Patent Description:
For most of the existing crimping-type IGBT modules, a chip is stressed by means of a spring or a disc spring. However, there is a problem of uneven stress of chips. For example, in the crimping-type semiconductor module disclosed in <CIT> and entitled "Crimping-type semiconductor module", a chip is stressed by means of the deformation of a spring, and the displacement during a deformation process needs to be compensated by a deformation buffer structure of a tube housing. During the process of repeated deformation, the deformation buffer structure of the tube housing is prone to producing a stress, which then causes the cracking of a metal welding layer of the tube housing and the gas leakage of a module, and thus damages the internal environment of the module, resulting in a reliability decrease or even a failure of the device.

For another example, in a large-power semiconductor module disclosed in Chinese patent publication <CIT> and entitled "Large-power semiconductor module", the stress of a chip unit is ensured by means of the structural deformation of a disc spring, and the movement of modules is realized by means of the displacement produced by the deformation of the disc spring. The limitations lie in that the modules can only move in a single direction, there is a difference in the actual displacement of the various modules due to the structural size precision of the various modules being inconsistent, which directly causes the stress difference of the chip unit, and thus affects the overall property of the modules. Moreover, a conductive bypass sheet is arranged around the disc spring, and the conductive bypass thin sheet needs to deform synchronously with the deformation of the disc spring. The characteristic of a bypass thin sheet being capable of normally deforming should be ensured, and therefore, it is not possible to make the bypass thin sheet big and thick, which directly limits the through-flow capability of the bypass thin sheet. In addition, when the modules are designed, it is necessary to reserve a certain deformation space for the bypass thin sheet, which also results in the overall volume of the modules being larger, and is inconducive to the increase of the power density of the modules.

For the above-mentioned problems in the existing technique, the present application provides a crimping-type IGBT module and a power semiconductor device, in order to solve some or all of the above-mentioned problems.

In a first aspect, the application provides a crimping-type IGBT module according to claim <NUM>, including a plurality of sub-modules capable of moving up and down relative to a tube housing. Each of the sub-modules includes:.

When a press-fitting force is not greater than an elastic force provided by the elastic member, the conductive cover plate extends out of the upper surface of the tube housing, both the conductive substrate and the pressure-bearing member extend out of the lower surface of the tube housing, and a lower surface of the conductive substrate is flush with the lower surface of the pressure-bearing member.

When the press-fitting force is greater than the elastic force provided by the elastic member, both the lower surface of the conductive substrate and the lower surface of the pressure-bearing member are flush with the lower surface of the tube housing, and an upper surface of the conductive cover plate is flush with the upper surface of the tube housing.

In one implementation according to the first aspect, each of the sub-modules further includes a buffer block. The buffer block is arranged between a module cover plate and the pressure-bearing member, and the buffer block is configured for buffering the pressure-bearing member when the pressure-bearing member moves upwards relative to the tube housing.

In one implementation according to the first aspect, each of the sub-modules further includes a conductive buffer pad arranged between the chips and the bypass busbar, the conductive buffer pad being configured for ensuring the reliability of electrical conduction between the chips and the bypass busbar.

In one implementation according to the first aspect, an expansion coefficient of the conductive buffer pad and a thermal expansion coefficient of the conductive substrate match a thermal coefficient of the chips, so as to avoid a defect occurring on a contact surface therebetween.

In one implementation according to the first aspect, the chips and the conductive substrate, as well as the chips and the conductive buffer pad are connected by means of welding or silver sintering.

In one implementation according to the first aspect, the conductive buffer pad and the conductive substrate are both made of molybdenum or a molybdenum-copper alloy.

In one implementation according to the first aspect, each of the sub-modules further includes a gate output probe, which is configured for outputting gate signals of the plurality of chips in parallel.

In one implementation according to the first aspect, each of the sub-modules further includes a side frame. A bottom face of the side frame is connected to edges of an upper surface of the conductive substrate in a sealed manner, so as to form a cavity with a sealed bottom portion and an open upper portion. The cavity is potted with silica gel, so as to form an insulation distance between the conductive substrate and the conductive buffer pad.

In one implementation according to the first aspect, each of the sub-modules further includes a pressure-bearing pad, which is arranged between the bypass busbar and the elastic member and is configured for buffering pressure transfer between the bypass busbar and the elastic member, so that the intensity of contact pressure between the chips is consistent.

In one implementation according to the first aspect, a first step is formed on an outer wall face of the pressure-bearing member, and a second step fitted with the first step is formed on an inner wall face of the tube housing, so as to limit a stroke of downward movement of the pressure-bearing member.

In a second aspect, the application provides a power semiconductor device according to claim <NUM>, including the crimping-type IGBT module according to the first aspect.

Compared with the prior art, the application has the following advantages.

