Patent Description:
A power module is a module obtained by combining and packaging electronic power devices based on specific functions, and is widely used in the fields of servo motors, frequency converters, inverters, and the like.

The power module is provided with a pin, thereby facilitating quick crimping or welding at a system end. In a process of packaging the power module, the pin passes through an injection mold. When a location of the pin changes, the entire injection mold needs to be replaced, to allow pins of different power modules to pass through. This is not conducive to a design change or development of a new power module of a same series. A development cycle of an injection mold is long, and costs are high.

How to make a same set of injection molds compatible with power modules of a same series that have different locations of pins should be a research and development direction of the industry.

<CIT> relates to a method and a clamp for manufacturing a pin-fin power module. The document describes the power module including a pin-fin substrate, an insulating material connected to the substrate and a power chip arranged on the insulating material. The substrate has a first surface and a second surface opposite to the first surface. The first surface is connected to an insulating material and the second surface has several fins on it. The clamp includes a main body with a flat upper surface and a flat lower surface, and holes provided on the upper surface of the main body, wherein the distribution of the holes is the same as the arrangement of the fins.

<CIT> relates to a method of manufacturing an electronic device having a molded resin case and a molding tool for forming the resin-molded case. The document describes the method comprising: disposing an electronic element on a wiring plate that is electrically coupled with a connector terminal; covering a first surface of the wiring plate with a first casing element and covering a second surface of the wiring plate with a second casing element to form the electronic circuit part; disposing the electronic circuit part in a case cavity of a molding tool in such a manner that an end portion of the connector terminal protrudes to an outside of the case cavity; and filling resin into the case cavity of the molding tool to form the resin-molded case while keeping a state where a first pressure that pushes the first casing element toward the wiring plate and that changes with time is substantially equal to a second pressure that pushes the second casing element toward the wiring plate and that changes with time.

This application provides an injection mold and an injection molding method, so that a same set of injection molds can be compatible with power modules of a same series that have different locations of pins, thereby facilitating a design change in a power module development process and development of a new power module of a same series. Embodiments labelled as inventive embodiments in the following, which are not covered by the scope of protection defined by the independent claims, are to be understood as examples helpful for understanding the invention, but not as embodiments of the invention.

According to a first aspect, this application provides an injection mold, including a housing and a cover. The housing is provided with a mold cavity. The mold cavity is configured to accommodate a power module. The cover is provided with a plurality of vias. The cover is detachably connected to the housing. The cover is located in the mold cavity and locates the power module jointly with the housing. The plurality of vias are configured to match a plurality of pins of the power module.

In this application, the cover is disposed, and the cover is provided with the vias for pins to pass through. By replacing covers with different arrangement manners of vias, a same set of injection molds can be compatible with power modules of a same series that have different locations of pins. Specifically, the housing includes a first housing and a second housing, the first housing is provided with a first cavity, the second housing is provided with a second cavity (the first cavity and the second cavity form the mold cavity), the first housing and the second housing are fastened to a device or a mold base, the power module is placed in the second cavity, the cover fits with the power module so that the pins of the power module pass through the vias, and then the first housing, the cover, the power module, and the second housing are in a press-fit to implement injection sealing. Arrangement manners of locations of vias on different covers are different. When injection molding is performed on power modules with different arrangement manners of pins, injection sealing can be implemented only through replacement with a cover provided with corresponding vias, without replacing the entire injection mold, thereby improving utilization of the first housing and the second housing, and resolving problems of a long development cycle and high costs of the injection mold. In addition, this can greatly reduce workload during switching between power modules of a same series in a production line, thereby improving efficiency of the production line.

According to a second aspect, this application provides an injection mold, including: a housing, provided with a mold cavity, where the mold cavity is configured to accommodate a power module; at least two covers, where each cover is provided with a plurality of vias, and arrangement manners of vias on different covers are different, to match a plurality of pins of power modules of different models. The housing selectively fits with one of the plurality of covers to jointly locate the power module.

In this application, a set of injection molds may include one housing (that is, one first housing and one second housing) and at least two covers. It may be understood that the at least two covers include a first cover and a second cover (there may be a plurality of first covers and a plurality of second covers). The first cover is provided with a plurality of first vias, and the second cover is provided with a plurality of second vias. An arrangement manner of the first vias on the first cover is different from an arrangement manner of the second vias on the second cover. Both the first cover and the second cover can be detachably connected in the mold cavity. The plurality of first vias and the plurality of second vias are configured to allow pins of power modules of different models to pass through.

