EP3257334A1

EP3257334A1 - Electronic component and method for producing an electronic component of this kind

Info

Publication number: EP3257334A1
Application number: EP16702703.6A
Authority: EP
Inventors: Karin Beart; Stefan Müller; Thomas Schmidt; Bernhard Schuch; Frieder Wittmann
Original assignee: Conti Temic Microelectronic GmbH
Current assignee: Vitesco Technologies Germany GmbH
Priority date: 2015-02-10
Filing date: 2016-02-01
Publication date: 2017-12-20
Also published as: US20170339790A1; DE102015210099A1; DE102015210099B4; JP2018506855A; WO2016128243A1

Abstract

The invention relates to an electronic component (E), comprising - a printed circuit board (1) with two opposite flat sides (1.2, 1.3) and a plurality of electronic components (2), and - a base plate (3). According to the invention, it is provided that a number of the electronic components (2) are each fixed on and electrically conductively connected to a rear flat side (1.2) of the printed circuit board (1) and a further number of the electronic components (2) are each fixed on and electrically conductively connected to a front flat side (1.3) of the printed circuit board (1), wherein the base plate (3) has at least one first cutout (3.1) for receiving electronic components (2) which are arranged on the rear flat side (1.2) of the printed circuit board (1). The invention also relates to a method for producing an electronic component (E) of this kind.

Description

description

Electronic component and method for producing such an electronic component

The invention relates to an electronic component according to the preamble of claim 1. The invention further relates to a method for producing such an electronic component.

Electronic components for integrated mechatronic controls, in particular control devices, which are installed in a transmission or engine compartment of a motor vehicle, have a plurality of electronic components, which are brought together on a circuit board to form an integrated circuit. The

Printed circuit board is usually equipped on one side with electronic components.

For the production of the electronic component is known, for example, a flat side of the circuit board with an electrically conductive adhesive, also referred to as conductive adhesive, z. As epoxy resin with electrically conductive fillers, and then to arrange all electronic components on the provided with conductive adhesive flat side.

Due to high demands on space and ambient temperatures, eg. Example, a temperature up to 150 ° C, the electronic component all electronic components designed as semiconductor components are arranged unhoused on the circuit board and electrically contacted by means of bonding wires in the form of thick-wire and / or thin-wire bonding

(Wire bonding).

When wire bonding is to ensure proper functionality of the electrical component is a high degree

Cleanliness of the populated flat side of the circuit board and the electronic components themselves required. This is possible for example by means of electrical conductive adhesive joints, which have a comparatively high electrical resistance and a low thermal conductivity. This can impair a functionality of the circuit arranged on the printed circuit board and thus of the electronic component.

In addition, it is required by the process that in addition to the semiconductor components all passive electronic components, eg. As sensors, capacitors, etc., and special components such. B. coils or quartz to fix by means of electrical conductive adhesive joints on the circuit board. Although passive components can usually be soldered, but this is not possible with the simultaneous arrangement of semiconductor components with bonding wires due to the above reasons, or at least not advantageous.

Furthermore, the electronic components to be bonded to certain terminations, which are made for example of gold or silver and thus very expensive. In addition, packaged semiconductor components can not be glued because they are usually available only as solderable components.

A thermal connection of the assembled printed circuit board via a flat, adhesive connection of the circuit board, in particular an unpopulated flat side of the circuit board with a base plate or a housing. In this case, all areas of the circuit are connected thermally equal regardless of a power loss occurring there.

The invention is therefore based on the object to provide an improved over the prior art electronic component and an improved method for producing such an electronic component.

With regard to the electronic component, the object is achieved according to the invention with the features specified in claim 1 solved. Regarding the method, the object is achieved according OF INVENTION ^¬ dung to those specified in claim 8 features.

Advantageous embodiments of the invention are the subject of the dependent claims.

