DE10331453B4 - Method for producing at least one thermal bridge in a substrate - Google Patents

Abstract

Method for producing at least one thermal bridge in a substrate for dissipating heat from heat sources that can be mounted or mounted on the substrate, in particular heat loss from electronic components,
a) in which at least one recess (4) is or is produced in the substrate (2),
b) in which at least one thermally conductive body (3), which has a greater thermal conductivity than the substrate, is introduced into the recess,
c) wherein the outer dimensions of the thermally conductive body are smaller than the inner dimensions of the recess, so that the thermally conductive body after insertion into the recess is spaced from the edge of the recess,
d) in which by a deformation of the thermally conductive body, a frictional connection (3A ', 3C', 3E ', 3G') is created between the body and the edge of the recess, by which the thermally conductive body is fixed in the recess,
e) in which for forming the thermally conductive body and generating the non-positive connection in ...

Description

The The invention relates to a method for producing at least one thermal bridge in a substrate.

at the production of electrical and electronic components is it common Practice to use individual electronic components on a substrate mount and in the desired electrical circuit by electrical connections with each other connect to. As materials for the substrate is predominant Plastics such as glass fiber reinforced Epoxy resins in the so-called printed circuit boards, however, less often, too Ceramics in use. In many applications, by the individual Electronic components not inconsiderable losses generated, leading to significant heating of the components and the Environment of the components on the substrate.

To the lead away from waste heat the electronic components on the substrate it is known that Substrate on the side facing away from the electronic components Substrate side on a metallic, in particular aluminum to solder existing heatsink. Around Heat from Components that have a high power dissipation density, ie produce a relatively high power loss in a small area, wegzutransportieren, so-called heat spreaders are known, the a good heat-conducting Material, such as copper, exist and usually one larger area than the associated Have component. The device is then placed on the heat spreader soldered and the heat spreader soldered to the mounted device on the substrate. Of the heat spreader Its name, therefore, is that it controls the heat flow from the hot component spreads to the substrate and thus a larger heat flow or improved Heat transport through heat conduction allows.

In the heat transport path from the semiconductor device to the heat sink are now several Thermal resistance, namely the Heat spreader, the substrate and the intermediate solder layers. It does that Substrate generally represents the proportionately largest thermal resistance. In some Applications used alumina ceramics has a comparatively high thermal conductivity or correspondingly a low thermal resistance. Nevertheless, this is enough thermal conductivity this ceramic is not sufficient to dissipate heat. If now a component with a higher one Power loss or heat generation is used, so you have to make larger, for example, the heat spreader. This in turn means that the lead wires from the device to adjacent electrical components or contacts must be chosen longer and thus also larger stray inductances in purchase must be taken. One more way to improve the heat dissipation consists in choosing a larger area for the electronic Component itself. However, this is extremely expensive.

to Improvement of the heat flow or the heat transport from the device to the heat sink it is now also known to incorporate thermal bridges in the substrate. This will be in a known embodiment punched a rectangular hole in a plastic circuit board and in this hole one in their outer dimensions chosen slightly larger, however in the contour exactly adapted to the inner dimensions of the hole, rectangular metal plate pressed in and flush with the substrate surface, on the electronic components are mounted, arranged. On the substrate with this pressed metal body are then while an assembly process the various electronic components applied, wherein thermally very critical components on the rectangular metal plate be applied. The continuous metal plate gets together with the substrate on the side facing away from the components underside soldered to the substrate with the heat sink. Thereby receives you have a good thermal conductivity Connection; from the device over the metal plate directly to the heat sink under training a thermal bridge and under bypass or Avoidance of high thermal resistance the circuit board.

This known method is based on the elastic property of the plastic circuit board material, when pressing the serving as a thermal bridge Metal plate gives way elastically and in turn through the elastic Restoring forces the metal plate holds along its entire circumference in the opening. The material distribution in the metal plate remains in the press-in process substantially unchanged.

DE 195 32 992 A1 discloses a method in which to be cooled thermal heavy duty electronic SMD components are connected on one side of a circuit board with a cooling plate made of aluminum or copper on the other side of the circuit board in each case by a Wärmeleitbrücke. In this known method, an inner bore is first drilled as a recess through the circuit board and the cooling plate and by an intermediate layer produced by bonding between the circuit board and the cooling plate. In this drilled recess is now introduced as a heat conduction bridge designed as a copper bolt metal body whose outer dimensions are initially smaller than the In NEN dimensions of the recess, so that the bolt can be easily used. Then the bolt is pressed together and compressed by means of two pressing rams from both sides, so that the compressed copper bolt is in intimate contact with the entire inner wall of the recess in the cooling plate and the printed circuit board and is frictionally fitted. In this case, a collar of the bolt is generated on the outside of the cooling plate. The component to be cooled is now connected to the copper stud on a free surface of the copper stud on the outside of the PCB.

