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DE-102023204016-B4 - THERMAL CONNECTION BETWEEN CONDUCTOR PLATE AND BASE PLATE WITH EPOXY SPRAY MATERIAL

DE102023204016B4DE 102023204016 B4DE102023204016 B4DE 102023204016B4DE-102023204016-B4

Abstract

Device comprising: a base plate (12); a printed circuit board PCB (14) connected to the base plate (12); an encapsulation housing (34); and a heat transfer layer formed as part of the encapsulation housing (34), wherein the heat transfer layer is arranged between the PCB (14) and the base plate (12) such that the heat transfer layer transfers heat from the PCB (14) to the base plate (12); wherein the base plate (12) and the PCB (14) are connected to each other by the encapsulation housing (34), the device further comprises: a first plurality of assembly openings (26) which are integrally formed as part of the PCB (14); and a second plurality of assembly openings (28) which are integrally formed as part of the base plate (12); wherein each of the first plurality of assembly openings (26) is aligned with a corresponding one of the second plurality of assembly openings (28), and a section of the encapsulation housing (34) extends through each of the first plurality of assembly openings (26) and the second plurality of assembly openings (28) extends.

Inventors

  • Uwe Stephan
  • Donald J. Zito

Assignees

  • Schaeffler Technologies AG & Co. KG

Dates

Publication Date
20260513
Application Date
20230502
Priority Date
20220502

Claims (19)

