WO2014090987A1

WO2014090987A1 - Printed circuit comprising a heat-transport insert device for cooling

Info

Publication number: WO2014090987A1
Application number: PCT/EP2013/076527
Authority: WO
Inventors: Karen Chauvin
Original assignee: Valeo Systemes Thermiques
Priority date: 2012-12-14
Filing date: 2013-12-13
Publication date: 2014-06-19
Also published as: FR2999862A1; EP2932805A1

Abstract

The invention relates to a printed circuit device comprising a first surface, a second surface, and at least one insert of a heat-transport material, characterized in that: the insert is permanent, and a second surface of the insert projects from the second surface of the printed circuit in order to dissipate calories.

Description

PCB having an insert cooler

heat

TECHNICAL FIELD OF THE INVENTION

The invention relates to printed circuits and more particularly to printed circuits having inserts. In particular, the subject of the invention is a printed circuit comprising a heat transfer insert.

By PCB will be understood (printed circuit board for printed circuit) in the context of the present description any printed circuit or any electronic card.

STATE OF THE PRIOR ART

In the state of the art, there are known cooling modes of printed circuits implementing via in which pions are inserted. Such embodiments imply, for the printed circuit, a mechanical stress at the time of the insertion of the pin. This weakens in fine the circuit board.

In the state of the art, there are also known printed circuits comprising copper inserts. One of the faces of such a copper insert is generally located under an electronic component of a face of a PCB. An opposite face of the insert and the opposite face of the PCB are coplanar. This allows the PCB thus formed to be produced by pressing, its faces being uniformly flat, and the press can then exert a uniform pressure on the entire surface of the PCB.

With such a PCB it is possible to use a radiator to promote the dissipation of calories produced by the component located above the face of the insert. The technique consists in fixing a radiator on the opposite face of the insert. Calories are then driven by the insert and dissipated by the radiator. This technique has at least two disadvantages:

A thermal interface is essential between the radiator and the PCB to ensure good thermal conductivity between the two elements (surface roughness). The thermal conductivity of this interface is much lower than that of copper. This interface degrades the transmission of calories between the insert and the radiator and thus reduces the efficiency of the heat dissipation system.

SUBSTITUTE SHEET (RULE 26) The use of a radiator imposes an additional component, the radiator itself, and a step of fixing said radiator. This increases the complexity of a PCB production process using this calorie dissipation technique.

SUMMARY OF THE INVENTION

The invention aims to remedy all or part of the disadvantages of the state of the art identified above, and in particular to provide means for cooling a component by improving the dissipation of the calories it produces. In the invention this dissipation is carried out via a copper insert which captures the calories under the component and leads them to a protruding portion of the insert to promote the dissipation of calories in the open air, or in a stream of air provoked. This solution in addition to solving the aforementioned problems allows more flexibility with respect to the mechanical constraints of packaging and / or integration. This solution also allows more freedom in the design of the printed circuit since the placement and shape of the insert are free.

For this purpose, one aspect of the invention relates to a printed circuit comprising a first face, a second face and at least one insert of a heat-transfer material, characterized in that:

the insert is permanent,

a second part of the insert is protruding from the second face of the printed circuit to dissipate calories.

In addition to the main features which have just been mentioned in the preceding paragraph, the method / device according to the invention may have one or more additional characteristics among the following, considered individually or according to the technically possible combinations.

a first part of the insert is plane and this first part and the first face of the main part of the printed circuit are coplanar,

the heat transfer material is chosen from at least copper or aluminum,

SUBSTITUTE SHEET (RULE 26) the first face of the main part of the printed circuit being considered in a horizontal plane, the second face of the main part of the printed circuit is a lateral edge of the printed circuit,

the projecting portion of the insert extends parallel to the first face of the printed circuit,

the projecting part of the insert is bent,

the projecting portion extends over a distance of the order of one centimeter.

the protruding part extends over a distance of between 0.5 centimeters and 30 centimeters.

- The projecting portion of the insert comprises at least one fin.

The invention also relates to a cooling device comprising a printed circuit according to one of the preceding claims, characterized in that the projecting portion of the insert is adapted to be disposed in a coolant flow.

The invention also relates to the use of a printed circuit as described above for dissipating thermal energy, the projecting portion of the insert being disposed in a flow of refrigerant fluid.

The invention relates to a method for manufacturing a printed circuit as described above, characterized in that the pressing step comprises an insertion step at least partially on the second face of the plate and on the second face of the insert of an additional layer made of a material not completely polymerized.