In a possible implementation, the injection mold further includes an elastic connection structure, and the elastic connection structure is connected to the cover, to implement an elastic connection between the cover and the housing. Specifically, one end of the elastic connection structure is connected to the cover, and the other end of the elastic connection structure is detachably connected to the inside of the housing. The housing compresses the elastic connection structure, and the elastic connection structure applies elastic pressure to the cover, so that the cover and the power module are in a press-fit.

In a possible implementation, the elastic connection structure includes a support rod and an elastic part, the support rod is elastically connected to the cover by using the elastic part, and the support rod is in contact with an inner surface of the housing. The elastic part may be a spring or the like. When the elastic part is compressed, the elastic part applies pressure to the cover, so that the cover presses against a board body of the power module, thereby preventing the board body of the power module from being damaged due to injection pressure.

In a possible implementation, the cover includes a first surface and a second surface that are opposite to each other, the via penetrates the first surface and the second surface, the support rod includes a first cylinder and a second cylinder, the first cylinder is located on a side of the first surface of the cover, the second cylinder includes a limiting part and a connecting part, the cover is provided with a limiting hole, the limiting part is located in the limiting hole and fits with a limiting structure in the limiting hole to prevent the limiting part from moving out of the cover from the side of the first surface, the connecting part extends out of the limiting hole and is fastened to the first cylinder, and the elastic part is sleeved on the connecting part and is elastically held between the first surface and the first cylinder. During molding, the first housing is in contact with the support rod and applies pressure to the support rod. The support rod has a scalable structure, and the support rod drives the elastic part to be compressed, so that the cover is tightly attached to the board body of the power module, and then injection molding is performed. The support rod and the elastic part may be integrated with the cover under the condition of ensuring processing precision. It may be understood that the support rod and the elastic part constitute a scalable elastic connection structure, and the elastic connection structure is configured to apply pressure to the cover to press against the power module. The elastic connection structure is not limited to the form of fitting between the support rod and the elastic part, and may be alternatively another elastic connection structure.

In a possible implementation, the housing includes a first housing and a second housing, the first housing is provided with a first cavity, the first cavity includes a first sub-cavity and a second sub-cavity, a stepped surface is formed at a joint between the first sub-cavity and the second sub-cavity, the second housing comprises a second cavity, the first housing and the second housing are snap-fitted so that the second cavity is connected to the first cavity, the cover is located in the first sub-cavity, a part of the power module is located in the second cavity, and a part of the power module is located in the second sub-cavity and is in contact with the stepped surface. In an injection molding process, gel is injected into the second sub-cavity and the second cavity, and a part of the power module is in contact with the stepped surface to prevent the gel from overflowing to the first sub-cavity and adhering to the pins extending into the first sub-cavity. Specifically, a size of the board body of the power module is greater than a size of the first sub-cavity. In a molding process, the first housing presses against the board body, that is, the board body is in contact with the stepped surface.

It may be understood that a size and a shape of a first cavity of a same set of injection molds need to be set based on locations and sizes of pins of power modules of a same series. The first sub-cavity has a hollowed-out structure, and a pin extends into the first sub-cavity through a via, thereby facilitating cleaning when gel overflows. Specifically, when gel overflows to the first sub-cavity and adheres to an inner wall of the first sub-cavity, the first housing may be separated from the second housing, and the hollowed-out first sub-cavity is separately cleaned.

In a possible implementation, a quantity of vias of each cover is greater than or equal to a quantity of pins of the power module, and an arrangement manner of vias of each cover matches a plurality of pins of at least one power module. When a quantity of vias of a cover is equal to a quantity of pins of a matching power module, that is, the vias are in a one-to-one correspondence with the pins, gel can be prevented from overflowing through excessive vias in which no pins are inserted. In this way, one cover corresponds to one type of power module, and another cover needs to be used when another power module with different locations of pins appears. When a sealing effect between the board body of the power module and the first housing is good and gel does not overflow to the cover, a quantity of vias of each cover may be alternatively set to be greater than a quantity of pins of a power module. In this way, a same cover can be compatible with at least two power modules with different locations of pins, thereby resolving problems of a long development cycle and high costs of the injection mold. In addition, this can greatly reduce workload during switching between power modules of a same series in a production line, thereby improving efficiency of the production line.

