A thermal pad evaluation device

Abstract

This utility model relates to a thermal pad evaluation device, comprising: a height gauge; a housing for accommodating the PCB board and optical components on the PCB board in an optical module, the housing comprising: a bottom shell and an upper cover placed on the bottom shell, the upper cover and the bottom shell being fixedly connected by screws; and a window on the upper cover, directly below the probe in the height gauge and corresponding to the location where the thermal pad is pressed by the PCB board, for the lower end of the probe to enter. The advantages are: this device can practically evaluate the specific performance of the thermal pad in the optical module, the data can be quantified, thus eliminating the need for manual pressing with tweezers and subjective judgment, resulting in high accuracy.

Description

Technical Field

[0001] This utility model relates to the field of optical module production and testing technology, specifically to a thermal pad evaluation device. Background Technology

[0002] In high-speed optical modules, the conventional method for heat dissipation of optical and electronic chips is as follows: When installing the PCB board and its optical components (including fiber arrays, PD chips, and TIA chips) into the housing, a thermal pad is placed on the back of the PCB board facing the optical and electronic chips for heat dissipation. The housing includes a bottom shell and a top cover placed on the bottom shell. The top cover and bottom shell are fixedly connected by screws. The bottom shell has lower protrusions on two side walls near its length to support the edges of the PCB board. The top cover has upper protrusions on two side walls along its length to press the edges of the PCB board downwards. The bottom shell has a support platform for supporting the thermal pad at the corresponding optical and electronic chip locations. The assembly process is as follows: First, place the thermal pad on the support platform in the bottom shell's inner cavity. Then, place the PCB board and its optical components into the bottom shell, close the top cover, and fix the top cover to the bottom shell with screws. Specifically... Figure 1 , Figure 2 , Figure 3 As shown; in this heat dissipation solution, the initial thickness of the thermal pad is designed to be 0.5mm±0.05mm. After the top cover is fixed to the bottom shell with screws, the thermal pad will be compressed, and the thickness of the thermal pad after compression is 0.25mm±0.05mm. When selecting and evaluating thermal pads, parameters such as compressibility and hardness are very important. If the thermal pad is too hard and cannot be compressed by more than 50%, it will cause the PCB board to deform. If the deformation of the PCB board is greater than 5μm, it will cause optical path displacement and may even cause the PD chip to damage the fiber array. Currently, when selecting thermal pads, the operation method is: engineers use tweezers to press and make subjective judgments, without specific data, which is inaccurate. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a thermal pad evaluation device to overcome the shortcomings of the prior art.

[0004] The technical solution of this utility model to solve the above-mentioned technical problems is as follows: A thermal pad evaluation device includes: a height gauge, and a housing for accommodating a PCB board in an optical module and optical devices on the PCB board is arranged on the worktable of the height gauge. The housing includes: a bottom shell and an upper cover placed on the bottom shell. The upper cover and the bottom shell are fixedly connected by screws. A window is opened on the upper cover directly below the probe in the height gauge and corresponding to the thermal pad pressed by the PCB board, allowing the lower end of the probe to enter.

[0005] Based on the above technical solution, the present invention can be further improved as follows.

[0006] Furthermore, the inner cavity of the bottom shell has lower bosses on two side walls near its length to support the edge of the PCB board.

[0007] Furthermore, the inner cavity of the top cover has upper bosses on its two side walls along its length, which are used to press down on the edge of the PCB board.

[0008] Furthermore, a support platform for supporting the heat-conducting pad is provided in the inner cavity of the bottom shell at the corresponding window.

[0009] Furthermore, the height gauge includes: a workbench, a first fixed rod, a second fixed rod, and a gauge. The first fixed rod is fixed vertically on the workbench, the second fixed rod is located above the workbench and distributed horizontally, one end of the second fixed rod is connected to the first fixed rod, and the gauge is located at the other end of the second fixed rod, and the gauge has a probe.

[0010] The beneficial effects of this invention are: the device can be used to evaluate the specific performance of the thermal pad in the optical module, and the data can be quantified, thus eliminating the need for manual pressing with tweezers and subjective judgment, resulting in high accuracy. Attached Figure Description

[0011] Figure 1 This is a structural diagram of a thermal pad, PCB board, and optical devices mounted on it inside a housing in the prior art. Figure 2 A side view of a PCB board and its optical devices being housed in a housing in the prior art. Figure 3 This diagram illustrates the structural deformation of a PCB board when a thermal pad is too hard to be compressed by more than 50%. Figure 4 This is a structural diagram of the thermal pad evaluation device in this utility model; Figure 5 This is a side view of the PCB board and the optical devices on it in this utility model when they are installed inside the housing; Figure 6 A structural diagram of a thermal pad evaluation device when only a PCB board and its optical components are mounted. Figure 7 A structural diagram showing the thermal pad, PCB board, and optical components mounted on it in the thermal pad evaluation device.

[0012] The attached diagram lists the components represented by each number as follows: 1. Height gauge, 110. Workbench, 120. First fixing rod, 130. Second fixing rod, 140. Gauge, 141. Probe, 2. Housing, 210. Bottom shell, 211. Lower boss, 212. Support, 220. Top cover, 221. Window, 222. Upper boss, 230. Screw, 3. PCB board, 4. Thermal pad. Detailed Implementation

[0013] The principles and features of this utility model are described below with reference to the accompanying drawings. The examples given are only for explaining this utility model and are not intended to limit the scope of this utility model.

