BGA chip circuit board bonding pad structure of computing power card
By designing a fixed PAD consisting of a copper layer and an insulating layer on the BGA chip circuit board, combined with a raised portion and a blind hole heat dissipation structure, the cracking problem caused by the stress difference between the high-power chip and the circuit board was solved, and the stability and heat dissipation efficiency were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- VICTORY GIANT TECH HUIZHOU CO LTD
- Filing Date
- 2025-05-28
- Publication Date
- 2026-05-05
AI Technical Summary
Existing BGA chip circuit boards, under the requirements of high power, high frequency and high reliability, cannot meet the problem of PCB bottom cracks caused by stress differences due to the four corner fixed PAD design.
Design a BGA chip circuit board pad structure for a computing power card. The fixed PAD is composed of a copper layer and an insulating layer. The protrusion is connected to or disconnected from the copper layer. The insulating layer surrounds the outer perimeter and an opening is set at the protrusion to form multiple parallel heat channels and elastic deformation space. Heat dissipation is achieved through blind holes or stacked holes.
It improves the stability of chip-circuit board bonding and heat dissipation efficiency, avoids stress concentration, reduces substrate cracks, and enhances electrical isolation reliability and thermal performance.
Smart Images
Figure CN224205319U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of circuit board technology, specifically to a solder pad structure for a BGA chip circuit board. Background Technology
[0002] With the advent of the AI era, AI computing cards require the use of high-power, high-frequency, and high-reliability chips with thousands of watts. During production testing, it was found that the stress difference between these high-power, high-frequency, and high-reliability chips and the circuit board (PCB) was too large, causing cracks to appear on the bottom of the PCB. This is mainly because the four corner fixing pads on the existing BGA chip circuit board are based on traditional chips. Traditional chips have a power of only a few watts, low frequency, and average reliability. It can be seen that the design of the four corner fixing pads on the traditional circuit board can no longer meet the requirements of product development. Utility Model Content
[0003] The purpose of this invention is to provide a BGA chip circuit board pad structure for computing cards that can improve heat dissipation efficiency, avoid stress concentration, and improve the bonding stability between the chip and the circuit board.
[0004] A BGA chip circuit board pad structure for a computing power card includes a substrate. A copper layer and an insulating layer are provided at each of the four corners of one side of the substrate. A plurality of fixed pads are arranged in a symmetrical array on the copper layer. Each fixed pad includes a main body and a plurality of protrusions. The protrusions are connected to or disconnected from the copper layer. If the protrusion is disconnected from the copper layer, the insulating layer completely surrounds the outer periphery of the fixed pad. If the protrusion is connected to the copper layer, the insulating layer has an opening corresponding to the position of the protrusion.
[0005] In the above scheme, both the outer periphery of the fixed PAD and the insulating layer are copper layers. This design increases the residual copper ratio in the BGA chip area of the computing card, effectively reducing the local temperature difference between the chip and the PCB, and reducing thermal stress caused by the mismatch of thermal expansion coefficients. The symmetrical distribution of multiple fixed PADs evenly disperses the mechanical load of the chip on the substrate, thereby reducing the stress difference between the BGA chip and the substrate area of the computing card, avoiding stress concentration that could lead to cracks in the substrate. The protrusions on the fixed PADs can increase the bonding force between the chip and the substrate. The instantaneous temperature rise during the operation of high-power chips may cause the copper layer to expand rapidly. Disconnecting the connection can reduce the tensile stress on the protrusions due to the difference in thermal expansion. The insulating layer completely surrounds the outer periphery of the fixed PADs, ensuring the reliability of electrical isolation. The openings in the insulating layer at the protrusions allow the protrusions to connect with the copper layer, which is equivalent to adding a vertical heat dissipation channel for the chip's heat. Heat can be quickly conducted to the interior of the substrate or heat dissipation components through the copper layer.