In a possible implementation, the via includes a first section and a second section, a limiting surface is formed between the first section and the second section, the pin includes a body part and a fixed part that protrudes from a periphery of the body part, a stepped surface is formed at a joint between the body part and the fixed part, the first section is configured to accommodate the body part, the second section is configured to accommodate the fixed part, and the stepped surface is in contact with the limiting surface to implement a sealed connection between the cover and the pin. The sealed connection between the cover and the pin can prevent injection molding gel from overflowing to the first sub-cavity through a gap between an inner wall of the via and the pin during injection molding. A specific structure of the pin includes but is not limited to a cylindrical pin, a regular polygonal pin, a flat pin, and an irregular pin. When the specific structure of the pin is changed, a shape of the via is also changed correspondingly.

In a possible implementation, the cover includes a first surface and a second surface that are opposite to each other, the via penetrates the first surface and the second surface, a sealing pad is disposed on the second surface, and the sealing pad is disposed at a periphery of the via, and/or the sealing pad is disposed on the limiting surface of the via. The sealing pad can implement tighter sealing between the pin and the cover, to prevent injection molding gel from overflowing to the first sub-cavity through a gap between an inner wall of the via and the pin during injection molding.

In a possible implementation, the cover includes a first surface and a second surface that are opposite to each other, the via penetrates the first surface and the second surface, a limiting block is disposed on the second surface of the cover, the power module is provided with a limiting hole, and the limiting block is embedded into the limiting hole to limit locations of the cover assembly and the power module. In other words, the cover and the power module are located and fastened through a detachable connection by using the limiting block and the limiting hole.

In a possible implementation, the power module is fastened to a support, and the support is bonded to an edge of the housing, to limit a location of the power module in the mold cavity. It may be understood that the power module may be alternatively located by using another structure. For example, a locating part is disposed on a circuit board of the power module, the housing is provided with a locating hole, and the locating part is embedded into the locating hole to locate the power module on the housing.

It may be understood that a plurality of mounting areas may be provided on the support at intervals (the mounting areas are hollow areas on the support, and power modules are fastened to the mounting areas). There may be two, three, four, five, or more mounting areas on each support. In other words, a plurality of power modules may be disposed on each support at intervals. In a molding process, one injection mold corresponds to one power module. In this way, injection sealing can be simultaneously performed on a plurality of power modules, thereby improving packaging efficiency of a production line.

In a possible implementation, the cover is made of one or more of a titanium alloy, a copper alloy, or stainless steel. The cover is usually characterized by a small thermal expansion coefficient, high temperature resistance, and high strength. The cover is made of one or more of a titanium alloy, a copper alloy, stainless steel, and the like. A cover made of a titanium alloy, a copper alloy, or stainless steel has a small thermal expansion coefficient and a light weight, thereby facilitating mounting during molding, detaching during demolding, and replacement of the cover.

In a possible implementation, there are a plurality of support rods, and the plurality of support rods are symmetrically distributed on the first surface. There may be a plurality of support rods, and the plurality of support rods are symmetrically and uniformly distributed on the cover. This can ensure that the entire cover is subject to uniform pressure during compression, to press against the power module, and can prevent the cover from being subject to a non-uniform force, which causes loose compression between the cover and a part of the board body of the power module, and causes damage to a part of the board body of the power module due to injection pressure.

According to a third aspect, this application provides an injection molding method: providing an injection mold, where the injection mold includes a housing and at least two covers, the housing is provided with a mold cavity, each cover is provided with a plurality of vias, and arrangement manners of vias on different covers are different; selecting one of the covers based on a distribution status of pins of a to-be-injection-molded power module, where an arrangement manner of vias on the cover matches an arrangement manner of pins of the power module; placing the to-be-injection-molded power module in the mold cavity; and mounting the cover to the to-be-injection-molded power module, so that the pins pass through the vias.

Specifically, after the cover is mounted, a first housing and a second housing are connected to form the housing. The housing surrounds the cover and the power module. A gel injection opening is provided on the housing, and is used for injecting gel (the gel may be silicone, silicon gel, resin, or the like) into a second sub-cavity and a second cavity, to completely seal the power module through injection molding, and provide insulation protection and dust prevention for the power module. In a demolding process, the first housing is separated from the second housing, a support rod and an elastic part are restored to an uncompressed state, and the cover and the injection-molded power module are taken out.

The injection mold in this application has a simple structure. By replacing covers with different arrangement manners of vias, a same set of injection molds can be compatible with power modules of a same series that have different locations of pins, thereby improving utilization of the housing (the first housing and the second housing), and resolving problems of a long development cycle and high costs of the injection mold. In addition, this can greatly reduce workload during switching between power modules of a same series in a production line, thereby improving efficiency of the production line.

