Compliant ground block and testing system having compliant ground block

A compliant ground block for a testing system for testing integrated circuit devices is disclosed. The compliant ground block includes a plurality of electrically conductive blade pairs in a side by side generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally slidable with respect to each other. The block also includes at least one elastomer configured to retain the plurality of blade pairs. Each blade pair of the plurality of blade pairs includes a first blade (or a first blade assembly) and a second blade. The first blade (or the first blade assembly) and the second blade are configured to generate scrubbing motions when the device under test is being pressed down on the compliant ground block or is being released from the compliant ground block.

TECHNICAL FIELD

This disclosure relates generally to the field of testing microcircuits (e.g., chips such as semiconductor devices, integrated circuits, etc.). More specifically, the disclosure relates to compliant ground blocks that provide electrical and/or thermal grounding to a device under test (DUT) by making contact to a load board of a testing system, and relates to testing systems having compliant ground blocks.

BACKGROUND

The manufacturing processes for microcircuits cannot guarantee that every microcircuit is fully functional. Dimensions of individual microcircuits are microscopic and process steps very complex, so small or subtle failures in a manufacturing process can often result in defective devices. Mounting a defective microcircuit on a circuit board is relatively costly. Installation usually involves soldering the microcircuit onto the circuit board. Once mounted on a circuit board, removing a microcircuit is problematic because the very act of melting the solder for a second time may ruin the circuit board. Thus, if the microcircuit is defective, the circuit board itself is probably ruined as well, meaning that the entire value added to the circuit board at that point is lost. For all these reasons, a microcircuit is usually tested before installation on a circuit board. Each microcircuit must be tested in a way that identifies all defective devices, but yet does not improperly identify good devices as defective. Either kind of error, if frequent, adds substantial overall cost to the circuit board manufacturing process.

Microcircuit test equipment itself is quite complex. First of all, the test equipment must make accurate and low resistance temporary and non-destructive electrical contact with each of the closely spaced microcircuit contacts. Because of the small size of microcircuit contacts and the spacing between them, even small errors in making the contact will result in incorrect connections. A further problem in microcircuit test equipment arises in automated testing. Testing equipment may test one hundred devices a minute, or even more. The sheer number of tests cause wear on the tester contacts making electrical connections to the microcircuit terminals during testing. This wear dislodges conductive debris from both the tester contacts and the device under test (DUT) terminals that contaminates the testing equipment and the DUTs themselves. The debris eventually results in poor electrical connections during testing and false indications that the DUT is defective. The debris adhering to the microcircuits may result in faulty assembly unless the debris is removed from the microcircuits. Removing debris adds cost and introduces another source of defects in the microcircuits themselves.

Other considerations exist as well. Inexpensive tester contacts that perform well are advantageous. Minimizing the time required to replace them is also desirable, since test equipment is expensive. If the test equipment is off line for extended periods of normal maintenance, the cost of testing an individual microcircuit increases. Test equipment in current use has an array of test contacts that mimic the pattern of the microcircuit terminal array. The array of test contacts is supported in a structure that precisely maintains the alignment of the contacts relative to each other. An alignment board or plate or template aligns the microcircuit itself with the test contacts. The test contacts and the alignment board are mounted on a load board having conductive pads that make electrical connection to the test contacts. The load board pads are connected to circuit paths that carry the signals and power between the test equipment electronics and the test contacts.

One particular type of microcircuit often tested before installation has a relatively large, centrally located ground (CG) terminal on a flat, bottom surface of the microcircuit package. The microcircuit signal and power (S&P) terminals surround the CG terminal in a predetermined array. Microcircuit packages having this configuration of terminals may be called CG packages. Establishing a solid ground connection to this pad is critically important to get reliable test results. ICs are not entirely uniform in their production, so making reliable contact with this ground pad is difficult.

BRIEF SUMMARY

Embodiments disclosed herein provide a solution that addresses each of the above-mentioned problems. Embodiments disclosed herein provide a compliant ground block that is composed of simple elements, uses an elastomeric component (e.g., made of a non-conductive material), is configurable to a wide-variety of shapes and sizes, can be cleaned by existing methods without changes, is robust in a production environment, and is low-cost. In one embodiment, the compliant ground block can be composed of a stack of blades (e.g., thin contact blades made of an electrical and/or thermal conductive material). Each blade of the blades is the same as each other. Each blade is inverted with respect to its adjacent blade in a longitudinal direction of the blade or the compliant ground block. Each contact blade has an elongated aperture near the center (e.g., below a centerline of the blade in the longitudinal direction), with the elongated aperture axis perpendicular to the axis of compliance of the ground block. In one embodiment, the contact portion of the blade has raised teeth or protrusions that make good contact with the DUT and load board ground pads.

Also disclosed is a compliant ground block for a testing system for testing integrated circuit devices. The compliant ground block includes a plurality of electrically conductive blades in a side by side generally parallel relationship. The blades are configured to be longitudinally slidable with respect to each other. The block also includes an elastomer configured to retain the plurality of blades. Each blade of the plurality of blades includes a first end and a second end opposite to the first end in a longitudinal direction. The plurality of blades is arranged so that the first end of each blade of the plurality of blades is opposite to the first end of an adjacent blade in the longitudinal direction, so that the first end of one blade is adjacent to the second end of the adjacent blade. The elastomer is at least tubular (e.g., hollow or solid cylindrical) in part and non-conductive.

Also disclosed is a testing system for testing integrated circuit devices. The testing system includes a DUT and a compliant ground block. The compliant ground block includes a plurality of blades and an elastomer configured to retain the plurality of blades. Each blade of the plurality of blades includes a first end and a second end opposite to the first end in a longitudinal direction. The plurality of blades is arranged so that the first end of each blade of the plurality of blades is opposite to the first end of an adjacent blade in the longitudinal direction. The elastomer includes a non-conductive outer surface. The plurality of blades includes a conductive outer surface. A size of the compliant ground block is at least partially aligned with a ground pad of the DUT.

Also disclosed is a method of assembling and positioning a compliant ground block in a testing system for testing integrated circuit devices. The method includes arranging a plurality of electrically conductive blades of the compliant ground block so that a first end of each blade of the plurality of blades is opposite to a first end of an adjacent blade in a longitudinal direction. The first end of one blade is adjacent a second end of an adjacent blade. The second end is opposite to the first end in the longitudinal direction. The method also includes retaining the blades with an elastomer of the compliant ground block. The blades is in a side by side generally parallel relationship. The blades are configured to be longitudinally slidable with respect to each other. The elastomer is at least tubular (e.g., hollow or solid cylindrical) in part and non-conductive. The method further includes installing the compliant ground block in a housing.

Like reference numbers represent like parts throughout.

DETAILED DESCRIPTION

A test contactor (i.e., a part of a test assembly including alignment plate, socket or membrane, etc.) can often provide electrical and thermal grounding to a DUT by making metal-to-metal contact to the printed circuit board (e.g., the load board) in an oversized ground contact area. It is very important that the force exerted by the ground contact in no way damages the DUT integrated circuit package or cracks the die housed within the package. A grounding system that has compliance has advantages to a non-compliant ground block because it can accommodate test handler, handler kit, and package tolerances. It will be appreciated that the term “compliance” may refer to a property of a material of undergoing elastic deformation or change in volume when subjected to an applied force. Compliance can be equal to the reciprocal of stiffness.

Typically, a few of the same compliant electrical contacts used for the S&P leads are used. Quite often, the limited space available in the ground area limits the number of signal contacts to be placed, thus reducing the electrical and thermal effectiveness of the ground. For example, a limited set of contact pins can be used in the ground area. Another approach is to install a solid block of metal (e.g., a solid copper insert) in the ground area, however that often does not work because of the complete or partial lack of compliance in the test system. In other words, the ground pad on the chip may make poor, inadequate or no contact with the ground conductor on the housing due to deviations from expected tolerances in chip package manufacture, temperature variations, misalignment by the insertion handler, etc. Another approach is to combine a metal block with compliant contact elements. This solves some of the problems in contactor grounding performance, however it adds a tremendous amount of cost to the contactor assembly. Another approach is to replace the metal ground block with a Z-axis conductive elastomer. The Z-axis conductive elastomer either has embedded wires or metallic particles suspended in the elastomer which provides the electrical and thermal ground contacts. The drawbacks of this approach is that these type of elastomers have very little usable compliance and easily get contaminated with debris. In some of these types of designs, a flexible metal layer may be added to improve the life. Another approach is the incorporation of a wedge-shaped metal blocks that are biased by a non-conductive elastomer.

Embodiments disclosed herein provide a compliant ground block for test contactors and other devices that includes, for example, a stack of plates (or blades) or other adjacent conductive elements), which in some embodiments contain an aperture that accepts an elastomer that is used as a compliant member. The aperture, in some embodiments, in the plate stack is shaped such that the compressive forces on the elastomer allow it to bulge/expand into an open cavity instead of shearing the elastomer and so that the compressive forces do not increase with deflection and make the plates immovable.

