Compression Loaded Printed Circuit Assemblies for Solder Paste Defect Mitigation

Abstract

The present disclosure relates to a compressive load printed circuit assembly for solder paste defect mitigation. A system for applying a compressive load on at least a portion of an application specific integrated circuit ("ASIC") ball grid array ("BGA") package during a rework or secondary reflow process is provided. The compressive load assembly may include a top plate and a compression plate. The compression plate may apply a compressive load on at least a portion of the ASIC using one or more compression mechanisms. The compression mechanisms may each include a bolt and a spring. The bolt may releasably couple the top plate to the compression plate and allow the compressive load to be adjusted. The spring may be located on the bolt between the top plate and the compression plate and may therefore apply a force in a direction away from the top plate and toward the compression plate. The compressive load may hold the solder joint and may prevent solder separation defects during the reflow process.

Description

Technical Field

[0001] The present disclosure relates to compressively loaded printed circuit assemblies for solder paste defect mitigation. Background Art

[0002] Components may be mounted to a printed circuit board ("PCB") using surface mount technology ("SMT"). SMT typically requires temporarily attaching the component to contact pads on a first surface of the PCB using solder paste before the paste is heated to a liquid state. The liquid then cools to a solid solder joint that connects the component to the contact pad. The solder paste may be heated using reflow soldering, in which the entire PCB - including the component and solder paste - is heated until the solder paste reflows to a liquid state. Once removed from the heat source, the liquid solder will form a solid solder joint between the component and the contact pad.

[0003] A double-sided printed circuit board ("PCB") may have components soldered to both sides of the PCB using SMT. To attach components to the second side of the PCB, the PCB may be placed so that the components to be attached are placed downward, and additional components may be temporarily attached to contact pads on the upward facing surface of the PCB using solder paste. The entire PCB may be subjected to reflow soldering again. After the second reflow soldering is completed, both sides of the PCB may have components attached. Summary of the invention

[0004] Aspects of the present disclosure are directed to a compressive load assembly for minimizing and mitigating solder defects and disconnections. In one aspect, a compressive load assembly for applying a compressive force on an application specific integrated circuit ("ASIC") package includes a top plate, a compression plate, and one or more compression mechanisms coupled to the compression plate and the top plate, wherein the one or more compression mechanisms are configured to apply a compressive load to the ASIC in a direction away from the top plate toward the compression plate. Each compression mechanism may include a compression member and at least one spring located on each compression member. The at least one spring may be positioned between the compression plate and the top plate.

[0005] Each compression member may include a head and a shaft. The compression plate may include one or more counterbores configured to accommodate the head of the compression member. The compression plate may include one or more through holes configured to accommodate the shaft of the compression member. The head of the compression member may be positioned on a first side of the top plate, and the at least one spring is positioned on a second side of the top plate opposite the first side.

[0006] The one or more compression members can be advanced or retracted so that the compression load is adjustable. When the one or more compression mechanisms are advanced, the compression load can be increased. When the one or more compression mechanisms are retracted, the compression load can be reduced.

[0007] The compression load assembly may further include one or more coupling mechanisms that releasably couple a printed circuit board ("PCB") with the compression plate. Each of the one or more coupling mechanisms may include an alignment stud and a threaded member. The alignment stud may be integrated with the compression plate and may include a threaded hole. The PCB may include at least one PCB through hole aligned with the threaded hole of the alignment stud. The at least one PCB through hole and the threaded hole of the alignment stud may be configured to receive the threaded member.

[0008] The one or more compression mechanisms may include at least six compression mechanisms. The at least six compression mechanisms may be distributed on a compression board. The at least six compression mechanisms may be configured to provide a uniform compression load across the entire ASIC. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A cross-sectional view of an ASIC package according to aspects of the present disclosure is shown.

[0010] Figure 2A A cross-sectional view of a deep-backdrilled VIPPO structure according to aspects of the present disclosure is shown.

[0011] Figure 2B A cross-sectional view of a VIPPO structure according to aspects of the present disclosure is shown.

[0012] Figure 2C A cross-sectional view of a non-VIPPO structure according to aspects of the present disclosure is shown.

[0013] Figure 3 Several structures are shown that connect components in an ASIC package according to aspects of the present disclosure.