An electronic component comprises a printed circuit board with two opposite flat sides and a plurality of electronic components, and a base plate. According to the invention, a number of the electronic components on a rear side of the printed circuit board and a further number of electronic components on a front side of the printed circuit board are respectively fixed and electrically conductively connected thereto, wherein the base plate has at least one first recess for receiving electronic components has, which are arranged on the back flat side of the circuit board.

The thus formed electronic component reduces a component density on the usually equipped front side flat side. Furthermore, an optimal temperature control of the electronic components as a function of power dissipation is possible. The recess in the base plate in this case corresponds to a cavity for receiving the electronic components, which are arranged on the back flat side of the circuit board.

Furthermore, the electronic component allows a combination of different connection technologies. For example, the number of electronic components by means of solder joints materially fixed on the back flat side and electrically connected to the circuit board. The further number of electronic components is adhesively connected to the front side flat side by means of an electrically conductive adhesive and electrically conductively connected to the printed circuit board by means of wire contacting.

Alternatively, the number of electronic components on the front side flat side by means of solder joints materially fixed and electrically connected to the circuit board. The further number of electronic components is then adhesively fixed on the back flat side and electrically connected by wire contacting with the circuit board.

Thus, it is possible to solder other electronic components in the circuit despite the use of an electrically conductive adhesive. This advantageously makes it possible to integrate low-loss, packaged semiconductor components in the circuit by means of soldering.

An embodiment of the invention provides that a position of one of the electronic components on one of the flat sides of the printed circuit board is dependent on a position of an electronic component on the opposite flat side of the printed circuit board with a certain power loss. This ensures a dissipation of high heat loss in electronic components with a high power loss. The temperature of such electronic components is thus optimized.

A further embodiment of the invention provides that the circuit board and the base plate are adhesively bonded together by means of a ^{Wärmeleit ¬} adhesive. Alternatively, the printed circuit board and the base plate can be soldered to each other ^¬.

An embodiment of the invention provides that the

Wire contacting at least one Dickbonddraht, z. B. aluminum, includes. Alternatively or additionally, the

Wire bonding at least one thin-bond wire, z. B. of gold.

A method for producing the described electronic component according to the invention comprises the following steps:

Providing an unpopulated printed circuit board,

Providing the plurality of electronic components,

- Equipping the circuit board with the majority of electronic Components, where

a number of electronic components arranged on the rear flat side, fixed in substance and electrically conductively connected to the circuit board, and

- Then arranged a further number of electronic components on the front side flat side, firmly bonded and electrically conductively connected to the circuit board, and

- Cohesive connection of the double-sided printed circuit board with the base plate, wherein the base plate is provided with at least a first recess for receiving electronic components, which are arranged on the back flat side of the circuit board. By means of the method according to the invention, a printed circuit board populated on both sides can be produced, with a larger number of electronic components being able to be soldered than in the prior art. A solder joint has a much lower thermal resistance than an adhesive bond, so that a functionality of the electronic component is improved.

An embodiment of the method according to the invention provides that the number of electronic components is soldered to the back flat side and that the further number elekt ^¬ ronic components adhesively connected to the front side flat side and electrically connected by wire bonding with the circuit board. In the method, therefore, various connection techniques for two-sided assembly of the circuit board can be combined.

The invention will be explained in more detail below with reference to drawings. Showing:

1 is a schematic sectional view of an embodiment according to the invention of an electronic component with a ^{printed circuit} board equipped on both sides, ^FIG .

2 schematically shows a sectional view of an alternative embodiment of the invention an electronic component with a double-sided printed circuit board and be tipped teeth ^¬

FIG. 3 shows a process flow diagram for a method according to the invention for producing an electronic component.

Corresponding parts are provided in all figures with the same reference numerals. 1 shows a sectional view, in particular a cross section of an exemplary embodiment of an electronic component E.

The electronic component E is provided for example for arrangement in a control unit for motor vehicles, in particular in a transmission control unit, wherein not all components of the electronic component E are shown.

The electronic component E comprises a printed circuit board 1 with a plurality of electronic components 2 and a base plate 3, which is materially connected to the printed circuit board 1.

