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EP-4057339-B1 - BASE PLATE HAVING SIDEWALL, POWER SEMICONDUCTOR MODULE COMPRISING THE BASE PLATE AND METHOD FOR PRODUCING THE BASE PLATE

EP4057339B1EP 4057339 B1EP4057339 B1EP 4057339B1EP-4057339-B1

Inventors

  • ZHANG, BIWEI
  • BEYER, HARALD
  • Maleki, Milad
  • TRUESSEL, DOMINIK
  • Ludwig, Maxime

Dates

Publication Date
20260506
Application Date
20210310

Claims (14)

  1. A base plate (10) for a power semiconductor module, wherein - the base plate (10) comprises a basic body (1) formed in one piece, - the basic body (1) has a front side (1A) and a rear side (1B), the front side (1A) comprising a mounting area (1M) of the base plate (10), - along at least one of its edges (1E), the basic body (1) has at least one elevated integral part forming at least one sidewall (11) projecting beyond the mounting area (1M) by a vertical height (11H), - at regions of the mounting area (1M), the basic body (1) has a vertical thickness (1T) extending between the front side (1A) and the rear side (1B), the vertical thickness (1T) being larger than the vertical height (11H) of the sidewall (11), - along all edges (1E), the basic body (1) comprises either at least one sidewall (11) or at least one groove (12) but not both sidewall (11) and groove (12) at the same edge (1E), wherein along at least one of its edges (1E), the basic body (1) comprises one elevated integral part forming the at least one sidewall (11), and - the at least one groove (12) extends along at least one of the edges (1E) of the basic body (1), wherein along a lateral direction, the mounting area (1M) is delimited by the groove (12).
  2. The base plate (10) according to claim 1, wherein the elevated integral part forms at least two sidewalls (11) projecting beyond the mounting area (1M), and the least two sidewalls (11) are located along two non-adjacent or opposite edges (1E) of the basic body (1).
  3. The base plate (10) according to claim 1, wherein the basic body (1) comprises two sidewalls (11) located at two opposite edges (1E) and two grooves (12) located at two another edges (1E) of the basic body (1).
  4. The base plate (10) according to one of the preceding claims, wherein the at least one sidewall (11) has a vertical height (11H) between 0.05 mm and 5.0 mm inclusive and an average lateral width (11W) between 0.05 mm and 10 mm inclusive.
  5. The base plate (10) according to one of the preceding claims, comprising a plurality of cooling fins (3) on the rear side (1B).
  6. The base plate (10) according to one of claims 1 to 5, wherein the at least one sidewall (11) is a vertical wall.
  7. The base plate (10) according to one of claims 1 to 5, wherein the at least one sidewall (11) is an inclined wall.
  8. The base plate (10) according to one of claims 1 to 5, wherein the at least one sidewall (11) is a round-shaped wall.
  9. The base plate (10) according to one of claims 1 to 5, wherein the at least one sidewall (11) is formed partially as vertical wall and partially as inclined wall.
  10. The base plate (10) according to one of claims 1 to 8, wherein the at least one sidewall (11) is formed partially as vertical wall and partially as round-shaped wall.
  11. A power semiconductor module (100) comprising the base plate (10) according to one of the preceding claims, further comprising a housing body (20), wherein - the housing body (20) laterally surrounds the base plate (10), and - the sidewall (11) is covered by the housing body (20) and serves as an anchoring structure which additionally fixes the housing body (20) to the base plate (10).
  12. A power semiconductor module (100) comprising the base plate (10) according to one of claims 1 to 10, further comprising a housing body (20), wherein - the housing body (20) laterally surrounds the base plate (10), and - the sidewall (11) is covered by the housing body (20) and the at least one groove (12) is at least partially filled by a material of the housing body (20) so that both the sidewall (11) and the groove (12) serve as anchoring structures which additionally fix the housing body (20) to the base plate (10).
  13. The power semiconductor module (100) according to one of claims 11 to 12, further comprising a module component (30), wherein - the module component (30) is fixed on the mounting area (1M) by a connection layer (2), and - the housing body (20) laterally surrounds the module component (30) .
  14. The power semiconductor module (100) according to claim 13, wherein the sidewall (11) and/or the groove (12) are/is formed to prevent material of the connection layer (2) from creeping towards an assembly surface (1Z).

