Reinforcement and heat dissipation structure and processing method for a PGA device with large mass and large power consumption

Abstract

The present invention discloses a reinforcement and heat dissipation structure and a processing method for a PGA device with large mass and large power consumption, including a PGA device disposed on a printed circuit board. A U-shaped metal bracket is provided on the top of the PGA device, and a Bergquist film is provided between the U-shaped metal bracket and the PGA device. A metal structure sheet is provided between the PGA device and the printed circuit board, and the metal structure sheet is in contact with the bottom of the PGA device. A metal frame is provided on the printed circuit board, and both the U-shaped metal bracket and the metal structure sheet are in contact with the metal frame. Epoxy glue is coated at the four corner positions of the PGA device. The reinforcement and heat dissipation structure and the processing method of the present invention can not only reliably reinforce the PGA device with large mass and large power consumption, but also effectively solve the heat dissipation problem of the PGA device, improving the reliability of the spaceborne product.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic systems and equipment, and more specifically, to a reinforcement and heat dissipation structure and processing method for a PGA device with large mass and large power consumption. Background Art

[0002] PGA packaging is one of the most commonly used packaging forms for electronic components. In this type of packaging, internal signals are led out through pins at the bottom of the ceramic packaging body, and then interconnected with the PCB pads through solder joints between the pin leads and the PCB pads. There is a relatively special type in PGA packaging, that is, a part of the pins is missing in the middle area at the bottom of the body, as Figure 1 shown. Due to the characteristics of large mass and large volume of PGA devices, fewer pins will cause each pin on the device to bear a large weight. When subjected to temperature and mechanical stress, solder joint failure may occur; in addition, PGA devices also have the characteristics of high integration and large power consumption. Therefore, it is necessary to reinforce and dissipate heat for this type of PGA device with large mass and large power consumption.

[0003] Currently, the traditional device reinforcement method is to carry out epoxy reinforcement at the four corners of the device, which can meet the reinforcement requirements of common small-mass devices; the heat dissipation method is to lay a copper ground layer at the bottom of the device, and this heat dissipation method is only effective for small-power devices. Obviously, the traditional device reinforcement and heat dissipation methods can no longer meet the requirements of large-mass and large-power PGA devices.

[0004] In summary, it is necessary to design a reinforcement and heat dissipation method for a PGA device with large mass and large power consumption. Summary of the Invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a reinforcement and heat dissipation structure and processing method for a PGA device with large mass and large power consumption. The PGA device is fixed by a U-shaped metal bracket to enhance the mechanical strength of the PGA device and improve the environmental adaptability of the product; at the same time, the heat dissipation path of the PGA device is increased, the heat dissipation problem of large-power devices in the field of electronic systems and equipment is solved, the product cost is reduced, and the reliability of the product is improved.

[0006] To achieve the above object, the present invention provides the following technical solution: A reinforcement and heat dissipation structure for a PGA device with large mass and large power consumption, including a PGA device arranged on a printed circuit board. A U-shaped metal bracket is arranged on the top of the PGA device, and a Bergquist film is arranged between the U-shaped metal bracket and the PGA device; a metal structure sheet is arranged between the PGA device and the printed circuit board, and the metal structure sheet is in contact with the bottom of the PGA device; a metal frame is arranged on the printed circuit board, and both the U-shaped metal bracket and the metal structure sheet are in contact with the metal frame; epoxy glue is coated at the four corners of the PGA device.

[0007] Further, one end of the several types of metal brackets and one end of the metal structure sheet are both fixed to the metal frame by screws.

[0008] Further, the metal structure sheet is fixed to the pinless area at the bottom of the PGA device.

[0009] The present invention also provides a processing method for the reinforcement and heat dissipation structure of a large-mass and large-power-consumption PGA device, and the specific steps are as follows:

[0010] S1 Measure the thickness of the PGA device;

[0011] S2 Fix the metal structure sheet on the printed circuit board, and install the PGA device in step S on the metal structure sheet;

[0012] S3 Bond the Bergquist film on the several types of metal brackets, install the several types of metal brackets on the PGA device in step S, and perform electrical installation welding;

[0013] S4 After welding, perform epoxy reinforcement at the four corners of the PGA device.

