WO2013135791A1

WO2013135791A1 - Method, device, and system for a power circuit

Info

Publication number: WO2013135791A1
Application number: PCT/EP2013/055189
Authority: WO
Inventors: Tobias Steckermeier; Roland Brey
Original assignee: Continental Automotive Gmbh
Priority date: 2012-03-16
Filing date: 2013-03-14
Publication date: 2013-09-19
Also published as: DE102012204133A1

Abstract

A method for producing an electronic power circuit comprises the steps of placing a first electronic component on the surface of a substrate material, placing a bus bar on the surface of the substrate material, placing a second electronic component on the surface of the bus bar, and heating the assembly in order to solder the assembly together. The invention further relates to the bus bar and a system of bus bars for the method.

Description

description

Method, device and system for a power circuit The invention relates to an electronic power circuit. In particular, the invention relates to a method of manufacturing an electronic power circuit, a power rail for the electronic power circuit, and a system of multiple power rails for the power circuit.

An electronic power circuit includes a circuit board or other substrate and an electronic device exposed to currents of such high power that it heats up during operation. The power circuit therefore further comprises a sufficiently sized busbar, on the one hand to ensure an electrical connection to the electronic component, and on the other hand dissipate accumulating heat. There are different proposals to attach the substrate, the busbar and the electronic component together. In a first variant, the busbar is wholly or partially within the carrier material. For this purpose, a recess must be introduced into the carrier material, which corresponds exactly to the dimensions of the busbar. In the region of the recess, other elements, in particular an electrical connection running within the carrier material, can not be carried out. Adjacent busbars must maintain a predetermined minimum distance so that remaining structures of the carrier material survive the production process without damage. At the same time, the bus bar must not be too thin, so that a sufficient side surface is available for connection to the carrier material. In some variants, the busbar must be glued to the substrate, which can require a considerable manufacturing effort. Often need to after the gluing excess adhesive residues are removed, which can contribute to further increased manufacturing costs.

In another variant, the bus bar is glued to an upper or lower surface of the carrier material or fastened by means of a pin or a rivet. If the busbar is located with respect to the carrier material on the opposite side of the electronic component, an additional element, such as the rivet, must be used for the electrical and thermal connection of the electronic component. If the busbar lies between the carrier material and the electronic component, an automatic assembly by means of a surface placement machine can be impeded by the additional height of the busbar. In addition, the vertical elements of this variant can lead to mechanical difficulties in further processing.

It is therefore an object of the present invention to provide an approach which at least partially reduces the disadvantages mentioned.

The claimed in the claims objects solve this problem. It is therefore disclosed a method, a bus bar and a system of bus bars, in particular with the features of the independent claims. The subclaims give preferred embodiments again.

In order to achieve the stated object, in particular a method for the simplified production of an electronic power circuit with a busbar is disclosed. Furthermore, a suitable busbar and a system of such busbars is disclosed.

A method for producing an electronic power circuit described here comprises steps of placing a first electronic component on the surface a substrate, placing a bus bar on the surface of the substrate, placing a second electronic device on the surface of the bus bar, and heating that array to solder the electronic components, the bus bar, and the substrate together.

In this way, the bus bar can be treated as an electrical component that is placed on the surface of the carrier material when the circuit is assembled. The assembly, for example by means of a placement machine, can thereby be substantially simplified. Due to the simplified assembly can a

Positioning accuracy of the busbar on the substrate to be increased. In particular, the first electronic component and the busbar can find in the same plane contact with the surface of the carrier material, which can simplify the assembly.

In addition, multiple bus bars can be mounted close to each other on the surface of the substrate. The thickness or vertical height of the busbar can be chosen flexibly. The thickness of the carrier material can be varied or maintained independently of this. A number of critical dimensions of the bus bar and substrate can be reduced. A tolerance chain between the busbar and the first electronic component can be improved, since both elements are installed by means of the same process on the carrier material. An electrical and thermal connection between the second electronic component and the busbar can be improved, since no additional element such as a cutout, a microvia, a rivet or a pin for the electrical and mechanical connection of the second electronic component to the busbar is required. Furthermore, it is advantageous according to the described method that the surface of the carrier material can be flat before placement, whereby a preparation of the carrier material, for example by attaching soft solder at planned contact points between the carrier material and the busbar or the carrier material and the first electronic component, can be relieved. By soldering the bus bar to the substrate, an electrical (and mechanical) connection between the two elements can be made automatically. An additional connecting element, such as a rivet or a vertical pin, are not needed. Manually executed steps can be dispensed with as far as possible, so that the method is particularly suitable for automated industrial mass production.

