WO2004096513A2 - Metal-plastic composite component and methods for the production thereof - Google Patents

Abstract

The invention relates to a metal-plastic composite component having a conductor comb for equipping with at least one electronic component. The at least one electronic component has at least one SMD component with stratiform electrical contacts, and the conductor comb has at least two electrically conductive supporting strips each having at least one peninsular contact surface for mechanically fastening and electrically contacting one of the stratiform electrical contacts of the SMD component. The inventive metal-plastic composite component also comprises a plastic injection molded part, with which at least the SMD component and, in part, the conductor comb are encapsulated. In the area of the peninsular contact surfaces, at least one supporting element is arranged on these peninsular contact surfaces and joined to the conductor comb in a mechanically fixed manner so that the supporting element rises above the peninsular contact surfaces, and the supporting element is only partially covered by the plastic injection molded part. The invention also relates to appropriate methods for producing a metal-plastic composite component.

Description

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Metal-plastic composite component and method for its production

The invention relates to a metal-plastic composite component with a conductor comb for fitting with at least one electronic component, the at least one electronic component comprising at least one SMD component, in particular with layer-shaped contacts, and wherein the conductor comb has at least two electrically conductive carrier strips, each of which Have at least one peninsular contact surface for mechanical fastening and electrical contacting of the SMD component, in particular one of the layer-shaped electrical contacts, and suitable methods for producing such a metal-plastic composite component.

Such metal-plastic composite components are known from DE 196 40 255 A1, which discloses a method for producing an electrical module with a plastic-molded lead frame. The punched leadframe is provided with solder paste and equipped with components. The components are attached by reflow soldering. A bending process on the leadframe can take place directly after punching or only after soldering. The lead frame, including the components, is then overmolded in a first phase, with niches remaining in the first plastic injection molded part for inserting extra parts. A permanent magnet is mentioned as an extra part. The first plastic injection molded part is then overmolded in a second phase. When the leadframe is overmolded in the first phase, the contacts between the soldered components and the leadframe can be damaged or torn off due to the spray pressure. Deformation of the lead frame with undesired contact formation between the conductor tracks of the lead frame can also occur.

Such metal-plastic composite components tend to fatigue due to temperature changes, which can lead to the contacts shearing off. It is now the object of the invention to provide metal-plastic composite components which withstand thermal cycling in the range between -50 ° C to + 150 ° C and to eliminate such problems when encapsulating conductor combs equipped with electronic components and a suitable metal-plastic - Specify composite component and suitable processes for its production.

To achieve the object, the carrier strips have elastic structures in their areas adjacent to the peninsula-shaped contact surfaces, which have a higher elasticity than the rest of the conductor comb. The metal-plastic composite components according to the invention have proven themselves for use in the range from -50 ° C. to + 150 ° C. against temperature fluctuations. The different coefficients of thermal expansion of the carrier strip and the injection molded plastic part lead to a load in the area of the connection between the electronic components and the carrier strip when the composite component is heated, which means a further source of danger for damage to the electrical connection. The elastic structures are suitable for absorbing the different thermal expansion of the carrier strips compared to the plastic injection molding and for relieving the connection areas between the conductor comb and the components.

To produce the metal-plastic composite component, the area of the peninsula-shaped contact surfaces is supported against the injection molding tool.

Supporting the conductor comb in the area of the peninsula-shaped contact surfaces or the elastic structures against the injection mold protects the conductor comb and the connection to the electrical component from deformation due to the injection pressure.

Arrangements for supporting the conductor comb in the area of the peninsula-shaped contact surfaces or the elastic structures against the injection mold can protect the conductor comb or the connection to the electrical component from deformation by the injection pressure with one or more support elements between the injection mold and the peninsula-shaped contact surfaces or the elastic structures. Adequate deformation of the conductor comb leads to damage to the electrical contact or to damage to the electrical component. Support elements can be attached to the injection mold as well as to the metal-plastic composite component for this purpose, but do not necessarily have to. In a preferred embodiment, the object is achieved in that in the region of the peninsula-shaped contact surfaces at least one support element is arranged on the peninsula-shaped contact surfaces and is mechanically fixed to the conductor comb in such a way that the support element rises above the peninsula-shaped contact surfaces. Preferably, the support element is only partially covered by the injection molded plastic part.

Relevant metal-plastic composite components are particularly advantageous if the at least one support element is arranged perpendicular to the peninsula-shaped contact surfaces; the at least one support element is formed from the material of the carrier strips; at least one support element is designed as a separate part fastened to the conductor comb;

- A support element is arranged on a peninsula-shaped contact surface; in particular the support elements are each in the form of a tab; and / or the support elements are arranged parallel to one another and at the same height; the carrier strips have, in their regions adjoining the peninsula-shaped contact surfaces, elastic structures which have a higher elasticity than the rest of the conductor comb; in particular the elastic structure by at least one omega-shaped and / or at least one S-shaped and / or one Z-shaped and / or at least one L-shaped and / or at least one V-shaped and / or at least one U-shaped and / or at least one multiply kinked area is formed; and / or the carrier strips have a smaller cross-section in the area of the elastic structure than in the area of the peninsula-shaped contact areas.

