130. The heater156may be configured to raise the temperature (e.g., heat) of the device100, and the cold plate162may be configured to lower the temperature (e.g., cool) of the device100. The thermal head's ability and speed at thermally controlling the temperature of the device100may depend on the thermal coupling between its components and the device100.

The force mechanism132may be configured to apply a force to the device100to enhance the thermal coupling between the thermal head150and the device100. The controller158may be configured to send one or more signals to the thermal head150to control one or more of its components. For example, the controller158may send a current or voltage signal to the heater156to cause it to heat the device100. As another example, the controller158may send a current or voltage signal to a valve metering the flow inside the cold plate162or associated chiller to cause it to cool down the device100. Additionally or alternatively, the controller158may send a current or voltage signal to cause the force mechanism132to apply more or less force to the thermal head150, thereby improving the thermal coupling between the thermal head150and the device100without damaging it. As one non-limiting example, the thermal controller may be a field-programmable gate array (FGPA)-based proportional-integral-derivative (PID) controller.

The socket121may be configured to electrically couple power connections and/or test signals from the tester141to the device100, or from the device100to the tester141. The tester141may send test signals and/or receive response signals for determining the performance of the device100. In some embodiments, the tester141may monitor the power being supplied to one or more of: the DUT, a component, or zones of the DUT. Although the figure illustrates the test system190as comprising one or more components, embodiments of the disclosure may include additional components, or one or more components may not be included. Additionally or alternatively, although one configuration of the test system is shown, embodiments of the disclosure may comprise other configurations such as the thermal head comprising an additional adapter located on the bottom side of the device100.

Example Thermal Head Comprising a Plurality of Adapters

FIG.2Aillustrates a top view of an example device comprising a plurality of zones, according to some embodiments. Device200may comprise a plurality of components, such as component202A, component202B, and components203A-H mounted on a substrate210. The device200may comprise one or more high-power components (e.g., components202), one or more low-power components (e.g., components203), or a combination thereof. In some embodiments, the device200may comprise any type of component (e.g., chips or packages); non-limiting examples include logic, RF, analog, digital, power, diodes (e.g., light emitting diodes (LEDs)), sensors (e.g., image sensors), microelectromechanical systems (MEMS), integrated passive devices (IPDs), power management units or integrated circuits (PMUs, PMICs), etc. Additionally or alternatively, the device200may comprise other types of components including, but not limited to, resistors, capacitors, inductor, transistors, etc.

As one non-limiting example, the device200may be a SiP device used for high performance computing (HPC) applications. Component202A and component202B may be processor chips (e.g., CPU and/or GPU chips) surrounded by dynamic random access memory (DRAM) chips, for example. The memory chips may be individual chips, packaged chips, through-silicon via (TSV) stacked chips (e.g., high bandwidth memory (HBM) devices), or the like. In some embodiments, one or more components may be located in close proximity to one or more other components. For example, memory chips may be placed close to the processor chips to reduce signal delays and noise in the memory to processor interconnections, improving overall performance due to, e.g., higher transfer speeds and reduced latency. The close proximity may cause the temperature from one component to affect the temperature of another component.

FIG.2Billustrates a cross-sectional view of the device200along line A-A, as drawn inFIG.2A. Line A-A may be drawn through components202B,203D, and203H. The components202B,203D, and203H may be mounted on and connected to the substrate210by way of interconnects206. In some embodiments, the components in a device200may be on a single layer of the substrate210. In some embodiments, the interconnects206may be component interconnects, such as solder balls, copper pillar bumps, C4 (controlled collapse chip connection) bumps, gold bumps, wire bonding, or conductive adhesive, as non-limiting examples. The interconnects206may allow the components to be mechanically and/or electrically connected to the substrate210. The substrate210may comprise any type of material, such as laminate. In some embodiments, the substrate210may comprise one or more layers of: conductive traces, conductive plane layers, dielectric layers, or a combination thereof. One or more vias may be used to connect conductive layers. The layer(s) and/or vias may be formed using a printed circuit board process. Embodiments of the disclosure may include other materials (e.g., ceramic, silicon, glass, molding compound, etc.) for creating the substrate210.

The components202/203and interconnects206may be located on the top side of the substrate210, and interconnects216may be located on the bottom side of the substrate210. In some embodiments, no components may be located on the bottom side of the substrate210. The interconnects216may be, for example, used to electrically couple the device200to a board. The board may be a test board, when the device200is being tested, or a system board, when the device is being used in a final product. When coupled to a test board, the interconnects216may electrically couple to a socket used to send test signals between a tester and the device200. The interconnects216may be solder balls, pins, leads, pads on the substrate210, or other forms of interconnects.

As one non-limiting example, the test board may send one or more test (input) signals to the device200and/or may receive one or more output signals from the device200. The test signal(s) may have a predetermined pattern. The output signal(s) may represent the electrical characteristics of the device200in response to applying the test signal(s) to the device200while being tested. In some embodiments, the testing may be performed using multiple sets of input and output signals, while operating the device200under the same or different conditions (e.g., different temperatures).

FIG.2Cillustrates a cross-sectional view of the device200along line B-B, as drawn inFIG.2A. Line B-B may be drawn through components202A and202B. In some embodiments, as shown in the figure, two or more components (e.g., chips or packages) may have different heights due to, e.g., different designs and/or manufacturing variations. For example, component202A may be shorter than component202B, resulting in a height difference220. In some embodiments, the height difference220may be due to differences in the types of components. For example, memory chip203A may be taller than processor chip202A. As another example, high-power chip202B may be taller than high-power chip202A. It is also contemplated that in instances where components202A and202B have the same height, they may be located at different planes after assembly to the substrate210due to differences in final solder size during assembly (e.g., differences in solder ball compression during soldering).

If the height differences of the components in the device200are not accounted for, the test system may not be able to adequately control the testing conditions of the components of the device100. For example, the test system may have an adapter or associated heater that contacts the top of component202B, but not the top of component202A, due to the height difference220. As a result, the test system may be thermally coupled to the component202B, but may not be adequately thermally coupled to the component202A. Such lack of thermal coupling may cause performance problems when testing the component202A. Example test systems of the disclosure are capable of simultaneously testing different components in one or more devices under test having different set point temperatures. The thermal control of the different components is such that they have temperatures within a tolerance (such as 1%, 5%, etc.) from respective set point temperatures without compromising the performance of the components. Additionally or alternatively, the test systems of the disclosure are able to test device(s) comprising multiple components having different heights at a given time without compromising thermal performance.

AlthoughFIGS.2A-2Cillustrate two components with eight other components located along the sides of a substrate, embodiments of the disclosure may include any number and/or arrangement of components. Additionally or alternatively, the components in a device may be arranged in any manner not shown in the figure.

Embodiments of the disclosure may include a test system comprising a thermal head configured to thermally control one or more devices under test.FIGS.3A-3Billustrates cross-sectional views of an example thermal head comprising a plurality of adapters, according to some embodiments. The thermal head350may be configured to test one or more devices. The device may comprise component302A, component302B, component303A, component303D, substrate310, interconnects306, and interconnects316, which may have one or more properties similar to component202A,202B,203A,203D, substrate210, interconnects206, or interconnects216, respectively.

The thermal head350may comprise a plurality of adapters330A-330D. Adapters330B and330C may be located at the inner regions of the thermal head350, and the adapters330A and330D may be located at the outer regions of the thermal head350. Each adapter330may be thermally coupled to a corresponding component of the device. In some embodiments, one or more (e.g., each) adapters may be thermally coupled to one component. In some embodiments, a first adapter may be thermally coupled to a first component, and a second adapter may be thermally coupled to a second component. Adapter330A may be thermally coupled to component303A, adapter330B may be thermally coupled to component302A, adapter330C may be thermally coupled to component302B, and adapter330D may be thermally coupled to component303D. In some embodiments, the number of adapters used for testing a device may be the same as the number of components in a device. In some embodiments, at least one adapter may be thermally coupled to one or more (e.g., at least two) components. For example, an adapter may be thermally coupled to a first component and a second component. In some embodiments, the number of adapters used for testing a device may be less than the number of components in a device.

