US-20230282553-A1 - POWER ELECTRONIC ASSEMBLY AND POWER MODULE FOR EMBEDDING IN A PRINTED CIRCUIT BOARD

US20230282553A1US 20230282553 A1US20230282553 A1US 20230282553A1US-20230282553-A1

Abstract

A power module for PCB embedding includes: a leadframe; a power semiconductor die with a first load terminal and control terminal at a first side of the die and a second load terminal at the opposite side, the second load terminal soldered to the leadframe; a first metal clip soldered to the first load terminal and forming a first terminal of the power module at a first side of the power module; and a second metal clip soldered to the control terminal and forming a second terminal of the power module at the first side of the power module. The leadframe forms a third terminal of the power module at the first side of the power module, or a third metal clip is soldered to the leadframe and forms the third terminal. The power module terminals are coplanar within +/−30 μm at the first side of the power module.

Inventors

STOEK THOMAS
DAECHE FRANK
TAN CHEE VOON

Assignees

INFINEON TECHNOLOGIES AG

Dates

Publication Date: 20230907
Application Date: 20230511
Priority Date: 20210621

Claims (17)

1 . A power electronic assembly, comprising: a printed circuit board (PCB); and a power module embedded in the PCB, wherein the power module comprises: a leadframe; a power semiconductor die having a first load terminal and a control terminal at a first side of the power semiconductor die and a second load terminal at a second side opposite the first side, the second load terminal being soldered to the leadframe; a first metal clip soldered to the first load terminal and forming a first terminal of the power module at a first side of the power module; and a second metal clip soldered to the control terminal and forming a second terminal of the power module at the first side of the power module, wherein the leadframe extends to the first side of the power module and forms a third terminal of the power module at the first side of the power module, or a third metal clip is soldered to the leadframe and forms the third terminal of the power module, wherein the PCB includes electrically conductive vias that extend through one or more insulating layers of the PCB and contact the first terminal, the second terminal and the third terminal of the power module at the first side of the power module.
2 . The power electronic assembly of claim 1 , wherein the first terminal, the second terminal and the third terminal of the power module are coplanar within +/−30 μm at the first side of the power module.
3 . The power electronic assembly of claim 1 , wherein the power module is a molded module.
4 . The power electronic assembly of claim 1 , wherein the first metal clip of the power module has a plurality of slots configured as a reservoir for accommodating solder paste used to solder the first metal clip to the first load terminal of the power semiconductor die.
5 . The power electronic assembly of claim 1 , wherein the second metal clip of the power module has one or more slots configured as a reservoir for accommodating solder paste used to solder the second metal clip to the control terminal of the power semiconductor die.
6 . The power electronic assembly of claim 1 , wherein the first metal clip of the power module has a plurality of slots configured as a reservoir for accommodating solder paste used to solder the first metal clip to the first load terminal of the power semiconductor die, and wherein the second metal clip of the power module has one or more slots configured as a reservoir for accommodating solder paste used to solder the second metal clip to the control terminal of the power semiconductor die.
7 . The power electronic assembly of claim 1 , wherein the power semiconductor die has a thickness less than 100 μm, and wherein each of the first load terminal, the second load terminal and the control terminal of the power semiconductor die comprises Cu and has a thickness less than 10 μm.
8 . The power electronic assembly of claim 1 , wherein the third terminal of the power module at the first side of the power module is formed by a region of the leadframe that extends to the first side of the power module.
9 . The power electronic assembly of claim 1 , wherein the third terminal of the power module at the first side of the power module is formed by the third metal clip soldered to the leadframe.
10 . A power module for embedding in a printed circuit board (PCB), the power module comprising: a leadframe; a power semiconductor die having a first load terminal and a control terminal at a first side of the power semiconductor die and a second load terminal at a second side opposite the first side, the second load terminal being soldered to the leadframe; a first metal clip soldered to the first load terminal and forming a first terminal of the power module at a first side of the power module; and a second metal clip soldered to the control terminal and forming a second terminal of the power module at the first side of the power module, wherein the leadframe extends to the first side of the power module and forms a third terminal of the power module at the first side of the power module, or a third metal clip is soldered to the leadframe and forms the third terminal of the power module, wherein the first terminal, the second terminal and the third terminal of the power module are coplanar within +/−30 μm at the first side of the power module.
11 . The power module of claim 10 , wherein the first metal clip has a plurality of slots configured as a reservoir for accommodating solder paste used to solder the first metal clip to the first load terminal of the power semiconductor die.
12 . The power module of claim 10 , wherein the second metal clip has one or more slots configured as a reservoir for accommodating solder paste used to solder the second metal clip to the control terminal of the power semiconductor die.
13 . The power module of claim 10 , wherein the power semiconductor die and part of the leadframe are embedded in a molding compound.
14 . The power module of claim 10 , wherein the first metal clip has a plurality of slots configured as a reservoir for accommodating solder paste used to solder the first metal clip to the first load terminal of the power semiconductor die, and wherein the second metal clip has one or more slots configured as a reservoir for accommodating solder paste used to solder the second metal clip to the control terminal of the power semiconductor die.
15 . The power module of claim 10 , wherein the power semiconductor die has a thickness less than 100 μm, and wherein each of the first load terminal, the second load terminal and the control terminal of the power semiconductor die comprises Cu and has a thickness less than 10 μm.
16 . The power module of claim 10 , wherein the third terminal of the power module at the first side of the power module is formed by a region of the leadframe that extends to the first side of the power module.
17 . The power module of claim 10 , wherein the third terminal of the power module at the first side of the power module is formed by the third metal clip soldered to the leadframe.

