Solid-state insulation packaging method for pulse power module

Abstract

The invention discloses a solid insulation packaging method for a pulse power module, which is suitable for circuit board insulation packaging and comprises the following steps: fixing a PMMA (Polymethyl Methacrylate) partition plate between two circuit boards, placing the circuit boards in a potting mold, pouring potting soft glue into the potting mold, placing the mold in a constant-temperature oven for curing at 60-80 DEG C, naturally cooling to room temperature after curing, and demolding. The preparation method of the potting flexible glue comprises the following steps: mixing the epoxy resin and the curing agent to obtain a mixed solution, then adding the SiO2 powder, and stirring to form a turbid liquid, namely the potting flexible glue, and the addition amount of the SiO2 powder accounts for 10% of the total mass of the potting flexible glue. The method provided by the invention can effectively improve the electron impact stress resistance of the pulse power module in an environment with a high voltage change rate and a high current change rate, thereby improving the insulation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pulse power module production and manufacturing, in particular to a solid insulation packaging method for a pulse power module. BACKGROUND

[0002] The insulation packaging of a circuit board in the field of a pulse power module is one of the important processes for realizing insulation protection functions, and the use of soft glue filling is one of the circuit board packaging processes, which can make the circuit board module have certain insulation characteristics. For some pulse power high-voltage modules, the epoxy resin soft glue filling packaging is more suitable in terms of use scene and function realization requirements, but some pulse power high-voltage modules have the problems of small filling space, high voltage change rate, high current change rate and stress change caused thereby, so that the traditional insulation packaging materials and processes cannot meet the requirements and further exploration is needed. SUMMARY

[0003] The purpose of the present application is to solve the problems of high voltage change rate, high current change rate and large stress change in the prior art, and to provide a solid insulation packaging method for a pulse power module, which can improve the ability to withstand electronic impact stress and improve the insulation performance of the product.

[0004] The technical scheme of the present application is described in detail as follows: The present application provides a solid insulation packaging method for a pulse power module, which is suitable for circuit board insulation packaging. The PMMA (polymethyl methacrylate) partition plate is fixed between two adjacent circuit boards, placed in a filling mold, and then the filling soft glue is poured into the filling mold. The mold is placed in a constant temperature oven at 60-80℃ for curing, and then naturally cooled to room temperature after curing. The mold can be removed. The preparation method of the filling soft glue is as follows: mixing epoxy resin and curing agent to obtain a mixed solution, then adding SiO2 powder and stirring to obtain a suspension liquid, which is the filling soft glue. The amount of SiO2 powder added accounts for 10% of the total mass of the filling soft glue.

[0005] Optionally or preferably, in the above method, the thickness of the PMMA partition plate is 1mm. The thickness of the PMMA partition plate can also be appropriately adjusted according to the packaging size space.

[0006] Optionally or preferably, in the above method, the curing conditions are set as follows: first, 80℃ for 1-1.5 hours, then 50℃ for 5-6 hours, and finally 60℃ for 3-5 hours.

[0007] Optionally or preferably, in the above method, the filling soft glue is treated by vacuum bubble removal, and the treatment conditions are as follows: vacuum degree ≮-0.095MPa until no bubbles are generated.

[0008] Optionally or preferably, in the above method, the particle size of the SiO2 powder is ≤5 μm.

[0009] Optionally or preferably, in the above method, the purity of SiO2 in the SiO2 powder is ≥99.9%. High-purity common silicon micro powder (SiO2 purity ≥99.9%) on the market is suitable for the present application.

[0010] Compared with the prior art, the present application has the following beneficial effects: PMMA is a hard transparent organic glass material with high molecular weight and high molecular density. Placing PMMA between two adjacent circuit boards can effectively increase the insulation strength of the epoxy resin curing system. Adding a small amount of SiO2 powder to the epoxy resin curing system in the potting soft glue is beneficial to improve the resistivity of the potting system, increase heat dissipation during curing reaction, and reduce boiling phenomenon. Adding SiO2 powder in a proper proportion to the potting soft glue and setting PMMA as a partition can greatly increase the ability to withstand electronic impact stress and improve insulation properties such as breakdown voltage.