  1. Device comprising: a base plate (12); a printed circuit board (PCB) (14) connected to the base plate (12); an encapsulation housing (34); and a heat transfer layer formed as part of the encapsulation housing (34), wherein the heat transfer layer is arranged between the PCB (14) and the base plate (12) such that the heat transfer layer transfers heat from the PCB (14) to the base plate (12); wherein the base plate (12) and the PCB (14) are connected to each other by the encapsulation housing (34), the device further comprising: a first plurality of assembly openings (26) formed integrally as part of the PCB (14); and a second plurality of assembly openings (28) formed integrally as part of the base plate (12); wherein each of the first plurality of assembly openings (26) is aligned with a corresponding one of the second plurality of assembly openings (28), and a section of the encapsulation housing (34) extends through each of the first plurality of assembly openings (26) and the second plurality of assembly openings (28).
  2. Device according to Claim 1 , wherein the encapsulation housing (34) further comprises: a first layer (34a) arranged on one side of the PCB (14); and a second layer (34b) arranged on one side of the base plate (12); wherein the heat transfer layer is arranged on the side of the PCB (14) opposite the first layer (34a), and the heat transfer layer is arranged on the side of the base plate (12) opposite the second layer (34b).
  3. Device according to Claim 2 , further comprising: at least one flow opening (30a, 30b) which is integrally formed as part of the base plate (12); wherein at least one section of the encapsulation housing (34) is arranged in the at least one flow opening (30a, 30b) and is integrally formed with the heat transfer layer and the second layer (34b) and is arranged between the heat transfer layer and the second layer (34b).
  4. Device according to Claims 2 or 3 , wherein the heat transfer layer further comprises a third layer of the encapsulation housing (34) arranged between the PCB (14) and the base plate (12), the third layer electrically isolating the base plate (12) from the PCB (14).
  5. Device according to one of the preceding claims, further comprising: at least one spacer (12c, 12d, 12e) which is integrally formed as part of the base plate (12); wherein the at least one spacer (12c, 12d, 12e) is in contact with the PCB (14) and the at least one spacer (12c, 12d, 12e) extends through the heat transfer layer.
  6. Device according to Claim 5 , furthermore comprising a distance between the PCB (14) and the base plate (12) which corresponds to the length of the spacer (12c).
  7. Device according to one of the preceding claims, further comprising: at least one support (60) which is integrally formed as part of the encapsulation housing (34) such that the at least one support (60) is integrally formed with the heat transfer layer; wherein the at least one support (60) extends through one of the first plurality of assembly openings (26) and at least one of the plurality of second openings (28).
  8. Device according to one of the preceding claims, further comprising circuits (18) mounted on the PCB (14), wherein at least a section of the circuits (18) is covered by the encapsulation housing (34) and heat generated by the circuits (18) is transferred to the base plate (12) through the heat transfer layer.
  9. Device according to one of the preceding claims, further comprising: a cover (24) which is integrally formed as part of the base plate (12); and a cavity (22) which is integrally formed as part of the cover (24); wherein a section of the heat transfer layer adjoins the cover (24), and the cover (24) adjoins an area of the PCB (14) which is not occupied by the encapsulation housing (34).
  10. Device according to Claim 9 , further comprising: a circumferential lip (42) which is integrally formed as part of the base plate (12) such that the circumferential lip (42) surrounds the cover (24); wherein a section of the heat transfer layer adjoins the circumferential lip (42).
  11. Device according to one of the preceding claims, further comprising: at least one groove (46a, 46b, 50a, 50b) which is integrally formed as part of the encapsulation housing (34) such that is designed such that one section of the at least one groove (46a, 46b, 50a, 50b) is formed by the heat transfer layer, and another section of the at least one groove (46a, 46b, 50a, 50b) is formed by the second layer (34b); wherein a section (48a, 48b, 48c, 48d) of the base plate (12) is arranged in the at least one groove (46a, 46b, 50a, 50b), thereby connecting the base plate (12) and the encapsulation housing (34).
  12. A method for manufacturing a device comprising the following steps: providing a base plate (12); providing a printed circuit board (PCB) (14); and providing circuits (18) mounted on the PCB (14); contacting the PCB (14) with the base plate (12); overmolding sections of the base plate (12), sections of the circuits (18), and sections of the PCB (14) with an epoxy to form an encapsulation housing (34) having a heat transfer layer, wherein the encapsulation housing (34) connects the base plate (12) to the PCB (14) and the heat transfer layer transfers heat from the PCB (14) to the base plate (12), further comprising the following steps: providing a first plurality of assembly openings (26) formed integrally as part of the PCB (14); and providing a second plurality of assembly openings (28) that are integrally formed as part of the base plate (12); aligning each of the first plurality of assembly openings (26) with a corresponding one of the second plurality of assembly openings (28) when the PCB (14) is brought into contact with the base plate (12) such that a section of the encapsulation housing (34) extends through each of the first plurality of assembly openings (26) and the second plurality of assembly openings (28) once the epoxy has been overmolded around sections of the base plate (12) and the PCB (14).
  13. Procedure according to Claim 12 , further comprising the steps of overmolding sections of the base plate (12) and the PCB (14) with the epoxy such that the heat transfer layer is arranged on the side of the PCB (14) opposite the first layer (34a) of the encapsulation housing (34), and the heat transfer layer is arranged on the side of the base plate (12) opposite the second layer (34b) of the encapsulation housing (34).
  14. Procedure according to Claim 13 , further comprising the steps of: providing at least one flow opening (30a, 30b) which is integrally formed as part of the base plate (12); overmolding sections of the base plate (12) and the PCB (14) with the epoxy such that at least one section of the encapsulation housing (34) is arranged in the at least one flow opening (30a, 30b) and is integrally formed with the heat transfer layer and the second layer (34b).
  15. Procedure according to one of the Claims 12 until 14 , furthermore encompassing the steps of electrically insulating the base plate (12) from the PCB (14) by means of the heat transfer layer.
  16. Procedure according to one of the Claims 12 until 15 , further comprising the steps of overmolding sections of the base plate (12) and the PCB (14) with the epoxy to form at least one support (60) as part of the encapsulation housing (34) such that the at least one support (60) is integrally formed with the heat transfer layer and the at least one support (60) extends through one of the first plurality of assembly openings (26) and at least one of the plurality of second openings (28).
  17. Procedure according to one of the Claims 12 until 16 , further comprising the following steps: providing a cover (24) that is integrally formed as part of the base plate (12); and providing a cavity (22) that is integrally formed as part of the cover (24); overmolding sections of the base plate (12) and the PCB (14) with the epoxy such that a section of the heat transfer layer is adjacent to the cover (24) and the cover (24) is adjacent to an area of the PCB (14) that is not occupied by the encapsulation housing (34).
  18. Procedure according to one of the Claims 12 until 17 , further comprising the following steps: providing at least one spacer (12c, 12d, 12e) which is integrally formed as part of the base plate (12) and is in contact with the PCB (14); overmolding sections of the base plate (12) and the PCB (14) with the epoxy such that the at least one spacer (12c, 12d, 12e) extends through the heat transfer layer.
  19. Procedure according to one of the Claims 12 until 18 , further comprising the following steps: providing at least one groove (46a, 46b, 50a, 50b) which is integrally formed as part of the encapsulation housing (34); Overmolding of sections of the base plate (12) and the PCB (14) with the epoxy to form the encapsulation housing (34) such that a section of the at least one groove (46a, 46b, 50a, 50b) is formed by the heat transfer layer, another section of the at least one groove (46a, 46b, 50a, 50b) is formed by the second layer (34b) and a section (48a, 48b, 48c, 48d) of the base plate (12) is arranged in the at least one groove (46a, 46b, 50a, 50b), thereby connecting the base plate (12) and the encapsulation housing (34).

