Method for observing and unsealing a bga device

Abstract

The application provides a BGA device observation method and opening method, which comprises the following steps: S10, heating the BGA device; S20, separating the chip from the PCB board; S30, corroding and opening the front surface of the chip by using acid liquid; S40, cleaning by using cleaning liquid; and S50, observing the front surface of the chip by using a microscope. Through the application, the technical problem that the BGA device is not easy to open and the chip inside the BGA device is difficult to observe is solved.

Description

Technical Field

[0001] This invention relates to the field of BGA packaging technology, and more particularly to a method for observing and unpacking BGA devices. Background Technology

[0002] A BGA (Ball Grid Array Package) device consists of a metal cover, a chip, and a PCB stacked sequentially. The chip is soldered to the PCB on the front and bonded to the metal cover on the back using adhesive and hardener. The BGA device is attached as a single unit to the external PCB. Generally, separating a BGA device from the external PCB is relatively straightforward. However, separating a fully packaged PCB device—that is, separating the internal PCB from the chip—is a more complex operation.

[0003] A primary method for studying BGA devices is to observe the chips within them. To observe the chips in a BGA device, the PCB board connected to the front of the chip must first be removed.

[0004] Molded devices typically employ chemical wet encapsulation, primarily including manual acid boiling and automated encapsulation. Because PCBs are resistant to strong acids, BGA devices require mechanical pretreatment; otherwise, encapsulation by machine is difficult. However, forcibly separating the PCB from the metal cover carries a significant risk of damaging the chip, making machine encapsulation impractical.

[0005] For opening BGA devices, the manual acid boiling method can be used. During the strong acid etching process, the device must be taken out of the high-temperature acid boiling beaker every few minutes to observe its degree of corrosion. The corroded material must be manually peeled off layer by layer until it is completely separated from the chip.

[0006] Repeatedly removing devices from beakers boiled in acid at high temperatures to observe their opening effect poses a high risk to the operator. The repeated use of tweezers can also damage the chip. In addition, if the etching time is not properly controlled, excessive high-temperature and strong acid etching can often cause the chip surface coating to crack or peel off, posing a risk of opening failure. Summary of the Invention

[0007] The purpose of this invention is to provide a method for observing and opening BGA devices, so as to alleviate the technical problem that BGA devices are not easy to open and the internal chips are difficult to observe.

[0008] The above-mentioned objectives of the present invention can be achieved by the following technical solutions:

[0009] This invention provides a method for observing a BGA device. The BGA device includes a metal cover plate, a chip, and a PCB board stacked sequentially. The PCB board is located on the front side of the chip, and the metal cover plate is located on the back side of the chip. An adhesive and a hardener for securing the chip are filled between the metal cover plate and the PCB board. The observation method includes:

[0010] Step S10: Heat the BGA device;

[0011] Step S20: Separate the chip from the PCB board;

[0012] Step S30: Use acid to etch and open the front side of the chip;

[0013] Step S40: Clean using cleaning solution;

[0014] Step S50: Use a microscope to observe the front side of the chip.

[0015] In a preferred embodiment, in step S10, the metal cover plate is placed on a heating stage to heat the BGA device until the bonding points of the chip melt, at which point the heating is stopped.

[0016] In a preferred embodiment, the temperature of the heating table is set to 320℃~340℃; after the solder joints on the surface of the PCB board melt, the heating continues for 1~2 hours.

[0017] In a preferred embodiment, step S20 includes: step S21, using a blade to cut close to the side of the PCB board near the chip, applying a force away from the chip to the PCB board, and applying a force away from the chip to the metal cover plate.

[0018] In a preferred embodiment, after step S21, the metal cover is separated from the chip, and the PCB board is bonded to the chip. Step S20 includes step S22, which is performed after step S21. In step S22, the PCB board is peeled off layer by layer.

[0019] In a preferred embodiment, in step S30, the corrosion opening is performed using a plastic seal opening device.

[0020] In a preferred embodiment, the opening parameters of the plastic seal opening device are: etching temperature 90°C, etching time 200s, etching acid solution is 95% fuming nitric acid, etching flow rate 5ml / min, and acid rinsing time 5s.

[0021] In a preferred embodiment, in step S40, the chip is placed in a cup containing cleaning fluid, and the cup is placed in an ultrasonic cleaner for cleaning.