In a preferred embodiment, solder is applied in the form of solder paste on the substrate before it is placed on the first electronic component or the busbar. In particular, the solder paste can be printed in one operation on the flat surface of the substrate, for example in screen printing technique.

For the connection of the second electronic component to the surface of the busbar, a molded part made of soft solder can be attached to the busbar before the second electronic component is placed on it. In one embodiment, the molding is attached to the bus bar before it is placed on the substrate.

In another embodiment, an adhesive is applied between the bus bar and the carrier material prior to heating. In particular, the adhesive may be attached to the bus bar or substrate before the bus bar itself is placed on the substrate. The adhesive, for example in the form of one or two adhesives points, can serve to fix the busbar until the busbar is soldered to the substrate.

A bus bar for connecting an electronic component to a substrate described herein comprises a bottom surface having a planar portion for surface mounting the bus bar to the substrate and a top surface having a planar portion for surface mounting an electronic component to the bus bar. In particular, the lower and upper surfaces are provided on opposite sides of the bus bar.

Preferably, the dimensions of the busbar are sufficiently small to allow the busbar to be fitted to the carrier material by means of a placement machine for

To enable surface mount components. For automated assembly, a plurality of bus bars can be provided on a corresponding tray In a particularly preferred embodiment, a recess for receiving a depot of soft solder is arranged in the upper surface of the bus bar Depot may be provided by a preformed piece of soft solder ("preform"). The assembly of the second electronic component as a last operation before soldering the electronic power circuit can be facilitated. An inventive system of multiple busbars for

Connection of an electronic component to a carrier material comprises a first and a second of the busbars described above, wherein the first busbar has a lateral projection and the second busbar has a corresponding lateral recess, so that the busbars are directly adjacent to each other while engaging the projection in the recess can be arranged NEN. The recess and the projection are in particular complementary to each other.

By juxtaposing a plurality of first and second busbars so different busbars can be assembled. A number of different parts in the electronic power circuit can thereby be reduced, which can result in cost advantages in the production.

In a preferred embodiment, the first and second bus bars have cross sections which are derived from a common basic shape. The basic shape may in particular comprise a rectangle or a square. The first and second busbars can be on the one or more sides of each other in the manner of puzzle pieces can be applied to each other, in particular to limit each other gapless.

As electronic components components are referred to, which are used to implement an electronic circuit. The components themselves are electrical or electronic circuit components, for example semiconductor components, capacitors, inductors, lines or connection contacts. Preferably, at least one of the components, in particular the method, the busbar or the system, a power component, in particular a power semiconductor device. Power components are preferably placed on the power rail or power components are preferably placed on the power rail. In particular, the second component is a power component, preferably a semiconductor component. At least one of the components, at least one of the components, which has its own housing, and in particular the at least one power component is preferably a surface-mounted device or an SMT component. The power device is set up, a Current of preferably at least 1 A, 5 A, 10 A, or 20 A to lead or switch.

According to a further aspect, at least one of the components is a switch, in particular an electronic switch. Furthermore, at least one of the components and in particular the second component may be a MOSFET, an IGBT, a thyristor, a TRIAC, a transistor or a diode or comprise at least one of these semiconductor components. Furthermore, provision can be made for a power component to be connected via a bus bar according to the invention to a line or to a connection contact which is designed for power applications and designed in particular for carrying currents of at least 1 A, 5 A, 10 A or 20 A. is.

In addition, at least one of the components may be an integrated circuit, in particular a microcontroller, a drive circuit, a processor or a driver circuit, which is set up for outputting control signals to a power component. Such control signals are provided with currents of preferably less than 1 A, less than 100 mA or less than 10 mA. The components are adapted to the current to be conducted, switched or controlled, in particular by means of line cusps. The first component is preferably an integrated circuit, in particular a microcontroller, a drive circuit, a processor or a driver circuit, or discrete or a passive or active device configured for currents not greater than 1 A, 100 mA or 10 mA.

The components comprise at least one passive and / or at least one active circuit component or component. The components comprise at least one discrete and / or at least one integrated circuit component.

