A large-size CLCC packaged detector assembly and its soldering method

Abstract

This invention relates to a CLCC packaged detector assembly and its soldering method, addressing the technical problem in existing technologies where large-size CLCC packaged devices are directly soldered to printed circuit boards, leading to cracking of the solder joints under environmental stress due to alternating forces. The invention provides a large-size CLCC packaged detector assembly and its soldering method, comprising a CLCC packaged detector and a ceramic substrate with a similar coefficient of thermal expansion to the CLCC packaged detector. The detector is placed on top of the ceramic substrate. The CLCC packaged detector refers to a CLCC packaged detector with a side length greater than 10.18 mm, and the similar coefficient of thermal expansion means that the difference between their coefficients of thermal expansion is less than or equal to 1.0 ppm / ℃. The CLCC packaged detector has multiple device solder terminals, and the ceramic substrate has multiple first solder pads, each corresponding to one of the multiple device solder terminals. A pre-fabricated solder pad is provided between the first solder pad and the device solder terminal, and both the first solder pad and the device solder terminal are connected to the pre-fabricated solder pad via flux.

Description

Technical Field

[0001] This invention relates to CLCC packaged detector components and their soldering methods, specifically to a large-size CLCC packaged detector component and its soldering method. Background Technology

[0002] Currently, directly soldering large-sided CLCC (Ceramic Leaded Chip Carrier) packages (typically referring to CLCC packages with a side length greater than 10.18mm) onto printed circuit boards is problematic. Due to the significant difference in thermal expansion coefficients between the package and the printed circuit board, the solder joints are susceptible to cracking under alternating stress in environmental stress, leading to reduced soldering reliability. Therefore, directly soldering large-sided CLCC packages onto printed circuit boards is a prohibited process in aerospace applications. Consequently, when soldering large-sided CLCC packages, the package type is usually modified, such as using PGA (Pin Grid Array) or CQFP (Ceramic Quad Flat Package) packages.

[0003] For imported large-size CLCC packaged devices with high-level, high-sensitivity, and high-precision assembly and adjustment limitations, it is impossible to change the package form to achieve soldering with the printed circuit board. While methods such as ball-mounting on the bottom of the device, selecting a special PCB material, or performing secondary packaging can be used to solder imported large-size CLCC packaged devices to the printed circuit board, these methods are costly, unsuitable for precision optomechanical products, and difficult to apply in large quantities in aerospace engineering.

[0004] Therefore, the shortcomings of the above-mentioned prior art are: when large-size CLCC packaged devices are directly soldered to printed circuit boards, the solder joints are prone to cracking under environmental stress due to alternating forces, making it difficult to apply large-size CLCC packaged devices directly to printed circuit boards in aerospace engineering. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problem in the prior art where large-size CLCC packaged devices are directly soldered to printed circuit boards, and the solder joints are prone to cracking under environmental stress due to alternating forces. Therefore, this invention provides a large-size CLCC packaged detector assembly and its soldering method.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] A large-size CLCC packaged detector assembly, which is special in that:

[0008] It includes a CLCC packaged detector and a ceramic substrate with a similar coefficient of thermal expansion to the CLCC packaged detector, with the detector placed on top of the ceramic substrate; the CLCC packaged detector refers to a CLCC packaged detector with a side length greater than 10.18 mm, and the similar coefficient of thermal expansion means that the difference between the two coefficients of thermal expansion is less than or equal to 1.0 ppm / ℃.

[0009] The CLCC packaged detector is provided with multiple device solder terminals, and the ceramic substrate is provided with multiple first solder pads, with each of the multiple first solder pads corresponding to one of the multiple device solder terminals.

[0010] A pre-made solder pad is provided between the first solder pad and the device solder end, which is used to weld the first solder pad and the device solder end after vacuum heating and cooling;

[0011] The surfaces of the preformed solder pad that contact the first solder pad and the device solder end are coated with a sticky flux, and the first solder pad and the device solder end are connected to the preformed solder pad through the flux.

[0012] Furthermore, it also includes flexible plates distributed on the outer sides of both ends of the ceramic substrate;

[0013] The ceramic substrate has a plurality of second pads at one end near the flexible plate, and the flexible plate has a plurality of third pads corresponding to the second pads on one side near the ceramic substrate. A connecting conductor is provided between the second pads and the third pads.