Embodiments disclosed herein provide a solution that addresses each of the above-mentioned problems. Embodiments disclosed herein provide a compliant ground block that is composed of simple elements, uses an elastomeric component (e.g., made of a non-conductive material), is configurable to a wide-variety of shapes and sizes, can be cleaned by existing methods without changes, is robust in a production environment, and is low-cost. In one embodiment, the compliant ground block can be composed of a stack of blades (e.g., thin contact blades made of an electrical and/or thermal conductive material or plating). In some embodiments, each blade of the blades is identical to lower manufacturing costs. In other embodiments, each blade of the blades may not be identical. Every other blade may have an inverted orientation with respect to its adjacent blade in a height/vertical/longitudinal direction of the blade or the compliant ground block. Each contact blade may have an elongated aperture near the center (e.g., below a centerline of the blade in the height direction), with the elongated aperture axis perpendicular to the axis of compliance of the ground block. In one embodiment, the contact portion of the blade may have raised teeth or protrusions that make good contact with the DUT and load board ground pads.

FIG.1Ais a perspective view of a part of a test system100for receiving a DUT110for testing, according to one embodiment.

The test system100includes a test assembly120for a DUT (e.g., a microcircuit, etc.)110. The test assembly120includes a load board170that supports an alignment plate160having an opening or aperture130that precisely defines the X and Y (see the coordinate indicators X and Y, where the coordinate X is perpendicular to the coordinate Y, and the coordinate Z is perpendicular to the plane of X and Y) positioning of the DUT110in test assembly120. If the DUT110has orientation features, it is common practice to include cooperating features in aperture130. Load board170carries on its surface, connection pads connected to a cable180by Signal and Power (S&P) conductors. Cable180connects to the electronics that perform that electrical testing of the DUT110. Cable180may be very short or even internal to the test assembly120if the test electronics are integrated with the test assembly120, or longer if the test electronics are on a separate chassis.

A test contact array140having a number of individual test contact elements precisely mirrors the terminals (see112inFIG.1B) carried on the surface of the DUT110. When the DUT110is inserted in the aperture130, terminals of the DUT110precisely align with test contact array140. The test assembly120is designed for compatibility with a test contact array140incorporating the device. Test contact array140is carried on a contact membrane or sheet or socket150. Socket150initially includes an insulating plastic core layer with a layer of conductive copper on each surface of the core layer. The core layer and the copper layers may each be on the order of 25 microns thick. Individual test contacts in array140are preferably formed on and in socket150using well-known photolithographic and laser machining processes. Socket50has alignment features such as holes or edge patterns located in the area between alignment plate160and load board170that provide for precise alignment of socket150with corresponding projecting features on alignment plate160. All of the test contacts140are in precise alignment with the socket150alignment features. In this way, the test contacts of array140are placed in precise alignment with aperture130.

FIG.1Bis a perspective bottom view of a DUT110, according to one embodiment. The DUT (e.g., a microcircuit, etc.)110includes a top main surface (not shown), and a bottom main surface114opposite to the top main surface in the Z (see the coordinate indicators X, Y, and Z inFIG.1A) direction. In one embodiment, the DUT110can have flat no-leads packages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN). Flat no-leads, also known as micro lead-frame (MLF) and SON (small-outline no leads), is a surface-mount technology, one of several package technologies that connect the DUT110to the surfaces of e.g., socket150or other printed circuit boards (PCBs) without through-holes. In one embodiment, flat no-lead can be a near chip scale plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands (e.g., terminals112) on the package bottom provide electrical connections to the socket150or the PCB. Flat no-lead packages can include an exposed thermally conductive pad (e.g., the ground pad116in the middle of the surface114) to improve heat transfer out of the DUT110(e.g., into the PCB). The QFN package can be similar to the quad-flat package (QFP) and a ball grid array (BGA).

FIG.2Ais a side-view drawing of a portion of the test system100for receiving the DUT110for electrical testing, according to one embodiment.FIG.2Bis a side-view drawing of the test system100ofFIG.2A, with the DUT110electrically engaged, according to one embodiment.

As shown inFIG.2A, the DUT110is placed onto the test assembly120, electrical testing is performed, and the DUT110is then removed from the test assembly120. Any electrical connections are made by pressing components into electrical contact with other components; there is no soldering or de-soldering at any point in the testing of the DUT110. The entire electrical test procedure may only last about a fraction of a second, so that rapid, accurate placement of the DUT100becomes important for ensuring that the test system100is used efficiently. The high throughput of the test assembly120usually requires robotic handling of the DUT110. In most cases, an automated mechanical system places the DUT110onto the test assembly120prior to testing, and removes the DUT110once testing has been completed. The handling and placement mechanism may use mechanical and optical sensors to monitor the position of the DUT110, and a combination of translation and rotation actuators to align and place the DUT110on or in the test assembly120. Alternatively, the DUT110may be placed by hand, or placed by a combination of hand-fed and automated equipment.

The DUT110typically includes signal and power terminals112(see also terminals112ofFIG.1B) that connect to the socket150or other PCBs. The terminals may be on one side of the DUT100, or may be on both sides of the DUT110. For use in the test assembly120, all the terminals112should be accessible from one side of the DUT110, although it will be understood that there may be one or more elements on the opposite side of the DUT110, or that there may be other elements and/or terminals on the opposite side that may not be tested by accessing terminals112. Each terminal112is formed as a small, pad on button side of the DUT110or possibly a lead protruding from the body of the DUT110. Prior to testing, the pad or lead112is attached to an electrical lead that connects internally to other leads, to other electrical components, and/or to one or more chips in the DUT. The volume and size of the pads or leads may be controlled quite precisely, and there is typically not much difficulty caused by pad-to-pad or lead-to-lead size variations or placement variations. During testing, the terminals112remain solid, and there is no melting or re-flowing of any solder.

The terminals112may be laid out in any suitable pattern on the surface of the DUT110. In some cases, the terminals112may be in a generally square grid, which is the origin of an expression that describes the DUT110, QFN, DFN, MLF or QFP for leaded parts. There may also be deviations away from a rectangular grid, including irregular spacing and geometries. It will be understood that the specific locations of the terminals may vary as needed, with corresponding locations of pads on the load board170and contacts on the socket150or housing being chosen to match those of the terminals112. In general, the spacing between adjacent terminals2is in the range of 0.25 to 1.5 mm, with the spacing being commonly referred to as a “pitch”. When viewed from the side, as inFIG.2A, the DUT110displays a line of terminals112, which may optionally include gaps and irregular spacing. These terminals112are made to be generally planar, or as planar as possible with typical manufacturing processes. In many cases, if there are chips or other elements on the DUT110, the protrusion of the chips is usually less than the protrusion of the terminals112away from the DUT110.

The test assembly120ofFIG.2Aincludes a load board170. The load board170includes a load board substrate174and circuitry that is used to test electrically the DUT110. Such circuitry may include driving electronics that can produce one or more AC voltages having one or more particular frequencies, and detection electronics that can sense the response of the DUT110to such driving voltages. The sensing may include detection of a current and/or voltage at one or more frequencies. In general, it is highly desirable that the features on the load board170, when mounted, are aligned with corresponding features on the DUT110. Typically, both the DUT110and the load board170are mechanically aligned to one or more locating features on the test assembly120. The load board170may include one or more mechanical locating features, such as fiducials or precisely-located holes and/or edges, which ensure that the load board170may be precisely seated on the test assembly120. These locating features typically ensure a lateral alignment (X, Y, seeFIG.1A) of the load board170, and/or a longitudinal alignment (Z, seeFIG.1A) as well.

In general, the load board170may be a relatively complex and expensive component. The housing/test assembly120performs many functions including protecting the contact pads172of the load board170from wear and damage. Such an additional element may be an interposer membrane (or socket)150. The socket150also mechanically aligns with the load board170with suitable locating features (not shown), and resides in the test assembly120above the load board170, facing the DUT110. The socket150includes a series of electrically conductive contacts152, which extend longitudinally outward on either side of the socket150. Each contact152may include a resilient element, such as a spring or an elastomer material, and is capable of conducting an electrical current to/from the load board170from/to the DUT110with sufficiently low resistance or impedance. Each contact152may be a single conductive unit, or may alternatively be formed as a combination of conductive elements. In general, each contact152connects one contact pad172on the load board170to one terminal112on the DUT110, although there may be testing schemes in which multiple contact pads172connect to a single terminal112, or multiple terminals112connect to a single contact pad172. For simplicity, we assume in the text and drawings that a single contact152connects a single pad172to a single terminal112, although it will be understood that any of the tester elements disclosed herein may be used to connect multiple contact pads172connect to a single terminal112, or multiple terminals112to a single contact pad172.

Typically, the socket150electrically connects the load board pads172and the bottom contact surface of the DUT110. Although the socket150may be removed and replaced relatively easily, compared with removal and replacement of the load board170, we consider the socket150to be part of the test assembly120for this document. During operation, the test assembly120includes the load board170, the socket150, and the mechanical construction that mounts them and holds them in place (not shown). Each DUT110is placed against the test assembly120, is tested electrically, and is removed from the test assembly120. A single socket150may test many DUTs110before it wears out, and may typically last for several thousand tests or more before requiring replacement. In general, it is desirable that replacement of the socket150be relatively fast and simple, so that the test assembly120experiences only a small amount of down time for socket replacement. In some cases, the speed of replacement for the socket150may even be more important than the actual cost of each socket150, with an increase in tester up-time resulting in a suitable cost savings during operation.

