Packaging structure and packaging method of infrared detector

Abstract

The invention relates to the technical field of infrared detectors, and discloses a packaging structure of an infrared detector, which comprises an optical window, a bracket, an infrared detection chip and a substrate, the substrate is of a flat plate structure; the support is of a frame-shaped structure. The infrared detection chip is connected to the upper surface of the substrate; and the optical window and the bracket as well as the bracket and the substrate are welded through welding flux to form a packaging structure. According to the packaging structure, the requirements of miniaturization, light weight, diversification and low cost of the infrared detector module can be met. Meanwhile, the invention further provides a packaging method of the infrared detector.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared detectors, and in particular to a packaging structure and a packaging method of an infrared detector. Background Art

[0002] At present, the infrared detector module usually adopts the ceramic pin grid matrix tube shell (CPGA), which is a plug-in package. The specific manufacturing method is: in a vacuum environment, the ceramic pin grid matrix tube shell is used as the bearing cavity of the entire infrared detector module, and the infrared chip is attached or welded to the ceramic pin grid matrix tube shell through metal paste or alloy solder sheet, and then the chip is connected to the ceramic pin grid matrix tube shell circuit through metal wire; then the getter installed inside the ceramic pin grid matrix tube shell or on the back of the optical window is activated; finally, the ceramic pin grid matrix tube shell and the optical window are connected together through the solder sheet for high vacuum packaging. However, the use of ceramic pin grid matrix tube shell to package infrared chips has the disadvantages of high cost, few optional specifications, large size, and single output mode.

[0003] CN201910288205 discloses an infrared sensor vacuum packaging structure and a vacuum packaging method, including a shell, an infrared chip, a getter, an optical window and a metal cover, the optical window is fixed to the top of the metal cover through a solder sheet, the bottom of the metal cover is provided with a groove, the getter is fixed in the groove, the bottom of the metal cover is fixed to the top of the shell through a solder sheet, the top of the shell is provided with an opening and a metal pad is prepared in the opening, the infrared chip is fixed in the opening and connected to the metal pad by a gold wire, and the bottom of the shell is provided with a pin connected to the metal pad. A packaging method is also disclosed, comprising the following steps: 1. Fixing an infrared chip on a housing, and connecting the infrared chip to a metal pad on the housing using a gold wire to form an upper cavity structure; fixing a getter on a metal upper cover, and fixing an optical window to the metal upper cover through a solder sheet under high temperature vacuum to form a lower cavity structure; 2. High-temperature degassing is performed on the upper cavity structure and the lower cavity structure obtained in step 1, and the lower cavity is activated by a vacuum reflow soldering machine, and the upper cavity structure and the lower cavity structure after the getter activation are sealed under high temperature vacuum to form a closed cavity. The housing of the packaging structure belongs to a ceramic pin-grid matrix tube shell, and it also needs to be sealed with a metal upper cover, so the structure is relatively complex and the cost is relatively high. However, the packaging method requires first welding the optical window to the metal upper cover, and then welding the metal upper cover to the housing, which requires two welding steps, has many operation steps, and is inefficient.

[0004] CN202011563618 discloses a method for manufacturing an infrared detector module, comprising the following steps: S1, providing a ceramic substrate, wherein the ceramic substrate has a first surface and a second surface in a thickness direction (H); S2, metalizing the first surface of the ceramic substrate using a surface deposition process and forming a first metal layer, a second metal layer and a plurality of third metal layers, wherein the second metal layer surrounds the outside of the first metal layer, and the plurality of third metal layers are located between the second metal layer and the first metal layer; S3, metalizing the second surface of the ceramic substrate using a surface deposition process and forming a plurality of fourth metal layers; S4, making connecting circuits on the first metal layer, the plurality of third metal layers and the plurality of fourth metal layers of the ceramic substrate; S5, using a surface deposition process to deposit metal layers on the second metal layer and form a metal dam protruding from the first metal layer, the metal dam and the ceramic substrate together constitute the outer shell of the infrared detector module; S6, providing an infrared chip, fixing the infrared chip on the first metal layer of the ceramic substrate, and electrically connecting the infrared chip to the plurality of third metal layers using wires; S7, providing a getter, setting the getter in the outer shell, and activating the getter in a vacuum environment; S8, providing an optical window and a first connector, and fixing the optical window to the metal dam of the outer shell through the first connector in a high-temperature vacuum environment, so that the optical window and the outer shell form a closed detector cavity. After the wiring is completed on the ceramic substrate, this method needs to construct a metal dam through a surface deposition process, and there are many steps in the packaging, which affects the production efficiency.