[0022] In a preferred embodiment, the temperature of the ultrasonic cleaner is set to 40℃-50℃, and the cleaning time is 0.8-1.2 minutes.

[0023] This invention provides a method for unpacking a BGA device. The BGA device includes a metal cover plate, a chip, and a PCB board stacked sequentially. The PCB board is located on the front side of the chip, and the metal cover plate is located on the back side of the chip. An adhesive and a hardener for securing the chip are filled between the metal cover plate and the PCB board. The unpacking method includes:

[0024] Step S10: Heat the BGA device;

[0025] Step S20: Separate the chip from the PCB board;

[0026] Step S30: Use acid to etch and open the front side of the chip;

[0027] Step S40: Clean using cleaning solution.

[0028] The features and advantages of this invention are:

[0029] The BGA device observation method provided by this invention, in step S10, heating can change the adhesive layer, hardener layer, solder joints, and bonding points inside the packaged BGA device. This causes the adhesive layer to denature, weakening its adhesive effect; the hardener layer to soften; and the solder joints to melt, weakening the connection strength between the chip and the PCB board. This reduces the difficulty of separating the PCB board from the chip, creating conditions for PCB board peeling. Therefore, in step S20, the force applied during separation is smaller, ensuring smooth removal of the PCB board, exposing the front side of the chip, and avoiding damage to the chip. After etching and unpacking in step S30, the chip is cleaned in step S40, facilitating observation of the front side of the chip and experimental analysis in step S50. This observation method improves the safety factor of the unpacking operation and ensures the success rate of BGA device unpacking, creating better conditions for chip observation in step S50. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the observation method for the BGA device provided by the present invention;

[0032] Figure 2 This is a schematic diagram of step S21 in the observation method for the BGA device provided by the present invention;

[0033] Figure 3 This is a schematic diagram of the BGA devices after the PCB board has been separated.

[0034] Figure 4 This is a schematic diagram of step S10 in the observation method for BGA devices provided by the present invention;

[0035] Figure 5 This is a schematic diagram of the plastic encapsulation opening device in the observation method for BGA devices provided by the present invention;

[0036] Figure 6 This is a schematic diagram of the pad used in the observation method for BGA devices provided by the present invention;

[0037] Figure 7 This is a schematic diagram of step S30 in the observation method for BGA devices provided by the present invention.

[0038] Explanation of icon numbers:

[0039] 10. Chip; 11. Front side of chip; 12. Bonding point; 20. Metal cover plate; 30. PCB board; 41. Adhesive layer; 42. Hardener layer; 43. Solder joint;

[0040] 50. Heating table; 51. Surface of the heating table;

[0041] 61. Blade; 62. Tweezers;

[0042] 70. Plastic sealing and opening equipment; 71. Acid spray nozzle; 72. Gasket; 73. Gasket opening. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figure 2 As shown, the BGA device includes a metal cover plate 20, a chip 10 and a PCB board 30 stacked in sequence. The PCB board 30 is located on the front side 11 of the chip, and the metal cover plate 20 is located on the back side of the chip 10. The space between the metal cover plate 20 and the PCB board 30 is filled with adhesive and hardener for fixing the chip 10.

[0045] An adhesive layer 41 is formed between the chip 10 and the PCB board 30, and between the chip 10 and the metal cover plate 20. A hardener is disposed between the two adhesive layers 41 to form a hardener layer 42. Figure 2 As shown, two adhesive layers 41 cover the top and bottom surfaces of the chip 10, and a hardener layer 42 is located on the outside of the chip 10, surrounding the chip 10.

[0046] Example 1

[0047] This invention provides a method for observing BGA devices, such as... Figure 1 As shown, the observation method includes: step S10, heating the BGA device; step S20, separating the chip 10 from the PCB board 30; step S30, using acid to etch and open the front side 11 of the chip; step S40, cleaning with cleaning solution; and step S50, observing the front side 11 of the chip using a microscope.

[0048] In step S10, heating alters the adhesive layer 41, hardener layer 42, solder joints 43, and bonding points 12 inside the packaged BGA device. This causes the adhesive layer 41 to denature, weakening its adhesive effect; the hardener layer 42 to soften; and the solder joints 43 to melt. This weakens the connection between the chip 10 and the PCB board 30, reducing the difficulty of separating the PCB board 30 from the chip 10 and creating conditions for peeling off the PCB board 30. Consequently, in step S20, the force applied during separation is smaller, ensuring the smooth removal of the PCB board 30 and exposing the front side of the chip 10 without damaging it. After etching and unpacking in step S30, step S40 cleans the chip 10, facilitating observation of the front side of the chip 10 and experimental analysis in step S50. This observation method improves the safety of the unpacking operation and ensures a high success rate for BGA device unpacking, creating better conditions for observing the chip 10 in step S50.