FIG.2Ashows the relationship between the test assembly120and the DUTs110. When each DUT110is tested, it is placed into a suitable robotic handler with sufficiently accurate placement characteristics, so that a particular terminal112on the DUT110may be accurately and reliably placed (in X, Y and Z, seeFIG.1A) with respect to corresponding contacts152on the socket150and corresponding contact pads172on the load board170. The robotic handler (not shown) forces each DUT110into contact with the test assembly120. The magnitude of the force depends on the exact configuration of the test, including the number of terminals112being tested, the force to be used for each terminal, typical manufacturing and alignment tolerances, and so forth. In general, the force is applied by the mechanical handler of the tester (not shown), acting on the DUT110. In general, the force is generally longitudinal, and is generally parallel to a surface normal of the load board170.

FIG.2Bshows the test assembly120and DUT110in contact, with sufficient force being applied to the DUT110to engage the contacts152and form an electrical connection154between each terminal112and its corresponding contact pad172on the load board170. As stated above, there may alternatively be testing schemes in which multiple terminals112connect to a single contact pad172, or multiple contact pads172connect to a single terminal112, but for simplicity in the drawings we assume that a single terminal112connects uniquely to a single contact pad172.

FIG.3is an exploded view of the building blocks of a test contactor122of a test assembly120for the testing of a DUT, according to one embodiment. It will be appreciated that the connection assembly such as fasteners and/or parts that mount and manipulate the various building blocks of the testing assembly are not shown.

The test contactor122includes an optional stiffener190, a socket (also known as membrane)150, an alignment plate160, and an optional clamping plate195. The stiffener190can provide structural support to a load board (not shown also as known as daughter board, PCB, etc., seeFIGS.1A-2B) to minimize deflection to ensure socket150contacting with the load board. The load board is used to route signals from the DUT (via the socket150) to a tester (not shown) or vice versa. The tester is used to test the DUT (e.g., by sending commands/inputs to the DUT and/or by receiving data/outputs from the DUT). The load board is mounted to a test head in the tester. In the test assembly120, the load board is disposed between the stiffener190and the socket150.

The socket150is used to provide a pathway for inputs/outputs of the DUT to the tester (via the load board). The device alignment plate160is to align the DUT to the socket150. The alignment plate160is aligned and is attached to the stiffener190by e.g., fasteners that go through holes of the socket150and the load board. The alignment plate160has a recess/opening (e.g., in the middle of the alignment plate150) with alignment features and a holder (e.g., Z direction up-stop) to hold the DUT and align the DUT to the socket150(so that the S&P pins/pads/leads/balls/lines of the DUT are aligned with the S&P pins/pads/leads/balls/lines of the socket150).

The clamping plate195can be optional. The clamping plate195can hold the DUT firmly against the load board (via the alignment plate160and the socket150) during testing. In one embodiment, vacuum (instead of the clamping plate195) can be used as a hold down mechanism for the DUT. In another embodiment, the alignment of the DUT (by the alignment plate160) can be made as flush as possible, and the DUT can be held at the corners rather than using a clamping plate.

FIG.4is a perspective view of a test assembly120, according to one embodiment. The test assembly120includes a socket150and an alignment plate160. The circled portion A of the test assembly120includes a housing (of the test contactor).

FIG.5Ais an enlarged top view of a portion (the circled portion “A”) of the test assembly120ofFIG.4, according to one embodiment.FIG.5Bis an enlarged bottom view of a portion (the circled portion “A”) of the test assembly120ofFIG.4, according to one embodiment.

The test contactor includes a housing220. A plurality of S&P terminals210is disposed on the housing220. The housing has an opening in e.g., a central portion of the housing, to accommodate a block230. In one embodiment, the block230is a compliant ground block. It will be appreciated that in one embodiment, the size of the opening that accommodating the block230matches the size of the ground pad116of the DUT110(seeFIG.1B). The S&P terminals210align with the S&P terminals112of the DUT110(seeFIG.1B).

FIG.6Ais a perspective top view of a compliant ground block230installed in a housing220of a test contactor, according to one embodiment.FIG.6Bis a perspective bottom view of the compliant ground block230installed in the housing220of the test contactor, according to one embodiment. It will be appreciated that the housing220is simplified (e.g., not showing other components of the housing as shown inFIGS.5A and5B).

The housing220includes an opening222. As shown inFIG.6A, on the top surface of the housing220, the opening222may include four circumferential curve cutouts224at the four corners of the opening222. The cutouts224can help with preventing wear and tear caused by e.g., the sharp edges of the compliant ground block230. The compliant ground block230includes a plurality (e.g., two, at or about 20, or more for contact redundancy and for a big heat sink) of blades (or plates)232stacked together laterally in a thickness direction (e.g., Y direction, seeFIG.1A) of the blade232. In one embodiment, each of the blades232is the same as each other. A thickness of each blade is at or about 0.050 mm. A size/area of the top surface (e.g., having a rectangular or a square shape) of the compliant ground block230is at or about 1.1 mm2. As shown inFIG.6B, on the top surface of the housing220, the opening222may include two circumferential curve cutouts226at sides of the opening opposite to each other in the thickness direction of the blades232. The compliant ground block230includes an elastomer234. In one embodiment, the elastomer234has a cylindrical shape. The elastomer234is wedged into the housing, thus retaining the blade stack assembly (i.e., the blades232). In one embodiment, the diameter of the elastomer234is at or about 0.4 mm.

It will be appreciated that the cutouts226is designed to facilitate the installation of the compliant ground block230from e.g., the bottom side of the housing220. It will be appreciated that on the bottom surface of the housing220, the opening222can also include two circumferential cutouts226at sides of the opening opposite to each other in the thickness direction of the blades232. In such embodiment, the cutouts226can be designed to facilitate the installation of the compliant ground block230from e.g., the top side of the housing220as well. In one embodiment, each blade232can be plated with e.g., gold, etc. In another embodiment, each blade232may not be plated if the metal of the blade is metallurgically suitable.

FIG.7Ais an exploded view of a compliant ground block230to be installed in a housing220(showing a bottom surface of the housing) of a test contactor, according to one embodiment.FIG.7Bis a perspective view of a compliant ground block230, according to one embodiment.

The blades232form an aperture236at or near the middle of the blades232, which extends in the thickness direction of the blade232. The elastomer234is inserted through the aperture236and is wedged into the housing220, thus retaining the blades232in the housing220. As shown inFIG.7A, in one embodiment, the cutouts224and/or226may extend from the bottom surface of the housing220but not reach the top surface of the housing220. In another embodiment, the cutouts226may extend from the bottom surface of the housing220to the top surface of the housing220.

FIG.8Ais a perspective cross-sectional view of a compliant ground block230in an uncompressed state, according to one embodiment.FIG.8Bis an exploded view of the compliant ground block230in the uncompressed state, according to one embodiment.FIG.8Cis an exploded view of the compliant ground block230in a compressed state, according to one embodiment.FIG.8Dis a perspective cross-sectional view of a compliant ground block230in the compressed state, according to one embodiment.

FIG.9Ais a side view of a compliant ground block230in an uncompressed state, according to one embodiment.FIG.9Bis a side view of a compliant ground block230in a compressed state, according to one embodiment.

As shown inFIGS.8A and9A, the aperture236is elongated in a width/transverse direction (X direction) of the blade232to allow for compression of the elastomer234. The elastomer234contacts the top and bottom ends of the aperture236in a height direction (Z direction). Cavities238and240are formed between the left and right ends of the aperture236in the width direction. Two blades232(a top232and a bottom232) are shown inFIGS.9A and9B. Each of the blades is inverted in the height direction relative to an adjacent (adjacent in the thickness direction Y) blade. For example, each blade232has a first end244and a second end246opposite to the first end244in the height direction. The first end24of the bottom blade232is opposite to the first end244of the top blade232in the height direction. The second end246of the bottom blade232is opposite to the second end (not shown, behind the bottom blade232in the thickness direction) of the top blade232. The aperture236is disposed at or near middle of the stacked blades232. It will be appreciated that for each individual blade232, the aperture236is disposed below a central line in the height direction and is closer to the second end246than to the first end244. Each blade232may include a plurality of protrusions242at the first end244. In one embodiment, a distance between adjacent protrusions242can be the same. In one embodiment, each blade can be made of any conductive material such as copper, copper alloys, nickel alloys, steels, precious metals, etc. It will be appreciated that flexibility is not a requirement with respect to the blade. Elastomer can be made of any elastic rubber-like material such as silicone, etc. In one embodiment, the elastomer may be non-conductive.