[0006] Furthermore, the number of fixed PADs at each corner is between 5 and 9.
[0007] In the above scheme, the symmetrical array of 5-9 pads can increase the force in both the horizontal and vertical directions, thereby improving the connection stability between the chip and the substrate. It can ensure that the mechanical load of the chip on the substrate is evenly distributed in both the longitudinal and transverse directions, thus avoiding substrate cracking due to stress concentration.
[0008] Furthermore, the main body is circular, and there are four protrusions, which are connected to the copper layer.
[0009] In the above scheme, compared with traditional square or polygonal pads, the circular fixed PAD has no sharp corners, which can avoid the propagation of microcracks caused by stress concentration and improve the durability of the pad under thermal cycling and mechanical vibration. The four protrusions are symmetrically distributed at 90° (cross-shaped layout), ensuring that at least two protrusions bear the load when the fixed PAD is subjected to force in any direction, avoiding single-point failure. The four protrusions are directly connected to the copper layer, forming multiple parallel thermal channels, which significantly reduces thermal resistance.
[0010] Furthermore, the width of the protrusion is between 5 mil and 7 mil.
[0011] In the above scheme, the protrusion width design of 5mil~7mil (0.127mm~0.178mm) can provide elastic deformation space during thermal expansion or mechanical vibration, effectively absorbing the stress difference between the substrate and the chip.
[0012] Furthermore, the main body is circular, and there are two protrusions, which are distributed horizontally or vertically and connected to the copper layer.
[0013] In the above solution, the two protrusions are symmetrically distributed horizontally or vertically, which can specifically resist the main deformation of the PCB in the X-axis or Y-axis direction. Compared with the four protrusions, the processing accuracy is reduced, and the cost is more advantageous.
[0014] Furthermore, the main body is circular, and there are two protrusions that are distributed at a 45° angle and connected to the copper layer.
[0015] In the above scheme, the two protrusions are inclined at a 45° angle, which enables the fixed PAD to have a certain support and constraint in multiple directions such as horizontal, vertical and oblique. Compared with the horizontal or vertical protrusions, this 45° inclined distribution can more comprehensively cope with complex stress environment, avoid structural damage caused by excessive stress in one direction, and enhance the overall structural stability of the substrate.
[0016] Furthermore, the main body is circular, and there are two protrusions that are distributed at a 45° angle and are disconnected from the copper layer.
[0017] In the above scheme, the two protrusions, which are inclined at a 45° angle, can buffer and disperse these stresses from different directions. This distribution method enables the fixed PAD to have a certain buffering capacity in multiple directions, such as horizontal, vertical and oblique. Compared with protrusions distributed in a single direction, it can more comprehensively cope with stress in all directions and reduce stress concentration. When the circuit board is subjected to external force or thermal stress, the disconnected connection method allows the protrusions to have a certain independent movement space, which can better absorb and disperse stress, reduce the risk of pad damage and circuit breakage caused by stress concentration, and thus improve the reliability and stability of the entire substrate.
[0018] Furthermore, the main body is circular, and there are two protrusions that are vertically distributed and disconnected from the copper layer.
[0019] In the above design, the two vertically distributed protrusions can specifically buffer and disperse vertical stress. When the circuit board deforms vertically, the protrusions can absorb some of the stress through their elastic deformation, preventing stress concentration in the main body or other critical parts. This reduces structural damage caused by stress concentration, such as pad cracking and circuit breakage, thus improving the overall reliability and stability of the substrate. Compared with the copper layer connection design, the disconnection avoids stress being directly transferred from the protrusions to the copper layer and then diffused throughout the entire substrate. This relatively independent structure can better adapt to different levels of stress changes, further enhancing the substrate's ability to withstand stress.
[0020] Furthermore, the substrate is provided with a layer of blind holes or stacked holes, which are located in the middle of the fixed PAD.