By being thermally coupled, the temperature of an adapter may affect the temperature of a corresponding thermally-coupled component. In some embodiments, two or more adapters may be thermally independent from one another such that the temperature of one adapter and/or its corresponding thermally-coupled component may not affect the temperature of another adapter and/or its corresponding thermally-coupled component. For example, the adapter330B may be thermally independent from the adapter330C, resulting in the temperatures of the adapters and/or corresponding thermally-coupled components not affecting each other. In some embodiments, the adapters and/or thermally-coupled components may be independently controlled, such as independently thermally controlled.

The independent control may comprise one or more of: independent thermal control (e.g., using independent adapters, independent heaters, independent flow control, independent heat sinks. and/or independent cold plates), or independent force control (e.g., using independent force mechanisms). In this manner, the test system may provide different thermal control for different components of a device.

One or more properties of one or more adapters may be such that different properties (e.g., heights) of the components may be accounted for such that the heat transfer between a thermal head and a component may not be compromised due to, e.g., the size of the component. For example, one or more properties (e.g., size, force, etc.) of the adapter330B may be different than one or more properties of the adapter330C to account for the height difference between the component302A and the component302B. In some embodiments, the size (e.g., height) of an adapter and/or associated components may be related (e.g., inversely proportional) to the size of the corresponding thermally-coupled component. As one non-limiting example, the height of adapter330C may be taller (compared to the adapter330B) due to component302B being shorter (compared to the component302A).

In some embodiments, first adapter330B may have a first height and second adapter330C may have a second height. This difference in height may account for height differences between corresponding components of the device(s) under test. In some embodiments, first adapter330B may have a first thermal mass and second adapter330C may have a second thermal mass. The difference in thermal mass may account for differences in thermal masses between corresponding heaters. In some embodiments, first adapter330B may have a first surface area, and second adapter330C may have a second area. This difference in surface area may account for differences in surface area between corresponding components of the device(s) under test, or differences in thermal interface material (TIM) layers. The adapters may have other differences, such as different thermal conductivities, widths, etc. In some embodiments, differences in the adapters may lead to heating or cooling the components by different amounts.

The multiple-adapter thermal head of the disclosure comprises a monolithic adapter that is thermally coupled to components of a device under test. The monolithic adapter may be made of a continuous material. In some instances, the monolithic thermal head may comprise a monolithic cold plate, a monolithic heater, and/or a plurality of large-sized heaters (greater than 900 mm2, as one non-limiting example). An example adapter is described in more detail below.

As shown in the figure, the thermal head350may include one or more heaters356thermally coupled to one or more adapters and one or more components of one or more devices under test. For example, the adapter330B may be thermally coupled to a heater356B, and the adapter330C may be thermally coupled to a heater356C. The first heater356B may be configured to heat the first component302A, and the second heater356C may be configured to heat the second component302B. In some embodiments, two or more heaters356may be thermally independent from each other such that the thermal control of one and/or its corresponding thermally-coupled component may not affect the thermal control of another heater356and/or its corresponding thermally-coupled component. In some embodiments, one or more (e.g., each) adapters may be thermally coupled to a unique heater. In some embodiments, one or more adapters, such as the adapter330A shown inFIG.3A, may not be thermally coupled to a heater. Example heaters are discussed in more detail below.

A heater may be located close to a corresponding thermally-coupled component so that the delay between the change in temperature of the heater and the change in temperature of the device may be minimized. In some embodiments, at least one heater may be located adjacent to (e.g., contacts) at least one component, or an intermediate layer (e.g., a TIM layer) that contacts the component. In some embodiments, at least one heater may be located adjacent to (e.g., contacts) at least one adapter. The at least one heater and the at least one adapter may comprise mating alignment features for aligning the two together. Any misalignments may reduce the amount of thermal coupling between the heater and the adapter. Example mating alignment features may include, but are not limited to, protrusions on one surface and mating indents on another surface, or the perimeter shape of one element (e.g., the heater) and a corresponding recess or outline in the adapter or a retainer.

Embodiments of the disclosure may include a heater comprising a plurality of (e.g., at least two) heating elements that are spatially separated and thermally isolated using a thermal insulator between the heating elements. In some embodiments, a thermal insulator (e.g., a thermal insulating material or air) may be located between at least two heating elements to prevent or reduce thermal coupling between them. Example thermal insulating materials may include, but are not limited to, materials having low thermal conductivity (e.g., polymers, plastics), materials having a high void content (e.g., foam materials, mineral wool), air, vacuum, or the like. In some embodiments, the thermal insulating material may comprise through-holes or trenches for increased thermal isolation.

In some embodiments, a heater356may be a small-sized heater (less than 500 mm2, as one non-limiting example). Small-sized heaters may have increased complexity and/or manufacturing yields compared to large-sized heaters. Small-sized heaters may also be easier to control due to their lower thermal mass, particularly suitable for maintaining a device at or within a certain range from a set point temperature. In addition to being easier to control, small-sized heaters may operate faster (in terms of temperature change), making thermal control of a device under test more stable and accurate. In some embodiments, the size of a heater may be based on the size of the component that it is thermally coupled to. For example, a device under test may comprise a plurality of components having different sizes, such as large-sized components and small-sized components, and the corresponding test system may comprise a plurality of heaters having different sizes, such as large-sized heaters and small-sized heaters. In some embodiments, the surface areas of the device and heater that contact each other may be the same. An intermediate layer such as a TIM layer may also have the same surface area.

Additionally or alternatively, one or more TIM layers322may be used to enhance thermal coupling between an adapter and a corresponding component of the thermal head or DUT. In some embodiments, a TIM layer322may be located on at least one side of an adapter and/or a heater. The TIM layer322may be located between an adapter and a device (such as TIM layer322A located between adapter330A and component303A), between a heater and a device (such as TIM layer322B located between heater356B and component302A), or between an adapter and a heater (such as TIM layer332C located between adapter330C and heater356C). Additionally or alternatively, in some embodiments, a TIM layer may be located between an adapter and a heater, and the same or a different TIM may be located between the heater and a device (e.g., a TIM layer on both sides of the heater). In some embodiments, different TIM layers may have different properties. For example, the thermal resistance of the TIM layer322B may be different from the thermal resistance of the TIM layer322C. Example TIM layers are discussed in more detail below.

In some embodiments, one or more properties of the heater and/or TIM may be configured to account for different sized components such that the heat transfer between a heater (or an adapter) and a component may not be compromised due to the size of the component. Returning back to the previous example of component302A being taller than component302B, in some embodiments, the height of the heater356B and/or TIM layer322B may be less than the height of the heater356C and/or TIM layer322C.

Embodiments of the disclosure may further include one or more force mechanisms332A or332B to move a corresponding adapter closer to a thermally-coupled component. Example force mechanisms may include, but are not limited to, a spring, a lever coupled to a force applicator, or a force applicator. In some embodiments, the force mechanism332may apply a force onto one side of the adapter to move the other side closer to the surface of the TIM layer322and/or component. In some embodiments, movement of a first adapter is independent from movement of a second adapter; for example, movement of adapter330B may not cause movement of adapter330C, and therefore movement of heater356B may be independent from movement of heater356C. As one non-limiting example, the independent movement of the adapters may account for any height differences (e.g., due to manufacturing tolerances). Embodiments of the disclosure comprise test systems capable of independently controlling the forces on different components.

The disclosed thermal head may comprise one or more controllers. One example controller is a thermal controller configured to control one or more heaters. A thermal controller may send one or more signals to a given heater including, but not limited to, sending different signals to different heaters such that they are independently controlled. For example, a first signal sent to the first heater356B may adjust its temperature without affecting the second heater356C. In some embodiments, at least two components may be tested at different temperatures during a given test operation, and corresponding controllers and heaters may operate independently to maintain the components at those respective temperatures. For example, a first controller and corresponding heater356B may operate to insure the first component302A is at a first temperature, while a second controller and corresponding heater356C may operate to insure the second component302B is at a second temperature.

In some embodiments, at least two components and corresponding heaters356may have different changes in temperature. The at least two components may have different power dissipation levels, for example, and as a result, different changes in temperature. For example, the first component302A may dissipate a first power level, and the second component302B may dissipate a second power level. The first heater356B may operate at a first change in temperature corresponding to the first power level, while the second heater356C may operate at a second change in temperature corresponding to the second power level. Additionally or alternatively, the thermal controller may control the temperature(s) based on power dissipated from the component(s) of one or more devices under test.