[0049] In step S50, a high-powered microscope can be used to observe the internal structure of the chip 10 through the front side 11 of the chip. It can also include using a high-powered metallographic microscope to perform internal visual inspection and failure analysis on the chip 10 after it has been opened, or to perform a DPA test.

[0050] In step S10, the metal cover plate 20 can be placed on the heating stage 50 to heat the BGA device until the bonding points 12 of the chip 10 melt, at which point heating is stopped. The PCB board 30 has solder points 43 on its surface, and the adhesive layer 41 between the chip 10 and the PCB board 30 acts as an adhesive. Heating can cause the adhesive layer 41 to deform, weakening the adhesive effect, softening and weakening the hardener layer 42, and melting the solder points 43. In the BGA device, the chip 10 also has bonding points 12 on the side closest to the PCB board 30, such as... Figure 2 As shown, the bonding point 12 is not in direct contact with the PCB board 30. However, the inventors found that the presence of the bonding point 12 greatly increases the difficulty of separating the PCB board 30 from the chip 10. Therefore, the inventors made further improvements and adopted this implementation method, heating until the bonding point 12 melts, making it easier to separate the PCB board 30 from the chip 10 and exposing the chip 10.

[0051] like Figure 4 As shown, the side of the metal cover plate 20 facing away from the chip 10 is attached to the surface 51 of the heating stage. Heat is transferred to the metal cover plate 20 and then through the adhesive layer 41 between the metal cover plate 20 and the chip 10, to the chip 10 and the bonding points 12 on the chip 10. This facilitates the melting of the bonding points 12 and prevents the chip 10 from being damaged by overheating. Preferably, the surface 51 of the heating stage is facing upwards, and the metal cover plate 20 is facing downwards. The heating stage 50 can be placed in a fume hood, and the BGA can be heated in the fume hood. During heating, the fume hood is opened to ensure good ventilation.

[0052] Solder joint 43 is located on the surface of PCB board 30, and its melting status can be observed during heating. Bonding point 12 is enclosed, making it difficult to melt by heating and difficult to determine its melting state. In this embodiment, the temperature of the heating stage 50 is set to 320℃~340℃; after the solder joint 43 on the surface of PCB board 30 melts, heating continues for 1~2 hours to melt the bonding point 12, reducing the difficulty of subsequent separation of chip 10 from PCB board 30. Preferably, the temperature of the heating stage 50 is set to 330℃. Specifically, the solder balls of solder joint 43 on the surface of PCB board 30 are observed during heating; after the solder balls melt, heating continues for another 1~2 hours. During heating, the PCB board 30 darkens in color due to heat.

[0053] Step S10 alters the adhesive layer 41, hardener layer 42, solder joints 43, and bonding points 12 within the packaged BGA device, reducing the difficulty of separating the PCB board 30 from the chip 10. Step S20 includes: Step S21, using a blade 61 to cut close to the side of the PCB board 30 near the chip 10, applying a force away from the chip 10 to the PCB board 30 and to the metal cover plate 20. Through the blade 61, in conjunction with the forces applied to the PCB board 30 and the metal cover plate 20, at least one of the metal cover plate 20 and the PCB board 30 can be separated from the chip 10. During this process, the applied force is relatively small, avoiding damage to the chip 10 and creating better conditions for observing the chip 10 in step S50.

[0054] Specifically, in step S21, such as Figure 2As shown, wearing heat-resistant gloves, carefully pick up the BGA device onto the heat-resistant plate with tweezers 62. Hold the device upright with tweezers 62 in one hand, and use the blade 61 in the other hand to cut along the perimeter of the BGA device close to the chip 10 side of the PCB substrate. During the cutting process, avoid touching the edge of the chip 10 to prevent damage. Then, use tweezers 62 to fix the metal cover plate 20 with one hand, and use tweezers 62 to hold the PCB board 30. Apply force slightly in opposite directions with both hands.

