Apparatus and method for vertically-structured passive components

A manufacturing technique for constructing passive electronic components in vertical configurations is disclosed. Electrically passive components are constructed in a structure that is substantially perpendicular to target platform including a first plane to provide a larger electrode contact area and a smaller physical dimension. Passive components structured to be substantially perpendicular to a plane associated with a target platform can be directly connected to pad contacts of an integrated circuit or substrate or can be embedded in a package to reduce the area overhead of a passive component while improving the effectiveness of the passive components in their applications.

FIELD OF THE INVENTION

This invention relates generally to the manufacture of electronic components, and more particularly to using a structure which is substantially perpendicular to a first plane of a target platform to implement passive electronic components.

BACKGROUND OF THE INVENTION

Semiconductor components are often manufactured using a ball grid array (“BGA”) package, where metallic solder balls composing tin, silver and copper, are pre-soldered at pad contacts of a component package for soldering the semiconductor component to a target platform, such as a printed circuit board (“PCB”). Semiconductor components are also often manufactured in a leadless grid array (“LGA”) package where there are no solder balls at the pad contacts of the package. Instead, a thin layer of solder paste is printed on the metal contacts of a PCB during product assembly to solder the semiconductor component on the PCB.

Other packages are also used in semiconductor component manufacturing. For example, a quad flat-pack package (“QFP”) or a small outline integrated circuits package (“SOIC”) uses gull-wing shaped metal leads attached to the periphery of the package to couple the packaged semiconductor component to a PCB. As another example, a dual-in-line package (“DIP”) or a pin grid array package (“PGA”) sticks metal pins at the periphery of the package or at the bottom surface of the package for inserting the packaged part into a socket or for soldering it into a set of through-holes on a target platform, such as a PCB. Additionally, a ceramic-leaded chip carrier (“CLCC”) package or a plastic-leaded chip carrier (“PLCC”) package affixes J-shaped metal leads to the periphery of a packaged semiconductor component for connecting the semiconductor component to a target platform, such as a PCB.

One thing common to many conventional packages for semiconductor component is that nothing more than metal contacts, metal pins, or solder balls are attached to pad contacts of the packages to connect the semiconductor component to a target platform.

When using a semiconductor component, such as an integrated circuit (“IC”), passive components, also referred to as “passives,” such as resistors, capacitors or inductors, are often added to make the semiconductor component function properly. For example, decoupling capacitors are often connected to the power pins of an IC component to filter out power noises. A current limiting resistor is often coupled to a driver pin of an IC component to limit driver output current. Or, a termination resistor is often coupled to a signal path to suppress reflection in the high speed trace. Conventionally, these passives are often placed near the pins of the IC component to which the passive is coupled in order to maximize their effectiveness. However, these passives are placed beyond the IC package outline, which often occupy substantial area on the target platform and also compete with interconnect layout routing around the IC component, especially if the IC package has high pin-count.

FIG. 1illustrates a simplified version of a conventional printed circuit board (“PCB”) assembly, where a conventional, horizontally structured passive component120and an IC component130are soldered to a PCB100. The IC component130includes a set of IC pads135which are soldered to a set of target contacts115on PCB100. Solder balls connect the IC pad135and the target contact115on the PCB. To connect a passive component120to a pad of IC component130on the PCB100, two target contacts111and112are added to the surface of PCB100, where the electrodes121,122of the passive component120are connected to the target contacts111,112. To connect the electrode122of the passive component120to an IC pad135in the IC component130, an additional PCB trace114is added to the surface of PCB100, which connects target contact112to a corresponding target contact115in IC component130. In the example depicted byFIG. 1, the passive component120occupies PCB area, and may also block signal traces around the IC component130on the PCB100.