The invention will now be described in more detail with reference to the attached figures. Showing: Figure 1 is an electronic power circuit;

Figure 2 shows a method for producing the electronic

Power circuit of Figure 1;

FIG. 3 shows a modular bus bar for the power circuit from FIG. 1; and

FIG. 4 shows a system of different busbars corresponding to that of FIG. 3.

FIG. 1 shows a power circuit 100. A top view is shown in the upper area of the illustration and a longitudinal section through the power circuit 100 in the lower area.

The power circuit 100 comprises a carrier material 105, a bus bar 110, a first electronic component 115 and a second electronic component 120. The lower illustration additionally shows a cooling element 122 which, however, is not necessarily part of the power circuit 100.

The carrier material 105 preferably comprises a core 125, on the upper surface of which a conductor track 130 is arranged. Another trace 130 may extend on the bottom surface of the core 125, wherein opposing traces 130 may be interconnected in the vertical direction. The bus bar 110 and the first electronic component 115 can be soldered to the conductor track 130 of the carrier material 105 by attaching a soft solder to the upper surface of the carrier material 105, with which lower surfaces of the first electronic component 115 or the bus bar 110 in Kon- stand, and the solder is heated temporarily. In a preferred embodiment, the solder is in the form of solder paste 135 by means of a printing process on the upper Surface of the substrate 105 is attached before the bus bar 110 or the first electronic component 115 are placed on it. In order to fix the bus bar 110 on the carrier material 105, an adhesive 132 may be used which is applied to the bus bar 110 or the carrier material 105 before the bus bar 110 is placed. The adhesive 132 may be used, for example, to form one or more adhesive dots.

For soldering the second electronic component 120 to the busbar 110, a soft solder in the form of solder paste 135, as described above, can again be provided between the second electronic component 120 and the busbar 110. Alternatively, a molding 140 made of soft solder may be attached to the surface of the bus bar 110 or the lower surface of the second electronic part 120 before the second electronic part 120 is attached to the bus bar 110.

In the embodiment illustrated by way of example, the second electronic component 120 is connected to two adjacent busbars 110. Furthermore, the second electronic component 120 comprises a vertical connection for direct contacting with a conductor track 130 of the carrier material 105. In the illustrated variant, the carrier material 105 comprises a recess 145 to allow the cooling element 122, the lower surface of the busbar 110 to contact. The cooling element 122 is usually provided at a place of use of the power circuit 100 and may for example be made in automobile body in a body panel or connected to such. FIG. 2 symbolically shows steps of a method 200 for producing the electronic power circuit 100 from FIG. 1. In a first step 205, a soft solder, preferably in the form of solder paste 135, is applied to the surface of the carrier material 105. Subsequently, in a step 210, the first electronic component 115 is placed on the surface of the carrier material 105. This step is preferably carried out by means of an SMD placement machine. Further, after all of a plurality of first electronic components 115 are placed on the carrier material 105, in a step 215 the busbar 110 is likewise placed on the carrier material 105. This step can also be carried out by the placement machine. In one embodiment, an adhesive 132 is also attached to the substrate 105 or the bus bar 110 before the bus bar 110 is placed.

Although the busbar 110 can also be placed in front of one or more of the first electronic components 115 on the carrier material 105, it may be advantageous to mount the busbar 110 only late in order not to impair the accessibility of the carrier material 105 by the relatively large busbar 110 ,

In a subsequent step 220, soft solder in the form of the molding 140 is applied to the upper surface of the bus bar 110 or the lower surface of the second electronic component 120. Instead of molding 140, solder in another form, preferably as printable solder paste 135, may also be used. Subsequently, the second electronic component 120 is placed on the surface of the bus bar 110 in a step 225.

In order to ensure relative positioning of the bus bar 110 on the carrier material 105, the cooling element 122 or a correspondingly shaped spacer can be inserted into the recess 145 before a last step 230 is carried out in which the power circuit 100 heats up is to solder the electronic components 115, 120, the bus bar 110 and the substrate 105 together. After cooling of the power circuit 100, the cooling element 122 can be removed again. With the completion of the soldering process, the power circuit 122 is completed.