In some embodiments, two or more adapters may be thermally dependent, such that they are thermally coupled together. Two or more adapters (e.g., adapters330A and330D) may be coupled to the same inputs from the thermal controller. For example, the components303A and303D may be low-power memory chips or packages arranged in a row of four, such as shown by the arrangement of components203A-203D on the left side ofFIG.2Aor components203E-203H on the right side. A single adapter or a plurality of adapters may be thermally coupled to plurality of components. In some embodiments, the plurality of adapters and/or the plurality of components may have the same height.

Additionally or alternatively, the controller may comprise a force controller configured to send a plurality of signals to the thermal head to independently control one or more forces applied to one or more components. The force controller may send one or more signals to a given force mechanism, such as sending different signals to different force mechanisms to control the force applied by a given adapter. As one non-limiting example, a force controller may cause a first force to be applied to a first adapter330B and a second force to be applied to a second adapter330C. For example, the force controller may apply a larger force to a component having a larger surface area compared to a component having a small surface area. In some instances, the pressure on the larger surface area component may be the same as the pressure on the smaller surface area component.

In some embodiments, the thermal head350may comprise one or more cold plates configured to lower the temperature of one or more of: one or more adapters, one or more components, or the device.FIG.3Billustrates an example thermal head comprising a cold plate362. In some embodiments, at least two of the plurality of adapters may be thermally coupled to the same cold plate, such as adapter330B and330C being thermally coupled to cold plate362. Thermal energy may be transferred to/from the cold plate362to the adapter330B and/or adapter330C. The cold plate362may be located on the top side of one or more adapters330, and one or more heaters356may be located on the bottom side of the adapter(s)330. In some embodiments, the cold plate362can cool components303A and/or303D by, e.g., contacting at least a part of the force mechanisms332A and/or332B.

In some embodiments, the thermal head350may comprise a plurality of cold plates, such as shown inFIG.3C. At least two cold plates may be thermally independent from one another. Cold plate362B may be thermally coupled to the adapter330B, and the cold plate362C may be thermally coupled to the adapter330C. The thermal control of the cold plate362B may not affect the temperature and/or thermal control of the cold plate362C and vice versa, for example.

In some embodiments, movement of cold plate362B may be independent from movement of cold plate362C. The amount of force applied may depend on the properties of the corresponding component, heater, TIM, adapter, or a combination thereof. More force may be applied when a corresponding component has a larger surface area, for example. Example force mechanisms are discussed in more detail below.

In some embodiments, at least two components and corresponding cold plates362may have different changes in temperature due to, e.g., having different power dissipation levels. For example, the first component302A may dissipate a first power level, and the second component302B may dissipate a second power level. The first cold plate362B may operate with a first temperature corresponding to the first power level, while the second cold plate362C may operate with a second temperature corresponding to the second power level. Additionally or alternatively, the cold plates362B and362C may operate at different temperatures, such as when the corresponding components are tested at different temperatures.

The thermal controller may be configured to control one or more heaters (as discussed above), one or more cold plates, or both. To control the cold plate(s), the thermal controller may send one or more signals to one or more flow control valves associated with each cold plate. In instances where the thermal head comprises at least two cold plates, the thermal controller may send one signal to one cold plate's flow valve without affecting the flow through another cold plate's valve (independent flow control). The cold plate and associated thermally-coupled components (adapter, heater, component, etc.) may be thermally isolated from other (e.g., neighboring) cold plates and associated thermally-coupled components. In some embodiments, a thermal insulator (e.g., a thermal insulating material or air) may be disposed between neighboring cold plates.

The properties of a cold plate362may be based on the properties of a thermally-coupled adapter330. For example, the surface area of the cold plate362(that contacts the adapter) may be the same as the surface area of the adapter330(the top side of the adapter that contacts the cold plate). As discussed in more detail below, a cold plate362may comprise one or more cooling channels that a liquid or gas may flow through. The flow rate and/or temperature of the liquid or gas may affect the cooling abilities of the cold plate362.

Example Thermal Head

Embodiments of the disclosure may include one or more thermal heads with the properties as described herein. For purposes of simplifying the descriptions, some of the figures may illustrate some, but not all, portions of the disclosed thermal heads. A portion of a thermal head, comprising an adapter, will now be described, but the thermal head may include other portions not disclosed or in combination with the disclosures herein.FIG.4illustrates a cross-sectional view of a portion of a thermal head, according to some embodiments. The thermal head450is configured to thermally control a component402mounted on a substrate410. Although the figure illustrates a single adapter430and single component402on a single substrate410, embodiments of the disclosure may include any number of components (e.g., 2, 3, 4, 5, 10, etc.), any type of components (e.g., high-power chips, low-power chips, passive components, etc.), and any number of substrates.

When testing a device, it may be difficult, but important, to control the temperature of the device while being tested. In some instances, thermal control may require heating or cooling one or more components of the device at a rapid rate so that the component(s) may reach the set point temperature quickly and the temperature remains constant during the test.

The adapter430may comprise a continuous piece of thermally-conductive material. For example, the adapter430may comprise a metal such as copper, aluminum, silver, or a metal matrix composite (copper-diamond, aluminum-diamond, copper-graphite, aluminum-graphite, etc.). One or more properties (e.g., thermal mass, height, surface area, etc.) may be based on the set point temperature and/or the properties of the thermally-coupled heater and/or cold plate.

In some embodiments, the thermal head450may comprise a heater456. The heater456may be configured to apply heat to the component402. In some embodiments, the heater456may increase the temperature of the component402when, e.g., the component power is low and/or when its temperature is lower than the set point temperature of the component402. The heater456may be any type of heater including, but not limited to, a solid-state device (e.g., comprising a ceramic body with one or more resistive traces), a cartridge heater in a thermally-conductive body, a thermoelectric device (TED), a silicon-based semiconductor device, etc. In some embodiments, the heater456may have a low thermal mass. In some embodiments, the thermal mass of the heater456may be less than the thermal mass of the adapter430, the cold plate462, or both. In some embodiments, the thermal mass of the heater456may be at least 5 times lower than the thermal mass of the adapter430. In some embodiments, the thermal mass of the heater456may be at least 10 times lower than the thermal mass of the adapter430. The thermal mass of the heater456may affect its responsivity, temperature ramp rate, and conductive heat transfer, e.g., through the heater456, adapter430, cold plate462, or a combination thereof.

Additionally or alternatively, the thermal head450may comprise cold plate462. The cold plate462may be configured to cool the adapter430, which may thereby cool the heater456and/or component402. When the heater456is off, the cooled adapter430may cool the heater456. The cold plate462may include one or more cooling channels469, which may circulate liquid or gas to cool the cold plate462. Example liquids may include, but are not limited to, water, a heat transfer fluid, a refrigerant coolant, a gas, etc. In some embodiments, one or more other cooling mechanisms may be used to cool the cold plate462, such as a thermo-electric cooler (TEC) (as one non-limiting example). The TEC may cool the cold plate462below the temperature of a fluid circulating through the cold plate462, for example. As another (non-limiting) example, a chiller or a radiator may be used to cool the temperature of the fluid.

The adapter430may be configured to thermally couple to the component402. Better thermal coupling may lead to better thermal control. In some embodiments, thermal coupling may occur by way of the adapter430making contact with the component402and/or using one or more intermediate layers to facilitate heat transfer between the adapter430and the component402. TIM layers422are example intermediate layers.

In some embodiments, one or more TIM layers422may be located between one or more components of the thermal head450. A TIM layer422may be used to reduce thermal resistance, thereby enhancing the thermal coupling. For example, one TIM layer422may be located between the adapter430and the heater456, and/or one TIM layer422may be located between the heater456and the component402. As another example, a TIM layer422may be located between the cold plate462and the adapter430(not shown). In some instances, a TIM layer may be excluded, and instead, the cold plate462and adapter430may be one continuous material (e.g., a cold plate with one or more adapters machined out of its surface). A TIM layer may comprise one or more of: a thermal grease (e.g., oil or other material comprising embedded thermally-conductive particles such as metal particles or ceramic particles), a liquid material (e.g., glycol, water), a carbon material, a metallic malleable material (e.g., a low-melting point material such as indium, tin, or a combination of materials such as a thermally conductive elastomeric pad with an aluminum foil cover layer), a thermally conductive elastomeric pad, or the like.