[0005] Therefore, the technical problem to be solved by the present invention is: how to achieve the requirements of miniaturization, lightness, diversification, and low cost of the infrared detector module and improve production efficiency. Summary of the invention

[0006] The main purpose of the present invention is to provide a packaging structure for an infrared detector, which reduces the amount of ceramic sintering and the difficulty of substrate manufacturing by adopting a flat plate structure substrate and a frame structure bracket to form a packaging shell, thereby reducing the packaging cost. Secondly, since the substrate is a flat plate structure and the bracket is a frame structure, the height dimension of the infrared detector module is reduced, and the shape, size, and output mode of the parts can be freely designed, thereby meeting the miniaturization, lightweight, and diversification requirements of the infrared detector module.

[0007] At the same time, a packaging method for an infrared detector is also provided.

[0008] To achieve the above objectives, the technical solutions adopted in this application are:

[0009] A packaging structure of an infrared detector includes an optical window, a bracket, an infrared detection chip, and a substrate; the substrate is a flat plate structure; the bracket is a frame structure; the infrared detection chip is connected to the upper surface of the substrate; the optical window and the bracket, and the bracket and the substrate are welded by solder to form a packaging structure.

[0010] Preferably, the upper surface and the lower surface of the substrate are respectively provided with a first pad circuit and a second pad circuit; the first pad circuit and the second pad circuit are connected to each other; the infrared detection chip is connected to the first pad circuit; and the second pad circuit is connected to the peripheral circuit.

[0011] Preferably, a getter is provided on a side of the optical window close to the packaging shell.

[0012] Preferably, the material of the bracket is Kovar alloy; the material of the substrate is ceramic.

[0013] At the same time, a packaging method of an infrared detector is also provided, which is used to produce the packaging structure of the above-mentioned infrared detector, comprising the following steps:

[0014] Step 1: The infrared detection chip is mounted on the substrate; then the second solder sheet, the bracket, the first solder sheet, and the optical window are sequentially placed on the substrate to form a packaging structure;

[0015] Step 2: Under vacuum conditions, heating the package structure at a first temperature for 15 to 30 minutes to activate the getter on the optical window;

[0016] Step 3: After activating the getter, heat the packaging structure at the second temperature for 5 to 15 minutes to melt the first solder sheet and the second solder sheet, so that the bracket, the optical window, and the substrate are welded into one body to complete the packaging.

[0017] In some embodiments of the present invention, the package structure is heated at the first temperature for 15 min, 20 min, 25 min, or 30 min;

[0018] The package structure is heated at the second temperature for 5 min, 7 min, 9 min, 11 min, 13 min, and 15 min.

[0019] Preferably, before performing step 1, the following steps are performed:

[0020] Step A: metallizing the substrate through a surface deposition process to form a first pad circuit; forming a second pad circuit through a plane reflow process; and then connecting the first pad circuit and the second pad circuit by laser drilling and electroplating the holes in the substrate;

[0021] Step B: electroplating the surface of the bracket with nickel and gold;

[0022] Step C: heating the support and the substrate to degas the support and the substrate.

[0023] Preferably, the first solder sheet and the second solder sheet are both Au80Sn20 preformed solder sheets; the first solder sheet and the second solder sheet are adapted to the shape of the bracket.

[0024] Preferably, the first temperature is 250-280°C; the second temperature is 330-370°C.

[0025] In some embodiments of the present invention, the first temperature is preferably 250°C, 260°C, 270°C, 280°C;

[0026] The second temperature is preferably 330°C, 340°C, 350°C, 360°C, or 370°C.