At one off DE 42 20 966 C2 Known method, a circular cylindrical through hole is produced in a support plate below a component to be cooled as an integrated circuit and a heat sink consisting of copper, the undersize with respect to the through hole, inserted into the through hole with game. Now, by pressing from both sides in the axial direction, the heat sink widened or compressed by plastic deformation to the outside, so that there is a firm press fit of the heat sink in the through hole. The heat sink is cylindrical in one embodiment. Here, the axial axial compression of the heat sink, the entire outer surface of the heat mesenke is brought into frictional connection with the inner wall of the through hole. In another embodiment, the heat sink in a central region on a circumferential thickening, each with a transition-forming chamfers. During the axial compression of the heat sink, a circumferential interference fit of the heat sink in the through-bore, which fixes the heat sink extremely tightly, is now generated by the plastic deformation thereof, at least in the region of the thickening. In both versions according to DE 42 20 966 C2 the heat sink is fixed lot-free, fixed and precise parallel or flush to the support plate underside at high allowable Fertigungsstolexanzen of heat sink and through hole. After fixing the heat sink, the component to be cooled is thermally conductively bonded on one side and glued on the opposite side, the heat sink with serving as a heat sink metal part, which is part of the carrier plate receiving housing.

The US 5,014,904 A describes a method for dissipating heat from an electronic component on a printed circuit board. On the back of the circuit board, a cooling plate is arranged. A rectangular heat-conducting body is frictionally introduced into a corresponding rectangular opening in the printed circuit board by press-fitting or gluing and thermally connects the electronic component glued on one side to the cooling plate coupled on the other side.

In Applications where ceramic is used as substrate material Now, the problem is that such pressing a Metal plate or a metal bolt as in the described state the technology with plastic circuit boards is not possible. The brittle Ceramic substrate would namely at In many cases, such a press-fit process breaks or cracks.

Of the The invention is therefore based on the object, a method for Generating at least one thermal bridge in one Substrate, which also for brittle or brittle Substrate materials is suitable.

These Task is according to the invention solved with the features of claim 1.

• • Einbringen wenigstens eines wärmeleitenden (oder: wärmeleitfähigen) Körpers (oder: Inlays) mit einer größeren Wärmeleitfähigkeit (oder: einem kleineren Wärmewiderstand) als das Substrat (oder: das Substratmaterial) in wenigstens eine Aussparung in dem Substrat, wobei die Außenabmessungen des wärmeleitenden Körpers kleiner sind als die Innenabmessungen der Aussparung, so dass der eingebrachte wärmeleitende Körper von dem Rand der Aussparung beabstandet ist,
• • Umformen des in der Aussparung befindlichen oder gehaltenen wärmeleitenden Körpers zum Erzeugen einer kraftschlüssigen Verbindung zwischen dem Körper und dem Substrat am Rand der Aussparung, wodurch der wärmeleitende Körper in der Aussparung fixiert (oder: verankert) wird,
• • wobei bei dem Umformen des wärmeleitfähigen Körpers und der Erzeugung der kraftschlüssigen Verbindung in wenigstens zwei als Kontaktbereiche dienenden Randbereichen, die voneinander durch einen weiter vom Rand der Aussparung als diese Randbereiche entfernten Zwischenbereich getrennt sind, jeweils wenigstens eine Ausnehmung in dem wärmeleitfähigen Körper erzeugt wird und dadurch das Material im wärmeleitfähigen Körper zum Rand der Aussparung hin gezielt so fließt, dass nur die Randbereiche, nicht jedoch der dazwischen liegende Zwischenbereich des wärmeleitfähigen Körpers mit dem Substrat eine kraftschlüssige Verbindung eingehen.

The method according to claim 1 for generating at least one thermal bridge in a substrate (or a carrier) for dissipating heat on the substrate mountable or mounted heat sources, in particular heat loss of electronic components, comprising the method steps:

• Introducing at least one heat-conducting (or: heat-conducting) body (or: inlay) with a greater thermal conductivity (or a smaller thermal resistance) than the substrate (or substrate material) into at least one recess in the substrate, the outer dimensions of the heat-conducting body are smaller than the inner dimensions of the recess, so that the introduced heat-conducting body is spaced from the edge of the recess,
• Reshaping the thermally conductive body located in the recess to create a frictional connection between the body and the substrate at the edge of the recess, thereby fixing (or anchoring) the thermally conductive body in the recess,
• Wherein in the forming of the thermally conductive body and the generation of the frictional connection in at least two serving as contact areas edge regions which are separated from each other by a further from the edge of the recess than these edge regions intermediate region, at least one recess in the thermally conductive body is generated and As a result, the material in the thermally conductive body specifically flows toward the edge of the recess such that only the edge regions, but not the intervening intermediate region of the thermally conductive body, form a frictional connection with the substrate.

