A sol-gel device for large-size infrared detector chipsets

Abstract

The utility model discloses a kind of sol piece-taking devices for large-size infrared detector chip set, the device overall is rectangular, the outer ring structure of device is by the higher support structure of two sides of opposite side, the limiting structure of four corners and the lower pad protection structure splicing of two sides of opposite side, still include the chip protection structure that surrounds in the four around of hollow structure, the chip protection structure that surrounds in the four around of hollow structure and the article placing groove between chip protection structure and device outer ring structure, article placing groove opening is downward and with certain depth, for filling hygroscopic material, alcohol is stored in hygroscopic material, for the adhesive between the sol of reading out circuit and dowa heat-conducting sheet is dissolved.The utility model can promote the alcohol sol rate of adhesive between chip set and dowa heat-conducting sheet, also can avoid alcohol soaking chip set, reduce the risk of swelling of filling glue in chip set, avoid damaging chip set.

Description

Technical Field

[0001] This utility model relates to the field of infrared detector technology system - packaging technology - precision splicing and packaging technology of large-area array chips, specifically to a sol-gel chip removal device for large-size infrared detector chipsets. Background Technology

[0002] The chipset of an infrared detector mainly consists of two parts: a photosensitive chip and a readout circuit. The two parts are connected by flip-chip interconnection, and the photosensitive chip and the readout circuit are bonded together with filler glue to improve the reliability of the chipset.

[0003] Before formal packaging, detector chipsets need to be encapsulated in test Dewars for performance evaluation. Chipsets that pass the performance test are then selected for formal product packaging. Typically, test packaging uses acetal adhesive to attach the detector chipset to the thermal pad of the Dewar. After the chipset performance evaluation is complete, the detector chipset is removed from the thermal pad by dissolving the acetal adhesive with alcohol. Therefore, improving the efficiency of chipset testing and removal while avoiding damage to the chipset during the removal process has always been a key focus for researchers in this field.

[0004] Currently, the main method for removing chips in the infrared packaging technology field still relies on manually adding alcohol to dissolve the acetal adhesive in the bonding area. The operator adds an appropriate amount of alcohol to the thermally conductive plate of the test Dewar, allowing the alcohol on the thermally conductive plate to gradually penetrate the entire bonding area of ​​the chipset through capillary action, thus completely dissolving the acetal adhesive. If the chipset is large, the bonding area between the chipset and the thermally conductive plate of the Dewar will also increase. In this case, it is necessary to repeatedly add alcohol to slowly dissolve the acetal adhesive in the bonding area. However, the acetal adhesive in the bonding area is not carried away by the evaporation of alcohol. If the chipset is not successfully removed from the thermally conductive plate before the alcohol completely evaporates, the dissolved acetal adhesive will cause the chipset to continue to adhere to the thermally conductive plate. Therefore, the operator needs to constantly observe whether the alcohol on the thermally conductive plate of the Dewar is sufficient to wet the bonding gap between the chipset and the thermally conductive plate, and add more alcohol promptly if necessary.

[0005] With the development of infrared technology, the pixel size of detector chipsets has increased dramatically, and the chipset dimensions have also grown significantly. This has not only led to a significant improvement in detector resolution but also brought about the challenge of testing and retrieving large-size chipsets. Because the contact area between the large-size chipset and the heatsink is larger, the bonding area of ​​the heatsink also increases exponentially. During solvent-based chip removal, alcohol struggles to penetrate the entire bonding area, requiring the bonding gap between the chipset and the Dewar heatsink to be continuously moistened with alcohol. However, alcohol is volatile, necessitating continuous manual dripping of alcohol during the chip removal process to ensure it penetrates the bonding area. While this method is feasible for short periods, it becomes highly challenging for extended testing and chip removal operations.

[0006] Operators attempted to place the entire chipset in an atmosphere with a high alcohol concentration. While this ensured the gap between the chipset and the Dewar thermal pad remained constantly moistened with alcohol, it caused significant swelling of the adhesive between the photosensitive chip and the readout circuitry. This resulted in a disconnect between the photosensitive chip and the readout circuitry, leading to numerous defective pixels. Therefore, the invention provides a device that can continuously moisten the adhesive gap between the chipset and the Dewar thermal pad while preventing swelling of the adhesive after being soaked in alcohol. This is crucial for solving the challenge of testing and removing large-size infrared detector chipsets.