[0021] In the above scheme, blind vias or stacked vias can serve as heat dissipation channels, conducting the heat generated by heat-generating components such as chips from one side of the substrate to the other, increasing the heat dissipation area and heat dissipation path. Especially for chips with high power and severe heat generation, blind vias or stacked vias can more effectively dissipate heat, reduce the chip's operating temperature, improve the chip's stability and reliability, and extend its service life. The blind vias or stacked vias are located in the middle of the fixed PAD, which helps to distribute heat more evenly across the entire substrate, avoiding the occurrence of local overheating, reducing problems such as substrate deformation and solder joint failure caused by thermal stress concentration, and improving the overall thermal performance of the computing card BGA chip circuit board.
[0022] Furthermore, the blind hole is filled with electroplated copper or resin.
[0023] In the above scheme, copper has a high thermal conductivity. The copper-plated blind holes can serve as heat conduction channels, quickly transferring the heat generated by the chip and other heat-generating components to other parts of the substrate, thereby dissipating it. This effectively reduces the chip's operating temperature and improves its performance and reliability. Resin filling can fill the gaps inside the blind holes, forming a sealed structure that prevents moisture, dust, and other impurities from entering the blind holes, avoiding corrosion and damage to the circuits, and improving the circuit board's moisture-proof, dust-proof performance and service life.
[0024] The BGA chip circuit board pad structure of this utility model has the beneficial effects of improving heat dissipation efficiency, avoiding stress concentration, and improving the bonding stability between the chip and the circuit board. The outer periphery of both the fixing PAD and the insulating layer is a copper layer. This design increases the residual copper ratio in the BGA chip area of the computing card, effectively reducing the local temperature difference between the chip and the PCB, and reducing thermal stress caused by the mismatch of thermal expansion coefficients. Multiple fixing PADs are symmetrically distributed, evenly dispersing the mechanical load of the chip on the substrate, thereby reducing stress differences between the BGA chip and the substrate area and preventing stress concentration that could lead to substrate cracks. The protrusions on the fixing PADs increase the bonding force between the chip and the substrate. The instantaneous temperature rise during high-power chip operation may cause the copper layer to expand rapidly; disconnecting the connection reduces the tensile stress on the protrusions due to thermal expansion differences. The insulating layer completely surrounds the outer periphery of the fixing PADs, ensuring reliable electrical isolation. Openings in the insulating layer at the protrusions connect the protrusions to the copper layer, effectively adding a vertical heat dissipation channel for the chip's heat. Heat can be quickly conducted to the interior of the substrate or heat dissipation components through the copper layer. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the pad structure of a BGA chip circuit board for a computing power card according to one embodiment.
[0026] Figure 2 This is a schematic diagram of the fixed PAD structure in Example 1.
[0027] Figure 3 This is a schematic diagram of the fixed PAD structure in Example 2.
[0028] Figure 4 This is a schematic diagram of the fixed PAD structure in Example 3.
[0029] Figure 5 This is a schematic diagram of the fixed PAD structure in Example 4.
[0030] Figure 6 This is a schematic diagram of the fixed PAD structure in Example 5.
[0031] Explanation of reference numerals in the attached diagram: 1. Substrate; 2. Copper layer; 3. Insulating layer; 4. Fixing PAD; 41. Main body; 42. Protrusion; 5. Blind hole. Detailed Implementation
[0032] The following will describe in further detail the pad structure of a BGA chip circuit board for a computing power card according to this utility model, with reference to specific embodiments and accompanying drawings.