As shown inFIGS.8D and9B, the compliant ground block230is in a compressed state. The top surface of the compliant ground block230may contact the ground pad116(seeFIG.1B) of the DUT110. The bottom surface of the compliant ground block230may contact the ground portion of the load board170(seeFIG.1). Forces exerted from both the ground pad116and the ground portion of the load board170can compress the compliant ground block230by compressing the elastomer234. The round (in the cross-sectional side view inFIG.9A) elastomer may compress perpendicularly to the compression axis (in the height direction Z) and the flow of the elastomer may move into the elongated (in the width direction X) open areas (cavities238,240) of the aperture236. One advantage of such design is that the blades232have some freedom to gimbal over the elastomer234and can accommodate angular variations in the compliant ground block230compression into the open areas (cavities238,240). See e.g.,FIG.20.

FIG.10Ais a side view of a blade232, according to one embodiment.FIG.10Bis a perspective view of a blade232, according to one embodiment.

As shown inFIG.10A, a central line C1is between the first end244and the second246, and has a same distance from the first end244and the second246in the height direction. A center line C2of the aperture236in the height direction is disposed below C1(i.e., C2is closer to the second end246than to the first end244). In one embodiment, each blade232of the stack (the compliant ground block230) can be an identical component. In another embodiment, each blade232of the stack (the compliant ground block230) may not be identical. The first end244of the blade232includes a series of small protrusions (teeth) that are contact points to the DUT pad (e.g., ground pad) or the PCB (e.g., the load board or the socket) pad (e.g., ground pad). The second end246of the blade232may be flat. The aperture236is an elongated (in the width direction) hole that is roughly the same diameter as the elastomer234, but has a clearance cavity (238,240) on either side in the width direction. The stack (the compliant ground block230) is assembled by alternating the teeth up and down until a predetermined number of blades232make up the stack. The aperture236is centrally located laterally (in the width direction), but below center vertically (in the height direction)—thus resulting in the staggered up/down assembly (of the compliant ground block230) and allowing for the stack compression.

FIG.11Ais a side cross-sectional view of a compliant ground block230in an uncompressed state, according to one embodiment.FIG.11Bis a side cross-sectional view of a compliant ground block230in a compressed state, according to one embodiment.

Compared with the uncompressed state, the first end244of a blade232is closer to the second end246of an adjacent (adjacent in the thickness direction Y) blade232in the height direction Z.

FIG.12Ais a schematic view of a compliant ground block230in an uncompressed state, according to one embodiment.FIG.12Bis a schematic view of a compliant ground block230in a compressed state, according to one embodiment.

The compliant ground block230shows two blades (plates)232and the elastomer234. The upper and lower blades slide up and down against each other when force is applied to compress the elastomer234. When being compressed, the elastomer234installed in the aperture236compresses and shears. Each blade232slides against the mating (adjacent) blade. Some of the elastomeric resilience is taken up by a shear-type deformation of the elastomer234.

FIG.13Ais a perspective cross-sectional view of a compliant ground block230in a compressed state, according to one embodiment.FIG.13Bis a perspective cross-sectional view of a compliant ground block230, according to one embodiment.

As shown inFIG.13A, when being compressed, the elastomer234also slightly bulges into the cavities250vacated by the opposing (adjacent) blade (see the bulges248) in the height direction opposite to the direction of the force applied. As shown inFIG.13B, a portion “A” of the compressed compliant ground block230is enlarged. The blades232show that the corners (see the radius252, sized about a few microns) of the blades232in the thickness direction are not sharp. The non-sharp corners (the radius252) of the blades232can help reducing the shearing action of the blade232movement, and the distributed load of the elastomer234causes the elastomer234to squeeze into the aperture cavities (238,240).

In a larger blade stack (e.g., the compliant ground block230), the amount of shear can be greatly reduced because the load (e.g., the force applied) is distributed over the entire length of the elastomer234. Since the edges (in the thickness direction, see also252) of the aperture236also have a slight radius, thus reducing the shearing action of the blade movement. The distributed load of the elastomer234causes the elastomer234to squeeze into the aperture cavities (238,240). The sheer redundancy of the blades232can guarantee reliable electrical connection of the stack. Multiple blades232distribute load over elastomer234length, cause elastomer234to bulge out into open aperture cavity250rather than shear. Blade232edges (in the thickness direction) have small radius252that can minimize elastomer234cutting.

FIG.14Ais a perspective bottom view of a compliant ground block230ainstalled in a housing220aof a test contactor, according to one embodiment.FIG.14Bis a perspective cross-sectional view of a compliant ground block230ainstalled in a housing220aof a test contactor, according to one embodiment.FIG.14Cis another perspective cross-sectional view of a compliant ground block230ainstalled in a housing220aof a test contactor, according to one embodiment.FIG.14Dis a perspective cross-sectional view of a compliant ground block230a, according to one embodiment.FIG.14Eis an exploded bottom view of a compliant ground block230ato be installed in a housing220aof a test contactor, according to one embodiment.FIG.14Fis a side view of a blade232a, according to one embodiment.

It will be appreciated that regardingFIG.14A, the perspective top view of the compliant ground block230ainstalled in the housing220ais the same asFIG.6A, where the elastomer is not visible. It will also be appreciated that unless explicitly described herein, the components, material, size, attributes, and/or properties, etc. of the compliant ground block230aand/or the housing220aare the same or similar to those of the compliant ground block230and/or the housing220described in other embodiments.

As shown inFIGS.14A-14C and14E, the opening222aat the bottom surface of the housing220ahas a size that substantially matches (or for press-fit, slightly smaller than) a size of the compliant ground block230aso that the compliant ground block230acan be installed or inserted from the bottom of the housing220a. The opening222bat the top surface of the housing220ahas a size that is smaller than the size of the compliant ground block230ato support/maintain/stop the compliant ground block230a. The opening222aat the bottom surface of the housing220aextends in the height (Z) direction but does not reach the top surface of the housing220a. The corners of the opening222aare curved to help with preventing wear and tear caused by e.g., the sharp edges of the compliant ground block230a.

FIG.14Bis a perspective cross-sectional view of a compliant ground block230ainstalled in a housing220a, cut in the middle of the housing220aalong the thickness (Y) direction.FIG.14Cis a perspective cross-sectional view of the compliant ground block230ainstalled in the housing220a, cut in the middle of the housing220aalong the width (X) direction.

The blade232ahas recesses (or apertures)236aand236bat sides of the blade232ain the width (X) direction. The centerline C1of the blade is above the centerline C2of the recesses236aand236b. There is no opening in the middle of the blade232a. Each blade232ais inverted with respect to its adjacent blade232ain the height direction. In one embodiment, the recesses236aand236bcan have a half-circle shape. The elastomer234acan have an O-ring or other ring shape and can be stretched around blades232afor retention. The elastomer234acan snap over the concave semicircular apertures236aand236bon both sides of the blade232a.

FIG.15Ais a perspective bottom view of a compliant ground block230binstalled in a housing220bof a test contactor, according to one embodiment.FIG.15Bis an exploded bottom view of a compliant ground block230bto be installed in a housing220bof a test contactor, according to one embodiment.FIG.15Cis a side view of a blade232a, according to one embodiment.

It will be appreciated that regardingFIG.15A, the perspective top view of the compliant ground block230binstalled in the housing220bis the same asFIG.6A, where the elastomer is not visible. It will also be appreciated that unless explicitly described herein, the components, material, size, attributes, and/or properties, etc. of the compliant ground block230band/or the housing220bare the same or similar to those of the compliant ground block230and/or the housing220described in other embodiments. In one embodiment,FIG.15Cis the same asFIG.14F.

Compared withFIGS.14A-14E, inFIGS.15A and15B, two individual elastomer strips234bare used instead of an O-ring elastomer234a. Each of the elastomers234bmay have a cylindrical shape disposed on each side of the blades232ain the width (X) direction. Each of the elastomers234bextends in the thickness (Y) direction. A length of each elastomer234bmay be slightly greater than a thickness of the stacked blades232a. The stacked blades232aand each blade232ain inFIGS.15A and15Bmay be the same as the stacked blades232aand each blade232arespectively inFIGS.14A-14E.

InFIGS.15A and15B, the opening222cat the bottom surface of the housing220bhas an H-shape retention cut-outs, instead of the O-ring shape of222a. The opening222chas a size that substantially matches (or for press-fit, slightly smaller than) a size of the compliant ground block230bso that the compliant ground block230bcan be installed or inserted from the bottom of the housing220b. The opening222bat the top surface of the housing220bhas a size that is smaller than the size of the compliant ground block230bto support/maintain/stop the compliant ground block230b. The opening222bat the bottom surface of the housing220bextends in the height (Z) direction but does not reach the top surface of the housing220b. The corners of the opening222bare curved to help with preventing wear and tear caused by e.g., the sharp edges of the compliant ground block230b.

FIG.16Ais a perspective view of a compliant ground block230cin an uncompressed state, according to one embodiment.FIG.16Bis a perspective view of the compliant ground block230cin a compressed state, according to one embodiment.FIG.16Cis a side view of a blade232b, according to one embodiment.

It will be appreciated that some DUT ground pad and/or PCB (load board or socket) ground pad surfaces may be very delicate. The compliant ground block230ccan help to eliminate the teeth or protrusions in each blade and can provide a gentler touch. The contact edge (e.g., the first end244a) of the blade232bdoes not include the teeth or protrusions as in the blade232or232a. The compliant ground block230cis designed for customer devices and/or PCB ground pads with very fragile surfaces. It will be appreciated that the flat blade232bcan be combined with a tooth-blade232or232a.