[0027] Preferably, in step C, the heating temperature is 120-150° C., and the heating time is 10-20 hours.

[0028] In some embodiments of the present invention, the heating temperature is preferably 120°C, 130°C, 140°C, 150°C,

[0029] The heating time is preferably 10 h, 12 h, 14 h, 16 h, 18 h, or 20 h.

[0030] Preferably, in step A, the surface deposition process is evaporation, magnetron sputtering, electroplating or chemical plating.

[0031] Compared with the prior art, this solution has the following beneficial effects:

[0032] The packaging structure of this solution uses a packaging shell composed of a substrate and a bracket instead of a ceramic pin-grid matrix tube shell to place the infrared detection chip. Its advantages are:

[0033] 1. The packaging shell is composed of a substrate and a bracket instead of integrated ceramic sintering. The substrate is made of ceramic material and the bracket is made of Kovar alloy material, which reduces the amount of ceramic and the difficulty of ceramic sintering, thereby reducing the cost of the packaging shell and thus reducing the cost of the infrared detection module.

[0034] 2. The substrate adopts a flat structure, and the bracket adopts a frame structure. Both the substrate and the bracket are planar structures and the combination of the two reduces the difficulty of making the packaging shell. The size and shape of the packaging shell can be freely designed according to customer needs, simplifying the packaging process, reducing the overall thickness of the infrared detection module, and meeting the needs of miniaturization, lightweight and diversification of infrared detector modules.

[0035] The packaging method of the present invention, after metallization and wiring of the substrate, only needs to weld the optical window, bracket and substrate at one time by means of solder sheets to form an integrated packaging structure. There is no need to form a dam on the substrate by means of a surface deposition process, thus reducing the steps of the packaging process and improving production efficiency.

[0036] Secondly, by using planar reflow soldering to form pads on the lower surface of the substrate to replace the pin grid matrix for connecting with the peripheral circuit, the overall height of the infrared detection module is reduced and the connection difficulty between the infrared detection module and the peripheral circuit is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 An exploded view of the packaging structure of the infrared detector of Example 1;

[0038] Figure 2 This is a schematic structural diagram of the packaging structure of the infrared detector of Example 1;

[0039] Figure 3 This is a top view of the packaging structure of the infrared detector of Example 1.

[0040] Wherein: optical window 1; bracket 2; infrared detection chip 3; substrate 4; first solder sheet 5; second solder sheet 6; first solder pad circuit 7; second solder pad circuit 8. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the present application implemented as generally shown here can be arranged and designed in various different configurations.

[0042] Example 1

[0043] refer to Figure 1-3 A packaging structure of an infrared detector includes an optical window 1, a bracket 2, an infrared detection chip 3, and a substrate 4; the substrate 4 is a flat plate structure; the bracket 2 is a frame structure; the infrared detection chip 3 is connected to the upper surface of the substrate 4; the optical window 1 and the bracket 2, and the bracket 2 and the substrate 4 are welded by solder to form a packaging structure.

[0044] In this embodiment, the bracket 2 is manufactured by machining, and the bracket 2 and the substrate 4 are welded by solder to form a package shell. The solder is a solder sheet. The specific manufacturing process of the package structure is: fix the infrared detection chip 3 on the upper surface of the substrate 4, and connect it with the circuit in the substrate 4, then stack the solder sheet, the bracket 2, the solder sheet, and the optical window on the substrate 4 in sequence, heat and melt the solder sheet, so that the optical window 1, the bracket 2, and the substrate 4 are connected together to form a sealed structure, so that the infrared detection chip 3 is in a vacuum environment, and the sensitivity of the infrared detection chip 3 is ensured.

[0045] It should be noted that since the substrate 4 is a flat structure and the bracket 2 is a frame structure, both are planar structures, the manufacturing difficulty of the substrate 4 and the bracket 2 is relatively low, which can reduce the cost of the packaging shell, and the planar structure is easy to manufacture according to the customer's customized requirements for size and shape.