The following describes accompanying drawings used in embodiments of this application.

The following describes embodiments of this application with reference to accompanying drawings in embodiments of this application.

This application provides an injection mold and an injection molding method. The injection mold is mainly used to package a power module. The power module is a module obtained by combining and packaging electronic power devices based on specific functions, and has advantages of high current density, a low saturation voltage, high voltage resistance, high input impedance, a high switching frequency, and a low driving power. In addition, the power module integrates logic, control, detection, and protection circuits, thereby reducing a system size and development time, and also greatly enhancing system reliability. The power module is easy to use, adapts to a current modularization and integration-oriented development direction of power devices, and is widely used in the fields of servo motors, frequency converters, inverters, and the like. To maintain operation stability of the power module, the power module is usually packaged by using synthetic resin, to improve insulation and protection, and prevent the power module from being affected by an environment.

<FIG> is a schematic diagram of packaging a power module by using an injection mold. The injection mold <NUM> is fastened to a device <NUM> (the device <NUM> may be a plastic packaging machine). In a molding process, the device <NUM> operates to package the power module <NUM> into the injection mold <NUM>, to implement injection sealing of the power module <NUM> for insulation and protection.

First, this application provides an injection mold. A specific structure of the injection mold is as follows:
<FIG> is a schematic diagram of a structure of the injection mold, <FIG> is a schematic diagram of a structure of the injection mold before molding (a power module is placed), and <FIG> is a schematic diagram of a structure of the injection mold after molding. The injection mold <NUM> includes a housing <NUM> and a cover <NUM>. The housing <NUM> includes a first housing <NUM> and a second housing <NUM>. The housing <NUM> is provided with a mold cavity <NUM>. The first housing <NUM> is provided with a first cavity <NUM>, and the second housing <NUM> is provided with a second cavity <NUM>. The mold cavity <NUM> includes the first cavity <NUM> and the second cavity <NUM>. The mold cavity <NUM> is configured to accommodate the power module <NUM>. The cover <NUM> is provided with a plurality of vias <NUM>. The cover <NUM> is detachably connected to the housing <NUM>. The cover <NUM> is located in the mold cavity <NUM> and locates the power module <NUM> jointly with the housing <NUM>. The plurality of vias <NUM> are configured to match a plurality of pins <NUM> of the power module <NUM>.

In a possible implementation, there are at least two covers <NUM>, each cover <NUM> is provided with vias <NUM>, and arrangement manners of vias <NUM> on different covers <NUM> are different, to match a plurality of pins <NUM> of power modules <NUM> of different models. The housing <NUM> selectively fits with one of the plurality of covers <NUM> to jointly locate the power module <NUM>. Specifically, a set of injection molds <NUM> may include one housing <NUM> (that is, one first housing <NUM> and one second housing <NUM>) and at least two covers <NUM>. It may be understood that the at least two covers <NUM> include a first cover and a second cover (there may be a plurality of first covers and a plurality of second covers). The first cover is provided with a plurality of first vias, and the second cover is provided with a plurality of second vias. An arrangement manner of the first vias on the first cover is different from an arrangement manner of the second vias on the second cover. Both the first cover and the second cover can be detachably connected in the mold cavity. The plurality of first vias and the plurality of second vias are configured to allow pins <NUM> of power modules <NUM> of different models to pass through.

In this application, the cover <NUM> is disposed, and the cover <NUM> is provided with the vias <NUM> for pins <NUM> to pass through. By replacing covers <NUM> with different arrangement manners of vias <NUM>, a same set of injection molds <NUM> can be compatible with power modules <NUM> of a same series that have different locations of pins <NUM>. Specifically, the first housing <NUM> and the second housing <NUM> are fastened to a device or a mold base, the power module <NUM> is placed in the second cavity <NUM> of the second housing <NUM>, the cover <NUM> fits with the power module <NUM> so that the pins <NUM> of the power module <NUM> pass through the vias <NUM>, and then the first housing <NUM>, the cover <NUM>, the power module <NUM>, and the second housing <NUM> are in a press-fit to implement injection sealing. Locations of vias <NUM> on different covers <NUM> are different. When a design of the power module <NUM> is changed during development or a design of the pin <NUM> is changed during development of a new power module of a same series, injection sealing can be implemented only through replacement with a cover <NUM> provided with corresponding vias <NUM>, without replacing the entire injection mold <NUM>, thereby improving utilization of the first housing <NUM> and the second housing <NUM>, and resolving problems of a long development cycle and high costs of the injection mold <NUM>. In addition, this can greatly reduce workload during switching between power modules of a same series in a production line, thereby improving efficiency of the production line.