In this case, the invention is based on the first step in the idea of making the heat-conducting body provided as a thermal bridge smaller than the associated recess in the substrate, so that the heat-conducting body with clearance or distance in the recess in the substrate can be introduced without exerting a force on the wall of the recess.

The The invention is further based on the second step of thinking, according to which Introducing the heat-conducting body in the recess of the substrate now by forming the heat-conducting Body one frictional Connection between the heat-conducting body and to produce the substrate on the inner wall of the recess. There the thermally conductive body while this deformation is held in the recess, for example by resting on a support or tool, do not become additional during forming forces: or force components perpendicular to the substrate surfaces or generated parallel to the inner wall of the recess, but essentially only forces, which are directed orthogonal to the inner wall of the recess. Thereby Overall, the force on the substrate is reduced and reduces the risk of cracking or breakage in the substrate.

According to one third step of the invention, the transformation of the thermally conductive body through Generating at least one recess or taper in the body in Edge areas facing away from each other by a farther from the edge of the recess as these peripheral areas are separated intermediate area. As a result, flows Material in the heat-conductive body for Edge of the recess and finally affords the adhesion the edge of the recess, with the material distributed so targeted or so, that only the edges serving as contact areas, but not the intervening intermediate area frictionally with the substrate forms a connection.

Thereby can the non-positive Connection to these separate areas remain limited and the danger one too big Force on the substrate are kept low.

advantageous Embodiment and developments of the method according to the invention emerge from the dependent of claim 1 claims.

Preferably be from or on two opposite sides or surfaces in the thermally conductive body recesses in opposite directions Generated areas to generate the frictional connection. This allows one uniform material flow in the body from the rejuvenation generated between the recesses to the outside.

The Method is particularly advantageous in cases where the substrate from a fragile one or brittle Material or a ceramic, because of the lower force on the substrate as in the prior art.

The Shape of the recesses) in the substrate or the thermally conductive body can basically in wide limits are varied.

preferred Shapes for the recesses) in the substrate are versions with at least two at least partially mutually parallel side walls (or: inner walls). The side walls can be at least partially rectilinear or even (or: flat) and / or at least partially convexly curved run.

Especially can each or at least one recess with at least two parallel to each other, preferably rectilinear or even, extending side walls and with two other parallel to each other, preferably rectilinear, extending side walls and with four each two side walls be interconnected Eckwandungen be or become.

Around the risk of cracking in the substrate from the corners the recess is preferably an edge or Corner with two at an angle directly abutting side walls avoided.

To are or in a first variant, the Eckwandungen preferably convexly curved trained and / or go essentially continuously differentiable or smooth in the adjacent, in particular rectilinear or even, Sidewalls over. The transition is so continuous or continuous and the side walls as well the corner walls meet with equal slope (or: tangent).

In In a second variant, the corner walls of the Side walls to the outside outstanding - similar to one Bridgehead - and preferably convexly curved educated.

When Particularly advantageous, an embodiment has been found in which no separate Eckwandungen more are formed or but each two sidewalls directly merge into each other. In each case two side walls are then preferably convexly curved and the intermediate two side walls preferably flat or straight. The transition between two side walls is expedient again continuously differentiable.

The convex curvature of the corner areas or side walls of the recesses) corresponds to special essentially that of a circle or cylinder surface. Preferred is a semicircular or semi-cylindrical shape of the Eckwandungen or side walls.

It is now in a preferred development at least two opposite Side walls of the recess facing edge regions of the thermally conductive body respectively at least in a portion of the body, a material displacement or rejuvenation for generating a frictional connection with the associated side wall of the recess generated.

Further in particular has at least one thermally conductive body in two opposite, opposite each other Side walls of the recess facing edge regions, respectively at least two by a tapered intermediate area separate contact areas, which are used to generate the Frictionally caulked or provided with a rejuvenation or in which the material displacement is made.

In a production-technically efficient variant of the method with a caulking or pressing tool both or all contact areas one of a side wall facing edge region of the thermally conductive body at the same time caulked or reshaped.

At the Calking can in particular each one, in particular V-shaped groove on the opposite surfaces of the thermally conductive body in opposite Areas are generated.

Preferably becomes the thermally conductive body in the Generating the frictional connection is positioned and designed that the at least one substrate surface, the electronic Components assembled or equippable is, with a surface of the thermally conductive body in Substantially flush, preferably even after forming.

In a further development of the method is now on a surface of the thermally conductive body after its non-positive Connection in the recess of the substrate an electronic component and / or a heat spreader with at least one on the heat spreader arranged applied electronic component, in particular soldered. The Connection force of the non-positive connection of the thermally conductive body in The recess is preferably sufficiently large, so that when applying the electronic component or the heat spreader and the at least one electronic component on the surface of the thermally conductive body acting Force compensated by the connection force of the non-positive connection becomes.