As shown inFIG.16C, the blade232bis the same as the blade232ofFIG.10A, except that the first end244aof the blade232bis flat (without the protrusions242). Same as the blade232ofFIG.10A, two or four ends/corners of the blade232bare slightly trimmed to remove the sharp corners.

FIG.17Ais a side view of a compliant ground block230din an uncompressed state, according to one embodiment.FIG.17Bis a side view of the compliant ground block230din a compressed state, according to one embodiment.

It will be appreciated thatFIGS.17A and17Bare the same asFIGS.9A and9B, except that each blade232chas two or more apertures236c. Each aperture236caccommodate an elastomer234c. It will also be appreciated that large DUT or PCB ground pads can be accommodated by a compliant ground block230dthat uses two or more elastomers. Such embodiment can provide additional stability. The blade232ccan be divided equally in the width (X) direction based on the number of the apertures236c. Each aperture236cis centrally located laterally (in the width direction) in each division of the blade232c, but below center vertically (in the height direction). For example, as shown inFIGS.17A and17B, each blade232chas two apertures236c. The blade232ccan be divided into two parts along the width direction. Each aperture236cis centrally located laterally (in the width direction) in each part of the blade232c, but below center vertically (in the height direction) of that part.

FIG.18Ais a perspective view of a blade232d, according to one embodiment.FIG.18Bis a perspective view of a compliant ground block230e, according to one embodiment.FIG.18Cis a perspective view of a blade232e, according to another embodiment.

It will be appreciated that the blades232dand/or232eare the same as other blades such as232and232a-232c, except that the blades232dand/or232einclude bumps260. The blade232dinclude one or more bumps260. It will be appreciated that bump(s) may be part of the same material as the blade and are fabricated in the same process as the blade. The thickness of the bump(s) may be generally at or less than 10% of the thickness of the blade. As shown inFIG.18A, the blade232dincludes four bumps260near four corners of the blade232don a main side surface of the blade. Each bump260has a circular or any other suitable shape and extends (or is raised) in the thickness direction.

The blade232ehas one or more slight flexible cantilever member270. A U-shape opening280separates the cantilever member270from other part of the blade232e. The bump is disposed on or near the tip of the cantilever member270. As shown inFIG.18C, the blade232einclude two or more cantilever members270, each cantilever member270is disposed between an end of the aperture and an edge of the blade232e.

The bump(s)260can ensure electrical reliability (e.g., electrical connection reliability) from blade to blade, and focus the contact points to specific spots to guarantee reliable connection and provide some compliance in the blades stack-up.

It will be appreciated that the bumps can help to maintain good electrical contact among blades flat blades an slide up and down when compressed or uncompressed, and the biasing of the blades to each other is critical. If there are some debris between the two blades, the debris can decrease the electrical conductivity between the two blades. The bumps can help to improve the electrical connection between the blades on the PCB (load board or socket) side or on the DUT side. The bumps can put high stress points through the blades. When the bumps are on the tip of the cantilever, a flexible feature can be achieved.

FIG.19Ais a cross-sectional view of blades232f, according to one embodiment.FIG.19Bis a cross-sectional view of blades232g, according to another embodiment.FIG.19Cis a cross-sectional view of blades232h, according to yet another embodiment.FIG.19Dis a cross-sectional view of blades232i, according to yet another embodiment.

Curved or nested blades can help to improve the electrical connection between blades. The blades can be flexible members, allowing for thickness compliance. The blades can be fabricated with a curve (e.g., in a few micron scale) in the height Z direction. When the curved blades are stacked, higher force concentrations can improve the electrical contact pressure and lower contact resistance. The blades (i.e., the shapes of a blade and the adjacent blade) can be nested in various concave and/or convex configurations, such as concave-convex nesting232f, concave-concave nesting232g, and convex-convex nesting232h. The curves (convex, concave, etc.) can cause higher contact points and higher contact pressure from blade to blade. The blades can be tilted or angled blades232i. Slightly angling the blades232ican naturally bias (e.g., creating a normal force between the blades) each blade against the mating/adjacent plate over the compression cycle. The angle of the blade can vary from at or about 2 degrees to at or about 5 degrees from vertical.

FIG.20is a cross-sectional view of a compliant ground block230, according to one embodiment.FIG.20shows a DUT110on top of a compliant ground block230, where the DUT110is not presented perfectly flat. Such embodiment allows for a gimbaling motion—allowing for ground pads that are not flat.FIG.20illustrates that not only is the blade stack (i.e., the compliant ground block230) compliant in the Z direction, but the compliant ground block230allows for compliance if a DUT110is presented into the ground block at a slight angle, allowing for imperfections in the part handling.

FIGS.21A-21Eare side views of a blade232, according to some embodiments. It will be appreciated that the blade232ofFIGS.21A-21Ecan be the same as or similar to the blade232ofFIGS.10A and10B(including the centerlines C1and C2as shown inFIG.10A), except for the differences explicitly described hereinafter.

In an embodiment, the blade232can include a radius241A at one side of the blade232. The blade232can also include a radius241B at the other side of the blade232opposite to the one side of the blade232in the width/transverse direction (X direction). The radius (241A and/or241B) can extend from the top end244of the blade232to the bottom end246of the blade232. It will be appreciated that the radius (241A and/or241B) can provide improved assembly ease and allow blades232to tip and/or rock without catching on the housing220.

In an embodiment, the blade232can include chamfer243at one or more of the four corners of the blade232. The chamfer243can extend from the side (241A or241B) of the blade232to the end (244or246) of the blade232. It will be appreciated that the corner chamfer(s)243can provide improved assembly ease. In an embodiment, compared with the protrusion(s)242ofFIGS.10A and10B, the protrusion(s) or tip(s)242inFIGS.24A and24C-24Ecan be larger and can provide increased life and better wear conditions. It will be appreciated that in an embodiment (seeFIG.21B), the blade232can have a flat top end244without any protrusion242for low inductance and/or high gain applications.

In some embodiments, compared with the aperture236inFIGS.10A and10B, the apertures236D-236F inFIGS.21A-21Ecan have an increased size and can make room for a larger elastomer and provide more compliance. In some embodiments, the blade232can have an elliptical aperture236D, a rectangular aperture236E for increased compliance compared with the elliptical aperture, and/or an “X” shaped aperture236F for increased compliance and increased contact forces compared with the elliptical aperture.

In an embodiment, the blade232can include one or more relief channels245. The relief channel245can be disposed at a position (e.g., between the protrusions242) between the aperture (e.g.,236D-236F) and a side (241A or241B) in the X direction. The relief channel245can extend from the top end244of the blade232to the bottom end246of the blade232in the height direction (Z direction). The relief channel245can be recessed from the main surface of the blade232in the thickness direction (Y direction) of the blade232. The relief channel245can include a breakoff tab245A at an end of the relief channel245near the bottom end246. Curved (e.g., in the Z direction) recesses can be disposed at one or more of the two sides of the breakoff tab245A in the X direction. It will be appreciated that the relief channel(s)245can reduce wear from the breakoff tab(s)245A that may diminish life, and can add clearance that prevents wear and corrosion so that the blades232can meet the life specifications at a desired temperature.

In an embodiment, the blade232can include a notch (or opening)237extending from the bottom end246of the blade to the aperture (236D-236F). It will be appreciated that the notch237can have a trapezoid shape with a base at the bottom being longer than the base at the top of the notch237. One or more or the bases of the notch237may have a length less than the length of the aperture (236D-236F) in the X direction. Notch237may be any discontinuity in the aperture which allows for insertion of the elastomer. The notch or gap237preferably provides a one way opening which allows and elastomer to be received therein but inhibits it removal, primarily to having a larger peripheral gap and relative to the (smaller) inner gap. This can be accomplished with a tapering of the gap from external to internal. The notch is preferably in the bottom wall, but may be an intrusion in to any wall. It will also be appreciated that the notch237can aid in elastomer assembly in production or for field serviceability.

In some applications, surface(s) of the terminals/ground-pad of the DUT may be plated/coated with (or may be made of) e.g., gold, nickel-palladium-gold, matte tin, or the like. In the compliant ground block, the blade (that is configured to contact the DUT) may be plated/coated with (or may be made of) gold, palladium, or the like. For matte tin DUT terminals/ground-pad, the debris (matte tin, generated from the terminals/ground-pad) may stick onto the tips/protrusions of the DUT contacting blade when e.g., the DUT contacting blade is plated with (or made of) gold, which may increase the resistance and/or reduce the performance of the compliant ground block. In an embodiment, for matte tin DUT terminals/ground-pad, the DUT contacting blade being plated with (or made of) palladium can make the debris less sticky and can decrease the resistance and/or increase the performance of the compliant ground block. That is, using a palladium (plating or material) on at least the blade(s) contacting the DUT can reduce the amount of matte tin debris that sticks to the compliant ground block and improve the performance of the compliant ground block. The blade(s) that is configured to contact the load board can be plated with (or made of) palladium as well for the same reason or with/of gold for cost consideration.