[0055] After step S21, there are two scenarios: In the first scenario, the metal cover 20 separates from the chip 10, while the PCB board 30 remains bonded to the chip 10; in the second scenario, the PCB board 30 separates from the chip 10, while the metal cover 20 remains bonded to the chip 10. If it is the first scenario, then the separation of the chip 10 from the PCB board 30 in step S20 has been completed. Figure 3 As shown, the front side 11 of the chip is exposed, and step S30 can then be performed.

[0056] In the second scenario, the front side 11 of the chip is still covered by the PCB board 30. In this case, as... Figure 1 As shown, step S20 includes step S22, which is performed after step S21; in step S22, the PCB board 30 is peeled off layer by layer. By weakening the connection between the chip 10 and the PCB board 30 through step S10, conditions are created for peeling off the PCB board 30, which can ensure the smooth removal of the PCB board 30 and avoid damage to the chip 10.

[0057] Specifically, the PCB board 30 material covering the front of the chip 10 is carefully peeled off layer by layer using the blade 61 until the bonding points 12 on the surface of the chip 10 are exposed. Before peeling with the blade 61, the excess part of the PCB substrate about 0.5 cm away from the chip 10 can be mechanically removed to facilitate the peeling of the PCB board 30 layer by layer using the blade 61.

[0058] After the front side 11 of the chip is separated from the PCB board 30, the solder joints 43 of the chip 10 are chemically decapsulated using etching. This process removes residual solder balls from the front side of the chip 10, cleaning the chip 10 and facilitating subsequent observation and experimental analysis of the front side. In one embodiment of the invention, step S30 uses a plastic encapsulation decapsulation device 70 for etching. After the front side 11 of the chip is separated from the PCB board 30, molten solder joints 43 remain on the surface of the chip 10, affecting the observation of the chip 10 surface layout. With the front side 11 facing the acid spray port 71 of the plastic encapsulation decapsulation device 70, etching the surface of the chip 10 using the plastic encapsulation decapsulation device 70 can remove the solder balls from the front side of the chip 10 with high efficiency.

[0059] Specifically, in step S30, such as Figures 5-7As shown, the acid spray port 71 of the plastic encapsulation unpacking device 70 is equipped with a gasket 72, and the gasket 72 has a gasket opening 73. Depending on the size and shape of the chip 10, the gasket opening 73 is slightly larger than the size of the chip 10. The front side 11 of the chip faces down and is placed at the acid spray port 71 of the plastic encapsulation unpacking device 70. The front side 11 of the chip is exposed through the gasket opening 73, allowing it to receive the acid sprayed from the acid spray port 71. In some cases, after the BGA device is unpacked, the front side 11 of the chip is exposed, and the chip 10 is connected to other components. The gasket 72 and the gasket opening 73 limit the range of acid spraying, preventing the acid from corroding other components outside the chip 10 and avoiding damage to the internal structure of the BGA device.

[0060] Furthermore, the opening parameters of the plastic seal opening equipment 70 are as follows: etching temperature 90℃, etching time 200s, etching acid solution is 95% fuming nitric acid, etching flow rate 5ml / min, and acid rinsing time 5s, in order to improve the efficiency of corrosion opening.

[0061] In step S40, the chip 10 is placed in a cup containing cleaning fluid, and the cup is placed in an ultrasonic cleaner for cleaning. The ultrasound causes the cleaning fluid in the cup to vibrate, and the cleaning fluid acts on the chip 10, removing impurities from the surface of the chip 10 for easier observation. Acetone can be used as the cleaning fluid.

[0062] Furthermore, the ultrasonic cleaner temperature is set to 40℃-50℃, and the cleaning time is 0.8-1.2 minutes to remove dirt and impurities from the surface of chip 10 with high efficiency. Preferably, the temperature is set to 45℃, and the cleaning time is 1 minute.

[0063] The observation method for this BGA device is suitable for, for example... Figure 2 The BGA devices shown include Xilinx's XC7K325T-2FFG676I and XC4VSX55-10FFG1148I, and TI's TMS320C6455CTZA, among others.

[0064] Example 2

[0065] The present invention provides a method for opening a BGA device, the method comprising: step S10, heating the BGA device; step S20, separating the chip 10 from the PCB board 30; step S30, using acid to etch the front side 11 of the chip to open the package; and step S40, using a cleaning solution to clean the package.