Farther is in a development of the procedure the additional Process step provided that the substrate with the or in the recess (s)) frictionally fixed thermally conductive body (s) and preferably with the applied on the thermally conductive body electronic component or heat spreader with an electronic component applied thereto, on a thermally conductive, preferably metallic, heat sink, the a greater thermal conductivity as the substrate, applied, preferably soldered, is.

The at least one recess in the substrate can be considered to be to one side open cutout or preferably formed as a closed opening or be and / or produced by means of laser cutting.

The thermal conductivity the thermally conductive body is generally at least a factor of 2, preferably one Factor 3, greater than selected the thermal conductivity of the substrate material, at least in the direction of the heat flow. One preferred material for the thermally conductive body is Copper or a copper alloy.

Of the Distance of the thermally conductive body of The recess is generally dependent on the deformation of a desired Connecting force of non-positive Connection between body and substrate adapted. For example, in manufacturing different provided large thermally conductive body be to tolerances occurring at different lots of substrates in the recesses to compensate.

The Procedure may be in all embodiments also as a method for producing a substrate, in particular for electronic Components are called.

The The invention will be further explained below with reference to exemplary embodiments. there is referred to the drawing. Show it:

1 a substrate for electronic components having a substantially rectangular recess with rounded corners and a thermally conductive body which can be inserted into the recess as a thermal bridge in a plan view from above,

2 a substrate for electronic components with a substantially rectangular recess with bridgehead-like protruding bulges,

3 a substrate for electronic components with a substantially oval recess,

4 a longitudinal section through 3 in the section plane designated VV with the thermally conductive body not yet inserted,

5 a longitudinal section along with VV in 3 designated cutting plane through the substrate with already inserted into the recess thermally conductive body,

6 a cross section along in 3 with VII-VII designated cutting plane with not yet inserted into the recess thermally conductive body,

7 a longitudinal section through the substrate with the inserted into the recess thermally conductive body along the designated VII-VII cutting plane in 3 .

8th the substrate with inserted thermally conductive body in cross section according to 7 with two caulking tools on both sides of the thermally conductive body,

9 a cross-section through the substrate and thermally conductive body after caulking the thermally conductive body by the caulking,

10 a plan view of the substrate with caulked thermally conductive body according to 9 and 3 .

11 the substrate with the caulked thermally conductive body in the cross section according to 9 with electronic components placed on the substrate and the thermally conductive body,

12 the substrate and the thermally conductive body with electronic components according to 11 on a heat sink in cross section,

13 a square one. Recess with round corners and a thermally conductive body fixed to the sides of the square,

14 a square recess with round corners and a thermally conductive body fixed in the corners, matching parts and sizes are in the 1 to 14 provided with the same reference numerals.

The 1 to three each show in a plan view a part or section of a substrate 2 from a ceramic, in particular an aluminum oxide ceramic. The top surface or top of the substrate 2 is with 20 designated. In the substrate 2 is now each a recess (or: opening, hole) 4 generated, for example by a punching process or laser cutting. The recesses 4 in the 1 to 3 each have different shape or shape. The in the 1 to 3 selected contours or Umris se of the recess 4 in the substrate 2 Starting from the consideration, starting from a rectangular basic form - which would of course also be possible - the recess 4 make the corners of the rectangle rounder or completely obliterated. In fact, it has been found that, when the side walls are merged in one edge or corner, fine cracks can form at these corners due to the thermal and mechanical stress in the ceramic material, in particular due to the different thermal expansions in the ceramic of the substrate 2 and the metal, in particular aluminum, of the heat sink 16 ,

In the 1 to 3 are four side walls of the recess 4 With 4A . 4B . 4C and 4D designated. In the 1 and 2 form the side walls 4A . 4B . 4C and 4D Parts of a rectangle or inside hollow cuboid and are by corner areas 4F between the side walls 4A and 4B . 4G between the side walls 4B and 4C . 4H between the side walls 4C and 4D and 4E between the side walls 4D and 4A connected with each other. The corner areas 4E . 4F . 4G and 4H are now rounded or related to the recess 4 outwardly convex curved. This is where the corner areas go 4E to 4H in the respective adjacent side walls 4D and 4A respectively. 4A and 4B respectively. 4B and 4C respectively. 4C and 4D each smooth or continuously differentiable over. This means that the transition is continuous or continuous and the same slope or tangent to the contour is achieved from both directions at the transition point. The curvature is the same in the transition area or transition point. Through this smooth transition between the corners 4E to 4H and the side walls 4A to 4D Tensions are within the substrate 2 evenly distributed and the risk of cracking is reduced.