[0014] Figure 4 A perspective view of a compression load assembly according to aspects of the present disclosure is shown.

[0015] Figure 5 According to aspects of the present disclosure, Figure 4 Side perspective view of the compressive load assembly.

[0016] Figure 6 A side perspective view of a compression load assembly according to aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0017] The systems and methods described herein relate to a compressive load assembly that can apply a specific compressive load to an ASIC package during soldering to minimize the risk of solder joint failure or defects during reflow soldering or rework. During the manufacture of the ASIC package, the ASIC package can be soldered to a PCB via a BGA array, such as using a top SMT. Once soldered, the ASIC package and PCB can be flipped so that the top SMT can be used to mount other components via another BGA array on the opposite side of the PCB. In order to avoid separation of solder joints between the PCB and the ASIC package during reflow or soldering of other components, a compressive load assembly can be used to apply pressure on the ASIC package. The compressive load assembly can apply a compressive load on the ASIC package that is sufficient to prevent the solder joints connecting the ASIC package to the PCB from separating from the PCB or the ASIC package or otherwise causing defects.

[0018] Figure 1 An example system 100 is shown in which the features described herein may be implemented. As described herein, the example system 100 should not be considered limited to the scope of the present disclosure or the usefulness of the features described herein. The system 100 may include a first BGA package 182 and a second BGA package 184. The first BGA package 182 may be an ASIC package. The ASIC package may include an ASIC die 102, a package substrate 104 having a reinforcement ring 124, and a BGA array 114. The ASIC die 102 may be attached or otherwise mounted to the package substrate 104. The second BGA package 184 may be a power module BGA package, and in some examples, may include a power module 126 and a BGA array 116. The power module 126 may include a gearbox 108 and a multi-chip module ("MCM") 110. Between the first BGA package 182 and the second BGA package 184 may be a PCB 106.

[0019] The first BGA package 182 and the second BGA package 184 may be connected to the PCB 106 by soldering one or more BGA arrays 114, 116. For example, Figure 1 Further shown is a first BGA array 114 located between the package substrate 104 and the PCB 106 and a second BGA 116 array located between the PCB 106 and the power module 126. As shown, the BGA arrays 114, 116 can be aligned with the through-holes 118. However, in some examples, the BGA arrays 114, 116 may not be perfectly aligned, causing them to be offset from the through-holes 118. The package substrate 104 can be coupled to the PCB 106 by soldering the first BGA array 114, and the power module 126 can be coupled to the PCB 106 by soldering the second BGA array 116.

[0020] Figure 1The system 100 includes a vertical power delivery (“VPD”) assembly in which the package substrate 104 with the ASIC die 102 attached is mounted back-to-back on a power module 126 on the PCB 106. Power can then be delivered from the power module 126 to the ASIC package 102 through the PCB 106 via the first and second BGA arrays 114, 116.

[0021] Each BGA array 114, 116 can be aligned with a BGA footprint on the PCB 106. The BGA footprint on the PCB 106 can include structures such as VIPPO, deep back-drilled VIPPO, and non-VIPPO structures on or within the PCB 106. These structures can be used to route data from components connected to the BGA package to other locations and / or components. The VIPPO structure is a structure in which a conductive or non-conductive material completely fills the through-holes in the PCB 106 between the solder joints and / or BGA pads. In some examples, the VIPPO structure is plated with copper, which has a higher thermal conductivity and a lower "out-of-plane" coefficient of thermal expansion ("CTE") compared to the epoxy laminate of the PCB. The deep back-drilled VIPPO structure is a structure in which a portion of the conductive or non-conductive material is removed from the through-hole in the PCB, and the copper plating in that portion of the through-hole is removed. This results in a high CTE for the deep back-drilled VIPPO structure. The non-VIPPO structure is a structure in which no through-holes are used to connect the solder joints. However, the non-VIPPO structure has a high CTE, just like a PCB board. Mismatches in “out-of-plane” or Z-axis CTE between adjacent structures can result in solder separation defects during secondary reflow.