[0014] Further, in step S1, a vernier caliper is used to measure the thicknesses of the four corners of the PGA device respectively, and the average value is calculated as the thickness of the PGA device.

[0015] Further, in step S1, the height of the tinned solder is 0.8 mm to 1 mm from the bottom of the PGA device.

[0016] Further, in step S2, an insulating board is adhesively bonded to the bottom of the metal structure sheet through silicone rubber, the insulating board contacts the printed circuit board, and the insulating board has the same size as the metal structure sheet.

[0017] Further, in step S2, the thickness of the metal structure sheet is 0.9 mm to 1.2 mm, the insulating board is made of epoxy glass cloth board with a thickness of 0.15 mm to 0.25 mm, and the thickness of the silicone rubber is 0.05 mm to 0.15 mm.

[0018] Further, in step S3, according to the thickness of the PGA device and the deformation amount of the Bergquist film, the thickness of the Bergquist film bonded to the several types of metal brackets is obtained, and the deformation amount of the Bergquist film is 10% to 20%.

[0019] Further, in step S4, the epoxy reinforcement is to apply epoxy glue at the four corners of the PGA device, fix it at two places on each side, the applied thickness is 1.2 mm to 1.4 mm, and it is preliminarily cured at 25°C ± 5°C for 4 h, and then cured at 50°C ± 5°C for 6 h.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] The present invention discloses a reinforcement and heat dissipation structure for a PGA device with large mass and large power consumption. By using a type-J metal bracket to enhance the mechanical strength of the PGA device, the reinforcement problem of the PGA device with large mass and large power consumption is solved. At the same time, by setting a type-J metal bracket, a metal structure sheet, and a Bergquist film, the heat dissipation path of the PGA device is increased, the heat dissipation problem of the PGA device with large mass and large power consumption is solved, the mechanical strength and environmental adaptability of the PGA device are improved, the heat dissipation problem of large-power devices in the field of electronic systems and equipment is solved, the product cost is reduced, and the reliability of spaceborne products is improved.

[0022] The reinforcement and heat dissipation structure of the present invention has passed the mechanical test and temperature test with the spaceborne product, and has been flight-verified in the model task. It is a highly reliable reinforcement and heat dissipation structure. Description of the Drawings

[0023] Figure 1 Schematic diagram of the pinless area at the bottom of the PGA device;

[0024] Figure 2 Schematic diagram of the installation of the PGA device (side view);

[0025] Figure 3 Schematic diagram of the installation of the PGA device (top view);

[0026] Figure 4 Soldering joint diagram after mechanical and temperature tests;

[0027] Figure 5 Metallographic diagram of the soldering joint after mechanical and temperature tests.

[0028] In the drawings: 1 - type-J metal bracket; 2 - Bergquist film; 3 - PGA device; 4 - metal structure sheet; 5 - insulating board; 6 - printed circuit board; 7 - metal frame. Detailed Embodiment

[0029] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0030] The present invention proposes a reinforcement and heat dissipation structure for a PGA device with large mass and large power consumption, as Figures 1 to 3 shown, including: a type-J metal bracket 1, a Bergquist film 2, a PGA device 3, a metal structure sheet 4, an insulating board 5, and a metal frame 7 provided on a printed circuit board 6, wherein,

[0031] Before electrical installation, first, a metal structure sheet 4 is set in the pinless area at the bottom of the PGA device 3, an insulating board 5 with the same size as the metal structure sheet 4 is set between the metal structure sheet 4 and the printed circuit board 6, and the metal structure sheet 4 is fixed on the metal frame 7;

[0032] A several - type metal bracket 1 is installed on the top of the PGA device 3. A Bergquist film 2 is provided between the PGA device 3 and the several - type metal bracket 1. One end of the several - type metal bracket 1 is fixed on the metal frame 7, and the other end is fixed on the printed circuit board 6, thereby realizing the reinforcement of the PGA device 3.

[0033] After electrical installation, epoxy glue is coated at the four - corner positions of the body of the PGA device 3.