Description

AREA OF INVENTION The invention generally relates to a control unit which has a connection structure for connecting components of the control unit to a base plate using an overmolding process, wherein the connection structure facilitates the heat transfer from the PCB to the base plate. STATE OF THE ART Many applications use a control unit to control various components. Control units are used in various technology sectors, such as automotive, medical, and computer engineering. One type of control unit, such as a transmission control unit (TCU), is used to operate a transmission. TCUs typically include a printed circuit board (PCB) with various circuits, and the PCB is mounted on a base plate. The PCB and base plate are then assembled in the cavity of a housing, which contains various connectors that make electrical contact with the PCB. The PCB is typically mounted to the base plate using fasteners or an adhesive such as a thermally conductive adhesive (TCA). These known control units still require the ability to transfer heat from the PCB to the base plate, with the base plate acting as a heat sink. Existing designs involve the use of pressure-sensitive adhesive (PSA) or thermal acrylate adhesive (TCA) to bond the PCB and heat sink and transfer heat from the PCB to the heat sink. Some control units also include fasteners such as screws, in addition to PSA or TCA, to connect the PCB and heat sink. Manufacturing a control unit in this way requires additional material and dispensing equipment to provide this thermal interface for heat transfer between the PCB and the heat sink. Out of US 6 307 749 B1 A method for manufacturing an overmolded electronic module is known. The method comprises both overmolding a printed circuit board (PCB) and undermolding one or more surface-mounted circuit devices that are mechanically and electrically connected to the PCB by solder bead connections. The PCB is mounted on a heat sink that is thermally in contact with a surface of the device opposite the PCB. Finally, the PCB is overmolded with a polymer material to form an overmolded body that encloses the PCB and the circuit device along with the heat sink. The overmolding process is carried out such that a portion of the overmolded body completely undermoldes the circuit device and encapsulates its solder bead connections. Out of DE 10 2012 222 199 A1 A transmission control module for a motor vehicle transmission is known. For improved heat dissipation while minimizing overall height, the transmission control module comprises a primary and a secondary circuit board, the latter being populated with electronic components on one side. Electrical connections connect the primary and secondary circuit boards, and a matrix material is located in the area between the electronic components. The secondary circuit board and the components mounted on it are sealed from the environment. Furthermore, a carrier plate is provided, which can be attached to a transmission component on one side and forms at least one receiving volume on the opposite side. This receiving volume is enclosed laterally by side wall regions. The primary circuit board rests on these side wall regions, and the secondary circuit board is positioned with its first side facing the second side of the carrier plate in the receiving volume region such that the components project at least partially into the receiving volume, which is filled with the matrix material. BRIEF SUMMARY OF THE INVENTION One object of the invention is to provide a control unit that eliminates the need for a separate component, such as PSA or TCA, or fasteners to attach a PCB to a heat sink, while still maintaining desirable heat transfer properties. In one embodiment, the present invention comprises a control unit with a connection structure for connecting components of the control unit to a base plate, which is cost-effective, wherein the connection structure facilitates heat transfer from a printed circuit board (PCB) to the base plate and furthermore provides electrical insulation between the PCB and the base plate. In one embodiment, the control unit comprises circuits mounted on a PCB, and the PCB is mounted on a base plate. During manufacturing, the electronic circuits are overmolded with epoxy material. The epoxy material flows between the PCB and the base plate in such a way that an epoxy layer is formed between the The PCB and the base plate are arranged in an epoxy layer. This epoxy layer serves as a heat transfer layer, an electrical insulating layer, and a bonding structure to connect the PCB to the base plate. The epoxy material transfers heat from the PCB to the base plate (i.e., heat is transferred from the surface of the PCB in contact with the epoxy layer to the surface of the base plate in contact with the epoxy layer) and electrically insulates the PCB from the base plate. In one embodiment, the PCB is brought into contact with one or more spacers formed as part of the base plate d