[0046] Preferably, the upper surface and the lower surface of the substrate 4 are respectively provided with a first pad circuit 7 and a second pad circuit 8; the first pad circuit 7 and the second pad circuit 8 are connected to each other; the infrared detection chip 3 is connected to the first pad circuit 7; the second pad circuit 8 is connected to the peripheral circuit.

[0047] In this embodiment, the substrate 4 serves as a carrier for connecting the infrared detection chip 3 and the peripheral circuit. The infrared detection chip 3 is connected through the first pad circuit 7 and the second pad circuit 8 to the peripheral circuit, thereby transmitting the detection signal to the peripheral circuit. The first pad circuit 7 and the second pad circuit 8 are used to enable the infrared detection chip 3 to be connected to the peripheral circuit, and wiring can be performed according to actual needs. The second pad circuit 8 is used instead of the pin grid matrix to reduce the difficulty of connecting the infrared detection module with the peripheral circuit and improve efficiency.

[0048] Preferably, a getter is provided on one side of the optical window 1 close to the accommodating cavity.

[0049] In this embodiment, the vacuum degree in the packaging shell is maintained by activating the getter on the optical window 1 to prevent the optical window 1, the bracket 2 or the substrate 4 from releasing gas and affecting the sensitivity of the infrared detection chip 3 when the infrared detection chip 3 is working.

[0050] Preferably, the material of the bracket 2 is Kovar alloy; the material of the substrate 4 is ceramic.

[0051] In this embodiment, the material of the bracket 2 is preferably 4J29 Kovar alloy, and other suitable Kovar alloys may also be used, and the material of the substrate 4 is ceramic. 4J29 Kovar alloy has a low thermal expansion coefficient, good processing performance and mechanical properties, and is widely used in the fields of electric vacuum industry, aerospace, electronic packaging, etc., and can better weld the bracket 2 and the substrate 4 into a packaging shell, thereby reducing the cost of the packaging shell.

[0052] Example 2

[0053] refer to Figure 1-3 A packaging method for an infrared detector is used to produce the packaging structure of the infrared detector, comprising the following steps:

[0054] Step A: metallizing the substrate 4 by evaporation process, laying out the circuit on the upper surface of the substrate 4 to form the first pad circuit 7; laying out the circuit on the lower surface of the substrate 4 by plane reflow soldering to form the second pad circuit 8; drilling holes at the positions corresponding to the first pad circuit 7 and the second pad circuit 8 of the substrate 4 by laser drilling to form a plurality of holes, and then filling the plurality of holes by electroplating to connect the first pad circuit 7 and the second pad circuit 8; the material of the substrate 4 is ceramic, and the material of the bracket 2 is 4J29 Kovar alloy;

[0055] Step B: Electroplating the surface of the bracket 2 with nickel and gold to improve the subsequent welding effect of the bracket 2 with the optical window 1 and the substrate 4;

[0056] Step C: heating the support 2, the substrate 4, and the optical window 1 to achieve degassing of the support 2, the substrate 4, and the optical window 1, the heating temperature is 135° C., and the heating time is 15 hours;

[0057] Step 1: The infrared detection chip 3 is mounted on the substrate 4 through conductive glue, and the infrared detection chip 3 is connected to the first pad circuit 7 by a wire; the optical window 1 is placed on the upper clamping mold, and the second solder sheet 6, the bracket 2, the first solder sheet 5, and the substrate 4 are placed on the lower clamping mold in sequence, and then the upper clamping mold and the lower clamping mold are closed, so that the second solder sheet 6, the bracket 2, the first solder sheet 5, the optical window 1, and the substrate 4 are stacked into a packaging structure; the first solder sheet 5 and the second solder sheet 6 are both Au80Sn20 preformed solder sheets; the first solder sheet 5 and the second solder sheet 6 are adapted to the shape of the bracket 2;

[0058] Step 2: Adjust the vacuum furnace to a vacuum degree of 1×10 -5 Pa, heat the package structure at 265°C for 27 minutes to activate the getter on the optical window 1. The getter can improve the vacuum degree in the package structure, and the getter can continuously absorb the trace gas released by the substrate 4, the bracket 2, and the optical window 1 during the infrared detection module;

[0059] Step 3: After activating the getter, heat the packaging structure at 350°C for 10 minutes to melt the first solder sheet 5 and the second solder sheet 6, so that the bracket 2, the optical window 1, and the substrate 4 are welded into one body to complete the packaging.