Preferably, the pressing step comprises a heating step so as to complete the complete polymerization of said additional layer.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate:

FIG. 1, a variant of the invention comprising a rectilinear projecting part,

FIG. 2, a variant of the invention comprising a bent protrusion,

SUBSTITUTE SHEET (RULE 26) 3, a sectional representation of a variant of the invention comprising a projecting part comprising fins,

Figure 4, a top view of a variant of the invention having a projecting portion having fins.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

The invention will be better understood on reading the description which follows and the examination of the figures that accompany it. These are presented as an indication and in no way limitative of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

Figure 1 shows a circuit 101 printed on which tracks will be printed and soldered electronic components to obtain a printed circuit. The printed circuit 101 comprises a plate called the main part. The plate 101 is generally made of epoxy resin. The description remains valid with other materials. At least one of the faces of the printed circuit is intended to receive electronic components. These components are placed at predetermined locations. This face is a first face 102 of the printed circuit 101.

To simplify the reading of the present patent application, the first face 102 of the main part of the printed circuit is now called the first face 102 of the printed circuit and the second face 103 of the main part of the printed circuit is called second face. printed circuit board.

Figure 1 shows that the printed circuit 101 comprises, for example at a location in the main part for receiving an electronic component, a heat transfer insert 104. In this document, a heat transfer element designates a heat conducting element, that is to say a thermal conductor. In a variant, the insert 104 is made of copper. An important feature of the insert is that it is permanent, that is to say it is embedded in the printed circuit at the time of manufacture of said printed circuit. It is impossible to remove the insert 104 without destroying the circuit. It is therefore an inlaid and inseparable component of the printed circuit. It is also said that it is inserted into the mass during the manufacture of the printed circuit. Figure 1 shows that

SUBSTITUTE SHEET (RULE 26) the insert 04 comprises a first planar face 105 such that the surface of the first face 105 of the insert 104 and the first face 102 of the printed circuit 101 are coplanar. The first face 105 of the insert 104 is a first portion 105 of the insert 104. This coplanarity is valid at manufacturing tolerances. The fact that the first face 105 of the insert 104 and the first face 102 of the printed circuit 101 are coplanar means that the first face 105 of the insert 104 is visible and accessible when looking at the first face 102 of the insert 104. This makes it possible to place at this location an electronic component as if the printed circuit board 101 did not contain an insert.

The insert 104 may be made of any heat transfer material compatible with the printed circuit manufacturing process. For the example, aluminum is mentioned in addition to copper.

FIG. 1 shows that the circuit 101 printed has a second face 103 adjacent to the first face 102 of the printed circuit 101. This second face 103 of the circuit 01 is a lateral face of the printed circuit 101. With manufacturing tolerances close, the first face 102 of the printed circuit 101 and the second face 103 of the printed circuit 101 are perpendicular.

Figure 1 shows that the insert 104 extends in the mass of the printed circuit 101 and projects at the second face 103 of the printed circuit 101. The projecting portion 106 of the insert 104 is a second part 106 of the insert 104. The protruding portion 106 of the insert 104 extends parallel to a plane in which is the first face 102 of the printed circuit 101.

The distance over which the projecting portion of the insert 104 extends is of the order of one centimeter. The distance over which the projecting portion of the insert 104 extends is generally between 0.5 centimeters and 30 centimeters. This distance is a function of the amount of heat to be dissipated, the dissipation conditions and the maximum size allowed for the printed circuit 101. According to these constraints, the distance over which the projecting portion of the insert 104 extends is adapted. The more calories to be dissipated and the more space there is, the greater the projecting portion of the insert 104 is large.

In Figure 2, the projecting portion 106 of the insert 104 is bent. The direction in which the projecting portion 106 of the insert 104 extends is different from the plane in which the first face 102 of the printed circuit 101 extends.

FIRE I LLE OF REM PLACEM ENT (RULE 26) 2 shows that the protruding part 106 of the insert 104 is bent at 90 °, forming a bend 109, the direction in which the projecting portion 106 is orthogonal to the plane in which the first face 102 of the printed circuit extends. 01. In the variant of Figure 2 the elbow of the insert 104 is formed at the place where the insert 104 protrudes. In practice, this elbow 109 can be made at a distance from this place. This distance is for example of the order of one centimeter.

Bending or not the protruding part 106 of the insert 104 is guided by environmental considerations of the printed circuit 101. Bending the projecting portion 106 of the insert 104 can save space by reducing the overall area of the printed circuit 101. Bending the protruding portion 106 of the insert 04 may allow this portion 106 to be placed. protruding into a flow of air, natural or provoked, so as to improve the dissipation of calories.

Figure 1 shows that the projecting portion 106 of the insert 104 is flat. FIG. 4 shows a variant of FIG. 1 in which the protruding part 106 of the insert 104 has a fin 107 on its upper face 108. Arbitrarily the upper face of the projecting part is that seen when it is opposite the first face 105 of the insert 104.

Figure 4 shows that the fin 107 is a rectilinear protuberance. Figure 4 also illustrates that the upper face 108 of the insert 104 has a plurality of parallel fins. This parallelism is checked to manufacturing tolerances. The presence of these fins increases the overall surface of the protruding portion 106 of the insert 104 and thus improve its ability to dissipate calories.

