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DE-102024132964-A1 - A combination of a multilayer printed circuit board and a heat sink

DE102024132964A1DE 102024132964 A1DE102024132964 A1DE 102024132964A1DE-102024132964-A1

Abstract

A composite of a multilayer printed circuit board (PCB) and a heat sink is presented. The multilayer PCB has a component side designed for mounting at least one component and a heat sink side opposite the component side. The heat sink extends between the heat sink side and the component side of the multilayer PCB, such that the distance between the heat sink side and the component side corresponds to the material thickness of the multilayer PCB. In a central part located between the heat sink side and a portion of the component side designed for mounting the at least one component, the multilayer PCB has a material thickness that is reduced compared to the material thickness of a peripheral part of the multilayer PCB surrounding the central part. The heat sink is a single piece and has a projection that extends into the central part of the multilayer PCB to such an extent that it thermally contacts the heat sink side of the multilayer PCB in the central part of the multilayer PCB.

Inventors

  • Mario Baumann

Assignees

  • MARELLI GERMANY GMBH

Dates

Publication Date
20260513
Application Date
20241112

Claims (11)

  1. A composite (10) consisting of a multilayer printed circuit board (12) and a heat sink (14), wherein the multilayer printed circuit board (12) has a component side (18) designed for mounting at least one component (16) and a heat sink side (20) opposite the component side (18), and extends between the heat sink side (20) and the component side (16) of the multilayer printed circuit board (12), such that the distance of the heat sink side (20) from the component side (18) corresponds to a material thickness of the multilayer printed circuit board (12), and wherein the multilayer printed circuit board (12) has a material thickness in a central part (22) located between the heat sink side (20) and a partial surface of the component side (18) designed for mounting the at least one component (16), which is greater than the material thickness of a peripheral part (24) of the multilayer printed circuit board (12) that surrounds the central part (22). surrounding, reduced, characterized in that the heat sink (14) is one-piece and has a projection 26) which extends into the central part (22) of the multilayer printed circuit board (12) to such an extent that it thermally contacts the heat sink side (20) of the multilayer printed circuit board (12) in the central part (22) of the multilayer printed circuit board (12).
  2. network (10) according Claim 1 , characterized in that the thermal contact is effected by direct, pressing contact.
  3. Composite (10) according to one of the preceding claims, characterized in that the material thickness of the central part is 40 micrometers to 300 micrometers, in particular 70 micrometers.
  4. Composite (10) according to one of the preceding claims, characterized in that the material thickness of the peripheral part is 300 micrometers to 3200 micrometers, preferably 800 micrometers.
  5. Composite (10) according to one of the preceding claims, characterized in that the multilayer printed circuit board has a layer stack of n copper layers and n-1 fabric layers with FR4 plastic.
  6. network (10) according Claim 5 , characterized in that the number n lies between n = 4 and n = 12.
  7. network (10) according Claim 5 or 6 characterized in that the fabric of the fabric layers consists of glass fibers.
  8. group (10) according to one of the Claims 5 - 7 , characterized in that the copper layer closest to the component side is plated, that a fabric layer with FR4 plastic lies below it and a first inner copper layer lies below this.
  9. network (10) according Claim 8 , characterized in that the first inner copper layer is 10 micrometers to 150 micrometers thick, in particular 35 micrometers thick, and is thermally bonded to the uppermost copper layer.
  10. network (10) according Claim 9 characterized in that the fabric layer lying between these two copper layers is thermally bridged by one or more vias, the vias being able to be filled with thermally conductive material such as copper.
  11. A composite (10) according to one of the preceding claims, characterized in that the clear width of a pocket resulting from the reduction in material thickness and into which the projection of the heat sink extends is larger than the projection, so that an air gap is formed between the circuit board and the projection.

Description

State of the art The present invention relates to a composite of a multilayer printed circuit board and a heat sink according to the preamble of claim 1. Such a composite is known per se, wherein the multilayer printed circuit board has a component side designed for mounting at least one component and a heat sink side opposite the component side. The multilayer printed circuit board extends between its heat sink side and its component side. The distance between the heat sink side and the component side corresponds to a material thickness of the multilayer printed circuit board. In a central part, located between the heat sink side and a partial surface of the component side designed for mounting the at least one component, the multilayer printed circuit board has a material thickness that is reduced compared to the material thickness of a peripheral part of the multilayer printed circuit board surrounding the central part. The heat sink of the known composite has a copper core (coin) and a heat sink base. The heat sink base extends over the central part of the multilayer printed circuit board and the peripheral part. The copper core is a separate element from the heat sink base, which is thermally connected to the heat sink base via a copper base layer and a layer of thermal interface material (TIM). It is thermally connected to a component via a component-side copper layer, copper-filled micro-vias, and solder. The composite serves to dissipate heat from components such as high-power LEDs, as used particularly in automotive lighting systems. Devices for dissipating heat from components are also derived from the... US 2016/0270 227 A1 as from the DE 20 2014 006 215 U1 known. Disclosure of the invention The present invention differs from the prior art per se in that the heat sink is a single piece and has a projection that extends into the central part of the multilayer printed circuit board to such an extent that it thermally contacts the heat sink side of the multilayer printed circuit board in the central part of the multilayer printed circuit board. These features eliminate the need for PCB inserts such as coins. The desired result is more direct heat dissipation from components mounted on the circuit board and simpler assembly of the assembly, leading to a reduction in manufacturing costs. A preferred embodiment is characterized by the fact that the thermal contact is effected by direct, pressing contact. It is further preferred that the material thickness of the central part is 40 micrometers to 300 micrometers, in particular 70 micrometers. Another embodiment is characterized by the fact that the material thickness of the peripheral part is 300 micrometers to 3200 micrometers, preferably 800 micrometers. It is also preferred that the multilayer printed circuit board has a layer stack of n copper layers and n-1 fabric layers with FR4 plastic. Furthermore, it is preferred that the number n lies between n = 4 and n = 12. Another preferred embodiment is characterized by the fact that the fabric of the fabric layers consists of glass fibers. It is also preferred that the copper layer closest to the component side is plated, that a fabric layer with FR4 plastic lies beneath it, and that a first inner copper layer lies beneath this. It is further preferred that the first inner copper layer is 10 to 150 micrometers thick, particularly 35 micrometers thick, and thermally bonded to the uppermost copper layer. The fabric layer between these two copper layers is thermally bridged by one or more vias, which may be filled with a thermally conductive material such as copper. Another preferred embodiment is characterized in that the clear width of a pocket resulting from the reduction in material thickness, into which the projection of the heat sink extends, is larger than the projection, so that an air gap is created between the circuit board and the projection. Further features and/or advantages can be found in the description and the attached figures. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention. Drawings Exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description. In the figures, identical reference numerals denote identical elements or elements that are at least functionally equivalent. The figures show, in schematic form: 1 a first embodiment of a composite according to the invention; 2 a further embodiment of a composite according to the invention; and 3 a network that is known per se. 1 Figure 1 shows a section of a composite 10 consisting of a multilayer printed circuit board 12 and a heat sink 14 in a sectional view. The section plane is shown in both the 1 as well as in the other figures, for example, a yz-plane of a three-dimensional and right-handed coo