[0060] Example 3

[0061] A packaging method for an infrared detector, used to produce the packaging structure of the infrared detector, comprises the following steps:

[0062] Step A: metallizing the substrate 4 by magnetron sputtering process, laying out the circuit on the upper surface of the substrate 4 to form the first pad circuit 7; laying out the circuit on the lower surface of the substrate 4 by planar reflow soldering to form the second pad circuit 8; then drilling holes at the positions corresponding to the first pad circuit 7 and the second pad circuit 8 of the substrate 4 by laser drilling to form a plurality of holes, and then filling the plurality of holes by electroplating to connect the first pad circuit 7 and the second pad circuit 8; the material of the substrate 4 is ceramic, and the material of the bracket 2 is 4J29 Kovar alloy;

[0063] Step B: Electroplating the surface of the bracket 2 with nickel and gold to improve the subsequent welding effect of the bracket 2 with the optical window 1 and the substrate 4;

[0064] Step C: heating the support 2 and the substrate 4 to degas the support 2 and the substrate 4, the heating temperature is 150° C., and the heating time is 10 hours;

[0065] Step 1: The infrared detection chip 3 is mounted on the substrate 4 through conductive glue, and the infrared detection chip 3 is connected to the first pad circuit 7 by a wire; the optical window 1 is placed on the upper clamping mold, and the second solder sheet 6, the bracket 2, the first solder sheet 5, and the substrate 4 are placed on the lower clamping mold in sequence, and then the upper clamping mold and the lower clamping mold are closed, so that the second solder sheet 6, the bracket 2, the first solder sheet 5, the optical window 1, and the substrate 4 are stacked into a packaging structure; the first solder sheet 5 and the second solder sheet 6 are both Au80Sn20 preformed solder sheets; the first solder sheet 5 and the second solder sheet 6 are adapted to the shape of the bracket 2;

[0066] Step 2: Adjust the vacuum furnace to a vacuum degree of 1×10 -5 Pa, heat the package structure at 280°C for 15 minutes to activate the getter on the optical window 1. The getter can improve the vacuum degree in the package structure, and the getter can continuously absorb the trace gas released by the substrate 4, the bracket 2, and the optical window 1 during the infrared detection module;

[0067] Step 3: After activating the getter, heat the packaging structure at 330°C for 15 minutes to melt the first solder sheet 5 and the second solder sheet 6, so that the bracket 2, the optical window 1, and the substrate 4 are welded into one body to complete the packaging.

[0068] Example 4

[0069] A packaging method for an infrared detector, used to produce the packaging structure of the infrared detector, comprises the following steps:

[0070] Step A: metallizing the substrate 4 by electroplating, laying out the circuit on the upper surface of the substrate 4 to form the first pad circuit 7; laying out the circuit on the lower surface of the substrate 4 by plane reflow soldering to form the second pad circuit 8; then drilling holes at the positions corresponding to the first pad circuit 7 and the second pad circuit 8 of the substrate 4 by laser drilling to form a plurality of holes, and then filling the plurality of holes by electroplating to connect the first pad circuit 7 and the second pad circuit 8; the material of the substrate 4 is ceramic, and the material of the bracket 2 is 4J42 Kovar alloy;

[0071] Step B: Electroplating the surface of the bracket 2 with nickel and gold to improve the subsequent welding effect of the bracket 2 with the optical window 1 and the substrate 4;

[0072] Step C: heating the support 2 and the substrate 4 to degas the support 2 and the substrate 4, the heating temperature is 120° C., and the heating time is 20 hours;