These fins can be obtained, for example:

- By stamping:

After the production of the PCB, when the insert has already been inserted, Before the production of the PCB, when the insert has not yet been inserted,

By contribution of material:

- After the production of the PCB, when the insert has already been inserted,

Before the production of the PCB, when the insert has not yet been inserted.

In unrepresented variants:

SUBSTITUTE SHEET (RULE 26) several faces of the projecting portion 106 comprise fins, another face of the protruding portion 106 that the upper face of the projecting portion 106 comprises fins.

The length of the fins is preferably of the order of the distance over which the protruding portion 106 of the insert 104 extends. The width of the fins is of the order of one millimeter. The height of the fins is of the order of a millimeter. A preferred height is 3 millimeters. In practice the heights are between 2 and 8 millimeters.

The method of manufacturing a printed circuit according to the invention comprises at least the following steps:

a step of drilling a plate comprising a first face and a second face, so as to dig in the second face of the plate a hole having a given shape,

a step of introducing into said hole of a heat-transfer material insert having a shape adapted to penetrate into said hole and to project from the second face of the plate into a projecting portion of a second face of the insert, the first face of said main portion and the second face of said main portion being in intersecting planes.

a step of pressing said plate provided with said insert.

Said plate comprising a first and a second face is preferably made of a material which is a mixture of glass fibers and resin and which has completely polymerized.

Preferably, the pressing step comprises an insertion step on the first face 102 and / or on the face parallel to and opposite the first face 102 of an additional layer made of a material not completely polymerized.

Advantageously, the pressing step comprises a heating step so as to perform a complete polymerization of the additional layer.

At the end of the manufacturing process, the printed circuit previously described and illustrated in FIGS. 1 to 4 is obtained.

SUBSTITUTE SHEET (RULE 26) Note that the fact that the insert is introduced into the plate during the manufacture of the printed circuit ensures that it is permanent within the meaning of the present invention, as already explained.

The invention also relates to a cooling device comprising a printed circuit as described above, and characterized in that the projecting portion 106 of the insert 104 is adapted to be disposed in a coolant flow. By coolant is any thermal conductive fluid and compatible with the printed circuit 101. This is for example air.

The invention also relates to the use of a printed circuit as described above, for dissipating a thermal energy, the projecting portion (106) of the insert being disposed in a flow of refrigerant fluid.

The implementation of the invention allows simply having a printed circuit incorporating an effective cooling device. With the invention there is no loss of efficiency due to thermal interfaces between a coolant and a radiator. In the invention everything is integrated.

SUBSTITUTE SHEET (RULE 26)

Claims

A printed circuit (101) comprising a main portion comprising a first face (102) and a second face (103), said printed circuit comprising at least one insert (104) of a heat transfer material characterized in that:

the insert is permanent,

a second portion (106) of the insert (104) protrudes from the second face of the main portion to dissipate calories, the first face of said main portion and the second face of said main portion being in intersecting planes.

2. printed circuit board according to claim 1, characterized in that a first portion (105) of the insert (104) is flat and this first portion (105) and the first face (102) of the main portion of the printed circuit are coplanar.

3. Printed circuit according to one of the preceding claims, characterized in that the heat transfer material is selected from at least copper or aluminum.

4. Printed circuit according to one of the preceding claims, characterized in that the first face of the main part of the printed circuit being considered in a horizontal plane, the second face of the main part of the printed circuit is a side edge of the printed circuit. .

5. Printed circuit according to one of the preceding claims, characterized in that the projecting portion of the insert extends parallel to the first face of the printed circuit.

6. Printed circuit according to one of claims 1 to 5, characterized in that the projecting portion of the insert is bent.

7. Printed circuit according to one of the preceding claims, characterized in that the projecting portion extends over a distance of about one centimeter.

8. printed circuit board according to one of claims 1 to 7, characterized in that the projecting portion extends over a distance of between 0.5 centimeters and 30 centimeters.

9. Printed circuit according to one of the preceding claims, characterized in that the projecting portion of the insert comprises at least one fin.

10. Printed circuit according to claim 9, characterized in that the height of the fins is of the order of one millimeter.

SUBSTITUTE SHEET (RULE 26)

11. Cooling device comprising a printed circuit according to one of the preceding claims, characterized in that the projecting portion (106) of the insert is adapted to be disposed in a coolant flow.

12. Use of a printed circuit according to one of claims 1 to 10 for dissipating thermal energy, the protruding portion (106) of the insert being disposed in a flow of refrigerant, such as a flow of air .

13. A method of manufacturing a printed circuit according to one of claims 1 to 10, characterized in that it comprises a pressing step comprising a step of insertion at least partially of an additional layer made of a material not completely polymerized.

14. A method of manufacturing a printed circuit according to the preceding claim, characterized in that the pressing step comprises a heating step so as to complete the complete polymerization of said additional layer.

FIRE I LLE OF REM PLACEM ENT (RULE 26)