[0014] Furthermore, the connecting conductor has a shape that is straight at both ends and protrudes upward in the middle;

[0015] The contact portion between the connecting conductor and the second pad occupies more than three-quarters of the length of the second pad, and the contact portion between the connecting conductor and the third pad occupies more than three-quarters of the length of the third pad.

[0016] Furthermore, the planar dimensions of the prefabricated solder pad are the same as the planar dimensions of the first solder pad;

[0017] The thickness of the prefabricated sheet is 0.15 mm.

[0018] Furthermore, the packaging body of the CLCC-encapsulated detector is made of alumina ceramic with a thermal expansion coefficient of 7.1 ppm / ℃;

[0019] The ceramic substrate is made of HTCC ceramic with a coefficient of thermal expansion of 7 ppm / ℃;

[0020] The flexible plate is a glass fiber epoxy resin copper-clad laminate.

[0021] The connecting conductor is a silver-plated copper wire.

[0022] Meanwhile, the present invention also provides a welding method for a large-size CLCC packaged detector assembly, which is characterized by including the following steps:

[0023] S1. Clean the first pad on the ceramic substrate and the device solder joints on the CLCC packaged detector;

[0024] S2. Apply a sticky flux to the contact surfaces of the preformed solder pad, the first solder pad, and the solder end of the device.

[0025] S3. Adhere the pre-made solder pad to the first solder pad using flux;

[0026] S4. Place the CLCC packaged detector on the ceramic substrate and align the device solder terminals with the first solder pads one by one. Connect the device solder terminals to the pre-made solder pads through flux.

[0027] S5. Place the CLCC packaged detector, ceramic substrate and pre-made solder pad into the vacuum heating furnace;

[0028] The vacuum furnace is evacuated to below 1 torr, and the pre-made solder pads are melted by heating in the vacuum furnace. After heating is stopped, the device is allowed to cool naturally, so that the solder ends of the device are soldered together with the first solder pad, thus realizing the welding between the CLCC packaged detector and the ceramic substrate.

[0029] Further, step S1 specifically involves: using a non-woven cloth soaked in anhydrous ethanol to wipe the first pad on the ceramic substrate and the device solder joints on the detector.

[0030] Furthermore, in step S5, the specific steps for melting the preformed welding sheet by heating in a vacuum furnace are as follows:

[0031] The temperature is raised to T-20℃ in the vacuum heating furnace at a heating rate of 5℃ / min, and the preformed welding sheet is preheated at T-20℃ for 10min; where T is the liquidus temperature of the preformed welding sheet.

[0032] After preheating, the temperature in the vacuum heating furnace is increased to T+40℃ at a heating rate of 5℃ / min, and the precast welding piece is heated at T+40℃ for 3 minutes to melt the precast welding piece.

[0033] Furthermore, it also includes the following steps:

[0034] S6. After the CLCC packaged detector is soldered to the ceramic substrate, clean the second pad on the ceramic substrate and the third pad on the flexible plate.

[0035] S7. Protect the CLCC packaged detector on the ceramic substrate;

[0036] S8. Solder the two ends of the connecting conductor to the second and third pads respectively using solder.

[0037] Further, in step S6, the second pad on the ceramic substrate and the third pad on the flexible plate are wiped with a non-woven cloth soaked in anhydrous ethanol.

[0038] Step S7 is as follows:

[0039] S7.1 Apply tape to the upper surface of the CLCC-packaged detector and completely cover the glass plate on the CLCC-packaged detector;

[0040] S7.2. Apply a ring of tape to the ceramic substrate outside the CLCC packaged detector to protect and cover the soldered ends of the device and the first pad.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. The large-size CLCC packaged detector assembly provided by this invention avoids the problem of solder joint cracking under environmental stress caused by a large difference in thermal expansion coefficients by selecting CLCC packaged detectors and ceramic substrates with similar thermal expansion coefficients, thus overcoming the limitations imposed by restricted processes. Furthermore, this application uses prefabricated solder pads and adhesive flux to connect the first pad to the device solder end, eliminating the need for solder paste printing and tooling, enabling rapid mounting and improving efficiency. High-temperature vacuum sintering of the prefabricated solder pads melts them for welding, and the vacuum environment effectively isolates the material from oxygen, reducing bubble formation and improving welding quality.

[0043] 2. The large-size CLCC packaged detector assembly provided by the present invention has a ceramic substrate connected to external devices through a connecting conductor and a flexible plate. Since the connecting conductor is a silver-plated copper wire, which is soft, and the shape of the connecting conductor is straight at both ends and protruding upward in the middle, the connecting conductor can release the stress at the connection point through deformation.