[0073] Step 1: The infrared detection chip 3 is mounted on the substrate 4 through conductive glue, and the infrared detection chip 3 is connected to the first pad circuit 7 by a wire; the optical window 1 is placed on the upper clamping mold, and the second solder sheet 6, the bracket 2, the first solder sheet 5, and the substrate 4 are placed on the lower clamping mold in sequence, and then the upper clamping mold and the lower clamping mold are closed, so that the second solder sheet 6, the bracket 2, the first solder sheet 5, the optical window 1, and the substrate 4 are stacked into a packaging structure; the first solder sheet 5 and the second solder sheet 6 are both Au80Sn20 preformed solder sheets; the first solder sheet 5 and the second solder sheet 6 are adapted to the shape of the bracket 2;

[0074] Step 2: Adjust the vacuum furnace to a vacuum degree of 1×10 -5 Pa, heat the package structure at 250°C for 30 minutes to activate the getter on the optical window 1. The getter can improve the vacuum degree in the package structure, and the getter can continuously absorb the trace gas released by the substrate 4, the bracket 2, and the optical window 1 during the infrared detection module;

[0075] Step 3: After activating the getter, heat the packaging structure at 370°C for 5 minutes to melt the first solder sheet 5 and the second solder sheet 6, so that the bracket 2, the optical window 1, and the substrate 4 are welded into one body to complete the packaging.

[0076] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A packaging structure of an infrared detector, characterized in that: It includes an optical window, a bracket, an infrared detection chip, and a substrate; the substrate is a flat plate structure; the bracket is a frame structure; the infrared detection chip is connected to the upper surface of the substrate; The optical window and the bracket, as well as the bracket and the substrate are welded by solder to form a packaging structure.

2. The packaging structure of the infrared detector according to claim 1, characterized in that: The upper surface and the lower surface of the substrate are respectively provided with a first pad circuit and a second pad circuit; the first pad circuit and the second pad circuit are connected to each other; the infrared detection chip is connected to the first pad circuit; and the second pad circuit is connected to the peripheral circuit.

3. The packaging structure of the infrared detector according to claim 1, characterized in that: A getter is provided on one side of the optical window close to the packaging shell.

4. The packaging structure of the infrared detector according to claim 1, characterized in that: The material of the bracket is Kovar alloy; the material of the substrate is ceramic.

5. A packaging method for an infrared detector, characterized in that: The packaging structure for producing the infrared detector according to any one of claims 1 to 4 comprises the following steps: Step 1: The infrared detection chip is mounted on the substrate; then the second solder sheet, the bracket, the first solder sheet, and the optical window are sequentially placed on the substrate to form a packaging structure; Step 2: Under vacuum conditions, heating the package structure at a first temperature for 15 to 30 minutes to activate the getter on the optical window; Step 3: After activating the getter, heat the packaging structure at the second temperature for 5 to 15 minutes to melt the first solder sheet and the second solder sheet, so that the bracket, the optical window, and the substrate are welded into one body to complete the packaging.

6. The packaging method of the infrared detector according to claim 5, characterized in that: Before proceeding to step 1, perform the following steps: Step A: metallizing the substrate through a surface deposition process to form a first pad circuit; forming a second pad circuit through a plane reflow process; and then connecting the first pad circuit and the second pad circuit by laser drilling and electroplating the holes in the substrate; Step B: electroplating the surface of the bracket with nickel and gold; Step C: heating the support, substrate and optical window to achieve degassing of the support, substrate and optical window.

7. The packaging method of the infrared detector according to claim 5, characterized in that: The first solder sheet and the second solder sheet are both Au80Sn20 preformed solder sheets; the first solder sheet and the second solder sheet are adapted to the shape of the bracket.

8. The method for packaging an infrared detector according to claim 5, characterized in that: The first temperature is 250-280°C; the second temperature is 330-370°C.

9. The packaging method of the infrared detector according to claim 6, characterized in that: In the step C, the heating temperature is 120-150° C. and the heating time is 10-20 hours.

10. The packaging method of the infrared detector according to claim 6, characterized in that: In the step A, the surface deposition process is evaporation, magnetron sputtering, electroplating or chemical plating.

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