The above-mentioned features can be combined in any suitable manner or be replaced by equivalent features, as long as the objective of the invention can be achieved.

The invention will be described in more details below based on embodiments and referring to the accompanying drawings, wherein.

In the accompanying drawings, the same component uses the same reference sign. The accompanying drawings are not drawn to the same scale.

The invention will be further described below in conjunction with the accompanying drawings.

As shown in <FIG>, the application provides a crimping-type IGBT module <NUM>, including a plurality of sub-modules in a parallel layout. The sub-modules can move up and down relative to a tube housing (including a module outer frame <NUM> and a module cover plate <NUM>). The circuit topology graph of each sub-module is as shown in <FIG>. In <FIG>, C represents an IGBT collector, E represents an IGBT emitter, and G represents an IGBT gate. In an IGBT, the functions of a power switch and electric energy conversion are realized by means of a gate drive signal.

In order to realize a specified power output, the crimping-type IGBT module preferably includes six sub-modules (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) (as shown in <FIG>), each sub-module using a topology circuit as shown in <FIG>, where internal gate signals G are aggregated and output by a PCB, and a parallel topology circuit is as shown in <FIG>.

In order to more clearly illustrate the structure of the sub-module in details, with reference to <FIG>, one sub-module <NUM> therein is taken as an example for illustration. In <FIG>, the sub-module <NUM> includes a pressure-bearing member <NUM>, a conductive substrate <NUM>, a conductive cover plate <NUM>, a plurality of chips <NUM>, a bypass busbar <NUM> and an elastic member <NUM>.

The pressure-bearing member <NUM> can move up and down relative to the tube housing, so that a lower surface of the pressure-bearing member can extend out of a lower surface of the tube housing or be accommodated in the tube housing. As shown in <FIG>, a first step is formed on an outer wall face of the pressure-bearing member <NUM>, a second step fitted with the first step is formed on an inner wall face of tube housing, and the first step can abut against the second step, so as to limit a stroke of downward movement of the pressure-bearing member <NUM>.

The conductive substrate <NUM> and the conductive cover plate <NUM> can be accommodated in the tube housing or respectively extend out of the lower surface and an upper surface of the tube housing. The chips <NUM> are juxtaposed and spaced apart on the conductive substrate <NUM>.

The bypass busbar <NUM> is arranged above the chips <NUM>, with an upper part abutting against an upper surface of the pressure-bearing member <NUM>. When the conductive cover plate <NUM> moves downwards, the pressure-bearing member <NUM> can ensure the reliability of press-fitting between the conductive cover plate <NUM> and the bypass busbar <NUM>.

The elastic member <NUM> is arranged between the bypass busbar <NUM> and the conductive cover plate <NUM>. When a press-fitting force is not greater than an elastic force provided by the elastic member <NUM>, the conductive cover plate <NUM> extends out of the upper surface of the tube housing (i.e., an upper surface of the module cover plate <NUM>), both the conductive substrate <NUM> and the pressure-bearing member <NUM> extend out of the lower surface of the tube housing (i.e., a lower surface of the module outer frame <NUM>), and a lower surface of the conductive substrate <NUM> is flush with the lower surface of the pressure-bearing member <NUM>. When the pressure assembling force is greater than the elastic force provided by the elastic member <NUM>, the conductive substrate <NUM>, the conductive cover plate <NUM> and the pressure-bearing member <NUM> are all accommodated in the tube housing, and the lower surfaces of the conductive substrate <NUM> and the pressure-bearing member <NUM> are flush with the lower surface of the tube housing (i.e., the lower surface of the module outer frame), and the upper surface of the conductive cover plate <NUM> is flush with the upper surface of the tube housing (i.e., the upper surface of the module cover plate).

In the above-mentioned structure, when the sub-module <NUM> is in the free state, the conductive cover plate <NUM> (i.e., an emitter plate) protrudes out of a module upper mesa (i.e., the upper surface of the module cover plate <NUM>) by Δh1, the conductive substrate <NUM> (i.e., the collector plate) protrudes a module lower mesa (i.e., the lower surface of the module outer frame <NUM>) by Δh2, and the spacing between the lower surface of the conductive cover plate <NUM> and the bypass busbar <NUM> is ΔH. Since the conductive cover plate <NUM> (i.e., the emitter plate) and the bypass busbar are in a turned-on state, when the IGBT module is not subjected to an external press-fitting force, the conductive cover plate <NUM> (i.e., the emitter plate) and the conductive substrate <NUM> (i.e., the collector plate) are in a turned-off state. When the IGBT module is subjected to a press-fitting force (the press-fitting force needs to be greater than the elastic force of the elastic member <NUM>), the elastic member deforms, the conductive cover plate <NUM> is compressed by Δh1, and the conductive substrate <NUM> is compressed by Δh2, so that the lower surface of the conductive cover plate <NUM> is in press-fitting contact with the bypass busbar <NUM>, thereby ensuring the conductive cover plate <NUM> (i.e., the emitter plate) and the conductive substrate <NUM> (i.e., the collector plate) of the module are in a working preparation state (a state in which same can work once same are powered on), that is, ΔH = Δh1 + Δh2. The above-mentioned process is a press-fitting process of one sub-module of the IGBT module according to the application.