[0011] After the epoxy resin is mixed with the curing agent, the polymerization reaction begins. The polymerization reaction is exothermic. In the early stage of the reaction, the reaction is slow and the heat release is small. In the present application, the curing conditions are first raised to 80℃. High temperature is beneficial to increase the curing reaction rate. In the middle stage of the reaction, the reaction is fast and the heat release is more. The center temperature is higher, so reducing the temperature to 50℃ can effectively prevent the potting soft glue from boiling and damaging the electrical components when the temperature is too high. In the late stage of the reaction, the molecular weight of the participating reaction is large, the viscosity is greatly increased, and the reaction rate is reduced. At this time, appropriately increasing the environmental temperature to 60℃ can shorten the curing time and is beneficial to make the reaction more complete. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 The top view and side view structural schematic diagram of the sample block of the control group of Example 1.

[0013] Figure 2 The top view and side view structural schematic diagram of the sample block of the experimental group of Example 1.

[0014] Figure 3 The top view and side view structural schematic diagram of the sample block of the experimental group of Example 2, which is added with SiO2 powder in the potting soft glue formula.

[0015] Figure 4 The top view and side view structural schematic diagram of the sample block of Example 3, which is added with SiO2 powder in the potting soft glue formula and is provided with a PMMA partition in the middle.

[0016] Figure 5 The physical photo of the potting soft glue suspension liquid added with SiO2 powder in the formula. DETAILED DESCRIPTION

[0017] For the person skilled in the art to better understand the present application, the present application will be clearly and completely described below in combination with the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should fall within the scope of protection of the present application. The instruments and reagents used in the embodiments are from commercial channels if not otherwise specified.

[0018] Example 1: Verification of insulation performance improvement of PMMA separator for module The sample size was prepared based on the size requirements of the company's products, and the main test parameter was the withstand voltage value in the thickness direction of the sample.

[0019] Filling process: vacuum degassing of soft glue, vacuum degree ≮-0.095 MPa, until no bubbles are generated, fill the mold, put the mold in a constant temperature oven, 80℃ curing for 1-1.5 hours, 50℃ curing for 5-6 hours, then 60℃ curing for 3-5 hours, finally natural cooling to room temperature, demolding, and taking out the sample block.

[0020] Control group sample block: the soft glue for filling is composed of epoxy resin and curing agent, the sample block is 40×40×20mm in length, width and thickness, and the shape structure and size are as shown in Figure 1 .

[0021] Experimental group sample block: the soft glue for filling is composed of epoxy resin and curing agent, the sample block is 40×40×20mm in length, width and thickness, and a 1mm PMMA separator is placed in the middle position, and the shape structure and size are as shown in Figure 2 .

[0022] Epoxy resin: product of Sichuan Dongshu New Material Co., Ltd., model DQ2140E; curing agent: Sichuan Dongshu New Material Co., Ltd., model DQ2140H.

[0023] Three sample blocks were prepared at one time for each group, and parallel experiments were performed. The hardness of the prepared samples was less than 80HA (Shore hardness), and no further description was made.

[0024] A high-voltage direct-current power supply was used to connect the upper and lower surfaces of each sample block in the thickness direction, and a pulse voltage was applied with a repetition frequency of 10Hz, a pulse front of 30ns, and a pulse width of 80ns. The withstand voltage of the sample block was tested.

[0025] In the above insulation strength formula (1), E is the insulation strength, U is the breakdown voltage, and d is the thickness of the insulation material. According to formula (1), when the thickness of the insulation material (such as the sample block used in the present embodiment) is constant, the greater the breakdown voltage, the higher the insulation strength of the material.

[0026] The detection results are shown in Table 1 below: Table 1: Pressure resistance extreme value detection results of two groups of sample blocks As can be seen from Table 1, setting a PMMA partition can improve the insulation performance of the potting system.