The first housing <NUM> and the second housing <NUM> are snap-fitted and jointly form the housing <NUM> of the injection mold <NUM>, so that the second cavity <NUM> is connected to the first cavity <NUM>, to package the power module <NUM>. Specifically, the first cavity <NUM> in the first housing <NUM> includes a first sub-cavity <NUM> and a second sub-cavity <NUM>, and the second sub-cavity <NUM> is connected to the second cavity <NUM>, so that the first cavity <NUM> and the second cavity <NUM> form the mold cavity <NUM>. A size of the second sub-cavity <NUM> is greater than a size of the first sub-cavity <NUM>, the cover <NUM> is located in the first sub-cavity <NUM>, the power module <NUM> is located in the second sub-cavity <NUM> and the second cavity <NUM> (in other words, a part of the power module <NUM> is located in the second cavity <NUM>, and a part of the power module <NUM> is located in the second sub-cavity <NUM>), and the pins <NUM> of the power module <NUM> extend into the first sub-cavity <NUM>.

As shown in <FIG>, a stepped surface is formed at a joint between the first sub-cavity <NUM> and the second sub-cavity <NUM> (to be distinguished from a stepped surface on the pin <NUM>, the stepped surface herein is referred to as a first stepped surface <NUM>), a board body <NUM> of the power module <NUM> is located in the second sub-cavity <NUM>, and the board body <NUM> is in contact with the first stepped surface <NUM> to prevent gel from overflowing to the first sub-cavity <NUM>. In an injection molding process, gel is injected into the second sub-cavity <NUM> and the second cavity <NUM>, and the board body <NUM> is in contact with the first stepped surface <NUM> to prevent gel from overflowing to the first sub-cavity <NUM> and adhering to the pins <NUM> extending into the first sub-cavity <NUM>. It may be understood that a size of the board body <NUM> of the power module <NUM> is greater than a size of the first sub-cavity <NUM>. In a molding process, the first housing <NUM> presses against the board body <NUM>, that is, the board body <NUM> is in contact with the first stepped surface <NUM>.

A size of each of the second sub-cavity <NUM> and the second cavity <NUM> is greater than a size of the power module <NUM>, to accommodate the power module <NUM>. Specific sizes and shapes of the second sub-cavity <NUM> and the second cavity <NUM> need to be set based on an application environment of the packaged power module <NUM>.

It may be understood that a size and a shape of a first cavity <NUM> of a same set of injection molds <NUM> need to be set based on locations and sizes of pins <NUM> of power modules of a same series.

As shown in <FIG> and <FIG>, an elastic connection structure <NUM> is disposed on the cover <NUM>, to implement an elastic connection between the cover <NUM> and the housing <NUM>. The elastic connection structure <NUM> includes a support rod <NUM> and an elastic part <NUM>. The support rod <NUM> is elastically connected to the cover <NUM> by using the elastic part <NUM>. The support rod <NUM> is in contact with an inner surface of the housing <NUM>. Specifically, the cover <NUM> includes a first surface <NUM> and a second surface <NUM> that are opposite to each other, and the via <NUM> penetrates the first surface <NUM> and the second surface <NUM>. The support rod <NUM> includes a first cylinder <NUM> and a second cylinder <NUM>, the first cylinder <NUM> is located on a side of the first surface <NUM> of the cover <NUM>, and the second cylinder <NUM> includes a limiting part <NUM> and a connecting part <NUM>. The cover <NUM> is provided with a limiting hole <NUM>. The limiting part <NUM> is located in the limiting hole <NUM> and fits with a limiting structure in the limiting hole <NUM> to prevent the limiting part <NUM> from moving out of the cover <NUM> from the side of the first surface <NUM>. The connecting part <NUM> extends out of the limiting hole <NUM> and is fastened to the first cylinder <NUM>. The elastic part <NUM> is sleeved on the connecting part <NUM> and is elastically held between the first surface <NUM> and the first cylinder <NUM>.