[0044] 3. The welding method for the large-size CLCC packaged detector assembly provided by the present invention uses a specific temperature curve for welding. The heating rate of 5℃ / min can ensure that the device has minimal thermal shock. Preheating the pre-made solder pad to 20℃ below the liquidus temperature of the pre-made solder pad for 10 minutes can maximize the wetting effect of the flux, thereby eliminating the temperature gradient and reducing thermal deformation stress. Natural cooling can release the thermal deformation stress.

[0045] 4. The welding method for the large-size CLCC packaged detector assembly provided by the present invention involves attaching tape between the CLCC packaged detector and the second pad to form a protective strip during welding, and covering the glass cover on the CLCC packaged detector. This can reduce the introduction of foreign matter and static electricity, which plays a decisive and important role in product quality. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of an embodiment of the large-size CLCC packaged detector assembly of the present invention;

[0047] Figure 2 This is a temperature curve diagram in step S5 of an embodiment of the welding method for the large-size CLCC packaged detector assembly of the present invention.

[0048] Explanation of reference numerals in the attached figures: 1-CLCC packaged detector, 2-device solder pad, 3-first solder pad, 4-pre-fabricated solder pad, 5-ceramic substrate, 6-second solder pad, 7-third solder pad, 8-connecting conductor, 9-flex plate. Detailed Implementation

[0049] 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.

[0050] like Figure 1 As shown, this invention discloses a large-size CLCC packaged detector assembly. In order to eliminate the alternating stress introduced by the large difference in thermal expansion coefficients, the CLCC packaged detector 1 and the ceramic substrate 5 are selected with a difference in thermal expansion coefficients of less than or equal to 1.0 ppm / ℃ to avoid introducing alternating stress. In this embodiment, the CLCC packaged detector 1 is made of alumina ceramic with a thermal expansion coefficient of 7.1 ppm / ℃; the ceramic substrate 5 is made of HTCC (High Temperature Co-fired Ceramic) ceramic with a thermal expansion coefficient of 7 ppm / ℃.

[0051] like Figure 1 As shown, the CLCC packaged detector 1 is placed on top of the ceramic substrate 5; the CLCC packaged detector 1 is provided with multiple device solder terminals 2, and the ceramic substrate 5 is provided with multiple first solder pads 3, with each of the multiple first solder pads 3 corresponding to one of the multiple device solder terminals 2.

[0052] like Figure 1As shown, to eliminate the solder paste screen printing process and its tooling, achieve rapid placement, and improve efficiency, a pre-fabricated solder sheet 4 is placed between the first solder pad 3 and the device solder end 2. This pre-fabricated solder sheet 4 is used to weld the first solder pad 3 and the device solder end 2 after vacuum heating and cooling. The pre-fabricated solder sheet 4 melts and then welds the first solder pad 3 and the device solder end 2. Furthermore, the pre-fabricated solder sheet 4 needs to meet the following requirements: the planar dimensions of the pre-fabricated solder sheet 4 are the same as the planar dimensions of the first solder pad 3; the thickness of the pre-fabricated solder sheet 4 is 0.15 mm. The pre-fabricated solder sheet 4 is a sheet-shaped solder material made from conventional solder materials used in aerospace products. In this embodiment, the pre-fabricated solder sheet 4 is Sn63Pb37 solder, and the liquidus temperature T of Sn63Pb37 solder is 183.5℃.

[0053] like Figure 1 As shown, to ensure the relative position of the CLCC packaged detector 1 and the ceramic substrate 5, and the relative position of the first pad 3 and the device solder tip 2, a sticky flux is coated on the surfaces of the preformed solder pad 4 that contact the first pad 3 and the device solder tip 2. The first pad 3 and the device solder tip 2 are connected to the preformed solder pad 4 through the flux. In this embodiment, the sticky flux is a rosin-based liquid flux.

[0054] like Figure 1 As shown, in order to connect the ceramic substrate 5 to external devices and to release the stress at the connection between the external devices and the ceramic substrate 5, flexible plates 9 distributed on the outer sides of both ends of the ceramic substrate 5 are used to connect to the external devices. The flexible plates 9 are made of glass fiber epoxy resin copper-clad laminate. Multiple second pads 6 are provided on one end of the ceramic substrate 5 near the flexible plates 9, and multiple third pads 7 corresponding to the second pads 6 are provided on the side of the flexible plates 9 near the ceramic substrate 5. A connecting conductor 8 is provided between the second pads 6 and the third pads 7. To release the stress, the connecting conductor 8 is made of silver-plated copper wire, and the connecting conductor 8 has a shape that is straight at both ends and protrudes upwards in the middle.