2 shows another way to reduce cracking in the substrate 2 in which the corner areas are outwardly bulged and form convex curved bays or bulges. In the example of 2 are the transitions between the corner areas 4E to 4H and the side walls 4A to 4D not continuously differentiable, but only continuous and have peaks or edges. Here, in an embodiment, not shown, by a change in the curvature of Eckberei surface 4E to 4H to the side walls 4A to 4D towards a continuously differentiable transition can be achieved.

In 3 are now on the lateral sides of the recess 4 lying side walls 4B and 4D not like in 1 and 2 formed rectilinear and parallel to each other, but each convex curved or rounded. There are missing in 3 So separate corner areas between the side walls 4A to 4D , Rather, the straight side walls go 4A and 4C immediately and in a continuously differentiable transition into the convexly curved side walls 4B and 4D above. The radius of curvature of the curved side walls 4B and 4D is in particular constant, corresponding to a circular or cylindrical, in particular semicircular or semi-cylindrical (180 °), course.

A longitudinal extent or length of the recess 4 is in 1 to 3 A denotes a width or transverse dimension measured transversely thereto with B, the width B being the distance between the side walls 4A and 4C corresponds to and the length A is the maximum distance between the side walls 4B and 4D ,

In the recess 4 of the substrate 2 is now a thermally conductive body 3 can be used or used according to 1 to 3 smaller dimensions than the recess 4 has and thus used loose or with play in the recess or used. The body 3 has in the embodiments according to 1 to 3 a dumbbell-like or peanut-like shape on with two seen in its longitudinal direction at the ends widening areas and a taper in the middle. The transverse walls formed at the widened areas are with 3D and 3H referred to, on the longitudinal sides are each two outwardly projecting contact areas 3A and 3C such as 3E and 3G formed, each by an inwardly projecting intermediate area 3B respectively. 3F are separated from each other. In the area of intermediate areas 3B and 3F is the rejuvenation of the body 3 intended. In the area of contact areas 3A . 3C . 3E and 3G as well as the transverse wall 3D and 3H is the thermally conductive body 3 in the embodiment of 1 to 3 convexly curved. However, the contour or external shape of the body 3 also deviate from such a shape, in particular not be curved convex.

One in a longitudinal direction of the body 3 measured longitudinal extent or length of the body 3 with L, a maximum extent measured perpendicularly between the contact areas 3G or 3C and 3E or width of the body 3 is denoted by D.

At one of all side walls 4A . 4B . 4C and 4D the recess 4 spaced position of the body 3 in the recess 4 , as in 1 to 3 shown, the distance is in the longitudinal direction between one of the side walls 4B facing transverse wall 3D of the body 3 With 12 and one of the side walls 4D facing transverse wall 3H of the body 3 With 11 designated. The body 3 is in its longitudinal direction along the longitudinal direction of the recess 4 aligned. In its transverse direction are the distance of the contact areas 3A and 3C from the side wall 4A with d1 and the distance of the contact areas 3E and 3G from the side wall 4C drawn with d2. It is essentially true that the sum of d1, D and d2 is equal to the width B, that is to say B = d1 + D + d2, and correspondingly A = 11 + L + 12. These dimensions apply in 1 to 3 shown initial state in the recess 4 used, but not yet deformed thermally conductive body 3 ,

According to 4 and 6 becomes the body 3 in a further method step along the arrow shown in the recess 4 in the substrate 2 introduced or used.

The 5 and 7 show him in the recess 4 inserted body 3 , due to the distance of the body 3 to the inner wall of the recess 4 the body 3 of course from the recess 4 would fall out without a bracket or lock or fixation. Such a fixation is in 5 and 7 not shown.

The perpendicular to the surfaces 30 and 31 of the body 3 measured thickness is denoted by T, which is perpendicular to the surfaces 20 and 21 measured depth of the recess 4 that is the thickness of the substrate 2 corresponds, is denoted by C. Preferably, the dimensions C and T are substantially equal to a flush finish of the surfaces 30 and 20 such as 31 and 21 of body 3 and substrate 2 in the inserted state of the body 3 to enable.

The thermally conductive body 3 is provided as a thermal bridge for bridging or thermal shorting of the substrate 2 to heat or waste heat from one on the surface 30 of the body 3 to be mounted electronic component down through the substrate 2 through to an in 4 to 7 Not yet shown heat sink, on the lower surface 21 of the substrate 2 and accordingly on the lower surface 31 of the body 3 is arranged in heat-conducting contact. The body 3 consists of a highly thermally conductive or thermally conductive and at the same time ductile material such as copper or a copper alloy or another metal. However, the surfaces 30 and 20 such as 31 and 21 It is necessary to align the body exactly 3 before mounting the substrate 2 on the heat sink as well as before the application of electronic components to the sub strat 2 to fix.