Embodiments disclosed herein can also provide scrubbing action (or scrubbing motion, scrubbing effect, scrubbing affect, or the like) so that the DUT contacting blade(s) can slide on the surface(s) of the terminals/ground-pad of the DUT, provide self-cleaning of the debris (e.g., matte tin debris or the like), and/or knock off the debris.

FIG.22Ais a side view of a compliant ground block301.FIG.22Bis a perspective view of a blade pair (310,330) of the compliant ground block301ofFIG.22A.FIG.22Cis a perspective view of the compliant ground block301ofFIG.22A.FIG.22Dis a cross-sectional view of the compliant ground block301ofFIG.22A.FIG.22Eis an exploded view of the compliant ground block301ofFIG.22Aand a housing401for the compliant ground block301.

As shown inFIGS.22A-22E, the compliant ground block301includes a plurality of electrically conductive blade pairs. The material, arrangement, and/or disposition of the blade pairs are the same as the blades or blade pairs described herein, except for the differences explicitly disclosed below. The plurality of blade pairs are disposed in a side by side (in Y direction or thickness direction) generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally/vertically (Z direction, from the DUT to the load board) slidable with respect to each other.

Each blade pair includes a first blade310, a second blade330, and a single elastomer350configured to retain the plurality of blade pairs. The material, arrangement (including e.g., interaction with cavities238and240ofFIG.9A), and/or disposition of the elastomer350are the same as the elastomer(s) described herein, except for the differences explicitly disclosed below. The first blade310is configured to contact the DUT (e.g., the ground pad/terminal), and the second blade330is configured to contact the load board (e.g., the ground pad/terminal).

The blade310includes a plurality of protrusions or tips316at an end or upper edge of the blade310that is configured to contact the DUT. The blade310may also include gaps such as flat surface(s)318between the adjacent protrusions316. In an embodiment, all the flat surfaces318extend along a same line. Protrusions316are preferably spaced apart along at least the upper edge of the blade where it will engage a DUT contact pad.

The blade310further includes sides312and314. In an embodiment, when the compliant ground block301is assembled and in a free state (no force from either the DUT or from the load board is applied to the compliant ground block301, seeFIG.22A), the sides312and314extend in the Z direction, and the surfaces318extend at an angle with respect to the X direction (horizontal direction, transverse direction), so that the tip(s) at or towards the side312is disposed higher (closer to the DUT) than the tip(s)316at or towards the side314. The blade310also includes a hinge (or hinge point)320protruding from the side314. In an embodiment, the hinge320can be retained/fixed on the neighboring blade330or received within a recess in the housing so that the blade can deflect circumferentially in response to engagement with the DUT pad. In another embodiment, or the hinge320can be retained/fixed with in the housing401(e.g., into a recess of the housing) for the compliant ground block301.

The blade310may include a curved edge322that is configured to be tangent to a portion of a periphery of the elastomer350. The blade310may also include a straight edge portion324extending and transitioning from an end of the curved edge322roughly tangent to the elastomer outer surface.

The blade330includes an aperture334for the elastomer350to pass through in the Y direction. The aperture334is a through aperture (in Y direction) and is contained entirely in the blade330. The blade330also includes sides344and346, a top end332, and radius340and342at the top corners of the blade330. In an embodiment, the end332is has a flat surface extending in the X direction. At the bottom end, the blade330includes a plurality of protrusions or tips336similar to tips316. The blade330also includes surface(s)338(e.g., flat surfaces, curved surfaces, or the like) between the adjacent protrusions336.

During operation, the DUT may come down, making contact with and/or pressing the higher tip(s)316at or near the side312. The blade310is configured to swing or rotate about the hinge320(so that all tips316are at a same level in the X direction) when e.g., pressed down by the DUT, causing a scrubbing action where the tips translate somewhat across the face of the DUT pad. When the DUT is removed or released, the elastomer350can provide tension and rebound the blade310, causing a scrubbing action. Edge326extends from the hinge point320to the curved edge322. It is shown here as a straight edge but may follow other paths and may engage a stop (not shown) to limit downward movement of blade310.

It will be appreciated that when the blade310is fully pressed by the DUT (or when the compliant ground block301is in the free state), the end332of the blade330is at or below the tip(s)316of the blade310so that only blade310is contacting the DUT, and a bottom of the blade310is at or above the tips336of the blade330so that only the blade330is contacting the load board.

The housing401includes an enclosure440, a slot450for the elastomer350, a slot410for the blade pairs (310,330), and an opening420so that the compliant ground block301can contact the load board when it is accommodated in the housing401. The opening of the housing401(so that the compliant ground block301can contact the DUT when it is accommodated in the housing401) is not shown.

FIGS.23A-23Eare identical toFIGS.22A-22E, respectively, except for the difference(s) described below between the first blade310A of the compliant ground block302inFIGS.23A-23Eand the first blade310inFIGS.22A-22E. The blade310A is identical to the blade310, except that the surface/trough319of the blade310A is a curved surface and the surface/trough318of the blade310is a flat surface. In an embodiment, all the curved surfaces319extend along a same curved line. This curvature is preferably an arc interrupted by tips/peaks316. It will be appreciated that the curved surface(s)319can provide a better DUT contact than non-curved surface(s). Trough318may be used to receive debris which may fall off the DUT pad during scraping action.

FIG.24Ais a side view of a compliant ground block501.FIG.24Bis a perspective view of a blade pair (510,530) of the compliant ground block501ofFIG.24A.FIG.24Cis a perspective view of the compliant ground block501ofFIG.24A.FIG.24Dis a cross-sectional view of the compliant ground block501ofFIG.24A.FIG.24Eis an exploded view of the compliant ground block501ofFIG.24Aand a housing601for the compliant ground block501. This embodiment differs from the previous primarily in that the hinge is another biasing elastomer.

As shown inFIGS.24A-24E, the compliant ground block501includes a plurality of electrically conductive blade pairs. The material, arrangement, and/or disposition of the blade pairs are the same as the blades or blade pairs described herein, except for the differences explicitly disclosed below. The plurality of blade pairs are disposed in a side by side (in Y direction or thickness direction) generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally/vertically (Z direction, from the DUT to the load board) slidable with respect to each other.

Each blade pair includes a first blade510, a second blade530, and two elastomers (550A,550B) configured to retain the plurality of blade pairs. The material, arrangement, and/or disposition of the elastomers550A,550B are the same as the elastomer(s) described herein, except for the differences explicitly disclosed below. The first blade510is configured to contact the DUT (e.g., the ground pad/terminal), and the second blade530is configured to contact the load board (e.g., the ground pad/terminal).

The blade310includes a plurality of protrusions or tips516at an end of the blade510that is configured to contact the DUT. The blade510also includes flat surface(s)518between the adjacent protrusions516. In an embodiment, all the flat surfaces518extend along a same line. In the alternative, the blat surfaces518may be arcuate in the same way as they are inFIG.23B.

The blade510further includes sides512and514. In an embodiment, when the compliant ground block501is assembled and in a free state (no force from either the DUT or from the load board is applied to the compliant ground block501, seeFIG.24A), the sides512and514extend in the Z direction, and the surfaces518extend at an angle with respect to the X direction (horizontal direction, transverse direction), so that the tip(s) at or towards the side512is disposed higher (closer to the DUT) than the tip(s)516at or towards the side514.

The blade510includes a curved edge or recess524on side514that is configured to be tangent to a portion of a periphery of the elastomer550A, and a curved edge or recess522on side512that is configured to be tangent to a portion of a periphery of the elastomer550B. In a free state or being pressed by the DUT, the recess522is disposed below the recess524in the X direction.

The blade530includes sides543and545, a top end532, and radius540and542at the top corners of the blade530. In an embodiment, the end532is has a flat surface extending in the X direction. At the bottom end, the blade530includes a plurality of protrusions or tips536. The blade530also includes surface(s)538(e.g., flat surfaces, curved surfaces, or the like) between the adjacent protrusions536.

The blade530also includes an elongated recess with a curved edge or recess544on side545that is configured to be tangent to a portion of a periphery of the elastomer550B, and a curved edge or recess546on side543that is configured to be tangent to a portion of a periphery of the elastomer550A. In a free state or being pressed by the DUT, the recess544is disposed below the recess546in the X direction. The elastomer550A is configured to be biased into the recesses524and546, and the elastomer550B is configured to be biased into the recesses522and544.

It will be appreciated that in blade530, if the side545extends in its original direction, the elastomer550B may be entirely enclosed by the side545and the recess544. For recesses522,524, and546, if the corresponding side extends in its original direction, the corresponding elastomer is partially (not entirely) enclosed by the corresponding side and the corresponding recess.

In an embodiment, the elastomers (550A,550B) can have the same durometers. In another embodiment, the elastomers (550A,550B) can have different durometers to make the blade510swing/rotate more (e.g.,550A has a softer durometer than550B). It will be appreciated that having an elastomer on the short or hinging side514of the blade510can provide the blade510more freedom to move. If the elastomer at the rebounding side512has a softer durometer, the blade can move further. In fact, the durometers of all elastomers can vary stepwise or segment-wise along its longitudinal extent, or continuously varied, according to user needs.