[0033] like Figures 1 to 6 As shown in a preferred embodiment, the BGA chip circuit board pad structure of this utility model includes a substrate 1. Copper layers 2 and insulating layers 3 are provided at the four corners of one side of the substrate 1. A plurality of symmetrically arranged fixed pads 4 are provided on the copper layers 2. Each fixed pad 4 includes a main body 41 and a plurality of protrusions 42. The protrusions 42 are connected to or disconnected from the copper layers 2. If the protrusions 42 are disconnected from the copper layers 2, the insulating layer 3 completely surrounds the outer periphery of the fixed pad 4. If the protrusions 42 are connected to the copper layers 2, the insulating layer 3 has an opening corresponding to the position of the protrusions 42. The outer periphery of both the fixed pads 4 and the insulating layer 3 is the copper layer 2. This design increases the residual copper ratio in the BGA chip area of the computing card, effectively reducing the local temperature difference between the chip and the PCB, reducing thermal stress caused by mismatched coefficients of thermal expansion. The symmetrical distribution of multiple fixed pads 4 evenly disperses the mechanical load of the chip on the substrate 1, thereby reducing the stress difference between the computing card BGA chip and the substrate 1 area and preventing stress concentration that could lead to cracks in the substrate 1.
[0034] The protrusion 42 on the fixed PAD4 can increase the bonding force between the chip and the substrate 1. The instantaneous temperature rise when the high-power chip is working may cause the copper layer 2 to expand rapidly. Disconnecting the connection can reduce the tensile stress on the protrusion 42 due to the difference in thermal expansion. The insulating layer 3 completely surrounds the outer periphery of the fixed PAD4 to ensure the reliability of electrical isolation. The insulating layer 3 has an opening at the position of the protrusion 42 so that the protrusion 42 is connected to the copper layer 2, which is equivalent to adding a vertical heat dissipation channel for the chip heat. Heat can be quickly conducted to the interior of the substrate 1 or heat dissipation components through the copper layer 2.
[0035] like Figures 1 to 6 As shown, in some embodiments, the number of fixed PAD4s at each corner is between 5 and 9. The symmetrical array of 5-9 pads can increase the force in both the horizontal and vertical directions, thereby improving the connection stability between the chip and the substrate 1. It can ensure that the mechanical load of the chip on the substrate 1 is evenly distributed in both the longitudinal and lateral directions, thus avoiding cracking of the substrate 1 due to stress concentration.
[0036] like Figures 1 to 6As shown, in some embodiments, the width of the protrusion 42 is between 5 mil and 7 mil. The protrusion 42 width design of 5 mil to 7 mil (0.127 mm to 0.178 mm) can provide elastic deformation space during thermal expansion or mechanical vibration, effectively absorbing the stress difference between the substrate 1 and the chip.
[0037] like Figures 1 to 6 As shown, in some embodiments, a layer of blind vias 5 or stacked vias is provided on the substrate 1, with the blind vias 5 or stacked vias located in the middle of the fixed PAD 4. The blind vias 5 or stacked vias can serve as heat dissipation channels, conducting the heat generated by heat-generating components such as chips from one side of the substrate 1 to the other, increasing the heat dissipation area and heat dissipation path. Especially for chips with high power and severe heat generation, the blind vias 5 or stacked vias can more effectively dissipate heat, reduce the chip's operating temperature, improve the chip's stability and reliability, and extend its service life. The blind vias 5 or stacked vias located in the middle of the fixed PAD 4 help to distribute heat more evenly across the entire substrate 1, avoiding local overheating and reducing problems such as substrate 1 deformation and solder joint failure caused by thermal stress concentration, thereby improving the overall thermal performance of the computing card BGA chip circuit board.
[0038] like Figures 1 to 6 As shown, in some embodiments, the blind via 5 is filled with electroplated copper or resin. Copper has a high thermal conductivity, and the copper-filled blind via 5 can serve as a heat conduction channel, quickly transferring the heat generated by the chip and other heat-generating components to other parts of the substrate 1 for dissipation. This effectively reduces the operating temperature of the chip, improving its performance and reliability. Resin filling can fill the gaps inside the blind via 5, forming a sealed structure to prevent moisture, dust, and other impurities from entering the blind via 5, avoiding corrosion and damage to the circuitry, and improving the circuit board's moisture-proof, dust-proof performance and service life.