[0055] The specific welding method for the large-size CLCC packaged detector assembly of the present invention is as follows:

[0056] S1. Use non-woven cloth soaked in anhydrous ethanol to wipe the first pad 3 on the ceramic substrate 5 and the device solder terminal 2 on the CLCC packaged detector 1.

[0057] S2. Apply a sticky flux to the contact surfaces of the preformed solder pad 4, the first solder pad 3, and the device solder end 2.

[0058] S3. Adhere the prefabricated solder pad 4 to the first solder pad 3 using flux;

[0059] S4. Place the CLCC packaged detector 1 on the ceramic substrate 5, and make the device solder terminals 2 correspond one-to-one with the first solder pads 3. The device solder terminals 2 are connected to the pre-made solder pads 4 through flux.

[0060] S5. Place the CLCC packaged detector 1, ceramic substrate 5 and pre-made solder sheet 4 into a vacuum heating furnace;

[0061] Evacuate the vacuum heating furnace to below 1 torr;

[0062] like Figure 2 As shown, the temperature in the vacuum heating furnace is raised to 163.5℃ at a heating rate of 5℃ / min, and the pre-fabricated welding piece 4 is preheated at 163.5℃ for 10min.

[0063] After preheating, the temperature in the vacuum heating furnace is raised to 223.5℃ at a heating rate of 5℃ / min, and the precast welding piece 4 is heated at 223.5℃ for 3 minutes to melt the precast welding piece;

[0064] After heating is complete, the device is allowed to cool naturally, allowing the solder terminals 2 to be soldered together with the first solder pad 3, thus achieving the soldering between the CLCC packaged detector 1 and the ceramic substrate 5.

[0065] After the S6 and CLCC packaged detector 1 are soldered to the ceramic substrate 5, the second pad 6 on the ceramic substrate 5 and the third pad 7 on the flexible plate 9 are wiped with non-woven cloth soaked in anhydrous ethanol.

[0066] S7. Protect the CLCC packaged detector 1 on the ceramic substrate 5;

[0067] S7.1 Apply tape to the upper surface of the CLCC-encapsulated detector 1 and completely cover the glass plate on the CLCC-encapsulated detector 1;

[0068] S7.2. Apply a ring of tape to the ceramic substrate 5 on the outside of the CLCC packaged detector 1 to protect and cover the solder terminals 2 of the soldered device and the first solder pad 3.

[0069] S8. Solder the two ends of the connecting conductor 8 to the second pad 6 and the third pad 7 respectively using solder.

[0070] In this embodiment, to ensure the stability of the connection between the connecting conductor 8 and the second pad 6 and the third pad 7, such as... Figure 1 As shown, the contact portion between the connecting conductor 8 and the second pad 6 accounts for more than three-quarters of the length of the second pad 6, and the contact portion between the connecting conductor 8 and the third pad 7 accounts for more than three-quarters of the length of the third pad 7.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A large-size CLCC packaged detector assembly, characterized in that: It includes a CLCC packaged detector (1) and a ceramic substrate (5) with a thermal expansion coefficient similar to that of the CLCC packaged detector (1). The detector (1) is placed on top of the ceramic substrate (5). The CLCC packaged detector (1) refers to a CLCC packaged detector with a side length greater than 10.18 mm. The thermal expansion coefficients are similar, meaning that the difference between the thermal expansion coefficients of the two is less than or equal to 1.0 ppm / ℃. The CLCC packaged detector (1) is provided with multiple device solder terminals (2), and the ceramic substrate (5) is provided with multiple first solder pads (3), with each of the multiple first solder pads (3) corresponding to one of the multiple device solder terminals (2). A pre-made solder pad (4) is provided between the first solder pad (3) and the device solder end (2) for welding the first solder pad (3) and the device solder end (2) after vacuum heating and cooling; The surfaces of the preformed solder pad (4) that are in contact with the first solder pad (3) and the device solder end (2) are coated with a sticky flux. The first solder pad (3) and the device solder end (2) are connected to the preformed solder pad (4) through the flux.