In some embodiments, thermal coupling between the adapter430and the component402may be improved when there is a force applied to components of the thermal head450and/or the component402, making better contact. The thermal resistance between the adapter430and the component402may be related to the amount of applied force. The applied force may also impact the contact between socket contactors and interconnects416(which the test system uses to electrically connect to the component). Additionally or alternatively, the applied force may help prevent or reduce the component402and/or substrate410from unwanted warping, which may lead to defects.

Embodiments of the disclosure may include other types of intermediate layers including, but not limited to, bumps, posts, or other contacts over the surface of the adapter, cold plate, and/or heater to increase or decrease thermal coupling. The number, size, density, and/or pattern of the bumps, posts, or contacts may be configured such that a target thermal resistance between an adapter and a heater, an adapter and a cold plate, or a heater and a component may be obtained. In some embodiments, the thermal resistance may be configured according to the type of component or device. For example, the test system for a low-power component may be configured with high thermal resistance. A low-power heater may be used for thermal control, and due to the high thermal resistance, may be able to easily heat up the low-power component.

The thermal head450may further comprise one or more temperature sensors to measure the temperature of the adapter430, heater456, or cold plate462. The measured temperature may be used by the thermal controller to set, adjust, or maintain the temperature of the adapter430, heater456, and/or cold plate462. The measured temperature may be compared to a set point temperature, and the signals sent to the controller may be updated accordingly to minimize the difference between the measured temperature and the set point temperature. Setting, adjusting, or maintaining the temperature of the heater456may comprise setting, adjusting, or maintaining the current or voltage from the thermal controller to the heater456. Setting, adjusting, or maintaining the temperature of the cold plate462may comprise setting, adjusting, or maintaining the flow rate or temperature of the liquid or gas associated with the cold plate462. In some embodiments, the update frequency of the thermal controller for controlling the temperatures is less than 200 microseconds.

An example method for controlling the temperature of a component includes, but is not limited to, setting or adjusting the temperature based on whether the measured temperature (e.g., heater temperature) is above or below the set point temperature (or set point temperature range). If the measured temperature is above the set point temperature, the thermal controller reduces the amount of power to the heater. If the measured temperature is below the set point temperature, then the thermal controller increases the amount of power to the heater. In some embodiments, the heater may be configured for a specific power output of the thermal controller. As one example, the thermal controller is capable of powering the heater with up to 500 W using 100 V, where the heater generates 500 W with a 100 V supply (e.g., for the set point temperature or across the set point temperature range). In some embodiments, the heater may be configured for the corresponding component, such as the heater having an output power that is greater than the output power of the component. For example, a 30 W heater may be used to heat a 10 W component, while a 300 W heater may be used to heat a 100 W component. The lower the thermal mass of the heater, the more effective the heater456becomes in increasing the temperature of the component402quickly. In some embodiments, the thermal controller separately sets or adjusts different temperatures of the thermal head. For example, the controller sets or adjusts a DUT temperature, an adapter temperature, a cold plate temperature, etc.

Example Heater

FIG.5Aillustrate a cross-section diagram of an example heater, according to some embodiments of the disclosure. The figure illustrates one surface558of the heater556, which contacts an adapter530or one or more TIM layers (which would be located between the surface of the heater556and the adapter530). Another surface559of the heater556may contact a component of the DUT or a TIM layer (which would be located between the surface559of the heater556and a component of the DUT).

In some embodiments, the heater556may comprise a plurality of heater pins, one or more heating elements, one or more measurement traces, or a combination thereof. Some of the plurality of pins551(including pins551A and551B),553(including pins553A and553B),555(including pins555A and555B), and557(including pins557A and557B) may be pins used to carry electrical current into and out of the heater556. In some embodiments, the pins551,553,555, and/or557may be attached to one or more pads (not shown) on the heater556. Example methods for attaching the heater pins to the pads include, but are not limited to, brazing, soldering, gluing (e.g., using electrically-conductive epoxy), etc. As shown in the figure, one or more insulating layers566may insulate the pins551,553,555, and557from the adapter530, e.g., to prevent electrical shorts. The insulating layers566may be located around the heater pins, and/or between the heater pins and the adapter530. The insulating layers566may comprise one or more of: plastic, rubber, ceramic, or another dielectric. In some embodiments, an insulating layer566may be a hollow polytetrafluoroethylene (PTFE) tube with an inner diameter sized for the diameter of a heater pin and an outer diameter configured to fit into clearance holes in the body of the adapter530.

AlthoughFIG.5Aillustrates a single row of six heater pins, embodiments of the disclosure may comprise any configuration and number of heater pins, such as a single row of heater pins arranged around the perimeter of the surface of the heater, two heater pins in a row on one side of the heater, 10 or more heater pins in a row, 4 pins in two rows on two sides of the heater, or the like. In some embodiments, the plurality of heater pins may occupy less than 10%, 30%, 50%, etc. of the surface558of the heater556. In some embodiments, the inner region of the surface558of the heater556may exclude heater pins to allow the heater556to make contact with the adapter530at the inner region.

The heating elements563and565may be used to generate heat for the heater556. In some embodiments, the heating elements563and565may comprise resistors and/or resistive traces. The total area of thermal control by the heater556may depend on the properties of the heating elements563and565. For example, the heating elements563and565may be formed on separate layers within the body of the heater556, where one or more resistive traces of the heating element may be formed on a plurality of layers so that a target resistance within a target area of the heater556may be obtained. In some embodiments, the heating elements563and565may be located closer to the adapter530than the ground plane567and measurement trace561.

In some embodiments, each zone of the thermal head may comprise one or more heating elements and a measurement trace561. In some embodiments, any number of heating elements and measurement traces may be associated with a zone, depending on the power requirements of the zone and power limitations of the heating elements. In some embodiments, the total area of thermal control may be the same as the total surface area of the heater556. Alternatively, the total area of thermal control may be less (e.g., 20%) than the total surface area of the heater556. A heating element may be located throughout a large percentage (e.g., 80% or more) of the surface of the heater556, or certain zone(s) of the heater556. In some embodiments, one or more first heating elements may be associated with one or more first zones, and one or more second heating elements may be associated with one or more second zones. As one non-limiting example, the first heating elements and first zones may be high-power heating elements and high-power zones, respectively, while the second heating elements and second zones may be low-power heating elements and low-power zones, respectively.

The heating elements563and565may be configured to generate heat using, e.g., resistors. The heating elements may be electrically coupled to heater pins such that power via a current or voltage signal can be applied to the heater pins to turn on the corresponding heating elements. Power applied to pins553A and553B may cause the electrically-coupled heating element563to turn on and generate heat, and power applied to pins555A and555B may cause the electrically-coupled heating element565to turn on and generate heat. In some embodiments, the number of heating elements and/or heating element layers may be increased to increase the overall power output from the heater556at a given voltage. For example, a heater556may comprise five heating elements, each configured to generate 200 W at 200 VDC, thereby generating a total output power of 1000 W.

In some embodiments, the heater556may comprise a plurality of heating zones. In some embodiments, the heater556may comprise one or more insulating mechanisms to insulate two or more heaters or heating zones from each other. One example insulating mechanism comprises through-holes or trenches in the body of the heater at location(s) between the heating elements and edge(s) of the heating zones. Another example insulating mechanism comprises using different adapters for different zones, such as one or more first adapters and associated heaters for a first heating zone, and one or more second adapters and associated heaters for a second heating zone.

The measurement trace(s)561may be used for measuring the temperature of one or more surfaces (e.g., the surface559that contacts a component or an intermediate TIM layer) of the heater556. The measurement trace561may be located within the body of the heater556. The measurement trace561may be located close to the surface559, for example. In some embodiments, the measurement trace561may be a trace with a certain temperature coefficient of resistance such that its resistance can be correlated to a temperature reading, this type of device is also referred to as a resistance temperature detector (RTD).