[0034] In the above - mentioned structure, both the several - type metal bracket 1 and the metal structure piece 4 are fixedly connected to the metal frame 7 in contact by screws. Both the metal and the Bergquist film have good thermal conductivity. The heat dissipation generated by the PGA device 3 can be quickly transferred to the metal frame 7, increasing a good heat dissipation path, solving the heat dissipation problem of high - power - consumption devices in the field of electronic systems and equipment, and improving the reliability of the product.

[0035] A processing method for the reinforcement and heat dissipation structure of a large - mass and large - power - consumption PGA device of the present invention is as follows:

[0036] 1. Use a vernier caliper to measure the thickness of the four corners of the PGA device 3 respectively, and take the average value. The result is used as the body thickness of the PGA device 3.

[0037] 2. Use a tin pot to remove gold and tin - plate the pins of the PGA device and clean them. The tin - plating height is 0.8 mm to 1 mm from the bottom of the PGA device 3. Not only the pins of the device after tin - plating need to be cleaned, but also the central area at the bottom of the PGA device 3 needs to be cleaned.

[0038] 3. Use silicone rubber to bond the insulating board 5 and the metal structure piece 4 together, and then fix the metal structure piece 4 on the metal frame 7 by screws; install the PGA device 3 obtained in step 2 on the metal structure piece 4.

[0039] 4. Bond the Bergquist film 2 to the several - type metal bracket 1, and then install the several - type metal bracket 1 on the PGA device 3 obtained in step 3. The several - type metal bracket 1 is connected to the metal frame 7 by screws. After installation, electrical installation welding is carried out.

[0040] 5. After welding, carry out epoxy reinforcement at the four - corner positions of the PGA device 3.

[0041] Preferably, in step 3, the insulating board 5 is made of epoxy glass cloth board with a thickness of 0.15 mm to 0.25 mm, and the thickness of the metal structure piece 4 is 0.9 mm to 1.2 mm; use silicone rubber GD414 to bond the insulating board 5 and the metal structure piece 4, and the thickness of the silicone rubber is about 0.05 mm to 0.15 mm, and it is evenly applied; after bonding, the insulating board 5 contacts the printed circuit board 6, and the metal structure piece 4 contacts the bottom of the PGA device 3, and then it is fixed by screws.

[0042] Preferably, in step 4, the deformation of the Bergquist film is 10% to 20%; the thickness of the Bergquist film to be padded is calculated according to the body thickness of the PGA device 3 obtained in step 1 and the deformation of the Bergquist film 2.

[0043] Preferably, in step 5, after the PGA device 3 is installed, the J-shaped metal bracket 1 and the metal frame 7 are first fastened with screws and then welded.

[0044] Preferably, when applying the epoxy glue in step 5, it is completed by manual dotting or with the aid of a printing tooling. Holes are left at the four corners and in the middle of the PGA device 3, and 2 points are adhered to each side. The applied thickness is 1.2 mm to 1.4 mm, and the shape of the epoxy glue application is generally circular. Then it is preliminarily cured at 25°C ± 5°C for 4 h, and then cured at 50°C ± 5°C for 6 h.

[0045] The reinforcement and heat dissipation structure of the present invention enhances the mechanical strength of the PGA device 3, improves the environmental adaptability of the product, meets the requirements of the verification conditions, and is a highly reliable reinforcement method.

[0046] Example 1

[0047] Taking the central processing unit SiP module LSCCU01 as an example, according to a reinforcement and reinforcement method for a large-mass and large-power-consumption PGA device proposed by the present invention, it is implemented on the LSCCU01 module test fixture according to the above method steps. Specifically: The actual body height of the LSCCU01 module is measured with a vernier caliper to be 8.5 mm, and the thickness of the Bergquist film to be padded is calculated to be 2.0 mm; after the device is tinned and cleaned, it is installed on the metal structure piece 4 with the insulating board 5 pre-adhered, and then the J-shaped metal bracket 1 is fixed on the metal frame 7. After installation, the epoxy glue is used to reinforce the periphery of the PGA device 3.