[0022] Figures 2A-2C Different structures that can be associated with the BGA arrays 114, 116 are shown. As explained herein, different structures may each have different thermal gradients due to differences in the percentage of copper (or other metal) under the BGA package and / or pads. In some examples, whether conductive or non-conductive, the structures may have different thermal gradients due to differences in materials that would otherwise form vias, as further discussed herein. According to some examples, the system 100 discussed above can use the various structures shown, and therefore, CTE mismatches may occur for each solder joint.

[0023] Solder joints 214, pads 213, and substrate 204 may be part of a BGA package, similar to ASICBGA package 182 discussed above. Pads 215 may be a BGA footprint of PCB 206.

[0024] Figure 2AStructure 200a is shown where a solder joint having a deep back-drilled VIPPO structure is formed. The deep back-drilled VIPPO structure removes at least a portion of the non-conductive or conductive material in the pad and the through hole. For example, through hole 218 may extend from one end of PCB 206 to the other end. Figure 2A As shown, a portion 232 of the through hole 218 and / or the plating within the through hole 218 can be removed, for example, by back drilling. Therefore, only a portion 233 of the conductive and / or non-conductive material can remain in the through hole 218. The retained portion 233 can be coupled to the pad 215 or adjacent to the pad 215. The solder joint 214 of the BGA array 114 can be positioned between the pad 213 and the pad 215. The pad 213 can be coupled to the ASIC package 204 or the package substrate to which the ASIC package 204 is attached, and the pad 215 can be coupled to the PCB 206 and / or the portion 233 of the through hole 218. In some examples, the solder joint 214 can be aligned with the through hole 218 and the portion 233 of the through hole 218 that has been back drilled. The deep back drilled VIPPO structure can have a high or increased CTE throughout the through hole 218 and the portion 233 of the through hole that has been removed.

[0025] Figure 2B Structure 200b of solder joints using a VIPPO structure is shown. The VIPPO structure is similar to a deep back-drilled VIPPO structure, but a portion of the through hole is not removed. Therefore, the through hole 218 and thus the non-conductive or conductive material within the through hole 218 extends from one end of the PCB 206 to the other end. The through hole 218 can be coupled to the pad 215 or adjacent to the pad 215. The solder joint 214 of the BGA array 114 can be positioned between the pad 213 and the pad 215. The pad 213 can be coupled to the ASIC package 204, or the packaging substrate to which the ASIC package 204 is attached, and the pad 215 can be coupled to the PCB 206 and / or the through hole 218. In some examples, the solder joint 214 can be aligned with the through hole 218. The VIPPO structure can have a high thermal conductivity via 218.

[0026] Figure 2C Structure 200c of a solder joint having a non-VIPPO structure is shown. Therefore, the solder joint does not have a through hole directly below the PCB pad of the solder joint. This can occur due to a mismatch between adjacent solder joints. For example, if the BGA package is offset from the VIA, the pads 213, 215 and / or solder joint 214 may not be aligned with the through hole. Therefore, the solder joint will not use the VIPPO structure. However, the non-VIPPO solder joint can have a high CTE across the PCB 206.

[0027] Solder defects and separation typically occur when there is an out-of-plane CTE mismatch under adjacent solder joints associated with VIPPO and non-VIPPO or deep back-drilled VIPPO structures. In some examples, solder separation occurs when the component is subjected to secondary reflow, either during top-side SMT for bottom components or during rework of adjacent or mirrored BGA components. Additionally or alternatively, solder separation defects may occur due to the difference in thermal gradients of each solder joint with different structures in the PCB under the BGA pad of the solder joint. For example, the different thermal gradients may be due to the percentage of copper under the BGA package pad. Therefore, the copper content of each VIPPO structure may cause one solder joint to become liquidus before the adjacent solder joint. In some examples, the non-VIPPO solder joint can remain solid, so that when the PCB is heated, the non-VIPPO solder joint expands and pushes the solid solder joint and ASIC upward. This may cause the liquidus VIPPO solder joint to disconnect. In some examples, once the solder becomes liquidus, the solder joints on various VIPPO structures may separate between the solder and the intermetallic compound ("IMC").