In some embodiments, after manufacturing the heater556, resistances of the measurement trace561can be measured at different temperatures to generate pre-determined calibration information such as a calibration curve, calibration table, or associated relationships (between resistance and temperature). The pre-determined calibration information may be stored in, e.g., a non-volatile memory chip or coded into a 1D or 2D code (e.g., a linear barcode or 2D matrix barcode) or stored remotely in a database. The pre-determined calibration information may be used by a controller to determine the temperature of a heater or heat zone and use that knowledge to control one or more resistors (e.g., resistor563or resistor565) included in the heater for thermal control of a corresponding zone.

In some embodiments, a measurement trace561may be coated with a dielectric. The thickness of the dielectric may depend on the physical construction and limitations of the heater556. In some embodiments, the dielectric may have a thickness less than 2 mm. In some embodiments, the dielectric may have a thickness less than 0.4 mm. The measurement trace561may be located throughout the surface559of the heater556that contacts a component or intermediate layer (e.g., a TIM layer that contacts the component). For example, the area in which the measurement trace561is located may be the same as the area in which another heating element (e.g., resistor563or resistor565) is located, although these may be on different layers in the heater.

While some of the plurality of pins may be used to carry electrical current for heating, others may be used for shielding. Pins557A and557B, shown inFIG.5A, may be electrically coupled to a ground plane567for electromagnetic interference (EMI) shielding. The ground plane567may be grounded, providing an electrical ground path to the heater556during testing. During testing, the heaters may be turned on and off in rapid succession, at high voltages and currents, which can generate electrical noise that can potentially interfere with the testing circuitry or measurements. Shielding the heater elements with a ground plane567that covers them may reduce or eliminate the unwanted electrical noise. In some embodiments, the pins557A and557B may be electrically coupled to an adapter. For example, as shown in the adapter illustrated inFIG.5B, the adapter530comprises a hole525that provides access to the pin557A and/or pin557B. The hole525may expose ground pin523that may be attached to an adapter530by being, e.g., soldered, spot welded, brazed, glued (e.g., using an electrically-conductive adhesive), etc. In some embodiments, the pin557A and/or pin557B may be attached to the adapter530by, e.g., soldering. Having both the adapter530and ground plane567grounded improves the shielding of the heater elements compared to having only the ground plane567grounded. In the case where both the adapter530and ground plane567are grounded, there is an effective shield formed both above and below the heater elements.

In some embodiments, the adapter may include a retainer571. The retainer571may be configured as a mechanical attachment for attaching (e.g., requiring a tool for removal) the heater556to the adapter530. This mechanical attachment facilitates thermal coupling between the heater556and the adapter530. Example mechanism attachments include, but are not limited to, clamps, screws, retains, or the like. As shown in the figure, the retainer571may be located within the body of the adapter530, allowing the heater556and adapter530to have any sizes for surface areas, including the same-sized surface area (as one non-limiting example). With the size of the adapter being the same or substantially the same as the size of the corresponding component, the disclosed test systems are able to quickly change the temperature of the component due to, e.g., the thermal mass of the adapter. In some embodiments, the hole525in the adapter530provides access to one or more pins, such as pins557A and557B.

Additionally or alternatively, the retainer571may be configured for electrically coupling the adapter530to one or more ground pins523. The ground pin523may be flexible ground pins, for example, that allow the heater556and adapter530to expand at different rates. The heater556and adapter530may have different coefficients of thermal expansion, allowing the two to expand and contract at different rates with temperature changes without undue stress or strain on either component and while maintaining good thermal contact between the adapter530and the heater556.

In some embodiments, the heater is attached (e.g., requires a tool for removal) to the adapter. An attached heater results in better thermal coupling between the adapter, heater, and/or any intermediate layers. Without attaching the heater, any movement in the adapter and/or intermediate layers may limit how quickly heat can transfer from the heater to the adapter and/or corresponding component.

Referring back toFIG.5A, the ground plane567may be a solid ground plane or a perforated ground plane (the size of the perforations may be configured based on desired EMI frequencies). In some embodiments, the area of the ground plane567may be greater than or equal to the area of the heating elements. In some embodiments, the area of the ground plane may be at least 80%, 85%, 90%, 95%, etc. of the area of the surface of heater556. The ground plane567may be located within a certain depth from the surface of the heater556(that contacts a component or an intermediate layer), such as (but not limited to) less than 1.5 mm, less than 1 mm, less than 0.6 mm, etc.

Although not shown in the figure, the heater556may comprise a plurality of dielectric layers, a plurality of conductive layers, and/or a plurality of conductive vias for making electrical connections between the plurality of conductive layers. In some embodiments, the outer surfaces of the heater may comprise a protection layer (e.g., a dielectric such as ceramic) to protect the conductive layers located within the heater556.

Example Cold Plate

FIGS.6A and6Billustrate cross-section diagrams of an example cold plate, according to some embodiments of the disclosure. The cold plate662may be oriented such that its bottom surface691is located closest to a corresponding heater or adapter. The cold plate662comprises a cavity with an inlet and outlet for coolant671to circulate through the cooling channels669. The cavity may be formed by a top plate673and a bottom plate675. The cold plate662comprises a plurality of fins663. In some embodiments, the plurality of fins663may comprise fins that are long, rectangular fins or rounded pin fins. The plurality of fins663may be integrated into the bottom plate675and top plate673. In some embodiments, the plurality of fins663may be oriented perpendicular from the top plate673and/or bottom plate675. The plurality of fins663are used to increase the surface area that contacts the coolant671that flows through the cold plate662, thereby providing more effective heat transfer from the cold plate662to the coolant671.

Example Thermal Interface Material (TIM) Layers

The test system disclosed herein may use one or more TIM layers. A TIM layer may affect the thermal resistance between an adapter and a heater, an adapter and a cold plate, an adapter and a component, or a heater and a component. A TIM layer may be selected based on one or more properties of the thermal head, adapter, heater, cold plate, a component on the device under test, etc. The thermal resistance may be adjusted by configuring the thickness of the TIM layer and/or its thermal conductivity, for example. Additionally or alternatively, the surface area of a TIM layer may be adjusted by including one or more openings or holes727, as shown inFIG.7A. The thermal resistance of the TIM layer722may be configured based on size and/or number of openings or holes727. In some embodiments, the TIM layers722in a thermal head may be different, e.g., a first TIM layer may have a greater surface area than a second TIM layer.

In some embodiments, the TIM layer722may be configured based on the properties of the associated component and/or zone. For example, a high thermal resistance TIM layer may be used for a low-power component. In some embodiments, the properties of the TIM layers may be different for different components and/or zones of a device.

The TIM layer722may be formed using any technique, such as dispensing a liquid TIM722on a component or device, as shown in the example ofFIG.7B. Using a liquid TIM may help minimize gaps between an adapter and a component, for example, which may reduce the thermal resistance between the two; although other types of TIM materials may be included, such as a solid TIM material, a paste TIM material, or a grease TIM material. A reduced thermal resistance may be beneficial in instances, such as when an adapter does not comprise a heater, when an adapter is used only for cooling, when an adapter is used for adjusting the temperature of a high-power component, or when an adapter comprises a heater and is used for both heating and cooling, among others.

A liquid TIM may be dispensed on the component(s) or device prior to testing and then removed after testing has been completed. To determine whether the dispensed liquid TIM meets target properties (e.g., amount, location, thickness, etc. of the dispensed TIM), one or more techniques may be employed to inspect the dispensed liquid TIM, such as a machine vision system that visually inspects and compares it to one or more pre-determined criteria, or a system that tests its thermal resistance value. Based on whether or not the dispensed TIMs meet one or more target properties, the test system may proceed with performing the test (dispensed TIM qualifies), or create an alert (dispensed TIM does not qualify). In this manner, a device may be tested only when the TIM properties do not affect the testing of the device, ensuring that the testing results accurately represent the performance of the device. Too much dispensed liquid TIM may overflow onto one or more components and may adversely affect it during testing (e.g., if the liquid TIM is electrically conductive), or could pose a reliability issue for the device (e.g., if the liquid TIM induces corrosion or other deleterious effects). Too little TIM may lead to high thermal resistance(s), causing problems with the testing such as being able to maintain the component at a set point temperature. In some instances, if no TIM was dispensed and a high power is applied to the component, the component may fail due to thermally-induced catastrophic failure.

