阅读说明：本技术 半导体功率模块双面平行度与整体厚度的控制方法 (Control method for parallelism of two sides and integral thickness of semiconductor power module ) 是由 雷光寅 邹强 范志斌 于 2020-12-11 设计创作，主要内容包括：本发明属于半导体功率模块技术领域,具体为一种半导体功率模块双面平行度与整体厚度的控制方法。本发明在传统半导体功率模块设计的基础上引入第二层连接材料,实现功率模块双面平行度与整体厚度的精确、有效的控制,具体包括：将第二层材料在注塑过程前附着在功率模块的上、下两面；在第二层连接材料外面再附着外层材料,用以保护模块的内部结构；合模、固化,功率模块所承受的压力逐渐增大,使“第二连接层”变形,达到控制模块平行度和整体厚度的目的。本发明可以简化功率模块的制造工艺、提升良率、降低系统的电磁干扰,进一步提升功率模块的性能。(The invention belongs to the technical field of semiconductor power modules, and particularly relates to a method for controlling the parallelism of two sides and the overall thickness of a semiconductor power module. The invention introduces a second layer connecting material on the basis of the traditional semiconductor power module design, realizes the accurate and effective control of the double-side parallelism and the whole thickness of the power module, and specifically comprises the following steps: attaching a second layer of material to the upper and lower surfaces of the power module before the injection molding process; the outer layer material is attached outside the second layer connecting material to protect the internal structure of the module; and (3) closing the die, curing, and gradually increasing the pressure borne by the power module to deform the second connecting layer so as to achieve the purpose of controlling the parallelism and the overall thickness of the module. The invention can simplify the manufacturing process of the power module, improve the yield, reduce the electromagnetic interference of the system and further improve the performance of the power module.)

1. A method for controlling the double-sided parallelism and the overall thickness of a semiconductor power module is characterized in that a second layer connecting material is introduced on the basis of the design of a traditional semiconductor power module to realize the accurate and effective control of the double-sided parallelism and the overall thickness of the power module, and the method comprises the following specific steps:

(1) attaching a second layer of material to the upper and lower surfaces of the power module before the injection molding process; the adhesion process avoids exposure to a high-temperature environment and prevents the material from being cured in advance;

the second layer of material has certain scalability and can deform along with the increase of pressure;

(2) the outer layer material is attached outside the second layer connecting material to protect the internal structure of the module and provide more convenient mechanical installation and heat dissipation modes;

(3) and (3) closing the die and curing, wherein in the process, the pressure borne by the power module is gradually increased, so that the second connecting layer is deformed, and the purposes of controlling the parallelism and the whole thickness of the module are achieved.

2. The control method according to claim 1, wherein the second connection material is an organic polymer material epoxy resin or cyanate resin.

3. The control method of claim 1, wherein the second connecting material is an insulating material, and no additional insulating layer is used outside the module.

4. The control method of claim 1, wherein the outer layer is made of a metal material, so as to effectively reduce the electromagnetic interference caused by the high frequency switch.

5. Control method according to one of claims 1 to 4, characterized in that the initial thickness of the second layer connecting material in the non-stressed state is between 50 and 500 microns.

6. The method according to claim 5, characterized in that the temperature of the semiconductor power module is controlled in its softening temperature range, in particular between 25 and 150 degrees Celsius, depending on the different requirements of the material of the second layer connections.

7. The method of claim 6, wherein after the temperature is stabilized, a pressure in the range of 0.05 MPa-5 MPa is applied across the semiconductor power module and the temperature of the module is continuously increased to cure the second layer connecting material.

8. The method of claim 7, wherein the second layer of connecting material is cured for a time period of 1 minute to 2 hours.

Technical Field

The invention belongs to the technical field of semiconductor power modules, and particularly relates to a method for controlling the parallelism of two sides and the overall thickness of a semiconductor power module.