[0028] Figure 3 A plurality of structures 300 are shown in which solder joints are formed. The plurality of structures may be similar to those described with respect to Figures 2A-2C The structure described. For example, structure 300a may correspond to a deep back-drilled VIPPO structure, structure 300b may correspond to a VIPPO structure, and structure 300b may correspond to a VIPPO structure, and 300c may correspond to a non-VIPPO structure. Each structure 300a, 300b, 300c may have a different CTE and / or a higher thermal conductivity. The difference between the CTE and thermal conductivity between each structure 300a, 300b, 300c may cause some solder joints to become liquidus first. For example, solder joint 214 may become liquidus before solder joints 314a, 314b. Since solder joints 314a, 314b may remain solid longer than solder joint 214, the deep back-drilled VIPPO structure 300a and the non-VIPPO structure 300c may have greater expansion than the VIPPO structure 300b. In some examples, during the secondary reflow, this expansion may push the ASIC package 204 upward, thereby applying a tensile load on the solder joint 214. Once solder joint 214 becomes liquidus while solder joints 314 a , 314 b remain solid, solder joint 214 may be separated from the IMC at package pad interface 213 or PCB pad interface 215 .

[0029] For example, the structure 300 can be flipped so that the power module 126 is at the top. The structure 300 can be flipped to perform a secondary reflow process. The secondary reflow process can be used to solder the solder joint 374 to the BGA pad 373, and thus connect the BGA pad 373 to the structure 300a, 300b, 300c. During the secondary reflow process, the tension load on the VIPPO solder joint 214 may be due to the PCB expansion under the adjacent non-VIPPO pad. Since the solder joints 314a, 314b may still be solid, this expansion can push the ASIC package 204 away from the PCB. When the ASIC package 204 is pushed away from the PCB, the solder joint 214 is held in place by the VIPPO structure under the PCB BGA pad, so the solder joint 214 can be placed under tension. In some examples, the VIPPO structure has a lower "out-of-plane" CTE, which can act as a rivet that presses the solder joint down instead of expanding to push it away from the PCB. Additionally or alternatively, solder joint 214 may become liquidus before adjacent solder joints 314a, 314b due to the higher thermal conductivity of solder joint 214 beneath the PCB pad compared to solder joints 314a, 314b. In the example where solder joint 214 is in tension, it may separate from the IMC at the package pad or PCB pad. Figure 3 As shown, the solder joint 214 is separated from the package pad 213 by a space 303. According to some embodiments, the solder joint 214 may be separated from the PCB pad 215, and thus, the space may be between the solder joint 214 and the PCB pad 215.

[0030] In order to prevent solder separation defects, a compressive load component can be used after the BGA package is soldered between the ASIC package and the PCB and during the soldering of the power module to the PCB. Therefore, the ASIC package is located between the PCB and the compression plate. One or more compression mechanisms can be coupled to the top plate and the compression plate. One or more compression mechanisms can be configured to apply a compressive load to the compression plate, and thus to the ASIC package and the ASIC BGA package including the solder joints. In some examples, the compression mechanism can include a screw or a bolt, and at least one spring is positioned on the screw or the bolt so that the spring is positioned between the top plate and the compression plate. The screw or bolt can be tightened to adjust the amount of elastic force applied by the compression mechanism on the compression plate. Therefore, the elastic force applied to the compression plate can be transmitted to apply a compressive load on the ASIC package and the ASIC BGA package. The compressive load can be applied in a direction away from the top plate and toward the compression plate. According to some examples, when the top plate and the compression plate are coupled to the PCB, the compressive load can be toward the PCB.

[0031] The compressive load may overcome the tensile force to prevent solder separation defects. In some examples, the compressive load may be sufficient to overcome the tensile force to hold the solder joint during rework or secondary reflow. Additionally, the compressive load may not be sufficient to deform the solder joint shape or significantly change the solder standoff. The standoff may be the distance between the PCB and the ASIC after reflow.

[0032] In particular, the metal in the via of the VIPPO structure may have a lower "out-of-plane" CTE than the non-VIPPO and deep back-drilled VIPPO structures. In contrast, the non-VIPPO and deep back-drilled VIPPO structures may have a higher "out-of-plane" CTE than the VIPPO structure because less metal or no metal is positioned in the via.