During operation, the DUT may come down, making contact with and/or pressing the higher tip(s)516at or near the side512, and the whole blade510may come down as a result from the top side first, creating a scrubbing action as the tip(s)516slides along and the lower tip(s)516makes contact with the DUT one after the other. As the blade510rotates, the tips516may scrub along the ground pad of the DUT causing the scrubbing effect (for both rotation and lateral movement). That is, the blade510is configured to swing or rotate (e.g., due to its shape) about an axis (not shown) (so that all tips516are at a same level in the X direction) when e.g., pressed down by the DUT, causing a scrubbing action. When the DUT is removed or released, the elastomers550A and550B can provide tension and rebound the blade510, causing a scrubbing action.

It will be appreciated that when the blade510is fully pressed by the DUT (or when the compliant ground block501is in the free state), the end532of the blade530is at or below the tip(s)516of the blade510so that only blade510is contacting the DUT, and a bottom526of the blade510is at or above the tips536of the blade530so that only the blade530is contacting the load board. Blade510also differs from blade310A in there is an accurate extension that partially surrounds elastomer550B. Elastomer550B is surrounded roughly halfway around by this extension.

The housing601includes an enclosure640, a slot650A for the elastomer550A, a slot650B for the elastomer550B, a slot610for the blade pairs (610,630), and an opening620so that the compliant ground block501can contact the load board when it is accommodated in the housing601. The opening of the housing601(so that the compliant ground block501can contact the DUT when it is accommodated in the housing601) is not shown.

FIGS.25A-25Eare identical toFIGS.24A-24E, respectively, except for the difference(s) described below between the first blade510A of the compliant ground block502inFIGS.25A-25Eand the first blade510inFIGS.24A-24E. The blade510A is identical to the blade510, except that the surface519of the blade510A is a curved surface and the surface518of the blade510is a flat surface. In an embodiment, all the curved surfaces519extend along a same curved line. It will be appreciated that the curved surface(s)519can provide a better DUT contact than non-curved surface(s).

FIG.26Ais a side view of a compliant ground block700.FIG.26Bis a perspective view of a blade pair (710,730) of the compliant ground block700ofFIG.26A.FIG.26Cis a perspective view of the compliant ground block700ofFIG.26A.FIG.26Dis a cross-sectional view of the compliant ground block700ofFIG.26A.FIG.26Eis an exploded view of the compliant ground block700ofFIG.26Aand a housing701for the compliant ground block700.

As shown inFIGS.26A-26E, the compliant ground block700includes a plurality of electrically conductive blade pairs. The material, arrangement, and/or disposition of the blade pairs are the same as the blades or blade pairs described herein, except for the differences explicitly disclosed below. The plurality of blade pairs are disposed in a side by side (in Y direction or thickness direction) generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally/vertically (Z direction, from the DUT to the load board) slidable with respect to each other.

Each blade pair includes a first blade710, a second blade730, and a single elastomer750configured to retain the plurality of blade pairs. The material, arrangement, and/or disposition of the elastomer750are the same as the elastomer(s) described herein, except for the differences explicitly disclosed below. The first blade710is configured to contact the DUT (e.g., the ground pad/terminal), and the second blade730is configured to contact the load board (e.g., the ground pad/terminal).

The blade710includes a plurality of protrusions or tips716at an end of the blade710that is configured to contact the DUT. The blade710also includes flat surface(s)718between the adjacent protrusions716. In an embodiment, all the flat surfaces718extend along a same line. In another embodiment, instead of flat surface(s)718, there can be curved surface(s) between the adjacent protrusions716. All the curved surfaces can extend along a same curved line. It will be appreciated that the curved surface(s) can provide a better DUT contact than non-curved surface(s).

The blade710further includes sides712and714. In an embodiment, when the compliant ground block700is assembled and in a free state (no force from either the DUT or from the load board is applied to the compliant ground block700, seeFIG.26A), the sides712and714extend in the Z direction, the surfaces718extend in the X direction (horizontal direction, transverse direction), and all tips716are at a same level in the X direction.

The blade710includes a curved edge724that is configured to be tangent to a portion of a periphery of the elastomer750. The blade710also includes a straight edge725extending from an end of the curved edge724. The blade710further includes a sliding edge722extending from the side712to the bottom end726of the blade710.

The blade730includes a recess748(on side746) that is configured to be tangent to a portion of a periphery of the elastomer750. The elastomer750is configured to be biased into the recess748and the curved edge724. The blade730also includes sides744and746, a top end732, and radius740and742at the top corners of the blade730. In an embodiment, the end732is has a flat surface extending in the X direction. At the bottom end, the blade730includes a plurality of protrusions or tips736. The blade730also includes surface(s)738(e.g., flat surfaces, curved surfaces, or the like) between the adjacent protrusions736.

In an embodiment, the blade730includes a ramp preferably having an outwardly protruding ledge734partitioning the second blade into a first portion733and a second portion735along the ramp734. A thickness of the first portion733is greater than a thickness of the second portion735extends from a point at or near the radius740to a point at or near a middle of the bottom end of blade730. The ramp734is configured to support the sliding edge722. A thickness of the first portion733is greater than a thickness of the second portion735so that the sliding edge722can slide along the ramp734when the blade710is pressed by the DUT. In an embodiment, the thickness of the first portion733is the thickness of the second portion735plus a thickness of the blade710.

In another embodiment, the housing701includes a support structure (not shown) to support the sliding edge722so that the sliding edge722can slide along the support structure.

During operation, the DUT may come down, making contact with and/or pressing and/or pushing down on the tip(s)716of blade710. The blade710is configured to slide along/down the ramp734(or along/down the support structure of the housing701) and push against the elastomer750(one side of the elastomer750holding in the housing701and another side holding in the neighboring blade730) to retain tension when e.g., pressed down by the DUT, causing a scrubbing action. When the DUT is removed or released, the elastomer750can provide tension and rebound the blade710so that the blade710slides/returns back/up to its original position in a free state, causing a scrubbing action.

It will be appreciated that when the blade710is fully pressed by the DUT (or when the compliant ground block700is in the free state), the end732of the blade730is at or below the tip(s)716of the blade710so that only blade710is contacting the DUT, and a bottom726of the blade710is at or above the tips736of the blade730so that only the blade730is contacting the load board.

The housing701includes an enclosure704, a slot705for the elastomer750, a slot703for the blade pairs (710,730), and an opening702so that the compliant ground block700can contact the load board when it is accommodated in the housing701. The opening of the housing701(so that the compliant ground block700can contact the DUT when it is accommodated in the housing701) is not shown.

FIG.27Ais a side view of a compliant ground block800.FIG.27Bis a perspective view of a blade pair (810A and810B,830) of the compliant ground block800ofFIG.27A.FIG.27Cis a perspective view of the compliant ground block800ofFIG.27A.FIG.27Dis a cross-sectional view of the compliant ground block800ofFIG.27A.FIG.27Eis an exploded view of the compliant ground block800ofFIG.27Aand a housing801for the compliant ground block800.

As shown inFIGS.27A-27E, the compliant ground block800includes a plurality of electrically conductive blade pairs. The material, arrangement, and/or disposition of the blade pairs are the same as the blades or blade pairs described herein, except for the differences explicitly disclosed below. The plurality of blade pairs are disposed in a side by side (in Y direction or thickness direction) generally parallel relationship. Blades in the plurality of blade pairs are configured to be longitudinally/vertically (Z direction, from the DUT to the load board) slidable with respect to each other.

Each blade pair includes a first blade assembly (810A,810B), a second blade830, and two elastomers (850A,850B) and an optional elastomer850C configured to retain the plurality of blade pairs. The material, arrangement (including e.g., interaction with cavities238and240ofFIG.9A), and/or disposition of the elastomers (850A,850B,850C) are the same as the elastomer(s) described herein, except for the differences explicitly disclosed below. The blade assembly (810A,810B) is configured to contact the DUT (e.g., the ground pad/terminal), and the second blade830is configured to contact the load board (e.g., the ground pad/terminal).

In an embodiment, the blade assembly includes a first portion810A and a second portion810B that mirror each other in the Z direction.

The portion810A includes two or more protrusions or tips816at an end of the portion810A that is configured to contact the DUT. The portion810A also includes flat surface(s)818between the adjacent protrusions816. In an embodiment, all the flat surfaces818extend along a same line. In another embodiment, instead of flat surface(s)818, there can be curved surface(s) between the adjacent protrusions816. All the curved surfaces can extend along a same curved line. It will be appreciated that the curved surface(s) can provide a better DUT contact than non-curved surface(s).

The portion810A further includes sides812and814. In an embodiment, when the compliant ground block800is assembled and in a free state (no force from either the DUT or from the load board is applied to the compliant ground block800, seeFIG.27A), the side814extends in the Z direction, and the surface(s)818extends at an angle with respect to the X direction (horizontal direction, transverse direction), so that the tip(s)816at or towards the side814is disposed higher (closer to the DUT) than the tip(s)816at or towards the side812.