[0039] In the above embodiment, the fixed PAD4 is connected to the inner layer through the blind via 5 stacked via design. The inner layer is a copper surface or a ground layer. The blind via 5 can be directly connected to the copper surface for current flow or heat dissipation.
[0040] In addition, the PAD4 is fixed by connecting the inner layer through the blind via 5 stacked via design. The inner layer is the circuit layer. With the space of the circuit layer confirmed, the blind via 5 below the PAD4 is designed to connect a small copper surface. A safe distance is made between the small copper surface and the signal line. The copper width is larger where the spacing is large and smaller where the spacing is small. Example 1
[0041] like Figure 2As shown, in this embodiment, the main body 41 is circular, and there are four protrusions 42, which are connected to the copper layer 2. Compared with traditional square or polygonal pads, the circular fixed PAD4 has no sharp corners, which can avoid the propagation of microcracks caused by stress concentration and improve the durability of the pad under thermal cycling and mechanical vibration. The four protrusions 42 are symmetrically distributed at 90° (cross-shaped layout), ensuring that at least two protrusions 42 bear the load when the fixed PAD4 is subjected to force in any direction, avoiding single-point failure. The four protrusions 42 are directly connected to the copper layer 2, forming multiple parallel thermal channels, which significantly reduces thermal resistance. Example 2
[0042] like Figure 3 As shown, this embodiment is basically the same in structure and principle as Embodiment 1. The difference is that the main body 41 is circular, and there are two protrusions 42. The two protrusions 42 are distributed horizontally or vertically and connected to the copper layer 2. The two protrusions 42 are symmetrically distributed horizontally or vertically, which can specifically resist the main deformation of the PCB in the X-axis or Y-axis direction. Compared with four protrusions 42, the processing accuracy is reduced, which is more cost-effective. Example 3
[0043] like Figure 4 As shown, this embodiment is basically the same in structure and principle as Embodiment 1. The difference is that the main body 41 is circular, and there are two protrusions 42. The two protrusions 42 are distributed at a 45° angle and connected to the copper layer 2. The two protrusions 42 are distributed at a 45° angle, which enables the fixed PAD to have a certain support and constraint in multiple directions such as horizontal, vertical and oblique. Compared with the horizontal or vertical distribution of the protrusions 42, this 45° oblique distribution can more comprehensively cope with complex stress environment, avoid structural damage caused by excessive stress in one direction, and enhance the overall structural stability of the substrate 1. Example 4
[0044] like Figure 5As shown, this embodiment is basically the same in structure and principle as Embodiment 1. The difference is that the main body 41 is circular, and there are two protrusions 42. The two protrusions 42 are distributed at a 45° angle and are disconnected from the copper layer 2. The two protrusions 42 distributed at a 45° angle can buffer and disperse these stresses from different directions. This distribution method allows the fixed PAD to have a certain buffering capacity in multiple directions such as horizontal, vertical and oblique. Compared with the protrusions 42 distributed in a single direction, it can more comprehensively cope with stress in all directions and reduce stress concentration. When the circuit board is subjected to external force or thermal stress, the disconnected connection method allows the protrusions 42 to have a certain independent movement space, which can better absorb and disperse stress, reduce the risk of pad damage and circuit breakage caused by stress concentration, and thus improve the reliability and stability of the entire substrate 1.