[0048] After the installation and reinforcement of the LSCCU01 module are completed, mechanical tests (including: random vibration test, shock test) and temperature cycle test are carried out in sequence. The test conditions for each item are shown as follows:

[0049] Table 1 Random Vibration Condition Comparison Table

[0050]

[0051]

[0052] Table 2 Shock Test Condition Comparison Table

[0053]

[0054] Table 3 Thermal Cycle Test Condition Comparison Table

[0055]

[0056]

[0057] During the entire mechanical and temperature tests, the product worked normally, and its functional performance met the index requirements. The maximum surface temperature of the device was 72.5 °C, meeting the derating requirements. After the test, the solder joints were inspected under a 40x magnifying glass. After inspection, the quality of the solder joints was good, and no visible cracks or missing parts were found. The quality of the solder joints is as shown in Figure 4 shown; the solder joints were inspected by metallographic analysis. After inspection, the quality of the solder joints was good, and no visible cracks, fractures, or missing parts were found. The metallographic analysis of the solder joints is as shown in Figure 5 shown.

[0058] The test results show that the method for strengthening and heat dissipation of the large-mass and high-power PGA device proposed in the present invention can enhance the mechanical strength of the device, improve the environmental adaptability, solve the heat dissipation problem of high-power devices, help reduce the product cost, and improve the reliability of the product.

Claims

1. A reinforcement and heat dissipation structure for a large-mass, high-power PGA device, characterized in that: The invention comprises a PGA device (3) arranged on a printed circuit board (6), wherein a metal bracket (1) of several shapes is arranged on the top of the PGA device (3), and a Bergs film (2) is arranged between the metal bracket (1) and the PGA device (3); a metal structure sheet (4) is arranged between the PGA device (3) and the printed circuit board (6), and the metal structure sheet (4) is in contact with the bottom of the PGA device (3); a metal frame (7) is arranged on the printed circuit board (6), and the metal bracket (1) and the metal structure sheet (4) are in contact with the metal frame (7); and epoxy glue is coated on the four corners of the PGA device (3); One end of the several-shaped metal bracket (1) and one end of the metal structure sheet (4) are fixed to the metal frame (7) by screws; The metal structure sheet (4) is fixed to the pin-free area at the bottom of the PGA device (3); An insulating plate (5) is bonded to the bottom of the metal structure sheet (4) via silicone rubber, the insulating plate (5) is in contact with a printed circuit board (6), and the insulating plate (5) and the metal structure sheet (4) have the same size; The thickness of the metal structure sheet (4) is 0.9 mm to 1.2 mm, the insulating plate (5) is made of epoxy glass cloth with a thickness of 0.15 mm to 0.25 mm, and the thickness of the silicone rubber is 0.05 mm to 0.15 mm; The thickness of the Berggs film (2) bonded to the metal bracket (1) is obtained according to the thickness of the PGA device (3) and the deformation of the Berggs film (2), wherein the deformation of the Berggs film is 10% to 20%; The epoxy adhesive is applied to the four corners of the PGA device (3), with two adhesives on each side, with a coating thickness of 1.2 mm to 1.4 mm. The epoxy adhesive is initially cured at 25°C ± 5°C for 4 hours, and then cured at 50°C ± 5°C for 6 hours.

2. The processing method of a reinforcement and heat dissipation structure for a PGA device with large mass and large power consumption according to claim 1, characterized in that, The specific steps are as follows: S1 measures the body thickness of the PGA device (3); S2 fixes the metal structure sheet (4) on the printed circuit board (6), and installs the PGA device (3) in step S (1) on the metal structure sheet (4); S3: bonding the Berggs film (2) to the metal bracket (1), installing the metal bracket (1) on the PGA device (3) in step S (2), and performing electrical welding; After S4 welding, epoxy reinforcement is performed on the four corners of the PGA device (3).

3. The processing method according to claim 2, characterized in that: In step S1, a vernier caliper is used to measure the thickness of the four corners of the PGA device (3) respectively, and the average value is calculated as the thickness of the PGA device (3).

4. The processing method according to claim 2, characterized in that: In step S1, after measuring the thickness, the pins of the PGA device are de-golded, tin-plated and cleaned, and the height of the tin-plating is 0.8mm to 1mm from the bottom of the PGA device (3).

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