When the sub-module in <FIG> is press-fitted, the pressure of the chips <NUM> completely depends on a deformation amount ΔH of the elastic member <NUM>, and will not be affected by a variation of an external press-fitting force, such that the pressure uniformity of the chips <NUM> can be ensured.

In the embodiment as shown in <FIG>, the bypass busbar <NUM> is configured to have a shape of an approximate inverted "Ω", with its bending parts all being bent at right angles. The bottom portion of the bypass busbar is arranged above a conductive buffer pad <NUM>, and structures of two sides thereof abut against an upper surface of the pressure-bearing member <NUM>. The bypass busbar <NUM>, acting as a main path of an on-current, generally uses a copper sheet or an aluminum sheet, with a surface of the copper sheet or the aluminum sheet being plated with tin, nickel or silver. In the actual application, the thickness of the bypass busbar <NUM> can be flexibly adjusted according to the magnitude of a current. However, in the IGBT module disclosed in existing techniques, a bypass busbar must change along with the deformation of an elastic member, which limits that the bypass busbar must be thinned in order to satisfy a deformation capability.

Since the module outer frame <NUM> needs to have stronger anti-impact strength in addition to being used for the positioning and assembly of internal parts, and the anti-impact strength is greater than <NUM> KJ/m<NUM>. In the case of an unforeseen circumstance, for example, when the IGBT module fails and explodes, the module outer frame <NUM> can effectively prevent the internal parts from flying. The module outer frame <NUM> is preferably formed by injection molding of an enhanced composite fiber material.

The module cover plate <NUM> needs to be made of a material having a high comparative tracking index (CTI), great insulation performance and certain anti-pressure strength. The module cover plate <NUM> is preferably made of a polyester fiber material.

The pressure-bearing member <NUM>, acting as a bearing structure of the conductive cover plate <NUM> and the bypass busbar <NUM>, needs to have great anti-pressure strength in the height direction of the module outer frame <NUM> as the module outer frame <NUM>, so as to effectively share excess external pressure other than a supporting force in an orientation of an effective deformation amount of a spring assembly, such that the material will not deform. The pressure-bearing member <NUM> needs to have greater anti-impact strength in the length direction of the module outer frame <NUM>, such that in the case of an unforeseen circumstance, for example, when the IGBT module fails and explodes, same can effectively prevent the internal parts from flying. The pressure-bearing member is preferably formed by injection molding of an enhanced composite fiber material.

The conductive cover plate <NUM>, acting as an electrical connection structure and a pressure-bearing structure for external pressure, needs to have great electrical and thermal conduction performance and meet a certain rigid requirement, and preferably uses copper, molybdenum or a copper-molybdenum alloy.

Preferably, as shown in <FIG>, the sub-module <NUM> further includes a buffer block <NUM>. The buffer block <NUM> is arranged between the module cover plate <NUM> and the pressure-bearing member <NUM>, and the buffer block <NUM> is configured for buffering the pressure-bearing member <NUM> when the pressure-bearing member <NUM> moves up and down relative to the tube housing. The buffer block <NUM> is made of a flexible material such as sponge.

As shown in <FIG>, the sub-module <NUM> further includes a conductive buffer pad <NUM> arranged between the chips <NUM> and the bypass busbar <NUM>, and the conductive buffer pad is configured for ensuring the reliability of electrical conduction between the chips <NUM> and the bypass busbar <NUM>.

The conductive substrate <NUM> and the conductive buffer pad <NUM> are respectively in contact with lower surfaces and upper surfaces of the chips <NUM>, and the thermal expansion coefficient of the conductive substrate <NUM> and the thermal expansion coefficient of the conductive buffer pad <NUM> therefore need to match the thermal expansion coefficient of the chips <NUM> (generally being made of a silicon material), so that when the module is heated, the thermal expansion of the conductive substrate <NUM>, the conductive buffer pad <NUM> and the chips <NUM> being consistent is ensured, thereby avoiding the defects on contact surfaces therebetween, such as a stress, a crack or a hole. The conductive substrate <NUM> and the conductive buffer pad <NUM> are preferably made of molybdenum or a copper-molybdenum alloy.

Preferably, the chips <NUM> and the conductive substrate <NUM> are connected by means of welding or silver sintering, and the chips <NUM> and the conductive buffer pad <NUM> can also be connected by means of welding or silver sintering, i.e., so-called "double-sided welding of a chip" or "double-sided silver sintering of a chip".