[0007] Currently, researchers in this field primarily use manual alcohol addition to dissolve the acetal adhesive in the bonding area between the chipset and the Dewar thermal pad, enabling chip removal through solvent extraction. This method is inefficient for large chipsets and is technically challenging. Researchers have also attempted to remove the chipset by placing the Dewar cold head in an alcohol atmosphere. While this method achieves the desired result, it causes significant damage to the detector chipset. The adhesive in the chipset swells considerably under alcohol immersion, leading to desoldering between the photosensitive chip and the readout circuitry. In severe cases, this can render the chipset unusable, resulting in a waste of initial investment. Utility Model Content

[0008] To overcome the shortcomings of existing technologies, this invention designs a dedicated device for chip removal during testing of large-size infrared detector chipsets. This device can improve the alcohol dissolution rate of the adhesive between the chipset and the Dewar thermal pad, while avoiding alcohol immersion in the chipset, reducing the risk of swelling of the filler adhesive in the chipset, and preventing damage to the chipset. It enables rapid and efficient removal of the chipset from the thermal pad of the test Dewar, solving the current problem of difficult chip removal for testing large-size chipsets. After the application of this removal device, the difficulty of dissolution during testing is reduced, the testing time is shortened, the problem of alcohol immersion in the chipset filler adhesive is avoided, the yield rate of chipsets is improved, human resource input is reduced, and enterprises achieve cost reduction and efficiency improvement. It also reduces the generation of scrapped chipsets, which has a positive effect on environmental protection.

[0009] The infrared detector chipset consists of two parts: a photosensitive chip 1 and a readout circuit 2. These two parts are interconnected via flip-chip bonding. The photosensitive chip 1 and the readout circuit 2 are bonded together with filler adhesive to improve the chipset's reliability. A Dewar heatsink 3 is located between the chipset and the Dewar cold head 5, transferring heat from the chipset to the Dewar cold head 5 through contact conduction and reducing thermal stress on the chipset during temperature changes. A lead substrate 4 is located on both sides of the chipset and is connected to it via wire bonding, enabling signal transmission between the chipset and the external electrical interface of the Dewar. The Dewar cold head 5 is an internal tube structure. The Dewar heatsink 3, lead substrate 4, and chipset are all mounted on the Dewar cold head 5, serving to house the internal components and transfer cooling energy to the interior of the Dewar.

[0010] The technical solution of this utility model is as follows:

[0011] A sol-gel chip removal device for large-size infrared detector chipsets, wherein the infrared detector chipset consists of two parts: a photosensitive chip 1 and a readout circuit 2, which are connected by flip-chip interconnection. The photosensitive chip 1 and the readout circuit 2 are bonded together with filler adhesive to improve the reliability of the chipset. A Dewar heat-conducting sheet 3 is located between the chipset and the Dewar cold head 5, which transfers the heat of the chipset to the Dewar cold head 5 through contact conduction and reduces the thermal stress on the chipset during temperature changes. A lead substrate 4 is located on both sides of the chipset and is connected to the chipset by wire bonding to realize signal transmission between the chipset and the external electrical interface of the Dewar. The Dewar cold head 5 is the inner tube of the Dewar, and the Dewar heat-conducting sheet 3, the lead substrate 4, and the chipset are all mounted on the Dewar cold head 5, which serves to load the internal components of the Dewar and transfer the cooling energy to the inside of the Dewar. The device is rectangular in shape, and the outer ring structure of the device is composed of a higher support structure 6.1 on opposite sides, a limiting structure 6.2 at the four corners, and a lower pad protection structure 6.3 on opposite sides.