There is an additional potential problem in using the conventional passive components. For mobile or high density electronic products, there is a continuous trend to miniaturize the package size, including the supporting passives. For example, the common size of passive components used in a high density DRAM module design has been changed from a 0603 package having a dimension of 60 mils in length and 30 mils in width to a smaller 0402 package having a dimension of 40 mils long by 20 mils wide. In mobile devices, such as cellular phone, a 0201 package of 20 mils long by 10 mils wide which further reduces the size of area occupied by the passive components becomes more widely used. The current state-of-the-art for passive component is a 1005 package having a dimension of 10 mils in length and 5 mils in width. This reduced passive size makes it difficult to solder conventional passive components to a target platform, such as a PCB, because of the increased likelihood of insufficient soldering or solder bridging problems. Much of the difficulties in soldering smaller passives to a target platform originate from the horizontal structure in which most passives are fabricated, with an electrode at each end of the horizontal structure. A solution that can reduce the target platform area overhead used by the passive component and while reducing the bridging and/or insufficient soldering problem encountered by the ultra-small passives during PCB assembly is useful.

SUMMARY OF THE INVENTION

The present invention comprises an electronic device which implements an electrically passive component in a vertical configuration. More specifically, the electronic device is coupled to a target platform that is positioned substantially in a first plane. The electronic device comprises a first surface that is substantially parallel to the first plane and includes a first contact region. The electronic device also comprises a second surface substantially parallel to the first plane and including a second contact region. A structure, which is substantially perpendicular to the first plane, electrically connects the first contact region and the second contact region to implement one or more passive functions. An insulation sidewall is adjacent and external to the structure. In an embodiment, the insulation sidewall surrounds at least one of the first contact region or the second contact region. For example, the structure connects the first contact region and the second contact region to implement a resistor, a capacitor, an inductor, a conductive path, a diode device or a conductive path. As another example, the structure connects the first contact region and the second contact region to implement combinations of passive components, such as a resistor coupled to a capacitor, a resistor coupled to a conductive path, or other combinations of electrically passive components.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the present invention is now described with reference to the Figures where like reference numbers indicate identical or functionally similar elements. Also in the Figures, the left most digits of each reference number correspond to the Figure in which the reference number is first used.

One embodiment of the invention configures the passive components in a vertical structure with terminal electrodes fabricated at the top and the bottom surfaces of the vertical structure and with an insulation sidewall external to and adjacent to the structure and proximate to one or more of the electrodes, as shown inFIG. 2. As used herein, the term “vertical” is used to describe any orientation that is substantially perpendicular to a target plane. For example, an orientation where the structure of a passive component is substantially perpendicular to a plane of a target platform, such as a printed circuit board (PCB). In one embodiment, a vertically structured passive component, or “vertical passive,” comprises a first surface220and a second surface225parallel to the first surface and below the first surface. The first surface220includes a first contact region, such as a first electrode201, and the second surface includes a second contact region, such as a second electrode202. The vertical structure200,250electrically connects the first contact region, such as electrode201,251, and the second contact region, such as electrode202,252to implement one or more passive components. For example, the vertical structure200,250connects the first contact region and the second contact region to implement a resistor, a capacitor, an inductor, a conductive path, a diode device or a conductive path. As another example, the vertical structure200,250connects the first contact region and the second contact region to implement a combination of passive components, such as a resistor coupled to a capacitor, a resistor coupled to a conductive path or other combinations of passive components.

FIG. 2shows two examples of vertical passives, where one example vertical passive comprises a square vertical structure200which includes square contact regions, such as square electrodes201,202, and a square insulation sidewall210surrounding the square vertical structure200. Another example vertical passive component is the circular vertical structure250, also shown inFIG. 2. The circular vertical structure250includes circular contact regions, such as electrodes251,252, and a circular insulation sidewall260around the circular vertical structure250. However, the vertical passive components shown inFIG. 2are merely examples, and in other embodiments, vertical passives are implemented using vertical structures having other geometries, such as rectangular, rhomboidal, hexagonal, octagonal, half-circular or other irregular shapes. Additionally, in other embodiments, vertical passives are implemented using any combinations of these geometries, such as vertical passive having a square insulation sidewall and a circular contact region, such as a circular electrode. As shown inFIG. 2, the vertical passive may have a first axis that is substantially perpendicular to the plane of the target platform and a second axis that is substantially parallel to the plane of the target platform. The examples inFIG. 2are merely for illustration and are not an exhaustive list of possible implementations.