Description

The present disclosure relates to a base plate having sidewall/s for example for a power semiconductor module, a power semiconductor module comprising the base plate and methods for producing the base plate. When semiconductor chips are fixed to substrates or substrates are fixed to a base plate, due to wettability of surfaces, connecting material such as solder may spread on neighboring surfaces of the substrates or may spread over a large area of a mounting area of the base plate. This overflow of connecting material may cause contamination of areas for instance used for wire-bonding, or may lead to a reduced adhesion of an encapsulation material for instance of a housing body of a power semiconductor module resulting in delamination. Moreover, in virtue of the overflow of the connecting material, part of the connecting material may get lost, and it is possible that no sufficient connecting material is available for achieving a highly stable connection between the semiconductor chips and the substrates, between the substrates and the base plate, or between the semiconductor chips and the base plate. If no modifications of the base plate for instance for preventing the overflow of connecting material are introduced, a strong overflow of connecting material such as of solder may occur, resulting in an unwanted deposition of solder in other regions of the base plate, especially not only on the front side but also on side surfaces or on the rear side of the base plate. For solving these issues, solder resist may be coated on surfaces of the base plate or of the substrates to prevent or reduce the wetting of such surfaces. Coating surfaces with solder resistive material, however, requires additional processes in the production of the substrates or base plates causing higher manufacturing costs. Additionally, in case of using an organic coating material as solder resist, an outgassing of substances from the coating layer will have negative impact on further process steps for manufacturing a power semiconductor module comprising the power semiconductor module and the base plate or on the reliability and functionality of the power semiconductor module. Moreover, using solder resist may have negative impact on adhesion of encapsulation material. Another approach for preventing the overflow of connecting material is the preparation of grooves around the mounting area. In this disclosure, the mounting area is understood to mean a surface on a front side of the base plate for receiving module components like substrates and/or chips. The surface for fixing, for instance for screwing the base plate to carrier acting as a cooler will be referred to as assembly surface. The assembly surface can comprise surfaces outside the mounting area, for instance outside sidewall/s and/or groove/s on a front side of the base plate. However, it is possible that side surfaces and/or a rear side of the base plate can be additionally referred to as part of the assembly surface. Here, overflowing connecting material such as solder material may be collected in the grooves so that no portion or only a small portion of the assembly surface of the base plate will be contaminated by the connecting material. The grooves, however, shall be formed sufficiently large, for example in the case that thick solder meniscus shall be formed for enhancing the stability of the solder connection. This, however, will lead to a reduction of the size of the mounting area. Furthermore, on one hand, choosing a sufficiently large size of the groove, a large amount of connecting material will accumulate in the groove. This loss of connecting material may result in a locally insufficient or missing soldering connection or in the formation of voids for instance in regions next to the groove. On the other hand, if the size of the groove around the substrate soldering position is kept small, it may not sufficiently prevent the overflow of the connecting material. Documents EP 0 577 966 A1, US 2009/224384 A1, US 2002/011661 A1, US 6 667 545 B1, US 2015/235929 A1 and JP 2011 258814 A describe a component having a base plate or a printed circuit board and a semiconductor chip arranged on the base plate or or the printed circuit board, wherein the base plate or the printed circuit board has a structured upper surface. Document JP 2008 034601 A provides a semiconductor device having improved moisture resistance, and a manufacturing method thereof. This semiconductor device includes an island having a rear surface exposed to the outside, a semiconductor element mounted on the upper surface of the island, leads each having one end approximating to the island and electrically connected to the semiconductor element, and a sealing resin for covering the semiconductor element and the like in a state where the lower surface of the island is exposed to the outside. Embodiments of the disclosure relate to a base plate for instance for a power semiconductor module, wherein the base