[0045] In this embodiment, if the center-to-center distance between two adjacent fixed PAD4s is 36 mil and the diameter of the main body 41 is 17.8 mil, it can be known that the theoretical edge distance between two adjacent fixed PAD4s is 18.2 mil. Inserting a copper layer 2 trace or heat dissipation copper surface into the 18.2 mil gap will make the distance between the copper surface and the pads on both sides 5 mil, thus maximizing the copper coverage. Example 5
[0046] like Figure 6 As shown, this embodiment is basically the same in structure and principle as Embodiment 1, except that the main body 41 is circular and there are two protrusions 42. The two protrusions 42 are vertically distributed and disconnected from the copper layer 2. The two vertically distributed protrusions 42 can specifically buffer and disperse vertical stress. When the circuit board deforms in the vertical direction, the protrusions 42 can absorb part of the stress through their own elastic deformation, avoiding stress concentration in the main body 41 or other critical parts. This reduces structural damage caused by stress concentration, such as pad cracking and circuit breakage, and improves the overall reliability and stability of the substrate 1. Compared with the design of connecting to the copper layer 2, disconnecting the connection avoids the situation where stress is directly transmitted from the protrusions 42 to the copper layer 2 and then diffused to the entire substrate 1. This relatively independent structure can better adapt to different degrees of stress changes, further enhancing the substrate 1's ability to withstand stress.
[0047] In this embodiment, if the center-to-center distance between two adjacent fixed PAD4s is 36 mil, the diameter of the main body 41 is 17.8 mil, and the length of the protrusion 42 is 7 mil, then the length of one fixed PAD4 plus the protrusion 42 is 31.8 mil. It can be concluded that the theoretical distance between the edges of two adjacent fixed PAD4s is only 4.2 mil. The space here is too small, so the copper surface in the middle can be directly used to make the distance.
[0048] This invention discloses the working principle and process of a BGA chip circuit board pad structure for a computing power card. When the chip is operating, the heat generated is first transferred to the fixed PAD4 in contact with it. Since the fixed PAD4 is surrounded by a large copper layer 2, the heat quickly diffuses into the copper layer 2. The copper layer 2 evenly distributes the heat between the chip and the PCB, reducing localized overheating and thus lowering thermal stress caused by excessive localized temperature differences. During chip operation, certain vibrations and mechanical stresses are generated. Due to the symmetrical distribution of the fixed PAD4s, these mechanical stresses are evenly distributed across each fixed PAD4, making the stress on the entire substrate 1 more uniform and preventing stress concentration that could lead to cracks in the substrate 1.
[0049] In the description of this utility model, it should be understood that terms such as "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0051] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.
[0052] Although the description of this utility model has been given in conjunction with the specific embodiments described above, it is obvious to those skilled in the art that many substitutions, modifications, and variations can be made based on the above description. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.
Claims
1. A BGA chip circuit board pad structure for a computing power card, characterized in that, The substrate includes a copper layer and an insulating layer at each of the four corners of one side of the substrate. Several fixed PADs are arranged in a symmetrical array on the copper layer. Each fixed PAD includes a main body and several protrusions. The protrusions are connected to or disconnected from the copper layer. If the protrusions are disconnected from the copper layer, the insulating layer completely surrounds the outer periphery of the fixed PAD. If the protrusions are connected to the copper layer, the insulating layer has an opening corresponding to the position of the protrusion.
2. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The number of fixed PADs at each corner is between 5 and 9.
3. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The main body is circular, and there are four protrusions, which are connected to the copper layer.
4. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The width of the protrusion is between 5 mil and 7 mil.
5. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The main body is circular, and there are two protrusions. The two protrusions are distributed horizontally or vertically and connected to the copper layer.
6. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The main body is circular, and there are two protrusions. The two protrusions are distributed at a 45° angle and connected to the copper layer.
7. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The main body is circular, and there are two protrusions. The two protrusions are distributed at a 45° angle and are disconnected from the copper layer.
8. The BGA chip circuit board pad structure for computing power cards according to claim 1, characterized in that, The main body is circular, and there are two protrusions that are vertically distributed and disconnected from the copper layer.
9. The BGA chip circuit board pad structure for a computing power card according to claim 1, characterized in that, The substrate has a layer of blind holes or stacked holes, which are located in the middle of the fixed PAD.
10. The BGA chip circuit board pad structure for a computing power card according to claim 9, characterized in that, The blind hole is filled with electroplated copper or resin.