This is done in an in 8th shown forming step, in the recess 4 of the substrate 2 held thermally conductive body 3 by means of a forming tool or Stemmwerkzeuges 40 on the surface 30 and on the side of the surface 31 with another caulking tool 41 reshaped. Each of the caulking tools 40 and 41 has two Stemmdornen or Stemmkanten 45 and 46 respectively. 47 and 48 on that in the surface 30 respectively. 31 of the body 3 be bored or crushed and in the body 3 in the 9 and 10 shown grooves or depressions 5 and 6 such as 7 and 8th produce. When stemming the Stemmhub and preferably also the Stemm force can be controlled or regulated. Preferably, the substrate becomes 2 with the thermally conductive body 3 for support on the lower caulking tool 41 put on and then the upper prying tool 40 supplied in the direction indicated by the arrow.

The deformed body is now with 3 ' and its surface with the depressions 5 and 6 With 30 ' and its surface with the Vertie tests 7 and 8th With 31 ' , By creating the grooves or depressions 5 and 6 such as 7 and 8th preferably at opposite locations by appropriate formation of the forming mandrels 45 and 46 respectively. 47 and 48 and the spacing occurs, arise in the body 3 ' Tapering, which leads to a material flow or a material displacement to the outside to the inner wall of the recess 4 of the substrate 2 to lead. The depth and geometry of the wells 5 . 6 . 7 and 8th are now chosen so that the flow of material is strong enough to be in traction areas 10 and 11 the deformed contact areas 3A ' and 3C ' to the side wall 4A as well as in traction areas 12 and 13 the transformed contact areas 3E ' and 3G ' a non-positive connection between the materials of the body 3 ' and the material of the substrate 2 on the inside of the recess 4 to create.

As in 10 To recognize, the groove or depression overlaps 5 and 6 with the respective taper or the intermediate areas arranged on this side 3B ' and 3F ' , The material displacement is thus lower in this region of the taper, so that a material flow is reduced to the outside and a non-positive connection in these intermediate areas 3B ' and 3F ' with the inner wall of the recess 4 safely avoided. So there are specifically separate traction areas 10 . 11 . 12 and 13 between the body 3 in its contact areas 3A ' . 3C ' . 3E ' and 3G ' generated after deformation or deformation, based on the total circumference of the body 3 as well as the recess 4 have relatively small contact surfaces. These non-positive connections in the traction areas 10 . 11 . 12 and 13 However, the body is enough 3 tight enough in the recess 4 anchor to the position of the body 3 relative to the substrate 2 to fix in the further process sequences.

In a first of the further process steps is now on the upper surface 20 of the substrate 2 and the surface 30 ' in the substrate 2 held thermally conductive body 3 ' a common layer of solder paste is applied and the substrate 2 with the anchored body 3 ' is printed or equipped with electronic components and electrical connections between the components.

An example of such a finished electronic components-equipped substrate 2 with body 3 ' is in 11 shown. For example, several are on the substrate surface 20 soldered electronic components 26 as well as contact surfaces or conductor tracks 27 shown. On the parallel to the surface 20 of the substrate 2 running surface 30 ' of the body 3 ' is now over a solder layer 24 a heat spreader 14 and on the heat spreader over another solder layer 25 an electronic component, in particular a transistor, 15 applied. The heat spreader 14 consists of a good thermal conductivity material, preferably copper. The electronic component 15 is a semiconductor device such as a bipolar transistor or a field effect transistor (FET, MESFET, MOSFET), in particular based on silicon (Si) or gallium arsenide (GaAs). As a solder for the solder layer 25 between the transistor 25 and the heat spreader 14 For example, a gold (Au) tin (Sn) alloy may be used, as well as the solder layer 24 between the heat spreader 14 and the body 3 ' ,

In a next process step, the finished assembled arrangement of substrate is now 2 and body 3 ' on a heat sink 16 , as in 12 shown, applied, in particular soldered. This is a solder paste on the bottom 21 of the substrate 2 as well as the lower surface 31 ' of the body 3 ' applied and fused by heating in an oven, so that between the heat sink 16 and the substrate 2 as well as the body 3 ' a continuous layer of solder 28 arises, which is the substrate 2 and the body 3 ' with the heat sink 16 each firmly connects. About the solder layer 28 is also a thermally conductive connection between the thermally conductive body 3 ' and the heat sink 16 produced. As material for the solder layer 28 For example, a lead (Pb) tin (Sn) alloy can be used. In particular, if the heat sink 16 has a smaller surface area than the substrate 2 , usually becomes the heat sink 16 instead of the substrate 2 precoated with the solder paste.