[0027] Example 2: Verification of the improvement of the insulation performance of the module by adjusting the proportion of SiO2 powder The potting process, sample block size, number of samples, and pressure resistance extreme value detection method are the same as in Example 1, except for the sample block potting soft glue formula, which contains SiO2 powder, as shown in Table 2 below. Figure 3 The potting soft glue formula is as follows: Control group sample block: The potting soft glue is composed of epoxy resin, curing agent and SiO2 powder, and the SiO2 powder accounts for 50% of the total mass of the potting soft glue, i.e. epoxy resin + curing agent: SiO2 powder is 1:1.

[0028] Experimental group sample block: The potting soft glue is composed of epoxy resin, curing agent and SiO2 powder, and the SiO2 powder accounts for 10% of the total mass of the potting soft glue, i.e. epoxy resin + curing agent: SiO2 powder is 9:1.

[0029] The pressure resistance extreme value detection results of the two groups of sample blocks are shown in Table 2 below.

[0030] Table 2: Pressure resistance extreme value detection results of two groups of sample blocks As can be seen from the above table, after reducing the proportion of SiO2 powder to 10%, the pressure resistance extreme value of the entire potting soft glue system can be effectively improved.

[0031] Example 3: Verification of the improvement of the insulation performance of the module by simultaneously adding SiO2 powder and increasing the PMMA partition The potting process, sample block size, number of samples, and pressure resistance extreme value detection method are the same as in Example 1, and the potting soft glue is composed of epoxy resin, curing agent and SiO2 powder, and the SiO2 powder accounts for 10% of the total mass of the potting soft glue, i.e. epoxy resin + curing agent: SiO2 powder is 9:1.

[0032] Experimental group sample block: A 1mm thick PMMA partition is set in the middle, as shown in Table 3 below. Figure 4

[0033] The pressure resistance extreme value detection results of the sample blocks are shown in Table 3 below.

[0034] Table 3: Pressure resistance extreme value detection results of each sample block ​The results in Table 3 show that by adjusting the SiO2 powder content to 10% and setting a 1mm thick PMMA separator, the peak voltage can be increased to over 7300V, which can significantly improve the withstand voltage of the entire potting compound system and improve its insulation performance.

[0035] This article uses specific examples to illustrate the inventive concept in detail. The description of the above embodiments is only for the purpose of helping to understand the core idea of ​​the present invention. It should be noted that any obvious modifications, equivalent substitutions or other improvements made by those skilled in the art without departing from the inventive concept should be included within the protection scope of the present invention.

Claims

1. A solid-state insulating packaging method for a pulse power module, applicable to circuit board insulating packaging, characterized in that, Fix the PMMA partition between two adjacent circuit boards, place it in the potting mold, pour potting soft glue into the potting mold, place the mold in a constant temperature oven at 60℃-80℃ for curing, and after curing, let it cool naturally to room temperature before demolding. The method for preparing the potting soft glue is as follows: epoxy resin and curing agent are mixed to obtain a mixture, and then SiO2 powder is added and stirred into a suspension to obtain the potting soft glue. The amount of SiO2 powder added accounts for 10% of the total mass of the potting soft glue.

2. The method according to claim 1, characterized in that, The PMMA separator has a thickness of 1 mm.

3. The method according to claim 1, characterized in that, The curing conditions are specifically set as follows: first, cure at 80℃ for 1-1.5 hours, then at 50℃ for 5-6 hours, and finally at 60℃ for 3-5 hours.

4. The method according to claim 1, characterized in that, The potting compound undergoes vacuum degassing treatment under vacuum conditions of ≥-0.095MPa until no more bubbles are generated.

5. The method according to claim 1, characterized in that, The particle size of the SiO2 powder is ≤5μm.

6. The method according to claim 1, characterized in that, The purity of SiO2 in the SiO2 powder is ≥99.9%.

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