[0033] As described above, solder separation defects may occur when there is a mismatch under adjacent solder joints with VIPPO, non-VIPPO and / or deep back-drilled VIPPO structures. Solder separation defects may be caused by one or both of out-of-plane CTE mismatch and thermal gradient differences between adjacent solder joints with VIPPO and non-VIPPO or deep back-drilled VIPPO structures.

[0034] The compressive load assembly can apply a compressive load that overcomes the tension that typically causes solder separation defects. Additionally or alternatively, the compressive load can be low enough not to deform the solder joint shape or change the solder standoff. In some examples, the compressive load assembly holds the solder during rework or secondary reflow.

[0035] Figure 4 is a compressive load assembly 400 for applying a compressive force on the ASIC package during a reflow process. The compressive load assembly 400 may be configured to position the ASIC package with respect to the Figure 1 One or more components of the ASIC package described herein. In particular, the system can apply a compressive load to the BGA package to maintain the solder joints between the package and the PCB. For example, the assembly 400 can apply a compressive force to the ASIC BGA package 182 during rework or secondary reflow. Rework or secondary reflow may occur when the ASIC BGA package 182 is rotated 180 degrees about the horizontal axis of the ASIC BGA package 182, or flipped upside down to perform soldering of the second BGA package 184 or the power module BGA package to the PCB.

[0036] The compression load assembly 400 may include a top plate 340, a compression plate 354, a PCB 106, one or more compression mechanisms 350, and one or more alignment studs 344. The compression mechanism 350 may include a bolt 352 and a spring (eg, Figure 4). Assembly 400 may also include a stop assembly 457. The stop assembly may include a nut and a bolt. The stop assembly 457 may provide a hard stop or maximum compression distance. The stop assembly may ensure that the spring is not over-compressed and thus becomes damaged.

[0037] The top plate 340 may include one or more counterbores 346. Each counterbore 346 may include a through hole axially aligned with the counterbore 346. The counterbore 346 and the through hole may be configured to receive a bolt 352 of the compression mechanism 350. Each bolt 352 of the compression mechanism 350 may include a head 342 and a shaft 464 (in Figure 4 346). The head 348 of the bolt 352 can be assembled in the counterbore 346. The shaft of the bolt 352 can be assembled in the through hole. According to some examples, the shaft of the bolt 352 can be threaded, and the through hole receiving the shaft of the bolt 352 can have threads that match the threads of the shaft. Therefore, the bolt 352 can be threadedly coupled with the compression plate 354.

[0038] A spring may be located on the axis of each bolt 352. The spring may be positioned between the top plate 340 and the compression plate 354. The spring may apply a force on the compression plate 354 in a direction away from the top plate and toward the compression plate 354. The force applied by the spring may be evenly distributed across the compression plate 354 and may result in an evenly distributed force being applied to the ASIC BGA package 182. According to some examples, the spring force on the compression plate 354 applies a force on the ASIC BGA package 182 or a component of the ASIC BGA package 182, such as the ASIC die 102. Additionally or alternatively, the spring may be used to reduce or dampen vibrations during a reflow process.

[0039] As shown, there may be seven (7) compression mechanisms 350. However, in some examples, there may be six (6) compression mechanisms 350, three (3) compression mechanisms 350, nine (9) compression mechanisms 350, etc. Thus, the seven compression mechanisms 350 shown are merely an example and are not meant to be limiting.

[0040] The top plate 340, and thus the compression plate 354, can be releasably coupled to the PCB 106 via one or more coupling mechanisms. Each coupling mechanism can include an alignment stud 344 and a threaded member. Each alignment stud 344 can be coupled to the top plate 340. According to some embodiments, the alignment stud 344 can be integrated with the top plate 340. The alignment stud 344 can include a threaded hole or a threaded through hole along the longitudinal axis of the alignment stud 344. The threaded hole of the alignment stud 344 can be configured to accommodate a threaded member.

[0041] A threaded member may be inserted through a hole in PCB 106 to couple PCB 106 and top plate 340. The threaded member may be screwed into the threaded hole aligned with stud 344. Thus, PCB 106 and top plate 340 may be releasably coupled. By coupling PCB 106 and top plate 340, the spring of compression mechanism 350 may compress and thus exert a force on the ASIC package. In particular, the spring may exert a force on compression plate 354 and ASIC 102 in the direction of PCB 106, regardless of the orientation of the compression load assembly and the ASIC package (i.e., regardless of whether the compression load assembly and the ASIC package are upright or upside down). According to some examples, PCB 106 and top plate 340 may be permanently coupled.