In an embodiment, a vertical passive is sized to be compatible with a pad size and pin pitch associated with an integrated circuit (“IC”) component. The horizontal dimension of the vertical passive, such as the diagonal across a square vertical structure or the diameter of a circular vertical structure, may be on the order of millimeters or smaller. The height of the vertical passive is also in the millimeter range or smaller. Additionally, in an embodiment, the area of the contact regions of a vertical passive is large enough to provide a good contact with the pad of IC component in a soldered connection or to facilitate a good contact with the IC component in a solderless assembly.

A vertical passive may include an insulation sidewall as a protection layer, in one embodiment. The insulation sidewall may be adjacent to the vertical passive and external to the vertical passive. The insulation sidewall prevents solder bridging between electrodes and/or prevents an electrical short between an IC pad and a PCB target contact because of their narrow proximity when a thin vertical passive is placed in between.

The vertical structure may be used to implement many types of passive components, such as a resistor, a capacitor, an inductor, a ferrite bead or other passive components. In an embodiment, the vertical structure includes a plurality of passive components in a combination structure. The vertical structure also applies to semiconductor devices, such as a Zener diode, an ESD protection diode, a light emitting diode (“LED”), other diode devices or other semiconductor devices. In another embodiment, the vertical structure comprises a pure insulator or conductor for use as a mechanical support, a capacitor or an interconnection.

FIG. 3is an example showing compatibility of a vertical passive with respect to the pad size and pin pitch of an integrated circuit (“IC”) component and suitability of the vertical passive for connecting to an IC component.FIG. 3is an excerpt of the pad configuration of a leadless grid array-52 (“LGA-52”) package, which includes circular shaped pads of two different pad sizes. The first pad size is 1.0 mm in diameter, as shown in the leftmost column ofFIG. 3. The second pad size is smaller, 0.7 mm in diameter, as shown in the right three columns ofFIG. 3. The pad sizes are approximately half of the center distance between two nearest pads. In the LGA-52 package, the shortest center distance is 1.414 mm for the smaller pads and is 2.00 mm for the larger pads.

In an embodiment, to connect, or place, a vertical passive at a pad of the LGA-52 package shown inFIG. 3, two vertical passives are fabricated. A first vertical passive has a contact area diameter of 0.7 mm and a second vertical passive has a contact area diameter of 1.0 mm, matching the two pad sizes in LGA-52 package, respectively. In an embodiment where soldering is used to connect a vertical passive to a package pad contact, it is beneficial to surround the contact areas of a vertical passive with a protective insulation sidewall.

For example, if the diameters of two vertical passives, including the insulation sidewall used in an LGA-52 package, are chosen at 1.1 mm and 1.6 mm respectively, which is approximately 80% of the shortest center distance between two nearby pads at 1.414 mm and 2.0 mm, respectively, then the insulation sidewalls would have thicknesses of 0.2 mm [i.e. (1.1 mm-0.7 mm) divided by 2] and 0.3 mm [i.e. (1.6 mm-1.0 mm) divided by 2], respectively. In different embodiments, the insulation sidewall may be thicker or thinner than these values, as long as the dimension of insulation sidewall is sufficient to prevent solder bridging between the top and bottom electrodes at a vertical passive or to prevent shorting between pad contact on a LGA-52 package and target contact on PCB when a vertical passive is placed between them. Typically, the height of a vertical passive is smaller than the dimension of a horizontal cross section of the vertical passive.