[0066] In step S10, heating alters the adhesive layer 41, hardener layer 42, solder joints 43, and bonding points 12 within the packaged BGA device. This causes the adhesive layer 41 to denature, weakening its adhesive effect; the hardener layer 42 to soften and weaken; and the solder joints 43 to melt. This weakens the connection between the chip 10 and the PCB board 30, reducing the difficulty of separating the PCB board 30 from the chip 10 and creating conditions for peeling off the PCB board 30. Consequently, the force applied during separation in step S20 is smaller, ensuring the smooth removal of the PCB board 30 and exposing the front side of the chip 10 without damaging it. After etching and unpacking in step S30, step S40 cleans the chip 10, facilitating subsequent observation of the front side of the chip 10 and experimental analysis. This unpacking method improves the safety of the unpacking operation and ensures a high success rate for BGA device unpacking, creating better conditions for subsequent observation of the chip 10.

[0067] The above descriptions are merely a few embodiments of the present invention. Those skilled in the art can make various modifications or variations to the embodiments of the present invention based on the content disclosed in the application documents without departing from the spirit and scope of the present invention.

Claims

1. A method for observing a BGA device, the BGA device comprising a metal cover plate, a chip, and a PCB board stacked sequentially, the PCB board being located on the front side of the chip, the metal cover plate being located on the back side of the chip, and an adhesive and a hardener for securing the chip being filled between the metal cover plate and the PCB board, characterized in that... The observation methods include: Step S10: Heat the BGA device; Step S20: Separate the chip from the PCB board; Step S30: Use acid to etch and open the front side of the chip; Step S40: Clean using cleaning solution; Step S50: Observe the front side of the chip using a microscope; In step S10, the metal cover plate is placed on a heating stage to heat the BGA device until the bonding points of the chip melt, at which point the heating is stopped. The temperature of the heating table is set to 320℃~340℃; after the solder joints on the surface of the PCB board melt, the heating continues for 1~2 hours. Step S20 includes: Step S21, using a blade to cut close to the side of the PCB board near the chip, applying a force away from the chip to the PCB board, and applying a force away from the chip to the metal cover plate; After implementing step S21, the metal cover plate is separated from the chip, and the PCB board is bonded to the chip. Step S20 includes step S22 implemented after step S21. In step S22, the PCB board is peeled off layer by layer. In step S30, the corrosion opening is performed using a plastic seal opening device; The opening parameters of the plastic seal opening equipment are: etching temperature 90℃, etching time 200s, etching acid solution is 95% fuming nitric acid, etching flow rate 5ml / min, and acid rinsing time 5s; In step S40, the chip is placed in a cup containing cleaning solution, and the cup is placed in an ultrasonic cleaner for cleaning. Set the ultrasonic cleaner temperature to 40℃-50℃ and the cleaning time to 0.8~1.2 minutes.

2. A method for opening a BGA device, the BGA device comprising a metal cover plate, a chip, and a PCB board stacked sequentially, the PCB board being located on the front side of the chip, the metal cover plate being located on the back side of the chip, and an adhesive and a hardener for securing the chip being filled between the metal cover plate and the PCB board, characterized in that... The method of opening the seal includes: Step S10: Heat the BGA device; Step S20: Separate the chip from the PCB board; Step S30: Use acid to etch and open the front side of the chip; Step S40: Clean using cleaning solution; In step S10, the metal cover plate is placed on a heating stage to heat the BGA device until the bonding points of the chip melt, at which point the heating is stopped. The temperature of the heating table is set to 320℃~340℃; after the solder joints on the surface of the PCB board melt, the heating continues for 1~2 hours. Step S20 includes: Step S21, using a blade to cut close to the side of the PCB board near the chip, applying a force away from the chip to the PCB board, and applying a force away from the chip to the metal cover plate; After implementing step S21, the metal cover plate is separated from the chip, and the PCB board is bonded to the chip. Step S20 includes step S22 implemented after step S21. In step S22, the PCB board is peeled off layer by layer. In step S30, the corrosion opening is performed using a plastic seal opening device; The opening parameters of the plastic seal opening equipment are: etching temperature 90℃, etching time 200s, etching acid solution is 95% fuming nitric acid, etching flow rate 5ml / min, and acid rinsing time 5s; In step S40, the chip is placed in a cup containing cleaning solution, and the cup is placed in an ultrasonic cleaner for cleaning. Set the ultrasonic cleaner temperature to 40℃-50℃ and the cleaning time to 0.8~1.2 minutes.

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