The bottom 31 ' the thermally conductive body 3 ' In particular, it may be provided with a coating, for example a coating of gold or a gold-silver alloy, for better wetting with the solder of the solder layer 28 when applied to the heat sink 16 to reach. Likewise, the existing aluminum heat sink 16 be coated on its upper side with a coating, in particular of nickel, for better wetting with the solder or preferably be pre-coated with the solder paste layer in order to avoid the problems of oxidation of nickel. It is important, between the body 3 ' and the heat sink 16 preferably no. To have air or gas inclusions in order to ensure a homogeneous and flat heat conduction between the body 3 ' and the heat sink 16 through the solder layer 28 to enable.

The heat flow from the transistor 15 as a heat source through the solder layer 25 , the heat spreader 14 , the solder layer 24 , the thermal bridge serving body 3 ' and the solder layer 28 in the heat sink 16 is denoted by W and illustrated with dashed lines and arrows. Through the parallel to the surface 20 of the substrate 2 seen larger surface of the heat spreader 14 as well as the body 3 ' in relation to the transistor 15 the heat flow W is spread or fanned out and it is possible to dissipate a greater power loss (or amount of heat or heat energy per unit time) per unit area.

Preferably, several bodies can be used for mass production 3 or heat spreaders 14 be broken out of a prefabricated leadframe or punched out. In addition, multiple substrates may be populated in parallel on a raw substrate in one step and then separated or singulated by breaking or otherwise separating.

The ready assembled Substrate is preferably for a cable amplifier or CATV amplifier used, but can also be used in other applications.

The 13 and 14 show further execution options and geometries of the recess 4 in the substrate 2 and the corresponding body 3 in the recess 4 is fixed by adhesion and serves as a thermal bridge.

In the embodiment according to 13 is the recess 4 formed substantially square, so has side walls 4A to 4D essentially the same side length, which again, similar to in 1 , over rounded corner areas 4E to 4H connected to each other. The body 3 is now also equipped in its shape with a corresponding rotational symmetry or Drehzähligkeit and points in 13 as well as in 14 a substantially circular shape with a substantially circular base and four offset by 90 ° to each other outwardly projecting contact areas 3I . 3J . 3K and 3L ,

In the embodiment according to 13 becomes the body 3 now in the recess 4 arranged that the outwardly projecting contact areas 3I to 3L opposite the rectilinear side walls 4A to 4D come to rest and be connected after forming force-fit with these.

According to 14 on the other hand, the contact areas are provided 3I to 3L in the corner areas 4E to 4H the recess frictionally secure by forming or caulking. Basically, although caulking in the rectilinear Seitenwandungsbereichen is preferable, but how 14 shows, in principle, a caulking in the corners possible.

2

substratum

3

body

3 '

reshaped body

3A, 3C, 3E, 3G

contact area

3A ', 3C', 3E '3G'

deformed contact area

3B, 3F

intermediate area

3B ', 3F'

intermediate area

3D, 3H

transverse wall

3I, 3J, 3K, 3L

contact area

4

recess

4A, 4B, 4C, 4D

sidewall

4E, 4F, 4G, 4H

corner

5,6,7,8

groove

10,11,12,13

Adhesion area

14

heat spreader

15

transistor

16

heatsink

20,21,30,31

surface

30 ', 31'

surface

24.25

solder layer

26

electronic component

27

contact area

28

solder layer

40.41

forming tool

45,46,47,48

Stemmdorn

A

length

B

width

C

depth

D

width of the body

L

Length of the body

T

thickness

W

heat flow

Claims (32)