In this regard, preferred production methods include the following steps, in particular if the at least one support element is formed from the material of the carrier strips:

Equipping the conductor comb with the at least one electronic component,

Arranging the assembled conductor comb in an injection molding tool such that the at least one support element rests on at least one wall of the injection molding tool, and

Injection molding of the molded plastic part.

The support element does not have to be in contact over the entire spraying process, but at least at the beginning. In a preferred embodiment, the support element rests against a wall of the injection mold when the conductor comb is overmolded and provides support for the conductor comb during spraying, so that deformation due to pressure fluctuations and flow processes when filling the injection mold and curing the plastic is largely suppressed. The area of the support element which bears against the wall of the injection mold is not covered by the plastic injection molded part formed. This simple design measure protects the contact areas between the electronic components and the conductor comb and effectively protects them from damage. The support element can rise from the plane determined by two spatial axes, in which the semi-island-shaped contact surface is located, in different ways or project in the direction of the third spatial axis.

It is particularly preferred if the at least one support element is arranged perpendicular to the peninsula-shaped contact surfaces. Tilting or slipping of the support element with respect to the wall of the injection mold during the injection molding process, as could occur, for example, with a support element which is arranged at an angle unequal to 90 ° with respect to the plane in which a peninsular contact surface is located avoided with it.

The conductor comb is preferably formed from materials such as copper, copper alloys or steel, which can be processed in a simple manner by means of a stamping process.

If the metal-plastic composite component formed is to be used at temperatures in the range from -40 ° C. to + 150 ° C., it has proven to be useful if the carrier strips have elastic structures in their areas adjacent to the peninsula-shaped contact surfaces that have a higher structure Have elasticity than the rest of the conductor comb. The different coefficients of thermal expansion of the carrier strip and the injection molded plastic part cause a load in the area of the connection between the electronic components and the carrier strip when the composite component is heated, which means a further source of danger for damage to the electrical connection. The elastic structures are suitable for absorbing the higher thermal expansion compared to the plastic strip compared to the carrier strips and for relieving the connection areas between the conductor comb and the components. It has proven effective if the at least one support element is formed from the material of the carrier strips. However, it is equally possible to design the at least one support element as a separate part fastened on the conductor comb.

A support element is preferably arranged on a respective peninsula-shaped contact surface, so that the support strips are optimally supported in the injection mold.

The support elements are preferably each in the form of a tab.

It has also proven useful if the support elements are arranged parallel to one another and at the same height. However, they can also be arranged in a different way, e.g. offset from each other.

It has proven useful for the elastic structure if it has at least one omega-shaped and / or at least one S-shaped and / or at least one Z-shaped and / or at least one L-shaped and / or at least one V-shaped and / or at least one U-shaped and / or at least one multiply kinked area is formed.

It is particularly preferred if the metal strips have a smaller cross-section in the area of the elastic structure than in the area of the peninsula-shaped contact areas. This results in an additional increase in elasticity in this area.

In a further preferred embodiment, the object for a first method for producing a metal-plastic composite component, in which the at least one support element is formed from the material of the carrier strips, is achieved with the following steps:

Equipping the conductor comb with the at least one electronic component,

Arranging the assembled conductor comb in an injection molding tool such that the at least one support element rests on at least one wall of the injection molding tool, and

- Injection molding of the molded plastic part.

The object is achieved for a second preferred method for producing a metal-plastic composite component, in which the at least one support element is designed as a separate part fastened to the conductor comb, with the following steps: Forming the at least one support element in the area of the peninsula-shaped contact surfaces, the at least one support element being mechanically fixed to the conductor comb,

Equipping the conductor comb with the at least one electronic component, arranging the assembled conductor comb in an injection molding tool such that the at least one support element rests on at least one wall of the injection molding tool, and

- Injection molding of the molded plastic part.

It has proven to be useful if the at least one support element is formed by pre-molding a part of the conductor comb with plastic. The at least one support element can also be plugged onto the conductor comb or clamped or glued or riveted.