It can be seen that a vertical passive with a 0.7 mm contact area diameter and a 1.1 mm sidewall diameter has a larger contact area but a smaller component footprint than a conventional horizontally-structured passive in a 0603 package. The contact area of an electrode of a horizontally-structured passive in a 0603 package is about 0.25 mm×0.75 mm, or approximately 0.19 mm2. However, the contact area of a vertical passive having a contact area diameter of 0.7 mm is π×(0.35 mm)2or approximately 0.38 mm2, which is twice the electrode contact area of a horizontally-structured passive in a 0603 package. The increased contact area of the vertical passive allows better connection between the vertical passive and the target platform with improved electrical characteristics. For example, the larger contact area of the vertical passive enables a better solder connection between the vertical passive and the target platform. The physical dimension of vertical passive is also rather compact. The physical footprint of a vertical passive with a 1.1 mm in outer diameter, including the protective insulation sidewall, can be calculated as π×(0.55 mm)2or 0.95 mm2, which is slightly smaller than the horizontal cross-sectional area of a horizontally-structured passive in a 0603 package, which is approximately 1.125 mm2(60 mils×30 mils or 1.5 mm×0.75 mm).

In different embodiments, the vertical passives are surface mounted or bonded to the pad contact of an IC component.FIG. 4shows a side view of an example set of vertical passives mounted to an example integrated circuit (“IC”) component. The vertical passive420with passive contact421, for instance, is soldered to an IC pad contact401of IC component400. The insulation sidewall422surrounding the vertical passive420has a dimension larger than the IC pad contact401to prevent potential solder bridging among the passive contact423, the passive contact421and the IC pad contact401during soldering or bonding. In one embodiment, the insulation sidewall is fabricated to protect both passive contacts areas421,423, as shown by the insulation sidewall422. Alternatively, the insulation sidewall protects a single passive contact region, as illustrated by the insulation sidewall424. When the insulation sidewall424protects a single passive contact region, the unprotected passive contact region425has a larger area for use as an electrode by an external connection. In an embodiment, an IC component soldered with vertical passives at its pad contacts is coupled to a printed circuit board (PCB), or other target platform, using a soldered mounting method, a solderless mounting method or any other suitable connection method, where the passive contact region423electronically contacts a target contact on the target platform.

In an alternative embodiment, the vertical passive420is coupled to a metal pin attached to the periphery of the IC component or to the bottom surface of the IC component, such as in a pin grid array package (“PGA”) or similar configuration. These metal pins are for inserting into through holes or into a socket on a target platform, such as a printed circuit board (“PCB”). This allows the vertical passive420to be coupled to the IC component via the metal pin while remaining detached from the target platform.

As shown inFIG. 4, the vertical passive420attached to the IC component400is constructed so that the passive contact421is substantially parallel to a plane including the surface of the IC component400. The passive contact423is also substantially parallel to the plane including the surface of the IC component400. Hence, the passive contact421and the passive contact423are substantially parallel to the plane including the surface of the IC component. A structure is coupled to the passive contact421and the passive contact423, electrically connecting or coupling the passive contact421and the passive contact423to allow the vertical passive420to implement one or more passive functions. The structure is substantially perpendicular to the plane including the surface of the IC component. By orienting the structure connecting the passive contact421and the passive contact423substantially perpendicular to the plane including the surface of the IC component400, one or more passive components may be attached perpendicular to the pad of the IC component, conserving space on the target platform when the IC component400is assembled on the target platform.

As an alternative to pre-coupling vertical passives to the pad contacts of an IC component or device for subsequent assembly of the IC component or device on a target platform, a vertical passive may be pre-coupled to a target platform. For example, the vertical passive is pre-soldered to the target platform. Then an IC component or device is coupled to a vertical passive which is coupled to the target platform. In this embodiment, the pad contacts of the passives soldered to the target platform are configured to have an area compatible with the pad contacts of the IC component. In various embodiments, the target platform comprises a PCB, a packaged IC component, a bare die, a stacked die, a packaged device, a sensor, an electro-optical device, an electro-mechanical device, a flex or any other suitable platform. In an embodiment, vertical passives are be cascaded vertically, where resistor, capacitor, and/or inductor, are butted at the passive contact pads on top of each other.