[0014] Example 1 like Figure 4 , Figure 6 , Figure 7 As shown, a thermal pad evaluation device includes a height gauge 1 and a housing 2. The housing 2 is arranged on the workbench 110 of the height gauge 1. The housing 2 is used to accommodate the PCB board 3 in the optical module and the optical devices on the PCB board 3. The housing 2 includes a bottom shell 210, a top cover 220 and screws 230. The top cover 220 is placed on the bottom shell 210. The top cover 220 and the bottom shell 210 are fixedly connected by screws 230. A window 221 is opened on the top cover 220. The window 221 is located directly below the probe 141 in the height gauge 1, and the window 221 corresponds to the thermal pad 4 pressed by the PCB board 3. The lower end of the probe 141 in the height gauge 1 can enter the window 221. In this embodiment, the structure of the housing 2 is the same as that of the prior art except that a window 221 is opened on the top cover 220. The evaluation process is as follows: Open the top cover 220, do not place the heat-conducting pad 4 yet, put the PCB board 3 and the optical components on it into the bottom shell 210, then put the top cover 220 back on, and fix the top cover 220 and the bottom shell 210 together with screws 230. The lower end of probe 141 in height gauge 1 enters the cavity formed by upper cover 220 and bottom shell 210 through window 221 and contacts TIA chip or other position on PCB board 3, and records the height value reading G1 of height gauge 1. Loosen screw 230, open top cover 220, and remove PCB board 3 and its optical components. Then place thermal pad 4 in the corresponding position in the inner cavity of bottom shell 210, and put PCB board 3 and its optical components into bottom shell 210. Then replace top cover 220 and fix top cover 220 to bottom shell 210 with screw 230. After fixing top cover 220 to bottom shell 210 with screw 230, thermal pad 4 will be compressed, allowing the lower end of probe 141 in height gauge 1 to enter the cavity formed by top cover 220 and bottom shell 210 through window 221 and contact the position previously contacted (for example, if the previous contact was the upper surface of TIA chip, then this time it will still contact the upper surface of TIA chip). Record the height value reading G2 of height gauge 1, and calculate the difference between G2 and G1, that is, the deformation and arching amount of PCB board 3. If G2-G1>5μm, thermal pad 4 is judged to be unqualified; otherwise, it is qualified.

[0015] This device allows for the practical evaluation of the performance of the thermal pad 4 within the optical module. The data can be quantified, eliminating the need for manual pressing with tweezers or subjective judgment, thus ensuring high accuracy.

[0016] Example 2 like Figure 4 , Figure 5 As shown, this embodiment is a further improvement on embodiment 1, as detailed below: The bottom shell 210 has two lower bosses 211 on its two side walls in the length direction of the bottom shell 210. The lower bosses 211 in the bottom shell 210 can support the edge of the PCB board 3.

[0017] Furthermore, the inner cavity of the upper cover 220 has upper protrusions 222 on its two side walls along its length. The upper protrusions 222 in the inner cavity of the upper cover 220 can press down on the edge of the PCB board 3.

[0018] The bottom shell 210 has a support platform 212 in the corresponding window 221. The heat-conducting pad 4 is on the support platform 212, that is, it is supported by the support platform 212 and can be pressed down by the PCB board 3.

[0019] Example 3 like Figure 4 , Figure 6 , Figure 7 As shown, this embodiment is a further improvement on embodiment 1 or 2, as detailed below: The height gauge 1 includes a workbench 110, a first fixed rod 120, a second fixed rod 130, and a gauge 140. The first fixed rod 120 is fixed vertically on the workbench 110. The second fixed rod 130 is located above the workbench 110 and is distributed horizontally. One end of the second fixed rod 130 is connected to the first fixed rod 120. The gauge 140 is located at the other end of the second fixed rod 130 and has a probe 141. The structure of the height gauge 1 is existing technology, so its working principle will not be described in detail here.

[0020] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A thermal pad evaluation device, characterized in that, include: The height gauge (1) has a housing (2) on its workbench (110) for accommodating the PCB board (3) in the optical module and the optical devices on the PCB board (3). The housing (2) includes a bottom shell (210) and an upper cover (220) placed on the bottom shell (210). The upper cover (220) is fixedly connected to the bottom shell (210) by screws (230). A window (221) is opened on the upper cover (220) directly below the probe (141) in the height gauge (1) and corresponding to the heat-conducting pad (4) pressed by the PCB board (3) for the lower end of the probe (141) to enter.

2. The thermal pad evaluation apparatus of claim 1, wherein The bottom shell (210) has two lower bosses (211) on its two side walls near its length, which are used to support the edge of the PCB board (3).

3. The thermal pad evaluation apparatus of claim 2, wherein The inner cavity of the cover (220) has upper bosses (222) on its two side walls along its length direction for pressing down the edge of the PCB board (3).

4. The thermal pad evaluation apparatus of claim 2, wherein The bottom shell (210) has a support (212) in the inner cavity at the corresponding window (221) for supporting the heat-conducting pad (4).

5. An apparatus for evaluating a thermal pad according to any one of claims 1 to 4, characterized by The height gauge (1) includes: a workbench (110), a first fixed rod (120), a second fixed rod (130), and a gauge (140). The first fixed rod (120) is fixed vertically on the workbench (110), the second fixed rod (130) is located above the workbench (110) and distributed horizontally. One end of the second fixed rod (130) is connected to the first fixed rod (120), and the gauge (140) is located at the other end of the second fixed rod (130). The gauge (140) has a probe (141).

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