FIG. 3 shows a modular busbar 305 which can be used as a busbar 110 in the power circuit 100 from FIG. 1 and in particular can be processed by means of the production method 200 shown in FIG. Shown is a three-sided representation, with a front view at the top left, a side view at the top right and at the bottom a top view of the busbar 305. The busbar 305 has in plan view a cross-section or a base surface, which emerges from a rectangle, in particular from a square. On one side of the base body, a recess 310 and on another side a projection 315 is provided. In the figure 3, the recess 310 and the projection 315 are opposite to each other, but they can also lie in adjacent sides of the rectangular base body. The recess 310 and the projection 315 correspond to one another, so that the projection 315 of a first busbar 305 can engage as precisely as possible in the recess 310 of a second busbar 305. In this case, the busbars 305 are preferably without gap to each other. Correspondingly, the recess 310 and the projection 315 may also have trapezoids or rounded shapes in the manner of a puzzle piece, as illustrated. The recess and the projection are complementary to one another ausgestaltet, preferably such that they can be pushed into each other. The recess or the recess and the projection have no undercut. In order to facilitate an electrical and mechanical connection of the two abutting busbars 305, a recess 320 for receiving is in the region of the projection 315 of solder in the form of solder paste 135 or a molding 140 is provided. In other embodiments, the depression 320 may also be introduced into the busbar 305 in the region of a boundary of the depression 320.

FIG. 4 shows a system 400 of different modular busbars 305 in further embodiments 405 to 440. Each of the illustrated busbars 405 to 440 has at least one recess 310 or a projection 315. In this case, a basic form of all illustrated busbars 405 to 440 is based on the rectangular or quadratic basic shape which was explained above with reference to FIG.

Embodiments 405 and 415 are complementary to one another in that their plan views are mirror-inverted. The recess 310 and the projection 315 lie respectively on adjacent sides of the rectangular main body of the busbars 405 and 415, respectively. The other two sides do not form a corner, but are merged into one another in the form of an arc.

The busbar 435 additionally has a vertical recess 445. In addition, the rectangular or square basic body is extended in the representation of Figure 4 in the vertical direction, so that the recess 320 does not reduce the body.

LIST OF REFERENCE NUMBERS

100 power circuit

105 carrier material

110 busbar

115 first electronic component

120 second electronic component

122 cooling element

125 core

130 trace

132 adhesives

135 soft solder

140 molded part

145 recess

200 procedures

205 Applying solder paste

210 Place first component

220 Attaching a molding of soft solder

225 Place second component

225 heating

305 modular busbar

310 recess

315 ahead

320 deepening

400 system

405-440 modular busbars

445 recess

Claims

claims

A method (200) for making an electronic power circuit (100), comprising the steps of: a) placing (210) a first electronic device (115) on the surface of a substrate (105);

b) placing (215) a bus bar (110) on the

Surface of the carrier material (105);

c) placing (225) a second electronic component (120) on the surface of the bus bar (110); and

d) heating (230) the electronic components (115, 120), the bus bar (110) and the carrier material (105) in order to solder them together.

The method (200) of claim 1, further comprising attaching (205) solder paste (135) to the substrate (105) before placing (105) the first electronic component (115) or the bus bar (110) thereon.

The method (200) of claim 1 or 2, further comprising attaching (220) a soft solder molding (140) to the bus bar (110) before placing (110) the second electronic component (120) thereon.

A method (200) according to any one of the preceding claims, wherein an adhesive (132) is attached (215) between the bus bar (110) and the substrate (105).

Bus bar (110, 305, 405-440) for connecting an electronic component (120) to a carrier material (105), comprising the following features:

a lower surface having a planar portion for surface mounting the bus bar (110, 305, 405-440) on the substrate (105); and an upper surface having a planar portion for surface mounting an electronic component (120) to the bus bar (110, 305, 405-440).

A bus bar (110, 305, 405-440) according to claim 5, wherein the dimensions of the bus bar (110, 305, 405-440) are sufficiently small to allow the bus bar (110, 305, 405-440) to be mounted on the carrier material (110). 105) by means of a placement machine for surface mount components.

Bus bar (110, 305, 405-440) according to claim 5 or wherein on its upper surface a recess (320) for receiving a depot (135, 140) is arranged by soft solder.

A system (400) of a plurality of busbars (305, 405-440) for connecting an electronic component (120) to a carrier material (105), comprising a first (305, 405-440) and a second busbar (305, 405-440) according to one of claims 5 to 7, wherein the first busbar (305, 405-440) has a lateral projection (315) and the second busbar (305, 405-440) has a corresponding lateral recess (310), so that the busbars (305, 405-440) can be disposed immediately adjacent to each other by engaging the projection (315) in the recess (310).

The system (400) of claim 8, wherein the bus bars (305, 405-440) have cross-sections derived from a common basic shape.