The printed circuit board 1 represents a substrate or circuit carrier and serves for the mechanical fastening of the electronic components 2 and their electrical connection. For example, the circuit board 1 is formed of electrically insulating, fiber-reinforced plastic and has a number of electrically conductive tracks 1.1. Furthermore, the circuit board 1 has two flat sides 1.2, 1.3, wherein a rear flat side 1.2 one of the base ^¬ plate 3 facing side and a front side flat side 1.3 of the base plate 3 opposite side of the circuit board 1 is.

According to the invention, the circuit board 1 on both the front derseitigen ^¬ flat side and 1.3 on the back flat side on electronic components 1.2. 2 In other words: The circuit board 1 is equipped on both sides.

According to the present embodiment, an electrical resistance 2.1, an electrical capacitor 2.2 and a packaged semiconductor component 2.3, z. As a packaged diode or bipolar transistor, arranged and fixed by means of solder joints 4 mechanically on the back flat side 1.2 and electrically connected to the conductors 1.1. Since the rear flat side 1.2 is the base plate 3 to ^¬ facing flat side of the circuit board 1, the base ^¬ plate 3 has a first recess 3.1 for receiving the electrical resistance 2.1, the electric capacitor 2.2 and the packaged semiconductor component 2.3. The first recess 3.1 is provided with a filler 9, z. As a thermal paste or a potting compound.

Between unequipped sections of the rear flat side 1.2 of the circuit board 1 and the base plate 3, a heat meleitklebstoff 8 for cohesive connection of the circuit board 1 and the base plate 3 is arranged. The circuit board 1 is thus additionally connected thermally to the base plate 3. Alternatively, instead of the heat-conducting adhesive 8, a solder joint 4 may also be arranged. The base plate 3 is formed, for example, from metal. Alternatively, the base ^¬ plate 3 may be formed as a plastic-metal hybrid. On the front side flat side 1.3 are according to the embodiment shown as electronic components 2 two

unpackaged semiconductor components 2.4 and another electrical resistance 2.1 arranged.

An unheated semiconductor component 2.4 arranged on the left in the viewing direction is connected by means of a thick-bonding wire 5, e.g. B. an aluminum bonding wire, electrically conductively connected to the conductor tracks 1.1 and fixed by means of an electrically conductive adhesive 7 cohesively on the front side flat side 1.3.

An unheated semiconductor component 2.4 arranged in the viewing direction on the right is provided by means of two thin-bond wires 6, e.g. B. two gold bonding wires, electrically conductively connected to the Lei ^¬ terbahnen 1.1 and fixed by means of the electrically conductive adhesive 7 cohesively on the front Flachsei ^¬ te 1.3. The further electrical resistance 2.1 is both electrically conductively connected by means of the electrically conductive adhesive 7 with the conductor tracks 1.1 as well as firmly bonded to the front side flat side 1.3. Figure 2 shows an alternative embodiment of the electronic component E in a sectional view, in particular in a cross section.

The electronic component E comprises analogous to the previous embodiment, a printed circuit board 1 with a plurality of electronic components 2 and a base plate 3, which is materially connected to the circuit board 1.

Furthermore, the circuit board 1 analogous to the previous embodiment, a back flat side 1.2 and a front side flat side 1.3. According to the present embodiment, two electric resistances and an electric 2.1 Kondensa ^¬ 2.2 tor are on the back flat side 1.2 and electronic components 2 are arranged in each case by means of solder 4 and an electrically conductive adhesive 7 is electrically conductively connected to

Conductor 1.1 connected and fixed cohesively on the back flat side 1.2.

The base plate 3 in this case has two recesses 3.1, 3.2, wherein a first recess 3.1 the electric capacitor 2.2 and one of the electrical resistors 2.1 receives. A second recess 3.2 receives the other electrical resistance 2.1. Between unpopulated sections of the rear flat side 1.2 and the base plate 3, a ^{Wärmeleit ¬} adhesive 8 is also arranged for the cohesive connection of the circuit board 1 to the base plate 3 here. The circuit board 1 is thus additionally connected thermally to the base plate 3. Alternatively, instead of the heat-conducting adhesive 8, a solder joint 4 may also be present.