2. The large-size CLCC packaged detector assembly according to claim 1, characterized in that: It also includes flexible plates (9) distributed on the outer sides of both ends of the ceramic substrate (5); The ceramic substrate (5) has a plurality of second pads (6) at one end near the flexible plate (9), and the flexible plate (9) has a plurality of third pads (7) corresponding to the second pads (6) on one side near the ceramic substrate (5). A connecting conductor (8) is provided between the second pads (6) and the third pads (7).

3. The large-size CLCC packaged detector assembly according to claim 2, characterized in that: The connecting conductor (8) has a shape with straight ends and an upward protrusion in the middle; The contact portion between the connecting conductor (8) and the second pad (6) accounts for more than three-quarters of the length of the second pad (6), and the contact portion between the connecting conductor (8) and the third pad (7) accounts for more than three-quarters of the length of the third pad (7).

4. The large-size CLCC packaged detector assembly according to claim 1, characterized in that: The planar dimensions of the preformed solder pad (4) are the same as those of the first solder pad (3); The thickness of the prefabricated sheet (4) is 0.15 mm.

5. The large-size CLCC packaged detector assembly according to claim 2, characterized in that: The packaging body of the CLCC packaged detector (1) is made of alumina ceramic with a thermal expansion coefficient of 7.1 ppm / ℃; The ceramic substrate (5) is made of HTCC ceramic with a thermal expansion coefficient of 7ppm / ℃; The flexible plate (9) is a glass fiber epoxy resin copper-clad board; The connecting conductor (8) is a silver-plated copper wire.

6. A welding method for a large-size CLCC packaged detector assembly as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Clean the first pad (3) on the ceramic substrate (5) and the device solder joint (2) on the CLCC packaged detector (1); S2. Apply a sticky flux to the contact surfaces of the preformed solder sheet (4), the first solder pad (3), and the device solder end (2); S3. The pre-made solder pad (4) is attached to the first solder pad (3) with flux; S4. Place the CLCC packaged detector (1) on the ceramic substrate (5) and make the device solder terminals (2) correspond one-to-one with the first solder pad (3). The device solder terminals (2) are connected to the pre-made solder pad (4) through flux. S5. Place the CLCC packaged detector (1), ceramic substrate (5) and pre-made solder sheet (4) into a vacuum heating furnace; The vacuum furnace is evacuated to below 1 torr, and the pre-made solder pad (4) is melted by heating in the vacuum furnace. After heating is stopped, it is allowed to cool naturally, so that the device solder end (2) is welded together with the first solder pad (3), thus realizing the welding between the CLCC packaged detector (1) and the ceramic substrate (5).

7. The welding method for a large-size CLCC packaged detector assembly according to claim 6, characterized in that, The specific step S1 is as follows: using a non-woven cloth soaked in anhydrous ethanol to wipe the first pad (3) on the ceramic substrate (5) and the device solder terminals (2) on the detector (1).

8. The welding method for a large-size CLCC packaged detector assembly according to claim 6, characterized in that, In step S5, the specific steps for melting the preformed welding piece (4) by heating in a vacuum furnace are as follows: The temperature of the vacuum heating furnace is raised to T-20℃ at a heating rate of 5℃ / min, and the preformed welding piece (4) is preheated at T-20℃ for 10min; where T is the liquidus temperature of the preformed welding piece (4); After preheating, the temperature of the vacuum heating furnace is raised to T+40℃ at a heating rate of 5℃ / min, and the prefabricated welding piece (4) is heated at T+40℃ for 3 minutes to melt the prefabricated welding piece (4).

9. The welding method for a large-size CLCC packaged detector assembly according to claim 6, characterized in that, It also includes the following steps: S6. After the CLCC packaged detector (1) is soldered to the ceramic substrate (5), clean the second pad (6) on the ceramic substrate (5) and the third pad (7) on the flexible plate (9). S7. Protect the CLCC packaged detector (1) on the ceramic substrate (5); S8. Solder the two ends of the connecting conductor (8) to the second pad (6) and the third pad (7) respectively using solder.

10. The welding method for a large-size CLCC packaged detector assembly according to claim 9, characterized in that: In step S6, the second pad (6) on the ceramic substrate (5) and the third pad (7) on the flexible plate (9) are wiped with anhydrous ethanol using a non-woven cloth. Step S7 is as follows: S7.

1. Apply tape to the upper surface of the CLCC-encapsulated detector (1) and completely cover the glass plate on the CLCC-encapsulated detector (1); S7.

2. Apply a ring of tape to the ceramic substrate (5) on the outside of the CLCC packaged detector (1) to protect and cover the solder terminals (2) of the soldered device and the first pad (3).

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