[0012] The support structure 6.1 is in direct contact with the Dewar cold head 5, and serves to support the entire wafer retrieval device from both sides during sol-gel wafer retrieval. The shape of the limiting structure 6.2 is consistent with the loading surface shape of the Dewar cold head 5 and the lead substrate 4, allowing the wafer retrieval device to engage with the Dewar cold head 5 and the lead substrate 4, thus limiting its position. The pad protection structure 6.3 is located above the lead substrate 4, with a certain gap between it and the lead substrate 4, to prevent the wafer retrieval device from rubbing against the bonding pads on the lead substrate 4 during use, thus protecting the bonding pads.

[0013] The hollow structure 6.6 located in the center of the entire chip picking device has the same outer size as the photosensitive chip 1, which ensures that the alcohol in the placement groove 6.5 will not drip onto the photosensitive chip 1 during use, thus avoiding alcohol contamination of the photosensitive chip 1 after sol-gelling.

[0014] The chip protection structure 6.4, which surrounds the hollow structure 6.6, is used to protect the chip assembly placed below the hollow structure 6.6, prevent the solvent alcohol from seeping between the photosensitive chip 1 and the readout circuit 2, and avoid swelling of the filler adhesive in the chip assembly.

[0015] A storage groove 6.5 is located between the chip protection structure 6.4 and the higher support structures 6.1 on both sides of the outer ring structure of the device, the limiting structures 6.2 at the four corners, and the lower pad protection structures 6.3 on both sides of the outer ring structure. The storage groove 6.5 opens downward and has a certain depth. It is used to fill with water-absorbing material 7. The water-absorbing material 7 contains alcohol, which is used to dissolve the adhesive between the readout circuit 2 and the Dewar heat-conducting sheet 3.

[0016] The chip protection structure 6.4 has a certain gap with the photosensitive chip 1 to prevent the chip picking device from rubbing against the photosensitive chip 1 during use, thus protecting the photosensitive chip 1.

[0017] The placement groove 6.5 can completely cover the gap between the readout circuit 2 and the Dewar heat-conducting plate 3.

[0018] The hollow structure 6.6 is located directly above the photosensitive chip 1, allowing the photosensitive chip 1 to be fully exposed to the air during the chip removal process.

[0019] Preferably, a gap of 1-2 mm is left between the pad protection structure 6.3 and the lead substrate 4.

[0020] Preferably, a gap of 1-2 mm is left between the chip protection structure 6.4 and the photosensitive chip 1.

[0021] This utility model also provides a sol-gel extraction method for large-size infrared detector chipsets, including the following steps:

[0022] A. Add an appropriate amount of alcohol to the adhesive gap between the readout circuit 2 and the Dewar heat-conducting plate 3, soak the water-absorbing material 7 in the plate taking device 6 with alcohol, and then snap the soaked plate taking device 6 onto the Dewar cold head 5 according to the structure of the Dewar loading surface.

[0023] B. After the test Dewar with the chip removal device is installed is left to stand for a period of time, wait for the acetal adhesive used to bond the readout circuit 2 and the heat-conducting sheet 3 of the Dewar to be completely dissolved by the alcohol, the chip set that has completed the performance screening can be removed from the heat-conducting sheet 3 of the Dewar and then registered into the warehouse.

[0024] Further, step A includes the following steps:

[0025] A1. Fill an appropriate amount of absorbent material 7 into the placement groove 6.5 of the chip taking device. The amount of filling material should just fill the groove. The height of the filling material should be flush with the chip protection structure 6.4. This will prevent the filling material from falling out of the placement groove if there is too little filling material, and will also prevent the filling material from contacting the photosensitive chip if there is too much filling material.

[0026] A2. Apply a suitable amount of alcohol to the adhesive seam between the readout circuit 2 and the Dewar heat-conducting plate 3 to ensure that the adhesive seam between the readout circuit 2 and the Dewar heat-conducting plate 3 is wetted. Then soak the absorbent material 7 thoroughly with alcohol to ensure that the absorbent material filled into the storage groove 6.5 can hold a sufficient amount of alcohol;

[0027] A3. Attach the wetted chip removal device 6 to the Dewar loading surface. Pay attention to the placement of the chip removal device. The placement groove 6.5 of the chip removal device should completely cover the gap between the readout circuit 2 and the Dewar heat-conducting plate 3. The hollow structure 6.6 of the chip removal device should be located directly above the photosensitive chip 1. During the chip removal process, the photosensitive chip 1 can be completely exposed to the air.