On the front side of the flat side 1.3, two semiconductor components 2.3, z. As a housed field effect transistor and a packaged integrated circuit, an electrical capacitor 2.2 and an electrical resistance 2.1. The arranged on the front side flat side 1.3 electronic components 2 are each connected by means of solder joints 4 cohesively and electrically conductive with the front side flat side 1.3. FIG. 3 shows a process flow diagram of a method according to the invention for producing the electronic component E. The method will be described in more detail below with reference to the electronic component E shown in FIG.

In a first step Sl, the rear flat side 1.2 of the circuit board 1 is equipped with electronic Bautei ^¬ len 2, the power loss compared to other electronic components 2 is low because these electronic components 2 can be thermally directly to the base plate 3 attached ^¬ prevented and a resulting heat loss can not be dissipated efficiently.

Preferably, a soldering process is performed for fixing and electrical contacting of the electronic components 2. The electronic components 2 Al ternatively ^¬ can be connected with the rear side flat side ^¬ 1.2 also adhesive and electrically conductive by means of a conductive adhesive. A wire contact (wire bonding) is not possible on the back flat side 1.2, since a necessary cleanliness of the surfaces due to the soldering processes can not be ensured.

The position of the electronic components 2 on the rear flat side 1.2 is selected depending on a future position of electronic components 2 on the front side 1.3, which have a high power dissipation and thus produce a high waste heat compared to the other electronic components 2.

In a second step S2 is applied to the front side ^¬ flat side 1.3 of the circuit board 1, the electrically conductive adhesive 7, z. B. by screen printing. Subsequently, all electronic components 2 are glued to the front side 1.3, which are provided for Drahtkontak- tion and have a high power dissipation.

Here, one of the unhoused semiconductor components 2.4 after curing of the electrically conductive adhesive 7 by means of Dickbonddrahts 5 electrically connected to the conductors 1.1.

The other of the unhoused semiconductor components 2.4 is electrically connected to the printed conductors 1.1 after curing of the electrically conductive adhesive 7 by means of the thin-bonded wires 6.

The second electrical resistance 2.1 is electrically connected to the conductor tracks 1.1 exclusively by means of the electrically conductive adhesive 7 and also fixed in a material-locking manner on the front side 1.3, as already described in FIG. By using the electrically conductive adhesive 7 on the front side of the flat side 1.3 contamination on the front side flat side 1.3 can be minimized, so that an optimal contact surface for wire contact sicherge ^¬ is.

In a third method step S3, the printed circuit board 2 equipped on both sides is connected to the base plate 3 in a material-locking manner, for B. by means of the heat-conducting adhesive 8 or al ^¬ ternatively by means of another soldering process.

The base plate 3 has to receive the electronic construction ^¬ parts 2 on the back flat side 1.2, the recess 3.1, as already described. As a result, an overall height of the electronic component E remains the same, so that no additional space requirement arises.

The recess 3.1 can optionally be filled with the filling material 9. The filling takes place either before the cohesive connection of the base plate 3 with the circuit board 1 or by means introduced in the base plate 3 channels (not shown here). By means of the filling material 9 is a thermal connection of the total merged on the circuit board 1 circuit over the prior art increased. The aforementioned channels in the base plate 3 and / or channels in the circuit board 1 make it possible to avoid or at least reduce air bubbles.

The solution according to the invention described allows a combination of different connection technologies with the option of spatially separate processes, so for example

Soldering processes on the back flat side 1.2 and Leitkleben and Drahtkontaktieren on the front side flat 1.3. In addition, a temperature of the circuit on the circuit board 1 in dependence on a power loss of individual electronic components 2 is possible. In other words, the solution according to the invention enables a partial heating of the circuit on the printed circuit board 1 in thermally relevant areas.