[0042] In another example, assembly 400 may include a bottom plate. In such an example, top plate 340 and therefore compression plate 354 may be releasably coupled to the bottom plate via one or more coupling mechanisms. As described above, the coupling of top plate 340 and compression plate 354 to the bottom plate may be similar to the coupling of top plate 340 and compression plate 354 to PCB 106.

[0043] Figure 5 A side perspective view of a compressive load assembly 500 is shown. Assembly 500 may be similar to Figure 3 The assembly 400 is described, and therefore, the same or similar reference numerals may be used to describe similar components. The compression load assembly 500 may include a top plate 340, a compression plate 354, a reinforcement 466, one or more compression mechanisms 350, one or more alignment studs 344, and one or more threaded members 460 for coupling the PCB 106 to the alignment studs 344. The compression mechanism 350 may include a bolt 352 and a spring 462.

[0044] As described above, the top plate 340 may be coupled to the PCB 106 via the alignment studs 344. The threaded members 460 may be inserted through holes in the PCB 106 and into threaded holes of the alignment studs 344. The threaded members 460 threadably couple the PCB 106 to the top plate 340.

[0045] As shown, each spring 462 of the compression mechanism 350 can be positioned between the top plate 340 and the compression plate 354. The spring 462 can apply a compressive force or compressive load on the compression plate and therefore on the ASIC 102. The compressive load can be adjusted by rotating the bolt 352. For example, tightening the bolt 352 can compress the spring 462. The greater the compression of the spring 462, the greater the force applied by the spring 462 on the compression plate 354. Conversely, loosening the bolt 352 can decompress the spring 462. The less the compression of the spring 462, the less the force applied by the spring 462 on the compression plate 354. Therefore, the compressive load generated by the compression mechanism can be adjusted based on the specifications required to manufacture the ASIC package.

[0046] According to some examples, as shown, assembly 500 has PCB 106 as a bottom layer and top plate 340 as a top layer. When assembly 500 is flipped over so that PCB 106 is the top layer and top plate 340 is the bottom layer, assembly 500 can maintain solder joints during a reflow process.

[0047] For example, during the reflow process, the metal of the VIPPO structure may be heated first due to the metal throughout the through-hole. As previously described, the metal in the through-hole of the VIPPO structure may have a lower "out-of-plane" or Z-axis CTE than the non-VIPPO and deep back-drilled VIPPO structures. In contrast, the non-VIPPO and deep back-drilled VIPPO structures may have a higher "out-of-plane" CTE than the VIPPO structure because less metal or no metal is positioned in the through-hole. In some examples, the solder joints above the VIPPO structure may become liquidus before the solder joints above the non-VIPPO and / or deep back-drilled VIPPO structures, so that the solder joints above the non-VIPPO and / or deep back-drilled VIPPO can remain solid. When the non-VIPPO and deep back-drilled VIPPO structures are heated, the package substrate is pushed outward, which may weaken or disconnect the VIPPO structure. Once the non-VIPPO and deep back-drilled VIPPO are completely liquid, strain can be removed from the VIPPO structure. Thus, the compressive load assembly 500 can be used to remove and / or reduce stress on solder joints above the VIPPO structure, while liquefying solder joints above the non-VIPPO and deep back-drilled VIPPO structures. The uniform compressive load applied by the compression mechanism 350 can maintain the liquefied solder joints above the VIPPO structure, while liquefying solder joints above the non-VIPPO and deep back-drilled VIPPO structures. In some examples, the compressive load can prevent the solder joints above the VIPPO structure from separating between the bulk solder and the IMC at the BGA pad. Additionally or alternatively, the compressive load can overcome or be greater than the tension that causes the solder separation defect.

[0048] The compressive load assembly 500 may have a thermal mass that does not significantly affect the reflow profile of the power module. Additionally or alternatively, the compressive load system 500 may withstand up to 245 degrees Celsius of a tin-silver-copper (SAC) reflow profile without introducing warping effects to the ASIC solder joints. The ASIC solder joints may be solder joints between a PCB and an ASIC.