As another alternative embodiment, the vertical passive is embedded in a package.FIG. 5illustrates an example integrated circuit (“IC”) package with vertical passives embedded in the package. The embedded vertical passives may be directly attached to a pad contact at the package, directly attached to the pad contact at internal IC component or attached to a pad contact in between the package and the internal IC component.

InFIG. 5, a passive contact521of the vertical passive520, for instance, is attached to a component contact511of an IC component510included in an IC package500. The passive contact522at the opposite end of the vertical passive520is connected to a package contact541through an internal conduction path551. The IC component510may be an integrated circuit die.

Within an IC package, variations in alignment between component contacts, passive contacts, or package contacts in an IC package are allowed. Internal conduction paths can be used to connect the package contacts, the passive contacts, or the component contacts in the IC package, as illustrated by the package internal conduction paths551,552, and553. Hence, the embedded vertical passives can be placed at locations that meet the IC package fabrication needs. In some cases, there could be no embedded passive between the component contact and the package contact, as the package internal conduction path554shown.

The package mold590, functions similarly to the protective insulation sidewall of a discrete vertical passive. In an embodiment, the package mold590encapsulates the IC component and the embedded vertical passives while leaving the package contact openings exposed.

In an embodiment, the IC package with embedded vertical passives uses explicit metal pins, as in the case of DIP or PGA package, to replace flat contact pads, as in the case of the ball grid array package (“BGA”). Alternatively, the contact pads of the IC package with embedded passives are implemented using explicit gull-wing-shaped or J-shaped metal leads as in the case of quad flat-pack (“QFP”), small outline integrated circuits (“SOIC”), plastic-leaded chip carrier (“PLCC”), or ceramic-leaded chip carrier (“CLCC”) packages. For solderless assembly, conductive elastomer may be attached to contact pads of IC package. Similarly, the component or device in a package including embedded vertical passives may be an integrated circuit, a bare die, a stacked die, a packaged device, a stacked device, a sensor, a diode, or an electro-mechanical element.

In one embodiment, to couple the vertical passive components to a PCB, a thin layer of solder of a few thousandths of an inch (“mils”) is pre-coated at the surface of electrodes at the vertical passives, which may replace and obviate the solder paste printing step used in traditional surface mount assembly. Pre-coating the electrode surfaces with a thin layer of solder may also prevent removal of residual solder paste remaining on a stencil after printing, reducing environmental contaminations.

There are other advantages in using the vertical passives. Because vertical passives are sandwiched, or embedded, between an integrated circuit (“IC”) component and a PCB after assembly, the performance of passive components is improved, such as providing capacitive charges in situ at the power pin to meet the IC transient switching need. Use of vertical passives also removes explicit traces that connect passive components to an IC component on a PCB or other target platform, reducing spurious noise. Additionally, the PCB or substrate area overhead used by traditional passives is substantially reduced by vertical passives, enabling manufacture of a more compact electronic product.

In an embodiment, a vertical passive includes a combination structure of two or more passive components. For example, a vertical passive includes a combination structure such as a resistor and a capacitor, a resistor and a conduction path, a capacitor and a conduction path, an inductor and a conduction path, a ferrite bead and a conduction path, a diode and a conduction path, an electro-optical device and a conduction path, a resistor and a capacitor and a conduction path or other combination of passive components. In one configuration, a vertical passive including a combination structure has more than two contact regions, such as more than two electrodes. The combination structure of passive elements may be implemented by vertically cascading passives or vertically combining passives in parallel. Vertical passives including a combination structure may be directly coupled to the pad contacts of a package or directly embedded in a package to improve effectiveness of the combination structure of passive components and to minimize the physical area occupied by passive components.

FIG. 6illustrates example connections of passive components, such as a capacitor, or a combination of a capacitor and a resistor to an example integrated circuit (IC) component. InFIG. 6, capacitor C1is a decoupling capacitor connected to a power input (VCC) of the IC component, indicated as pin1inFIG. 6. The pin2connection inFIG. 6is a series connection of a resistor and a capacitor, which may be used in the feedback circuit of an active filter, PWM driver output, or high pass filter. The connection to pin3, shown inFIG. 6, is a resistor and capacitor connected to implement a low pass filter. Implementations of vertical passives and combination structures including two or more passive elements provide additional details about use of the vertical structure.