Furthermore, the solution according to the invention enables a reduction pieces cation of component density on a flat side of the printed circuit ^¬ plate 1 due to the double-sided printed-circuit board. 1

Further, despite the use of the electrically conductive adhesive 7, electronic components 2 can be soldered. Thus, it is also possible to integrate power loss arms, packaged semiconductor components ^¬ 2.3 in the circuit by soldering. Mechanically and chemically sensitive thin bonding wires 6 and Dick ^¬ bond wires are protected because they are not applied until after the soldering process. Thus, chip resistors and

Chip capacitors and special components are used, which have a lower cost compared to the prior art termination. For example, terminations can be used from inexpensive tin, the components with such terminations have a high availability. ₁

Reference sign list

1 circuit board

1.1 trace

1.2 rear flat side

1.3 front flat side

2 electronic component

2.1 electrical resistance

2.2 electrical capacitor

2.3 housed semiconductor component

2.4 unhoused semiconductor component

3 base plate

3.1 first recess

3.2 second recess

4 solder joint

5 Dickbond wire

6 thin bond wire

7 electrically conductive adhesive

8 heat-conducting adhesive

9 filling material

E electronic component

Sl to S3 process step

Claims

claims

1. Electronic component (E) comprising

- A printed circuit board (1) with two opposite flat sides (1.2, 1.3) and a plurality of electronic

Components (2), and

a base plate (3),

characterized in that a number of the electronic components (2) on a back flat side (1.2) of the printed circuit board (1) and a further number of electronic components (2) on a front side flat side (1.3) of the printed circuit board (1) each fixed and electrically are conductively connected thereto, wherein the base plate (3) at least a first recess (3.1) for receiving electronic components (2), which are arranged on the rear flat side (1.2) of the Lei ^¬ terplatte (1).

2. Electronic component (E) according to claim 1,

characterized in that the number of electronic components (2) by means of solder joints (4) cohesively fixed on the back flat side (1.2) and are electrically connected to the circuit board (1).

3. Electronic component (E) according to claim 1 or 2, characterized in that the further number of electro ^¬ African components (2) by means of an electrically conductive

Adhesive (7) adhesive to the front side flat side (1.3) and are electrically conductively connected by wire contacting with the circuit board (1).

4. Electronic component (E) according to one of the preceding claims,

characterized in that a position of the elekt ^¬ tronic components (2) on one of the flat sides (1.2, 1.3) of the printed circuit board (1) depending on a position of an electro ^¬ African component (2) on the opposite flat side (1.2, 1.3) the printed circuit board (1) with a certain power loss is.

5. Electronic component (E) according to one of the preceding claims,

characterized in that the printed circuit board (1) and the base plate (3) by means of a Wärmeleitklebstoffs (8) are materially interconnected.

6. Electronic component (E) according to one of Ansprü ^¬ che 3 to 5,

characterized in that the wire contacting comprises at least one Dickbonddraht (5).

7. Electronic component (E) one of claims 3 to 6, characterized in that the wire contacting comprises at least one thin-bonding wire (6).

8. A method for producing an electronic component (E) according to any one of the preceding claims, characterized by the following steps:

Providing an unpopulated printed circuit board (1),

Providing the plurality of electronic components (2),

- Equipping the printed circuit board (1) with the plurality of electronic components (2), wherein

a number of the electronic components (2) arranged on the rear flat side (1.2), fixed materially and electrically conductively connected to the circuit board (1), and

- Subsequently, a further number of electronic ^{components ¬} (2) arranged on the front side flat side (1.3), fixed materially and electrically connected to the Lei ^¬ terplatte (1), and

- materially connecting the both sides equipped Lei ^¬ terplatte (1) with the base plate (3), wherein the base plate (3) with at least a first recess (3.1) for receiving electronic components (2) is provided on the back flat side (1.2 ) of the printed circuit board (1) are arranged.

9. The method according to claim 8,

characterized in that

- The number of electronic components (2) with the back Flat side (1.2) is soldered and

- The further number of electronic components (2) with the front side flat side (1.3) is adhesively connected and electrically connected by means of wire bonding with the circuit board (1).