Example Thermal Head for a Device Comprising Stacked Components

Embodiments of the disclosure may comprise other types of devices, such as a device that may comprise one or more stacked components.FIGS.8A and8Billustrate top and cross-sectional views, respectively, of a device including stacked components, according to some embodiments. The device800may include a plurality of components, such as component802B, component802T, and components803A-H mounted on a substrate810. One or more components may be stacked on one or more other components, such as component802T being a top component stacked on a bottom component802B. In some embodiments, the footprint of component802T may be smaller than the footprint of component802B. Component802B may be a high-power component, for example. In some embodiments, the stacked components802B and802T may be coupled together using, e.g., one or more interconnects818such as one or more of: TSVs, microbumps, or the like. In some embodiments, components803A-H may be auxiliary components.

As one non-limiting example, the component802T may be a cache memory chip, and the component802B may be a processor chip, where the component802T may be stacked on the component802B. In such an arrangement, the component802T may be a standalone chip (e.g., a chip capable of operating independently) that provides a higher memory capacity than an internal cache in the processor chip itself. Stacking a cache chip802T on top of the processor chip802B may reduce interconnect length, thereby increasing read/write speeds and reducing latency. In some embodiments, the component802B may be a high-power component, and the component802T may be a low-power component.

Device800may further include substrate810, interconnects806, and interconnects816, where one or more of: the substrate810, interconnects806, or interconnects816have properties similar to corresponding substrate210, interconnects206, or interconnects216, respectively. As shown inFIG.8B, there may be one or more height differences among the stacked components (comprising components802T and802B) and other components803C and803G in device800.

The adapters of the thermal head may be configured such that heat transfer between an adapter (and/or heater and/or cold plate) and stacked components may not be compromised.FIG.9Aillustrates a top view of an example device comprising stacked components, according to some embodiments. The device may comprise components903A-903H. Additionally, the device900may comprise at least one stacked component, which includes component902T stacked on component902B. Device900may have one or more properties (e.g., comprising interconnects to electrically couple components to a substrate, interconnects to electrically couple a substrate to a test system, etc.) similar to device100,200,800, or a combination thereof.

FIGS.9B and9Cillustrate cross-sectional views of a thermal head950and device, along line B-B and A-A, respectively, as drawn inFIG.9A. Thermal head950may comprise a first adapter930B and/or a first heater956B that are thermally coupled to a first component (e.g., one component902B and/or lower portion of the stacked components) and a second adapter930C and/or second heater956T thermally coupled to a second component (e.g., component902T and/or upper portion of the stacked components).

The test system may comprise a thermal head950. The thermal head950may comprise plurality of adapters including, but not limited to, adapters930A-930D. One or more adapters, such as adapters930A-930D may have one or more properties similar to other adapters disclosed herein, such as adapters330A-330D. For example, the adapter930A may not be thermally-coupled to a heater. As another example, the adapter930D may transfer force to a component applied by way of a spring or other force mechanism932F. The adapter930D may additionally or alternatively be contacting a TIM layer922F, located between the adapter930D and the component903F.

In some embodiments, one or more adapters may be thermally coupled to a first portion of the stacked components. For example, adapter930B may be thermally coupled to a component902B or a portion of a component902B of the stacked components. The thermal coupling may comprise one or more corresponding thermally-coupled components as making contact. For example, the adapter930B may be thermally coupled to a heater956B and a TIM922B. The adapter930B may contact the heater956B, for example. The TIM922B may contact a portion of the component902B, such as its outer region (e.g., outer perimeter).

Adapter930C may be thermally coupled to another component (e.g., component902T) or another portion of the stacked components. The adapter930C may be thermally coupled to a heater956T and a TIM922C, where the TIM922C may contact the top surface of the component902T. In some embodiments, the first adapter930C may be nested (fully or partially) within the second adapter930B. The second adapter930B may surround a plurality (two or more, such as four) sides of the first adapter930C. The first adapter930C and second adapter930B may be thermally coupled, for example.

In some embodiments, the corresponding first heater956T may be nested within the second heater956B. The second heater956B may surround a plurality (e.g., two or four) sides of the first heater956B. Similarly, the first TIM layer922C may be nested within the second TIM layer922B. In some embodiments, as shown in the figure, a TIM layer922C may be located between the components of the stacked components.

In some embodiments, the second adapter930C may be located in a hollow portion of and surrounded by the first adapter930B. In some embodiments, the first adapter930B, the corresponding heater956B, and/or the corresponding TIM922B may contact most (e.g., more than 50%) of the top surface of the component902B.

In some embodiments, thermal control of the first component902B in the stacked components and/or its thermally-coupled (first) adapter930B may be independent from thermal control of the second component902T in the stacked components and/or its thermally-coupled (second) adapter930C. In some embodiments, separate control signals may be transmitted to the corresponding heaters, cold plates, and/or force mechanisms.

The different adapters, heaters, and/or TIM layers for different portions of the stacked components may be configured accordingly. For example, the force applied by the adapter930C to both components in the stack (component902B and component902T) may be at least partially transferred as force applied to the bottom component (component902B). The adapters may apply force to different regions of component902B, so in some embodiments, the force applied by adapter930C may be less than the force applied by the adapter930B. As another example, the top component902T may a memory chip and the bottom component902B may be a processor. The heater956T for the top component902T may be less powerful than the heater956B for the bottom component902B. Additionally or alternatively, the adapter930C (contacting the top component902T, or an intermediate layer such as the heater956T and/or TIM922C) has a lower conductivity, smaller contact area, and/or higher TIM resistance compared to the adapter930B (contacting the bottom component902B).

One or more (e.g., each) of the adapters, heaters, cold plates, and/or TIM layers disclosed herein of a given device may account for differences in the properties of the corresponding components, such as different heights of the components and/or arrangement of components. In the example shown inFIGS.9A-9C, adapter930A, adapter930D, adapter930E, and adapter930F (and/or corresponding heaters, cold plates, TIM layers, or a combination thereof) may account for the height(s) of component903B, component903F, component903C, and component903G, respectively, and any associated TIM layers and/or interconnects. The adapter930B, heater956B, and/or TIM layer922B may account for the height of component902B and any associated TIM layers and/or interconnects. The adapter930C, heater956T, and/or TIM layer922C may account for the total height of components902B and902T and any associated TIM layers and/or interconnects. One or more force mechanisms may be used to move a corresponding adapter, heater, and/or cold plate closer to a thermally-coupled component. For example, the thermal head950may comprise a spring932B that moves adapter930A closer to the component903B and a spring932F that moves adapter930D and TIM922F closer to the component903F. Other force mechanisms may be used including, but not limited to, a lever, a force applicator, or the like.

Example Thermal Head for a Device Comprising Components on a Plurality of Sides of a Substrate

In some embodiments, a device under test may include component(s) and/or package(s) located on a plurality of sides of a substrate, such as device1000including components1002A and1002B located on the top side of the substrate1010, and component1002C located on the bottom side of the substrate1010, as shown in the top and cross-sectional views ofFIGS.10A and10B, respectively. The top view ofFIG.10Aillustrates the outline of component1002C (located on the bottom side of the substrate1010). As shown in the figures, in some embodiments, the component1002C may be located at different regions of the substrate1010along the x- and y-axes than the components1002A and1002B. In some embodiments, high-power component(s) may be located on one side of the substrate1010and low-power component(s) on the other side. Interconnects1006may be component or package interconnects that mount the components to the substrate1010. For example, interconnects1006A may mount the component1002A to the top surface of the substrate1010, interconnects1006B may mount the component1002B to the top surface of the substrate1010, and interconnects1006C may mount the component1002C to the bottom surface of the substrate1010. In some embodiments, the device1000may include interconnects1016to electrically couple the device1000to a board. The board may be a test board with a socket that engages the DUT (when the device1000is being tested) or a system board (when the device is being used in a package).