[0028] Further, step B includes the following steps:

[0029] B1. Place the test Dewar with the chip removal device in the work area and let it stand for a period of time. Let the absorbent material 7 soaked in alcohol in the storage groove 6.5 drip continuously to soak the gap between the heat-conducting plate 3 of the Dewar and the readout circuit 2. Ensure that alcohol can continuously enter the bonding area between the readout circuit 2 and the heat-conducting plate 3 of the Dewar through capillary action, so that the acetal glue in the whole area can be fully dissolved.

[0030] B2. The operator periodically removes the chip removal device 6 and checks the condition of the adhesive between the readout circuit 2 and the Dewar thermal pad 3. If the operator finds that the chipset still cannot be removed from the Dewar thermal pad 3, steps A2 and A3 need to be repeated to continue dissolving the acetal adhesive between the readout circuit 2 and the Dewar thermal pad 3.

[0031] B3. If the operator finds that the acetal adhesive between the readout circuit 2 and the Dewar thermal conductive plate 3 has been completely dissolved, the chip removal operation must be performed immediately. The detector chip set should be removed from the Dewar thermal conductive plate 3, and the surface of the removed chip set should be cleaned before it can be registered and stored.

[0032] As can be seen from the above technical solution, the sol-gel chip extraction device for large-size infrared detector chipsets of this utility model has at least one of the following beneficial effects:

[0033] (1) It reduces the difficulty of sol-gel removal of infrared detector chipsets, and can remove large-size chipsets from the heat-conducting sheet of the test Dewar more quickly and efficiently.

[0034] (2) It avoids the chip set being soaked in alcohol when taking the sol-gel chip, solves the problem of swelling of the filler glue in the chip set after soaking in alcohol, and reduces the scrap rate of the detector chip set;

[0035] (3) The optimization method of this utility model is simple and effective to operate and has very good repeatability. Attached Figure Description

[0036] Figure 1 : Three-dimensional structural diagram of the film taking device.

[0037] Figure 2 : Schematic diagram of the film taking device.

[0038] Figure 3 During the sample collection process, cross-sectional views and magnified views of the Dewar sample were tested from two directions. Figure 3 In the image: a) is a cross-sectional view of the Dewar test in the y-direction during the sample collection process; b) is a magnified view of position I; c) is a cross-sectional view of the Dewar test in the x-direction during the sample collection process; d) is a magnified view of position II.

[0039] In the picture:

[0040] 1-Photosensitive chip, 2-Readout circuit, 3-Dewar heat-conducting sheet, 4-Lead substrate, 5-Dewar cold head, 6-Soluble chip removal device of this utility model, 7-Water-absorbing material;

[0041] 6.1-Support structure, 6.2-Limiting structure, 6.3-Pad protection structure, 6.4-Chip protection structure, 6.5-Placement groove, 6.6-Koiler structure. Detailed Implementation

[0042] Example

[0043] See Figures 1-3 A sol-gel extraction device specifically designed for large-size infrared detector chipsets is disclosed. This device can increase the alcohol sol-gel rate of the adhesive between the chipset and the Dewar thermal pad, while avoiding alcohol immersion in the chipset and reducing the risk of swelling of the filler adhesive within the chipset. After implementation, this device reduces the manpower required for sol-gel extraction, minimizes damage to the detector chipset, and ensures safe sol-gel extraction after chipset performance screening. This extraction device is simple, effective, and easy to operate.