FIG. 7shows two example implementations of connecting a decoupling capacitor to a power input pin of an integrated circuit (“IC”) component using a vertical passive including a combination structure. The vertical passive including a combination structure700comprises a conductive plate and path701and a companion conductive plate702. Depending upon the capacitance requirement, the conductive plates may be interlaced to increase the capacitance, as shown in vertical passive including a combination structure700, where the conductive plate and path701has a reverse “F” shape and the conductive plate702has a “C” shape. Alternatively, if a smaller capacitance value is to be implemented, the conductive plate and path701may be a simpler inverse “L” shape and the conductive plate702may be a flat horizontal plate. Because the decoupling capacitor C1shown inFIG. 6has three connections, i.e. a connection to the VCC power Pin1of IC component, a connection to a power source and a connection to ground, three terminals are used to implement a vertical passive including a combination structure comprising a capacitor and a conduction path. Hence, split target contacts711and712are added to the surface of target platform790. In an embodiment, the target contact711which is connected to a power source (VCC) on a target platform is in contact with the conductive plate and path701at vertical passive, through which making contact with the power input pin (pin1inFIG. 6) of the IC component, supplying the IC component with power. A capacitor is formed between the conductive plate and path701and the conductive plate702, which is connected to ground through target contact712at the surface of target platform790.

The vertical passive including a combination structure750comprises a thin conductive path751and a thick dielectric752surrounding the conductive path751, which acts as an insulation layer. A capacitor is formed between the pad contact760of the IC component and the target contact762at the surface of target platform790. This implicitly provides the ability to adjust the capacitance value of the vertical passive including a combination structure751by varying the area of the target contact762connected to ground. Alternatively, a donut shaped passive contact, similar to the target contact762, may be fabricated at a first surface of the vertical passive including a combination structure750and a circular shaped passive contact, similar to the pad contact760may be fabricated at a second surface of the vertical passive including a combination structure750. Power (VCC) is supplied to the IC component (e.g., supplied to pin1of IC component shown inFIG. 6) through the target contact761, which is connected to a power supply (VCC) at the surface of the target platform790, and through the conductive path751, which makes electrical contact with the pad contact760of the IC component.

FIG. 8shows two example implementations of a capacitor and a resistor connected in series using a vertical passive including a combination structure800,850. The vertical passive including a combination structure shown in800or850comprises two passive components stacked along a first axis that is substantially perpendicular to the target platform, where the capacitor is at the top section of the combination structure connecting to pad contact of an IC component and the resistor is at the bottom section of the combination structure connecting to the target contact at the surface of target platform.

FIG. 9shows example implementations of a low-pass filter at an IC component pad contact comprising a resistor coupled to a capacitor (“RC low pass filter”) using a vertical passive including a combination structure. A vertical passive including a combination structure900includes a donut shaped passive contact at a first surface for connecting to a grounded donut shaped pad contact at IC and a circular shaped passive contact at a second surface for contacting RC output through a target contact at the surface of target platform, plus a resistive core with a passive contact connecting to a pad contact of the IC component at the center of the donut shaped passive contact and connecting to the target contact at the surface of target platform. Alternatively, two vertical passives may be used to implement a RC low pass filter, where two sets of pads of the IC component and two sets of target contacts at the surface of target platform, which are connected together, are used. In another embodiment, components within the vertical passive are oriented so that they are connected along an axis that is substantially parallel to the target platform.

While particular embodiments and applications of the present invention have been illustrated and described herein, it is to be understood that the invention is not limited to the precise construction and components disclosed herein and that various modifications, changes, and variations may be made in the arrangement, operation, and details of the methods and apparatuses of the present invention without departing from the spirit and scope of the invention as it is defined in the appended claims.