One end of the elastic connection structure <NUM> is connected to the cover <NUM>, and the other end of the elastic connection structure <NUM> is detachably connected to the inside of the housing <NUM>. The housing <NUM> compresses the elastic connection structure <NUM>, and the elastic connection structure <NUM> applies elastic pressure to the cover <NUM>, so that the cover <NUM> and the power module <NUM> are in a press-fit. The elastic part <NUM> may be a spring or the like. The elastic connection structure <NUM> is not limited to the form of fitting between the support rod <NUM> and the elastic part <NUM>, and may be alternatively another elastic connection structure.

Arrangement manners of vias <NUM> on different covers <NUM> are different. Locations of the vias <NUM> correspond to the pins <NUM> of the power module <NUM>. When a design of the power module <NUM> is changed during development or a design of the pin <NUM> is changed during development of a new power module of a same series, a same set of injection molds <NUM> can be compatible with power modules of a same series that have different locations of pins only through replacement with a cover <NUM> provided with corresponding vias <NUM>.

It may be understood that a quantity of vias <NUM> of each cover <NUM> may be greater than or equal to a quantity of pins <NUM> of the power module <NUM>, and an arrangement manner of vias <NUM> of each cover <NUM> matches a plurality of pins <NUM> of at least one power module <NUM>. When a quantity of vias <NUM> of a cover <NUM> is equal to a quantity of pins <NUM> of a matching power module <NUM>, that is, the vias <NUM> are in a one-to-one correspondence with the pins <NUM>, gel can be prevented from overflowing through excessive vias <NUM> in which no pins <NUM> are inserted. In this way, one cover <NUM> corresponds to one type of power module <NUM>, and another cover <NUM> needs to be used when another power module <NUM> with different locations of pins appears. When a sealing effect between the board body <NUM> of the power module <NUM> and the first housing <NUM> is good and gel does not overflow to the vias <NUM> of the cover <NUM>, a quantity of vias <NUM> of each cover <NUM> may be alternatively set to be greater than a quantity of pins <NUM> of each power module <NUM>. In this way, a same cover <NUM> can be compatible with at least two power modules <NUM> with different locations of pins, thereby resolving problems of a long development cycle and high costs of the injection mold <NUM>. In addition, this can greatly reduce workload during switching between power modules of a same series in a production line, thereby improving efficiency of the production line.

As shown in <FIG>, the via <NUM> includes a first section <NUM> and a second section <NUM>, a limiting surface <NUM> is formed between the first section <NUM> and the second section <NUM>, the pin <NUM> includes a body part <NUM> and a fixed part <NUM> that protrudes from a periphery of the body part <NUM>, a stepped surface <NUM> is formed at a joint between the body part <NUM> and the fixed part <NUM>, the body part <NUM> is accommodated in the first section <NUM>, the fixed part <NUM> is accommodated in the second section <NUM>, and the stepped surface <NUM> is in contact with the limiting surface <NUM> to implement a sealed connection between the cover <NUM> and the pin <NUM>. The sealed connection between the cover <NUM> and the pin <NUM> can prevent injection molding gel from overflowing to the first sub-cavity <NUM> through a gap between an inner wall of the via <NUM> and the pin <NUM> during injection molding.

It may be understood that, as shown in <FIG>, to improve a sealing effect between the cover <NUM> and the pin <NUM>, a sealing pad <NUM> may be disposed on the second surface <NUM> of the cover <NUM>, and the sealing pad <NUM> is disposed at a periphery of the via <NUM>. The sealing pad <NUM> may have an integrated structure and is fastened to the second surface <NUM>, or the sealing pad <NUM> may have a split structure, that is, a plurality of sealing pads <NUM> spaced from each other are disposed on the second surface <NUM>.

In another implementation, a sealing pad <NUM> may also be disposed on the limiting surface <NUM> of the via <NUM>.

The sealing pad <NUM> is disposed to prevent gel from overflowing through a gap between the via <NUM> and the pin <NUM> during injection molding.

The cover <NUM> is usually characterized by a small thermal expansion coefficient, high temperature resistance, and high strength. The cover <NUM> may be made of one or more of a titanium alloy, a copper alloy, stainless steel, and the like. A cover <NUM> made of a titanium alloy, a copper alloy, or stainless steel has a small thermal expansion coefficient and a light weight, thereby facilitating mounting during molding, detaching during demolding, and replacement of the cover <NUM>. A side surface of the cover <NUM> (the side surface of the cover <NUM> is a surface, of the cover <NUM>, that is located between the first surface <NUM> and the second surface <NUM>) is attached to an inner wall of the first sub-cavity <NUM>, to prevent gel from overflowing to the first surface <NUM> through a gap between the side surface of the cover <NUM> and the inner wall of the first sub-cavity <NUM>.