[0044] This utility model provides a sol-gel chip removal device for large-size infrared detector chipsets. The device includes a support structure 6.1, a limiting structure 6.2, a pad protection structure 6.3, a chip protection structure 6.4, a placement groove 6.5, and a hollow structure 6.6; wherein:

[0045] The outer ring structure of the wafer picker consists of a support structure 6.1, a limiting structure 6.2, and a pad protection structure 6.3. For example... Figure 3 As shown in d), the contact support relationship between the support structure 6.1 of the chip picking device and the Dewar cold head 5 (the support structure 6.1 needs to be in direct contact with the Dewar cold head 5) serves to support the entire chip picking device during use. The limiting structure 6.2 needs to be designed according to the shape of the Dewar device surface, allowing the chip picking device to engage with the Dewar cold head 5 to provide a certain limiting effect. The pad protection structure 6.3 needs to have a 1mm gap between itself and the lead substrate 4. Figure 3 As shown, this prevents the chip picking device from rubbing against the pads on the lead substrate during use, thus protecting the lead pads.

[0046] The internal structure of the chip extraction device consists of a chip protection structure 6.4, a placement groove 6.5, and a hollow structure 6.6. For example... Figure 3 As shown in b), the gap fit between the pad protection structure 6.3 of the chip picker and the lead substrate 4, and the gap fit between the chip protection structure 6.4 and the photosensitive chip 1 (the chip protection structure 6.4 needs to have a 1mm gap with the photosensitive chip 1) are designed to prevent the chip picker from rubbing against the photosensitive chip during use and to protect the photosensitive chip. The placement groove 6.5 needs to be open downward and have a certain depth to be filled with sufficient water-absorbing material 7. The hollow structure 6.6 needs to be consistent with the outer dimensions of the photosensitive chip 1 to ensure that alcohol will not drip onto the photosensitive chip 1 during use.

[0047] Based on the design scheme of the film taking device, it was prepared by mechanical processing;

[0048] The chip picker is ultrasonically cleaned after processing to ensure that it will not contaminate the chipset in subsequent use.

[0049] The snap-fit ​​position between the limiting structure 6.2 and the lead substrate 4.

[0050] A sol-gel extraction method for large-size infrared detector chipsets includes the following steps:

[0051] Step 1: Fill an appropriate amount of absorbent material 7 into the placement groove 6.5 of the chip taking device. The amount of filling material should just fill the groove. The height of the filling material should be flush with the chip protection structure 6.4. This will prevent the filling material from falling out of the placement groove if there is too little filling material, and will also prevent the filling material from contacting the photosensitive chip if there is too much filling material.

[0052] Step 2: Apply a suitable amount of alcohol to the adhesive gap between the readout circuit 2 and the Dewar heat-conducting plate 3 to ensure that the adhesive gap between the readout circuit 2 and the Dewar heat-conducting plate 3 is wetted. Then, thoroughly soak the absorbent material 7 in alcohol to ensure that the absorbent material filled into the storage groove 6.5 can hold a sufficient amount of alcohol.

[0053] Step 3: Attach the wetted chip removal device 6 to the Dewar loading surface. Pay attention to the placement of the chip removal device. The placement groove 6.5 of the chip removal device should completely cover the gap between the readout circuit 2 and the Dewar heat-conducting plate 3. The hollow structure 6.6 of the chip removal device should be located directly above the photosensitive chip 1. During the chip removal process, the photosensitive chip 1 can be completely exposed to the air.

[0054] Step 4: Place the test Dewar with the chip removal device installed in the work area and let it stand for a period of time. Allow the absorbent material 7 soaked in alcohol in the storage groove 6.5 to drip continuously, soaking the gap between the heat-conducting sheet 3 of the Dewar and the readout circuit 2. Ensure that alcohol can continuously enter the bonding area between the readout circuit 2 and the heat-conducting sheet 3 of the Dewar through capillary action, so that the acetal glue in the entire area can be fully dissolved.

[0055] Step 5: The operator periodically removes the chip removal device 6 and checks the condition of the adhesive between the readout circuit 2 and the Dewar thermal pad 3. If the operator finds that the chipset still cannot be removed from the Dewar thermal pad, steps 2 and 3 need to be repeated to continue dissolving the acetal adhesive between the readout circuit 2 and the Dewar thermal pad 3.

[0056] Step 6: If the operator finds that the acetal adhesive between the readout circuit 2 and the Dewar thermal conductive plate 3 has been completely dissolved, the operator must immediately perform a routine chip removal operation to remove the detector chip set from the Dewar thermal conductive plate 3. After the removed chip set is cleaned, it can be registered and stored in the warehouse.