Although the figures illustrate chips, packages, or other components as mounted on the surface of a substrate, embodiments of the disclosure may comprise one or more components that are partially or fully enclosed within the substrate. For example, the device under test may be an embedded die or fan-out wafer-level type of package.

FIG.11illustrates a cross-sectional view of a part of a test system comprising a thermal head and a DUT having components on a plurality of sides of a substrate, according to some embodiments. The device may comprise components1102A and1102B located on the top side of substrate1110and component1102C located on the bottom side. The thermal head may comprise a plurality of adapters1130A,1130B, and1130C for independent control of components1102A,1102B, and1102C, respectively.

In some embodiments, the thermal head may comprise one or more adapters configured to thermally couple to corresponding components from a plurality of sides of a substrate. The adapters1130A and1130B are configured to thermally couple from the top side of the substrate1110, and the adapter1130C is configured to couple from the bottom side of the substrate1110. In some embodiments, the thermal coupling and/or contact of the adapters to the plurality of sides of the substrate may occur simultaneously.

Additionally or alternatively, the test system1190may comprise one or more mechanisms for electrically coupling to send and/or receive test signals from the device. A socket body1170may comprise test contact pins1172, which may contact and/or electrically couple to the interconnects1116of the device. The properties of the adapters1130A,1130B, and1130C may have similar properties to the adapters discussed herein.

Embodiments of the disclosure may include any of the properties including those described herein, such as (but not limited to) the device comprising additional components not shown in the figure, one or more adapters thermally coupled to a plurality of components, using a passive or active temperature control, using a passive or active force mechanism, etc.

Example Force Mechanisms

One (non-limiting) example force mechanism may comprise a piston.FIG.12Aillustrates an example piston, according to some embodiments of the disclosure. The thermal head may comprise the force mechanism, an adapter1230, a cold plate1262, and a heater1256.

A piston1243is coupled to a ramp1204and a roller1205. The piston1243may move in accordance with the amount of applied force. For example, movement of the piston1243to the right along the x-axis causes the ramp1204to move, applying a greater amount of force on the roller1205, which then applies a greater amount of force on the top of the thermal head may then cause an applied force to the component1202. The amount of applied force may be measured by a transducer1239.

In some embodiments, the piston1243and at least a portion of the ramp1204may be located off to the side of the thermal head, creating an overall shorter profile than if the force applicator were located on top of the thermal head. The piston1243, ramp1204, and/or roller1205may be used and exchanged for a certain type of component, such as a specific SiP DUT where a greater amount of force is desired (e.g., a high pin-count or ball-count SiP). The specific SiP DUT may be tested without having to change the rest of the test system by removing any other force mechanism and replacing it. The other force mechanism may be attached or detached using screws, bolts, or attachment means.

Another example force mechanism comprises a cam-roller, such as the one shown inFIG.12B. The cam-roller comprises a cam1207A and a roller1207B. The cam1207A rotates in a certain direction, such as clockwise, where the rotation of the cam adjusts the amount of force to be applied via the roller1207B in the z-direction.

In some embodiments, at least one force applied by the force mechanism(s) may be a variable force, wherein the variable force may be different at the beginning of a test (right when testing begins) and during the test, or during the test and at the end of the test (right when testing ends). In some embodiments, the variable force may be force that has been adjusted during the test. In some embodiments, the at least one force may be a fixed force that is the same at the beginning of the test and during the test, or during the test and at the end of the test. Embodiments may include other types of force mechanisms; example force mechanisms are discussed below.

Example Test Systems

FIG.13Aillustrates a cross-sectional view of an example test system, according to some embodiments. The test system1390may comprise a thermal head and a socket. The device may comprise a plurality of components1302,1303A, and1303B mounted on a substrate1310. The substrate1310may comprise interconnects1316to electrically couple to a tester (not shown). The socket comprises a socket body1318comprising test contact pins1317. Movement of the socket body1318towards the device or movement of the device towards the socket body1318may cause the test contact pins1317to electrically couple to the interconnects1316.

One of the force mechanisms included in the test system1390may comprise a pusher1331and force applicator1333for electrically coupling the device to the test contact pins1317of the test system1390for testing (e.g., sending and/or receiving electrical signals from the tester to the device). The force applicator1333pushes the pusher1331, which then pushes one or more unpopulated portions of the substrate1310of the device towards the socket body1318and corresponding test contact pins1317. The force applicator1333can be any type of device that applies a force including, but not limited to, a pneumatic or hydraulic cylinder, a pneumatic or hydraulic diaphragm, a stepper motor, a linear motor, a server motor, an electroactive polymer actuator, a shape memory alloy actuator, an electromagnetic actuator, a rotary motor, an electromechanical actuator, a piezoelectric actuator, a voice coil, or other active force application device. The force applicator1333may apply a force between 5-300 kgf, including any force in between.

In some embodiments, the test system may comprise a transducer1329that measures the force being applied by the force applicator1333in real-time (while the force is being applied). The transducer1329can generate one or more force measurement signals used as feedback for a controller communicating to the force applicator1333to adjust the force applied such that a target force is met. The transducer1329can comprise a pneumatic load cell, a hydraulic load cell, an inductive load cell, a capacitive load cell, a magnetorestrictive device, a strain gauge-based sensor, a force sensitive resistor, a thin film device, a piezoelectric device, or the like. Although the figure illustrates the transducer1329as having a width that is the same as the pusher1331, embodiments of the disclosure may include a transducer1329that has a width smaller than the width of the pusher1331. In some embodiments, the test system1390may comprise one or more springs (not shown) that may be used to return the pusher1331, transducer1329, and/or force applicator1333to a home position when the force applicator1333is not applying a force. Additionally, in some embodiments, the test system1390may comprise a home sensor (not shown) used to indicate when the pusher1331, transducer1329, and/or force applicator1333are in the home position. The home position may be the position where the pusher1331, transducer1329, and/or force applicator1333are located the furthest away from the thermal head and/or not applying a force to it, for example.

Another force mechanism in the test system1390may comprise a force mechanism included in a thermal head. The thermal head force mechanism may comprise a force applicator1343for thermally coupling the device to the thermal head for thermal control of one or more components of a device under test. The force applicator1343may apply force to a cold plate1362and/or an adapter1330C of the thermal head. The force applicator1343can be any type of device that applies a force including, but not limited to, a pneumatic or hydraulic cylinder, pneumatic or hydraulic diaphragm, stepper motor, linear motor, server motor, voice coil, or other active force application device. The force applicator1343can apply a force including, but not limited to, between 1 kgf, 2 kgf, 100 kgf, 300 kgf, or 500 kgf. The thermal head may comprise a transducer1339(e.g., load cell, strain gauge-based sensor, force sensitive resistor, thin film device, piezoelectric device, or the like) that measures the force being applied by the force applicator1343in real-time and generates one or more force measurements signals used as feedback for a controller communicating to the force applicator1343to adjust the applied force to meet a target force. The force applicator1343may have any width, for example, the same width or smaller than the width of the adapter1330.

As shown with the example ofFIG.13A, embodiments of the disclosure may comprise active thermal control, passive thermal control, active force control, passive force control, or a combination thereof. Active thermal control may be used to set or change the temperature of one or more components of a device to a set point temperature (or within a given range). The active thermal control may comprise a heater1356, adapter1330C, and/or a cold plate1362, which change the temperature of one or more components in a device based on a thermal controller. A temperature sensor may be included for measuring the temperature of the device under test, where the measured temperature may be used as feedback by the thermal controller, heater1356, and/or cold plate1362.

Additionally or alternatively, the test system1390may comprise passive thermal control. Passive thermal control may allow one or more components in a device to change its temperature using, e.g., heat transfer. The passive thermal control may comprise one or more adapters1330A and1330B, which may transfer (e.g., exchange) thermal energy with one or more thermally-coupled components1303A and1303B, respectively. In some embodiments, the passive thermal control may allow the temperature of a thermally-coupled component to reach the temperature of the adapter1330. The adapters1330A and1330B may contact the components1303A and1303B, respectively. In some embodiments, the adapters1330A and1330B (for passive thermal control) may not be thermally coupled to a heater. In some embodiments, one or more adapters1330A and/or1330B may not be thermally coupled to a cold plate1362or may be thermally coupled to a cold plate1362that does not include cooling channels for circulation of a cooling material.