Background

The semiconductor power module is widely applied to industrial frequency conversion, current transformer, automobile motor controller and other occasions needing electric energy conversion, the basic structure of the semiconductor power module is as shown in fig. 1, and a power semiconductor device is bonded on a ceramic substrate or a copper substrate through a connecting material (generally welding or metal sintering). In order to enhance the heat dissipation performance, the upper surface of the semiconductor device is usually connected to the metal pad by the same process, and then connected to the upper substrate. Due to the existence of tolerance in the manufacturing process of the material, the integral tolerance is larger after a plurality of connecting processes, and the requirement of direct plastic package in the next step cannot be met. The existing module packaging solution is to polish at least one surface of a module after plastic packaging is finished so as to ensure the whole thickness control of the module. Not only increases the manufacturing cost, but also has great influence on the production yield of the module.

The parallelism of the upper and lower surfaces of the semiconductor power module and the overall thickness control have important significance for the practical application of the module. If the parallelism and the thickness of the module are not controlled within a certain range, flash is easily generated in the injection molding process, and even the module is directly damaged. The current mainstream approach is to try to make the mold thicker than the mold block during the injection molding process. And after the injection molding is finished, the upper surface and the lower surface of the module are polished, and the overflowing part is mechanically polished off, so that the control of parallelism and thickness is realized. However, this not only increases the manufacturing cost of the module, but the mechanical grinding process is also prone to damage to the module.

Disclosure of Invention

The invention aims to provide a method for controlling the parallelism of two surfaces and the whole thickness of a semiconductor power module, which has the advantages of convenient preparation, simple process and low cost.

The invention introduces a second layer connecting material (green in the figure) on the basis of the traditional semiconductor power module design, realizes the accurate and effective control of the double-side parallelism and the whole thickness of the power module, and comprises the following specific steps:

(1) attaching a second layer of material to the upper and lower surfaces of the power module before the injection molding process; the adhesion process avoids exposure to a high-temperature environment and prevents the material from being cured in advance;

the material has certain scalability and can deform along with the increase of pressure;

the thicknesses of the upper layer material and the lower layer material can be consistent or inconsistent;

(2) the outer layer material is attached outside the second layer connecting material to protect the internal structure of the module and provide more convenient mechanical installation and heat dissipation modes;

(3) and (3) closing the die and curing, wherein in the process, the pressure borne by the power module is gradually increased, so that the second connecting layer is deformed, and the purposes of controlling the parallelism and the whole thickness of the module are achieved.

In the present invention, the second connection material may be an organic polymer material such as epoxy resin, cyanate resin, or the like.

In the invention, the second connecting material is an insulating material, and an additional insulating layer is not needed outside the module;

in the invention, when the outer layer material is made of metal material, the problem of electromagnetic interference caused by high-frequency switches of the chip can be effectively reduced.

The invention can simplify the manufacturing process of the power module, improve the yield, reduce the electromagnetic interference of the system and further improve the performance of the power module.

Drawings

Fig. 1 is a schematic diagram of a semiconductor power module mechanism.

Detailed Description

In order to solve the problem that the accumulated tolerance of the thickness is too large in the module packaging process and influences the next plastic packaging process, one layer or multiple layers of shrinkable connecting materials (second layer connecting materials) are adopted, and the introduced connecting materials can be appropriately shrunk under the action of external pressure to make up the influence of the tolerance.

The second layer connecting material can be organic polymer materials such as epoxy resin or cyanate resin, and the initial thickness in a non-pressure state can be 50-500 micrometers. In the operation process:

(1) firstly, placing a second layer connecting material on the outer sides of an upper substrate and a lower substrate of the power module to ensure the cleanness degree of the substrates and no bubbles at an interface;

(2) controlling the temperature of the module within the softening temperature range of the module according to different requirements of the second layer connecting material, wherein the softening temperature range is usually 25-150 ℃;

(3) after the temperature is stabilized, applying a certain pressure, generally in the range of 0.05 MPa-5 MPa, to both ends of the module, and continuously raising the temperature of the module to solidify the second layer connecting material;

(4) and (4) releasing the pressure after the connecting material is completely cured for 1 minute to 2 hours, and finishing the module sample preparation.

On the outer surface of the second layer connecting material, a metal layer can be additionally added according to the requirement to protect the second layer connecting material from physical or chemical damage.

The selection of the second layer connecting material related by the invention has the characteristics of diversity and simple operation process. The tolerance requirement on the packaging material in the packaging process can be reduced, and the effect of reducing the cost is achieved. And because the module is not required to be polished after plastic packaging, the overall yield of the module is certainly improved.