[0049] Figure 6 is a side perspective view of the compression load assembly 600 . Figure 6 and Figure 5 Substantially similar, but also includes a plurality of protrusions 570 extending away from the compression plate 354 and toward the top plate 340 , and also includes a stiffener 572 located between the compression plate 354 and the ASIC 102 .

[0050] The compression plate 354 may have a plurality of protrusions 570. The protrusions 570 may be used to couple or align the top plate 340 with the compression plate 354. For example, each protrusion may have a threaded threaded hole configured to cooperate with the threads of the bolt 352. Therefore, the threaded hole of each protrusion 570 may threadably receive the bolt 352. The bolt 352 is screwed into the protrusions 570, thereby coupling the compression plate 354 and the top plate 340. According to some examples, the further each bolt 352 is screwed into each protrusion 570, the greater the compressive load applied by each spring 462 to the compression plate 354.

[0051] As shown, each spring 462 of the compression mechanism 350 can be positioned between the top plate 340 and the compression plate 354. The spring 462 can apply a compressive force or compressive load on the compression plate 354, which then applies a compressive force on the stiffener 572 while also applying a force on the ASIC BGA package 182 including the ASIC die 102. The stiffener 572 can be made of silicone and configured to absorb shock, thereby applying a uniform compressive load on the ASIC BGA package 182. According to some examples, the stiffener 572 can be a protective layer between the compression plate 354 and the ASIC die 102. As a protective layer, the stiffener 572 can protect the fragile components of the ASIC die 102 from being damaged by the hard compression plate 354.

[0052] The compressive load assembly can be used in examples other than those disclosed herein. For example, when soldering adjacent structures, the compressive load assembly can be used. In particular, due to different structures having different CTEs and thermal conductivities, it may be necessary to use a compressive load assembly to prevent solder separation defects from occurring. Therefore, the compressive load assembly can be used in other applicable situations besides the secondary reflow process.

[0053] Although the examples described herein relate to ASIC packages and power modules, the compressive load assembly can be used with other components attached to a substrate package, such as an integrated circuit, a system on a chip, a memory, etc. For example, the compressive load assembly can be used to attach any two separate components so that two BGA packages are mounted back to back. Therefore, references to ASIC packages and power modules herein are for illustration only and are not meant to be limiting.

[0054] Unless otherwise stated, the aforementioned alternative examples are not mutually exclusive, but can be implemented in various combinations to achieve unique advantages. Since these and other variations and combinations of the features discussed above can be utilized without departing from the subject matter defined by the claims, the aforementioned description of the embodiments should be carried out by way of illustration rather than by way of the subject matter defined. As required. In addition, the provision of the examples described herein and the phrases expressed as "such as", "including", etc. should not be interpreted as limiting the subject matter of the claims to specific examples. On the contrary, these examples are intended only to illustrate one of many possible embodiments. In addition, the same reference numerals in different figures may identify the same or similar elements.

Claims

1. A compressive load assembly for applying a compressive force on a ball grid array (BGA) package, the compressive load assembly comprising: roof; one or more coupling mechanisms configured to releasably couple the top plate to a printed circuit board PCB, wherein each of the one or more coupling mechanisms comprises an alignment stud and a threaded member, wherein the alignment stud is integral with the top plate and includes a threaded hole; and One or more compression mechanisms are coupled to the top plate, wherein the one or more compression mechanisms are configured to apply a compressive load on the BGA package in a direction away from the top plate.

2. The compressive load assembly of claim 1, wherein: Each compression mechanism includes a compression member and at least one spring located on the compression member.

3. The compressive load assembly of claim 2, further comprising a compression plate, wherein: The at least one spring is positioned between the compression plate and the top plate.

4. The compressive load assembly of claim 2, wherein: Each compression member includes a head and a shaft.

5. The compressive load assembly according to claim 4, in, The top plate includes one or more countersunk holes, and Wherein, the one or more counterbores are configured to accommodate a head portion of each compression member.

6. The compressive load assembly of claim 4, further comprising a compression plate, in, The compression plate includes one or more through holes, and Wherein, the one or more through holes are configured to receive the shaft of each compression member.