Description

BACKGROUND Power semiconductor modules for embedding in a PCB (printed circuit board) typically include a large metal block with a power semiconductor die attached to the metal block. The metal block and power semiconductor die are embedded in a PCB insulator material such as FR4. Holes are then formed in the insulator material to access electrical contact pads of the power semiconductor die, and the holes are filled with an electrically conductive material such as copper. Additional semiconductor dies and other components such as passives (capacitors, inductors, resistors, etc.) are typically attached to the top side of the PCB. The process described above suffers from die placement accuracy issues and requires tight control for interfaces that are later connected by vias. Accurate gate pad contacting is particularly problematic, since the gate pad of a power semiconductor die is relatively small compared to the power/load pads. Furthermore, semiconductor material such as silicon is highly sensitive to laser drilling used to form the openings in the PCB insulator material, contamination from the PCB process, and ions present in FR4 and other types of glass-reinforced epoxy laminate materials used in PCB processing. Accordingly, there is a need for an embedded power semiconductor module that does not suffer from the problems described above and related methods of production. SUMMARY According to an embodiment of a method of batch producing power modules, the method comprises: applying a first solder paste to substrate sections of a leadframe structure; placing a plurality of power semiconductor dies on the first solder paste, each power semiconductor die having a first load terminal and a control terminal at a first side that faces away from the leadframe structure and a second load terminal contacting the first solder paste at a second side opposite the first side; applying a second solder paste to the first load terminal and the control terminal of each power semiconductor die; vertically aligning a metal clip frame with the leadframe structure, the metal clip frame comprising a first metal clip vertically aligned with the first load terminal of each power semiconductor die and a second metal clip vertically aligned with the control terminal of each power semiconductor die; pressing the metal clip frame toward the leadframe structure in a pressing direction, wherein a hard stop feature prevents further pressing when the hard stop feature is engaged; reflowing the first solder paste and the second solder paste to form a first soldered joint between each first metal clip and the corresponding first load terminal of each power semiconductor die, a second soldered joint between each second metal clip and the corresponding control terminal of each power semiconductor die, and a third soldered joint between the second load terminal of each power semiconductor die and the corresponding substrate section of the leadframe structure; and severing connections to the leadframe structure and to the metal clip frame, to form individual power modules. According to an embodiment of a method of producing an electronic assembly, the method comprises: embedding a power module in an electrically insulating body of a printed circuit board, the power module comprising: a leadframe; a power semiconductor die having a first load terminal and a control terminal at a first side of the power semiconductor die and a second load terminal at a second side opposite the first side, the second load terminal being soldered to the leadframe; a first metal clip soldered to the first load terminal and forming a first terminal of the power module at a first side of the power module; and a second metal clip soldered to the control terminal and forming a second terminal of the power module at the first side of the power module, wherein the leadframe extends to the first side of the power module and forms a third terminal of the power module at the first side of the power module, or a third metal clip is soldered to the leadframe and forms the third terminal of the power module; forming a plurality of openings in the electrically insulating body of the printed circuit board that expose the first terminal, the second terminal and the third terminal of the power module at the first side of the power module; and filling the plurality of openings with an electrically conductive material. According to an embodiment of a power electronic assembly, the power electronic assembly comprises: a printed circuit board (PCB); and a power module embedded in the PCB, wherein the power module comprises: a leadframe; a power semiconductor die having a first load terminal and a control terminal at a first side of the power semiconductor die and a second load terminal at a second side opposite the first side, the second load terminal being soldered to the leadframe; a first metal clip soldered to the first load terminal and forming a first terminal of the power mod