Claims

1. A sol-gel chip removal device for a large-size infrared detector chip group, wherein the infrared detector chip group consists of two parts, a photosensitive chip (1) and a readout circuit (2), which are interconnected by flip-chip bonding and filling adhesive, and a Dewar heat-conducting sheet (3) is located between the readout circuit (2) and the Dewar cold head (5) and connected to the readout circuit (2) by adhesive; characterized in that: The device is rectangular in shape. Its outer ring structure consists of a higher support structure (6.1) on both sides, a limiting structure (6.2) at the four corners, and a lower pad protection structure (6.3) on both sides. The support structure (6.1) directly contacts the Dewar cold head (5) and supports the entire device from both sides during solder sol-gel extraction. The limiting structure (6.2) is shaped to match the loading surfaces of the Dewar cold head (5) and the lead substrate (4), allowing the device to engage with the Dewar cold head (5) and the lead substrate (4) for positioning. The pad protection structure (6.3) is located above the lead substrate (4) and has a gap between it and the lead substrate (4) to prevent the device from rubbing against the bonding pads on the lead substrate (4) during use, thus protecting the bonding pads. The device also includes: The hollow structure (6.6) located in the center of the entire chip taking device is consistent with the outer size of the photosensitive chip (1), ensuring that the alcohol in the placement groove (6.5) will not drip onto the photosensitive chip (1) during the use of the chip taking device, thus avoiding alcohol contamination of the photosensitive chip (1) after sol-gelling. The chip protection structure (6.4) surrounding the hollow structure (6.6) is used to protect the chip group placed below the hollow structure (6.6), prevent the solvent alcohol from seeping into the space between the photosensitive chip (1) and the readout circuit (2), and avoid causing the filler glue in the chip group to swell. The storage groove (6.5) located between the chip protection structure (6.4) and the outer ring structure of the device has an opening facing downward and a certain depth, and is used to fill the absorbent material (7). The absorbent material (7) contains alcohol, which is used to dissolve the adhesive between the readout circuit (2) and the Dewar heat-conducting sheet (3).

2. The sol-gel sampling device as described in claim 1, characterized in that: A certain gap is left between the pad protection structure (6.3) and the lead substrate (4) to prevent the chip removal device from rubbing against the pads on the lead substrate during use, thus protecting the lead pads.

3. The sol-gel sampling device as described in claim 1, characterized in that: A certain gap is left between the chip protection structure (6.4) and the photosensitive chip (1) to prevent the chip taking device from rubbing against the photosensitive chip (1) during use, thus protecting the photosensitive chip (1).

4. The sol-gel sampling device as described in claim 1, characterized in that: The placement groove (6.5) can completely cover the gap between the readout circuit (2) and the Dewar heat-conducting plate (3).

5. The sol-gel sampling device as described in claim 1, characterized in that: The hollow structure (6.6) is located directly above the photosensitive chip (1), so that the photosensitive chip (1) can be completely exposed to the air during the chip removal process.

6. The sol-gel sampling device as described in claim 2, characterized in that: A gap of 1-2 mm is left between the pad protection structure (6.3) and the lead substrate (4).

7. The sol-gel sampling device as described in claim 3, characterized in that: A gap of 1-2 mm is left between the chip protection structure (6.4) and the photosensitive chip (1).

8. The sol-gel extractor as described in any one of claims 1-7, characterized in that: The heat-conducting sheet (3) of the Dewar transfers the heat of the chipset to the Dewar cold head (5) through contact conduction, and reduces the thermal stress on the chipset during temperature change; the lead substrate (4) is located on both sides of the chipset and is connected to the chipset through wire bonding to realize signal transmission between the chipset and the external electrical interface of the Dewar; the Dewar cold head (5) is the inner tube of the Dewar, and the heat-conducting sheet (3), the lead substrate (4) and the chipset are all installed on the Dewar cold head (5), which plays the role of loading the internal components of the Dewar and transferring the cooling energy to the inside of the Dewar.

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