7. The compressive load assembly of claim 4, wherein: The head of each compression member is positioned on a first side of the top plate, and the at least one spring of each compression mechanism is positioned on a second side of the top plate opposite the first side.

8. The compressive load assembly of claim 1, wherein: The one or more compression mechanisms are capable of advancing or retracting such that the compression load is adjustable.

9. The compressive load assembly of claim 8, wherein: As the one or more compression mechanisms advance, the compression load increases.

10. The compressive load assembly of claim 8, wherein: When the one or more compression mechanisms are retracted, the compression load is reduced.

11. The compressive load assembly of claim 2, wherein: The at least one spring is configured to dampen vibrations.

12. The compressive load assembly according to any one of claims 1 to 11, wherein: The one or more compression mechanisms include at least six compression mechanisms.

13. The compressive load assembly of claim 12, further comprising a compression plate, wherein: The at least six compression mechanisms are distributed on the compression plate.

14. The compressive load assembly of claim 13, wherein: The at least six compression mechanisms are configured to provide a uniform compressive load across the BGA package.

15. A compressive load assembly for applying a compressive force on a ball grid array (BGA) package, the compressive load assembly comprising: roof; one or more coupling mechanisms extending from the top plate, the one or more coupling mechanisms being configured to releasably couple the top plate with a printed circuit board (PCB), wherein each of the one or more coupling mechanisms comprises an alignment stud and a threaded member integrated with the top plate; and one or more compression mechanisms coupled to the top plate, wherein each of the one or more compression mechanisms comprises a compression member and at least one spring located on the compression member, wherein the one or more compression mechanisms are configured to apply a compressive load on the BGA package in a direction away from the top plate, wherein the top plate includes one or more countersunk holes, and Wherein, the one or more counterbores are configured to receive a head portion of the compression member.

16. A compressive load assembly for applying a compressive force on a ball grid array (BGA) package, the compressive load assembly comprising: roof; one or more coupling mechanisms extending from the top plate, the one or more coupling mechanisms being configured to releasably couple the top plate and a printed circuit board (PCB), wherein each of the one or more coupling mechanisms comprises an alignment stud and a threaded member, the alignment stud being integral with the top plate; and one or more compression mechanisms coupled to the top plate, wherein the one or more compression mechanisms are configured to apply a compressive load to the BGA package in a direction away from the top plate, Wherein, the PCB comprises at least one PCB through hole aligned with the threaded hole of the alignment stud, and the at least one PCB through hole and the threaded hole of the alignment stud are configured to accommodate the threaded member.

17. A compressive load assembly for applying a compressive force on a ball grid array (BGA) package, the compressive load assembly comprising: roof; one or more coupling mechanisms extending from the top plate, the one or more coupling mechanisms being configured to releasably couple the top plate with a printed circuit board (PCB), wherein each of the one or more coupling mechanisms comprises an alignment stud and a threaded member integrated with the top plate; and one or more compression mechanisms releasably coupled to the top plate and extending in a direction toward the BGA package, wherein the one or more compression mechanisms are configured to apply a compressive load to the BGA package in a direction away from the top plate, wherein each compression mechanism comprises a compression member that is at least partially threaded, and Wherein, the one or more compression mechanisms can be advanced or retracted in a threaded manner so that the compression load is adjustable.

18. A compressive load assembly for applying a compressive force on a ball grid array (BGA) package, the compressive load assembly comprising: roof; one or more coupling mechanisms extending from the top plate, the one or more coupling mechanisms being configured to releasably couple the top plate with a printed circuit board (PCB), wherein each of the one or more coupling mechanisms comprises an alignment stud and a threaded member integrated with the top plate; and one or more compression mechanisms adjustably coupled to the top plate and extending in a direction toward the BGA package, wherein each of the one or more compression mechanisms comprises a bolt and at least one spring positioned on each compression member, wherein, when each of the bolts is rotated in a first direction, the one or more compression mechanisms are configured to apply a first compressive load on the BGA package in a direction away from the top plate toward the BGA package, and Wherein, when each of the bolts is rotated in a second direction, the one or more compression mechanisms are configured to apply a second compression load on the BGA package in a direction away from the top plate toward the BGA package, and the second compression load is less than the first compression load.

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