The portion810A includes an edge820extending from an end of side814toward a bottom822of the portion810A. The edge820and the side812intersect at or around the bottom822.

The portion810B includes two or more protrusions or tips816at an end of the portion810B that is configured to contact the DUT. The portion810B also includes flat surface(s)818between the adjacent protrusions816. In an embodiment, all the flat surfaces818extend along a same line. In another embodiment, instead of flat surface(s)818, there can be curved surface(s) between the adjacent protrusions816. All the curved surfaces can extend along a same curved line. It will be appreciated that the curved surface(s) can provide a better DUT contact than non-curved surface(s).

The portion810B further includes sides812and814. In an embodiment, when the compliant ground block800is assembled and in a free state (no force from either the DUT or from the load board is applied to the compliant ground block800, seeFIG.27A), the side814extends in the Z direction, and the surface(s)818extends at an angle with respect to the X direction (horizontal direction, transverse direction), so that the tip(s)816at or towards the side814is disposed higher (closer to the DUT) than the tip(s)816at or towards the side812.

The portion810B includes an edge820extending from an end of side814toward a bottom822of the portion810A. The edge820and the side812intersect at or around the bottom822.

The portion810A mirrors the portion810B in the Z direction. The portion810A and the portion810B define or form a “V” shape recess. Hinge or pivot points (not show) is at or around the bottom(s)822so that the portion810A and the portion810B can rotate about the hinges.

The blade830includes sides844and846, a top end832, and radius840and842at the top corners of the blade830. In an embodiment, the end832is has a flat surface extending in the X direction. At the bottom end, the blade830includes a plurality of protrusions or tips836. The blade830also includes surface(s)838(e.g., flat surfaces, curved surfaces, or the like) between the adjacent protrusions836.

The blade830includes a recess845(on side844) that is configured to be tangent to a portion of a periphery of the elastomer850A. The elastomer850A is configured to be biased into the recess845and the edge820of the portion810A. The blade830also includes a recess847(on side846) that is configured to be tangent to a portion of a periphery of the elastomer850B. The recess845is disposed at a same level as the recess847in a horizontal direction. The elastomer850B is configured to be biased into the recess847and the edge820of the portion810B.

The blade830can include an optional aperture834for the optional elastomer850C to pass through in the Y direction. The aperture834is a through aperture (in Y direction) and is contained entirely in the blade830. The elastomer850C is disposed in the V-shape recess formed by side812. In an embodiment, the elastomer850C is smaller (e.g., has a smaller diameter) than the elastomers850A and850B. It will be appreciated that a small elastomer in the middle (of the blade830or of the blade assembly810A and810B) (for retention features) can keep tension and keep the parts in place.

During operation, the DUT may come down, making contact with and/or pressing the higher tip(s)316at or near the side814(of the portion810A and the portion810B). The blade assembly (810A,810B) is configured to rotate about the hinge (so that all tips816are at a same level in the X direction) when e.g., pressed down by the DUT, causing a scrubbing action. When the DUT is removed or released, the elastomers (850A,850B) can provide tension and rebound the blade assembly (810A,810B), causing a scrubbing action.

That is, when the DUT presses down, forcing the two portions (810A,810B) to further open and create a scrubbing effect on the DUT. The two portions (810A,810B) may press against the elastomers (850A,850B) and create tension. When the DUT is removed or released, the elastomers (850A,850B) may return the two portions (810A,810B) back to their position in a free state. The elastomers (850A,850B) are disposed at or on the sides (844,846), the blade830is facing down, and the two portions (810A,810B) (e.g., two smaller triangular blades) are sitting in between the elastomers (850A,850B). When the DUT presses down, it may force the two portions (810A,810B) to rock/rotate around/against the hinge (i.e., the pivot point) and create scrubbing motion.

It will be appreciated that when the two portions (810A,810B) are fully pressed by the DUT (or when the compliant ground block800is in the free state), the end832of the blade830is at or below the tip(s)816of the blade assembly (810A,810B) so that only the blade assembly (810A,810B) is contacting the DUT, and a bottom822of the blade assembly (810A,810B) is at or above the tips836of the blade830so that only the blade830is contacting the load board.

The housing801includes an enclosure804, a slot805A for the elastomer850A, a slot805B for the elastomer850B, an optional slot805C for the optional elastomer850C, a slot803for the blade pairs (810A and810B,830), and an opening802so that the compliant ground block800can contact the load board when it is accommodated in the housing801. The opening of the housing801(so that the compliant ground block800can contact the DUT when it is accommodated in the housing801) is not shown.

The description of the invention and its applications as set forth herein is illustrative and is not intended to limit the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible and practical alternatives to and equivalents of the various elements of the embodiments would be understood to those of ordinary skill in the art upon study of this patent document. These and other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.

Aspects

It is noted that any one of aspects below can be combined with each other.

Aspect 1. A compliant ground block for a testing system for testing integrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by side generally parallel relationship, blades in the plurality of blade pairs configured to be longitudinally slidable with respect to each other; and

an elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a first blade and a second blade,

the first blade includes a hinge and a curved edge tangent to a portion of a periphery of the elastomer, the first blade is configured to rotate about the hinge when pressed,

the second blade includes an aperture for the elastomer to pass through.

Aspect 2. The compliant ground block according to aspect 1, wherein the first blade includes a plurality of protrusions at an end of the first blade.

Aspect 3. The compliant ground block according to aspect 2, wherein the first blade includes curved surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 4. The compliant ground block according to aspect 2, wherein the first blade includes flat surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 5. The compliant ground block according to any one of aspects 1-4, wherein the aperture is a through aperture and is contained entirely in the second blade.

Aspect 6. A compliant ground block for a testing system for testing integrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by side generally parallel relationship, blades in the plurality of blade pairs configured to be longitudinally slidable with respect to each other; and

a first elastomer and a second elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a first blade and a second blade,

the first blade includes a first recess on a first side of the first blade and a second recess on a second side of the first blade, the second recess of the first blade is disposed below the first recess of the first blade in a horizontal direction,

the second blade includes a first recess on a first side of the second blade and a second recess on a second side of the second blade, the second recess of the second blade is disposed below the first recess of the second blade in a horizontal direction.

Aspect 7. The compliant ground block according to aspect 6, wherein the first blade includes a plurality of protrusions at an end of the first blade.

Aspect 8. The compliant ground block according to aspect 7, wherein the first blade includes curved surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 9. The compliant ground block according to aspect 7, wherein the first blade includes flat surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 10. The compliant ground block according to any one of aspects 6-9, wherein the first elastomer is configured to be biased into the first recess of the first blade and the first recess of the second blade, and the second elastomer is configured to be biased into the second recess of the first blade and the second recess of the second blade.

Aspect 11. A compliant ground block for a testing system for testing integrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by side generally parallel relationship, blades in the plurality of blade pairs configured to be longitudinally slidable with respect to each other; and

an elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a first blade and a second blade,

the first blade includes a recess on a first side of the first blade and a sliding edge extending from a second side of the first blade to a bottom end of the first blade,

the second blade includes a recess at a first side of the second blade,

the elastomer is configured to be biased into the recess of the first blade and the recess of the second blade.

Aspect 12. The compliant ground block according to aspect 11, wherein the first blade includes a plurality of protrusions at an end of the first blade.

Aspect 13. The compliant ground block according to aspect 12, wherein the first blade includes curved surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 14. The compliant ground block according to aspect 12, wherein the first blade includes flat surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 15. The compliant ground block according to any one of aspects 11-14, wherein the second blade includes a ramp partitioning the second blade into a first portion and a second portion along the ramp, the ramp is configured to support the sliding contact, a thickness of the first portion is greater than a thickness of the second portion.

Aspect 16. A compliant ground block for a testing system for testing integrated circuit devices, comprising:

a plurality of electrically conductive blade pairs in a side by side generally parallel relationship, blades in the plurality of blade pairs configured to be longitudinally slidable with respect to each other; and

a first elastomer and a second elastomer configured to retain the plurality of blade pairs,

wherein each blade pair of the plurality of blade pairs includes a first blade assembly and a second blade,

the first blade assembly includes a first portion and a second portion, the first portion of the first blade assembly and the second portion of the first blade assembly define a “V” shape recess,

the second blade includes a first recess on a first side of the second blade and a second recess on a second side of the second blade, the first recess of the second blade is disposed at a same level as the second recess of the second blade in a horizontal direction.

Aspect 17. The compliant ground block according to aspect 16, wherein the first blade assembly includes a plurality of protrusions at an end of the first blade assembly.

Aspect 18. The compliant ground block according to aspect 17, wherein the first blade assembly includes curved surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 19. The compliant ground block according to aspect 17, wherein the first blade assembly includes flat surfaces between adjacent protrusions of the plurality of protrusions.

Aspect 20. The compliant ground block according to any one of aspects 16-19, wherein the first elastomer is configured to be biased into the first recess of the second blade, and the second elastomer is configured to be biased into the second recess of the second blade.

Aspect 21. The compliant ground block according to any one of aspects 16-20, further comprising a third elastomer,

the second blade includes an aperture for the third elastomer to pass through, the aperture is a through aperture and is contained entirely in the second blade.