The elastic member <NUM> acts as a unique pressure applying structure of the chips <NUM>, that is, the stress of the chips <NUM> is completely provided by an elastic force caused by deformation of the elastic member <NUM>, and the material structure thereof is preferably a disc spring structure. In the actual application, the number and the combination method of disc springs can be flexibly configured according to the pressure of the chips. It will be understood that the elastic member <NUM> can also use the structure form such as a helical spring and a hydraulic spring, which can implement the same functions.

In the embodiment as shown in <FIG>, the sub-module <NUM> further includes a gate output probe <NUM>, which is configured for outputting gate signals from the plurality of chips in parallel. The gates of the chips <NUM> are aggregated by means of lead bonding, and then output signals by means of the gate output probe <NUM>. Preferably, the gate output probe <NUM> is made of copper or beryllium-copper, and contact points are plated with gold.

In the embodiment as shown in <FIG>, the sub-module further includes a side frame <NUM>. A bottom face of the side frame <NUM> is connected to edges of an upper surface of the conductive substrate <NUM> in a sealed manner, so as to form a cavity with a sealed bottom portion and an open upper portion. The cavity is potted with adhesive, preferably with silica gel, so that there is an insulation distance between the conductive substrate <NUM> and the conductive buffer pad <NUM>. The side frame <NUM> is preferably made of a polyester material, and the tolerable temperature of the polyester material is higher than <NUM>.

In the embodiment as shown in <FIG>, the sub-module <NUM> further includes a pressure-bearing pad <NUM>, which is arranged between the bypass busbar <NUM> and the elastic member <NUM> and is configured for buffering pressure transfer between the bypass busbar <NUM> and the elastic member <NUM>, so that the intensity of contact pressure between the chips <NUM> is consistent. The pressure-bearing pad <NUM> is preferably made of an aluminum material.

The stress condition of the sub-module according to the application when being press-fitted will be illustrated below in detail in conjunction with <FIG>.

As shown in <FIG>, when the module is subjected to a press-fitting force "Ftotal", a force decomposed into the module is divided into two components, one is "Fi", which is an applied force to the chips <NUM>, and the other one is "F<NUM>", which is an applied force to a pressure-bearing injection molded member <NUM>. F<NUM> is provided by a counter-acting elastic force produced by a deformation amount ΔH of the elastic member <NUM>, that is, F<NUM> = k * ΔH, where k is an elastic coefficient of the elastic member <NUM>, and F<NUM> = Ftotal - F<NUM>. Regardless of how the press-fitting force Ftotal changes, the force F1 applied to the chips <NUM> is fixed, and is only related to the elastic coefficient of the elastic member and not related to the press-fitting force Ftotal, thereby ensuring the reliability of the application of the module.

The crimping-type IGBT module according to the application can be applied to a power semiconductor device.

In summary, the application has the following advantages.

In the description of the present invention, it is to be understood that the terms of "above", "below", "bottom", "top", "front", "rear", "inside", "outside", "left", "right", etc. indicating orientation or position relationships are based on the orientation or position relationship shown in the accompanying drawings and are intended to facilitate the description of the present invention and simplify the description only, rather than indicating or implying that an apparatus or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and will not to be interpreted as limiting the invention.

Claim 1:
A crimping-type IGBT module (<NUM>), comprising a plurality of sub-modules (<NUM>-<NUM>) capable of moving up and down relative to a tube housing (<NUM>, <NUM>), wherein each of the sub-modules comprises:
a conductive substrate (<NUM>) and a conductive cover plate (<NUM>), which are capable of being accommodated in the tube housing or respectively extending out of a lower surface and an upper surface of the tube housing;
a plurality of chips (<NUM>), which are juxtaposed and spaced apart on the conductive substrate;
a pressure-bearing member (<NUM>), which is capable of being accommodated in the tube housing or extending out of the lower surface the tube housing;
a bypass busbar (<NUM>), which is arranged above the chips, and an upper portion of which abuts against an upper surface of the pressure-bearing member; and
an elastic member (<NUM>), which is arranged between the bypass busbar and the conductive cover plate, wherein
when a press-fitting force is not greater than an elastic force provided by the elastic member, the conductive cover plate extends out of the upper surface of the tube housing, both the conductive substrate and the pressure-bearing member extend out of the lower surface of the tube housing, and a lower surface of the conductive substrate is flush with the lower surface of the pressure-bearing member; and
when the press-fitting force is greater than the elastic force provided by the elastic member, both the lower surface of the conductive substrate and the lower surface of the pressure-bearing member are flush with the lower surface of the tube housing, and an upper surface of the conductive cover plate is flush with the upper surface of the tube housing.