<FIG> is a top view of a cover assembly. There may be a plurality of support rods <NUM>, and the plurality of support rods <NUM> are symmetrically and uniformly distributed on the cover <NUM>. This can ensure that the entire cover <NUM> is subject to uniform pressure during compression, to press against the power module <NUM>, and can prevent the cover <NUM> from being subject to a non-uniform force, which causes loose compression between the cover <NUM> and a part of the board body <NUM> of the power module <NUM>, and causes damage to a part of the board body <NUM> of the power module <NUM> due to injection pressure.

As shown in <FIG>, during molding, the first housing <NUM> is in contact with the support rod <NUM> and applies pressure to the support rod <NUM>. The support rod <NUM> drives the elastic part <NUM> to be compressed (the support rod <NUM> has a scalable structure), so that the cover <NUM> is tightly attached to the board body <NUM> of the power module <NUM>, and then injection molding is performed. The support rod <NUM> and the elastic part <NUM> may be integrated with the cover <NUM> under the condition of ensuring processing precision. The elastic part <NUM> is disposed, so that the cover <NUM> presses against the board body <NUM> of the power module <NUM>, thereby preventing the board body <NUM> of the power module <NUM> from being damaged due to injection pressure.

As shown in <FIG> and <FIG>, the cover <NUM> and the power module <NUM> are located and connected by using a limiting block and a limiting hole. Specifically, a limiting block <NUM> is disposed on the second surface <NUM> of the cover <NUM>, the power module <NUM> is provided with a limiting hole <NUM> (to be distinguished from the limiting hole <NUM> on the cover <NUM>, the limiting hole on the power module <NUM> is referred to as a first limiting hole <NUM>), and the limiting block <NUM> is detachably inserted into the first limiting hole <NUM> for locating and fastening. In other words, the cover <NUM> and the power module <NUM> are located and fastened through a detachable connection by using the limiting block <NUM> and the first limiting hole <NUM>.

As shown in <FIG>, <FIG>, the power module <NUM> includes a pin <NUM>, a board body <NUM>, a silicone pad <NUM>, a circuit board <NUM>, an electronic element <NUM>, and a support <NUM>. The electronic element <NUM> is located on the circuit board <NUM>. One end of the pin <NUM> is fastened to the circuit board <NUM>, and the other end of the pin <NUM> sequentially passes through a via on the silicone pad <NUM> and a via on the board body <NUM> (to distinguish from the via <NUM> on the cover <NUM>, the via on the silicone pad <NUM> and the via on the board body <NUM> are referred to as a first via <NUM>). After mounting is completed, the pin <NUM>, the board body <NUM>, the silicone pad <NUM>, the circuit board <NUM>, and the electronic element <NUM> are fastened to a mounting area <NUM> of the support <NUM>. The silicone pad <NUM> may have an integrated structure or a split structure. This is not limited in this application.

The pin <NUM> extends into the first sub-cavity <NUM> through the via <NUM>. The first sub-cavity <NUM> has a hollowed-out structure, thereby facilitating cleaning when gel overflows (specifically, when gel overflows to the first sub-cavity <NUM> and adheres to an inner wall of the first sub-cavity <NUM>, the first housing <NUM> may be separated from the second housing <NUM>, and the hollowed-out first sub-cavity <NUM> is separately cleaned). A specific structure of the pin <NUM> includes but is not limited to a cylindrical pin, a regular polygonal pin, a flat pin, and an irregular pin. This is not limited in this application, and may be arranged based on a specific application environment. A quantity and location distribution of pins <NUM> need to be set based on a specific application environment. This is not limited in this application.

In a molding process, the silicone pad <NUM> is pressed and deformed to provide a supporting force for the cover <NUM>, and perform sealing with the pin <NUM>, to provide good sealing performance, and prevent gel from overflowing to the first sub-cavity <NUM> through a gap between the pin <NUM> and the first via on the board body <NUM>. The silicone pad <NUM> may be a silicone pad with low hardness, for example, may be made of a soft silicone material, or may be made of another sealing material such as a rubber pad. This is not limited in this application.

The circuit board <NUM> includes but is not limited to an aluminum-based resin copper clad board, a copper-based resin copper clad board, or a double-sided copper clad ceramic board, and the electronic element <NUM> with an inversion, rectification, braking, or buffering function is welded on the circuit board <NUM>.