Embodiments of the disclosure may include both active and passive thermal control. For example, as shown in the figure, the test system may comprise one or more adapters1330A and1330B for passive thermal control and one or more adapters, such as adapter1330C, for active thermal control. In some embodiments, active thermal control may be used for components that have temperature set points or specific requirements, while passive thermal control may be used for other types of components (e.g., low-power components, components that do not have specific test temperature requirements, components whose performance is not sensitive to temperature, etc.).

Additionally or alternatively, any type of thermal control may be combined with any type of force control. For example, one or more adapters, such as adapters1330A and1330B for passive thermal control may be combined with passive force control, such as a spring, bellows, elastomer, or the like. As another example, a force applicator1343for active force control may be combined with a heater1356for active thermal control.

In some embodiments, different amounts of control may be used to account for different temperature set points or requirements, different component heights, different arrangements, etc.

FIG.13Billustrates a flowchart of an example method of operating the test system1390, according to some embodiments. Process1370comprises step1372where the test system1390sets the temperature of the thermal head to one or more set point temperatures. The ramp rate of the temperature may be as fast as possible or may be predetermined, for example. In step1374, the test system places the device to be tested in a socket. The temperature of the thermal head may reach the one or more set point temperatures before or after the device is placed in the socket.

In step1376, a first force may be applied to the device for electrically coupling the device to the socket. A transducer may measure the amount of force applied. If the measured force does not meet a threshold force, then the test system may cease process1370. Otherwise, in step1378, a second force may be applied to the device in order to bring the adapter(s)/heater(s)/TIM(s) in contact with the individual chips, e.g., the force need to thermally couple the thermal head to the device. A transducer measures the amount of force applied to the device, and ends the process if it does not meet a threshold force.

If the amount of first force and the amount of second force applied to the device meet their respective threshold forces, then the test system1390starts device testing (step1380). In some embodiments, the test system1390starts device testing in response to a start-of-test signal transmitted from one or more controllers (e.g., a handler, a thermal controller). During the test, the test system1390may optionally send one or more signals to the controller to change modes and/or set point temperature(s) (step1382). Example modes may comprise, but are not limited to, measuring the heater temperature, measuring the DUT temperature, etc. The mode may be changed in accordance with the examples of the disclosure.

In step1384, the test system1390completes the device testing and sends an end-of-test signal to the controller(s). The second force applied on the device may be removed (step1386), and then the first force applied on the device may be removed (step1388). In some embodiments, process1370may not proceed to step1388until the test system1390verifies that the second force applied on the device has been removed (in step1386). In some embodiments, process1370may not proceed to step1390until the test system1390verifies that the first force applied on the device has been removed (in step1388). In step1390, the device may be removed from the socket. One or more steps of process1370may be repeated, e.g., to test other devices.

Embodiments of the disclosure may comprise active thermal control for a plurality of components of a device, as shown inFIG.14. The test system1490may comprise a thermal head and a socket. In some embodiments, the thermal head comprises a force mechanism. The force mechanism (e.g., pusher1431, transducer1429, force applicator1433, force applicator1443, transducer1439, etc.) and socket (comprising socket body1418and test contact pins1417) may have one or more properties similar to the force mechanisms and socket discussed herein (e.g., described in the context ofFIGS.13and15). The device may comprise a plurality of components1403,1402A, and1402B mounted on a substrate1410. The substrate1410may comprise interconnects1416for receiving and/or transmitting test signals to and/or from a tester.

The test system1490may comprise a plurality of adapters1430A and1430B thermally coupled to component1402A and component1402B, respectively. The plurality of adapters1430may be thermally coupled to different heaters1456; adapter1430A is thermally coupled to heater1456A, while adapter1430B is thermally coupled to heater1456B. The plurality of adapters1430may be thermally coupled to different cold plates1462; adapter1430A is thermally coupled to cold plate1462A, while adapter1430B is thermally coupled to cold plate1462B. A thermal controller may be configured to independently control the temperatures of the component1402A and component1402B by way of the respective adapter1430A or1430B, heater1456A or1456B, and/or cold plate1462A or1462B. These may be two non-limiting examples of active thermal control.

Embodiments of the disclosure may further comprise passive thermal control. The thermal energy dissipated from the component1403may be allowed to transfer (e.g., dissipate) heat to adapter1430C.

Additionally or alternatively, the thermal head ofFIG.14may comprise both active and passive force control. For active force control, a force applicator1443applies force to the adapters1430A and1430B, which then applies force to components1402A and1402B. The amount of force applied, as measured by the transducer1439, may be controlled by a controller that determines the force to be applied by the force applicator1443. In some embodiments, the force control may not be independent for each adapter or component, such as the force applicator1443applying force to at least two adapters and/or components.

Embodiments of the disclosure my further comprise passive force control. The spring1432A may apply a force to the adapter1430C, which then applies force to the component1403. The amount of force applied may not be adjustable and may be based on the properties of the spring1432A.

Embodiments of the disclosure may comprise active force control for a plurality of components, according to some embodiments of the disclosure. The test system1590ofFIG.15may comprise a thermal head and a socket. The force mechanisms (e.g., pusher1531, transducer1529, force applicator1533, force applicators1543A and1543B, transducer1539A and1539B), other parts of the thermal head (e.g., cold plates1562A and1562B, adapters1530A,1530B, and1530C, heaters1556A and1556B), socket (comprising socket body1518and test contact pins1517), and parts of the device (e.g., interconnects1516, components1502A,1502B, and1503, substrate1510) may have one or more properties similar to the force mechanisms, parts of the socket, and parts of the device discussed herein (e.g., described in the context ofFIGS.13A and14).

Example Controller

As discussed above, one or more controllers may be used for the test systems and/or thermal heads of the disclosures.FIG.16illustrates a block diagram of an exemplary computer1602used for one or more controllers, according to embodiments of the disclosure. The computer may be a machine, within which a set of instructions, causes the machine to perform any one of the methodologies discussed herein, may be executed, according to embodiments of the disclosure. In some embodiments, the machine can operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked configuration, the machine may operate in the capacity of a server or a client machine in a server-client network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The machine can be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a cellular telephone, a web appliance, a network router, a switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine. A mobile device may include an antenna, a chip for sending and receiving radio frequency transmissions and wireless communications, and a keyboard. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one of the methodologies discussed herein.

The exemplary computer1602includes a processor1604(e.g., a central processing unit (CPU), a graphics processing unit (GPU), or both), a memory1606(e.g., read-only memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM), etc.), and a static memory1608(e.g., static random access memory (SRAM), etc.), which can communicate with each other via a bus1610.

The computer1602may further include a video display1612(e.g., a liquid crystal display (LCD) or light emitting diode (LED) display). The computer1602also includes an alpha-numeric input device1614(e.g., a keyboard), a cursor control device1616(e.g., a mouse), a disk drive unit1618, a signal generation device, a network interface device1622, and one or more wireless interface devices.

The computer1602may also include other inputs and outputs, including digital I/O and/or analog I/O. For example, the inputs and outputs may communicate with external devices, such as chillers, pressure controllers, force controllers, flow value controllers, etc., using any type of communication protocol.

The drive unit1618includes a machine-readable medium1620on which is stored one or more sets of instructions1624(e.g., software) embodying any one or more of the methodologies or functions described herein. The software may also reside, completely or at least partially, within the main memory1606and/or within the processor1604during execution thereof by the computer1602, the main memory1606and the processor1604also constituting machine-readable media. The software may further be transmitted or received over a network via the network interface device1622and/or a wireless device.

While the machine-readable medium1620is shown in an exemplary embodiment to be a single medium, the term “machine-readable medium” should be taken to include a single medium or multiple media (e.g., a centralized or distributed database and/or associated caches and servers) that store the one or more sets of instructions. The term “machine-readable medium” shall also be taken to include any medium that is capable of storing, encoding, or carrying a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present invention. The term “machine-readable medium” shall accordingly be taken to include, but not be limited to, solid-state memories, optical and magnetic media, and carrier wave signals.

Although examples of this disclosure have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of examples of this disclosure as defined by the appended claims.