Method for producing at least one thermal bridge in a substrate for dissipating heat from heat sources that can be mounted or mounted on the substrate, in particular heat loss from electronic components, a) in which in the substrate ( 2 ) at least one recess ( 4 ) is generated, b) in which at least one thermally conductive body ( 3 c) wherein the outer dimensions of the thermally conductive body are smaller than the inner dimensions of the recess, so that the thermally conductive body after insertion into the recess from the edge of the recess spaced d) in which by a deformation of the thermally conductive body, a frictional connection ( 3A ' . 3C ' . 3E ' . 3G ' ) is generated between the body and the edge of the recess, by which the thermally conductive body is fixed in the recess, e) in which for forming the thermally conductive body and generating the frictional connection in the thermally conductive body in at least two serving as contact areas edge regions ( 3A . 3C . 3E . 3G ) separated from each other by an intermediate area farther from the edge of the recess than these edge areas ( 3B . 3F ) are separated, in each case at least one recess ( 5 . 6 . 7 . 8th ) is generated and f) thereby the material in the thermally conductive body to the edge of the recess towards specifically flows so that only the edge regions, but not the intervening intermediate region of the heat-conductive body with the substrate form a frictional connection. The method of claim 1, wherein from or to two facing away from each other in the thermally conductive body recesses in opposite Areas are generated to generate the frictional connection. A method according to claim 1 or claim 2, wherein the substrate from a brittle or brittle Material exists. The method of claim 3, wherein the substrate comprises a ceramic exists. Method according to one or more of the preceding Claims, wherein the at least one recess in the substrate is at least two Sidewalls is or will be generated. The method of claim 5, wherein the at least two side walls of the recess at least partially to each other parallel, preferably straight, run. A method according to claim 5 or claim 6, wherein at least one and preferably at least two side walls the at least one recess extends at least partially convexly curved or run. The method of claim 7, wherein at least one and preferably at least two side walls of the recess at least partially circular or cylindrical, in particular semicircular or semi-cylindrical, extends or run. Method according to one or more of claims 5 to 8, wherein the at least one recess with at least two parallel to each other, preferably rectilinear, extending side walls and at least two further parallel to each other, preferably straight, running sidewalls is or is generated. Method according to one or more of claims 5 to 9, in which the at least one recess, each with two side walls interconnecting corner walls is or is generated. A method according to claim 10, wherein the corner walls convexly curved, in particular circular or cylindrical, are formed or become. The method of claim 10 or claim 11, wherein the corner walls projecting outwardly from the side walls are trained or become. Method according to one or more of claims 10 to 12, in which the Eckwandungen continuously differentiable or smooth in go over the adjacent side walls. Method according to one or more of claims 6 to 13, wherein at least two side walls of the at least one Recess directly into each other, preferably continuously differentiable or smooth, pass over. Method according to one or more of claims 5 to 14, in which lying between two convex curved side walls Side walls are straight or just created or are. Method according to one or more of the preceding claims, in which at least on two opposite side walls of the recess facing edge regions of the thermally conductive body in each case at least in a partial region of the body a recess for generating a frictional connection with the associated Side wall of the recess is generated. Method according to one or more of the preceding Claims, wherein the at least one thermally conductive body in two opposite, opposite side walls the recess facing edge regions in each case at least two through a rejuvenated Intermediate area has separate contact areas, to generate the frictional connection each with a recess be provided. Method according to one or more of the preceding Claims, in which with a caulking or pressing tool both or all contact areas one of a side wall of the recess facing edge region the thermally conductive body at the same time be caulked. Method according to one or more of the preceding Claims, in which during forming or caulking in each case one, in particular V-shaped, groove as a recess on the opposite surfaces of the thermally conductive body in opposite Areas is generated. Method according to one or more of the preceding Claims, in which the thermally conductive body in Generating the frictional connection is positioned and trained is that at least one surface of the thermally conductive body with at least one substrate surface of the substrate flush runs. A method according to claim 20, wherein a surface of the thermally conductive body with a substrate surface, that of a populated with electronic components or equippable substrate surface turned away, flush runs. The method of claim 20 or claim 21, wherein a surface of the thermally conductive body with one equipped with electronic components or equipable substrate surface flush runs. Method according to one or more of the preceding Claims, with that on a surface the heat-conducting body after its non-positive Connection in the recess of the substrate an electronic component and / or a heat spreader or heat conductor with at least one on the heat spreader or heat conductor arranged electronic component is applied. The method of claim 23, wherein the connection force the non-positive Connection of the thermally conductive body in the recess is at least so large that the at Applying the electronic component or the heat spreader or heat conductor on the surface of the thermally conductive body acting Force compensated by the connection force of the non-positive connection becomes. Method according to one or more of the preceding Claims, wherein the substrate with the at least one in the recess force fit fixed thermally conductive body and preferably with the on the heat-conducting Body upset electronic component or heat spreader or heat conductor with an electronic component applied thereto, on a thermally conductive, preferably metallic, heat sink, the a greater thermal conductivity as the substrate, applied, preferably soldered, is. A method according to claim 25, wherein a surface to be soldered of thermally conductive body and / or the heat sink and / or the heat spreader and / or heat conductor provided with a coating promoting the wetting by the liquid solder coating is or will, preferably a gold or nickel-containing coating. Method according to one or more of the preceding Claims, in which the at least one recess in the substrate is designed as a closed opening is or is. Method according to one or more of the preceding Claims, in which the at least one cutout in the substrate is produced by means of laser cutting becomes. Method according to one or more of the preceding Claims, where the thermal conductivity the thermally conductive body at least by a factor of 2, in particular a factor of 3, and preferably a factor of 10 is greater as the thermal conductivity of the substrate material. Method according to one or more of the preceding Claims, in which the thermally conductive body made Copper or a copper alloy. Method according to one or more of the preceding Claims, in which more of the thermally conductive body made be punched or broken out of a prefabricated leadframe or are. Method according to one or more of the preceding claims, wherein the forming force or the forming energy or the Stemmhub a Stemmwerkzeugs when forming the heat is controlled or regulated conductive body.