The support <NUM> is bonded to an edge of the second housing <NUM>, to limit a location of the power module <NUM> in the second cavity <NUM>. It may be understood that the power module <NUM> may be alternatively located by using another structure. For example, a locating part is disposed on the circuit board <NUM> of the power module <NUM>, the second housing <NUM> is provided with a locating hole, and the locating part is embedded into the locating hole to locate the power module <NUM> on the second housing <NUM>.

As shown in <FIG>, a plurality of mounting areas <NUM> may be provided on the support <NUM> at intervals (the mounting areas <NUM> are hollow areas on the support <NUM>, and power modules <NUM> are fastened to the mounting areas <NUM>). <FIG> merely shows two mounting areas <NUM> as an example. There may be alternatively three, four, five, or more mounting areas on each support <NUM>. This is not limited in this application. In other words, a plurality of power modules <NUM> may be disposed on each support <NUM> at intervals. In a molding process, one injection mold <NUM> corresponds to one power module <NUM>. In this way, injection sealing can be simultaneously performed on a plurality of power modules <NUM>, thereby improving packaging efficiency of a production line.

Further, this application provides an injection molding method. As shown in <FIG>, in an implementation, the injection molding method specifically includes the following steps.

T10: Provide an injection mold <NUM>, where the injection mold <NUM> includes a housing <NUM> and at least two covers <NUM>.

As shown in <FIG> and <FIG>, the housing <NUM> is provided with a mold cavity <NUM>, each cover <NUM> is provided with a plurality of vias <NUM>, and arrangement manners of vias <NUM> on different covers <NUM> are different.

T20: Select one of the covers <NUM> based on a distribution status of pins <NUM> of a to-be-injection-molded power module <NUM>.

It may be understood that an arrangement manner of vias <NUM> on the cover <NUM> matches an arrangement manner of the pins <NUM> of the power module <NUM>. T30: Mount the cover <NUM> to the to-be-injection-molded power module.

Specifically, first, the to-be-injection-molded power module is placed in the mold cavity <NUM>, and when the cover <NUM> is mounted to the to-be-injection-molded power module, the pins <NUM> pass through the vias <NUM>.

After the cover <NUM> is mounted, a first housing <NUM> and a second housing <NUM> are connected to form the housing <NUM>. The housing <NUM> surrounds the cover <NUM> and the power module <NUM>. A gel injection opening is provided on the housing <NUM>, and is used for injecting gel (the gel may be silicone, silicon gel, resin, or the like) into a second sub-cavity <NUM> and a second cavity <NUM>, so that the gel overflows and fills internal space of the second sub-cavity <NUM> and the second cavity <NUM>, and the gel is cured and molded, to completely seal the power module <NUM> through injection molding, and provide insulation protection and dust prevention for the power module <NUM>. In a demolding process, the first housing <NUM> is separated from the second housing <NUM>, and a support rod <NUM> and an elastic part <NUM> are restored to an uncompressed state, so that the cover <NUM> and the injection-molded power module <NUM> can be taken out. In this application, a general-purpose injection mold <NUM> that can be flexibly replaced is designed. The injection mold <NUM> includes a housing <NUM> and a replaceable cover <NUM>. A same set of injection molds <NUM> can be compatible with power modules of a same series that have different locations of pins <NUM> only by replacing the cover <NUM>. This reduces costs of replacing the injection mold <NUM>, and improves efficiency of a production line. The injection mold <NUM> in this application is applicable to power modules with a same outline size but different locations of pins <NUM>, thereby avoiding a problem that a new injection mold <NUM> needs to be developed with high costs and a long cycle when a new power module of a same series is developed. The injection mold has advantages of a simple structure, easy operations, and high reliability and universality.

Claim 1:
An injection mold (<NUM>), comprising a housing (<NUM>), a cover (<NUM>) and an elastic connection structure (<NUM>), wherein
the housing (<NUM>) is provided with a mold cavity (<NUM>), and the mold cavity (<NUM>) is configured to accommodate a power module (<NUM>); and
the cover (<NUM>) is provided with a plurality of vias (<NUM>), the cover (<NUM>) is detachably connected to the housing (<NUM>), wherein the elastic connection structure (<NUM>) is connected to the cover (<NUM>), to implement an elastic connection between the cover (<NUM>) and the housing (<NUM>), the cover (<NUM>) is located in the mold cavity (<NUM>) and locates the power module (<NUM>) jointly with the housing (<NUM>), and the plurality of vias (<NUM>) are configured to match a plurality of pins (<NUM>) of the power module (<NUM>).