The object is achieved for a third preferred method for producing a metal-plastic composite component, in which a conductor comb is equipped with at least one electronic component, the at least one electronic component comprising at least one SMD component with layered electrical contacts, and wherein the conductor comb has at least two electrically conductive carrier strips, each of which has at least one peninsula-shaped contact surface for mechanical fastening and electrical contacting of one of the layer-shaped electrical contacts of the SMD component, and wherein the carrier strips have elastic structures in their regions adjacent to the peninsula-shaped contact surfaces, which have a higher elasticity than the rest of the conductor comb, solved with the following steps:

Equipping the conductor comb with the at least one electronic component,

- Arranging the assembled conductor comb in an injection molding tool, the injection tool having at least one support element which touches the conductor comb in the region of the peninsula-shaped contact surfaces or the elastic structures, overmoulding parts of the assembled conductor comb and at least the at least one SMD component with a plastic and

Removing the at least one support element from the molded plastic part. With this method, openings remain in the area of the support elements removed from the plastic injection molded part in the plastic injection molded part, which extend as far as the carrier strips and / or peninsula-shaped contact surfaces and / or elastic elements. For all three methods, it has proven effective if the conductor comb is equipped with the at least one SMD component as follows:

Coating the peninsula-shaped contact surfaces with a solder paste,

- placing the layered electrical contacts of the SMD component on the coated peninsula-shaped contact surfaces,

- Connection of the layered electrical contacts of the SMD component with the peninsula-shaped contact surfaces by means of light soldering.

Light soldering has proven to be a particularly good process for permanently and mechanically firmly and gently connecting the electronic components to the conductor comb.

SMD components are called "surface mounted device". SMD components are electronic components that can have a resistor, a capacitor or an inductor, such as resistors, capacitors, inductors, LEDs, ICs, transistors or diodes. These can have layered electrical contacts.

FIGS. 1 to 4a are intended to explain the metal-plastic composite component according to the invention and the method according to the invention by way of example.

So shows:

FIG. 1 shows a conductor comb with two carrier strips,

FIG. 2 shows the conductor comb from FIG. 1 after a bending process in a three-dimensional view,

3 shows the conductor comb from FIG. 2 with an SMD component mounted thereon in three dimensions

4, a metal-plastic composite component with conductor comb and SMD component from FIG. 3 in a three-dimensional view including hidden lines, FIG. 4a the metal-plastic composite component from FIG. 4 without hidden lines.

Figure 1 shows the conductor comb 2, which is formed from two carrier strips 2a, 2b made of CuSnδ, which were punched out of a metal strip. The carrier strips 2a, 2b each have a peninsular contact surface 2c, 2d. In addition, the carrier strips 2a, 2b have elastic structures 2e, 2f in their regions adjacent to the peninsula-shaped contact surfaces 2c, 2d, which have a higher elasticity than the rest of the conductor comb 2. This becomes achieved by reducing the cross section of the carrier strips 2a, 2b in the region of the elastic structures 2e, 2f and also by 90 ° bending.

FIG. 2 shows the conductor comb 2 from FIG. 1 after a bending process in a three-dimensional view. The edges of the peninsula-shaped contact surfaces 2c, 2d were bent such that a support element 6a, 6b was formed perpendicular to the peninsula-shaped contact surfaces 2c, 2d from the material of the carrier strips 2a, 2b.

FIG. 3 shows the conductor comb 2 from FIG. 2 with an SMD component 3 mounted thereon in a three-dimensional view. The SMD component 3 has layered electrical contacts 4a, 4b, which are each electrically and mechanically firmly connected to one of the peninsula-shaped contact surfaces 2c, 2d. This is preferably done with the aid of a solder paste that is applied to the peninsula-shaped contact surfaces 2c, 2d, placing the SMD component 3 on the solder paste and connecting the peninsula-shaped contact surfaces 2c, 2d and the layer-shaped electrical contacts 4a, 4b by light soldering.

FIG. 4 shows a metal-plastic composite component 1 with the conductor comb 2 and the SMD component 3 from FIG. 3 in a three-dimensional view including hidden lines (shown in dashed lines). The SMD component 3 and parts of the conductor comb 2 were overmolded with a plastic injection-molded part 5, parts of the support elements 6a, 6b not being covered by the plastic injection-molded part 5. The conductor comb 2, including the SMD component 3, is inserted into an injection molding tool in such a way that the supporting elements 6a, 6b rest against a wall of the injection molding tool and support the conductor comb 2 against the wall during the injection molding process. Warping, warping or bending of the conductor comb 2 while the liquid plastic is being shot into the injection mold to form the plastic injection molded part 5 is thus effectively reduced or avoided. The connection between the layer-shaped, electrical contacts 4a, 4b of the SMD component 3 and the peninsula-shaped contact surfaces 2c, 2d is thereby protected and possible faults in the electrical contact are avoided.

FIG. 4a shows the metal-plastic composite component 1 from FIG. 4 without hidden lines. It can now be seen more clearly that the regions of the support elements 6a, 6b that were pressed against a wall in the injection mold during the injection process are not covered with the plastic injection-molded part 5. Instead of the support elements 6a, 6b arranged in the region of the peninsula-shaped contact surfaces 2c, 2d and / or elastic regions, it is also possible, for example, to use those which are arranged in the injection mold in such a way that after removal of the metal-plastic composite component 1 from the injection mold there is a The opening in the area of the plastic injection-molded part 5 remains, where the support elements 6a, 6b are located in FIG. 4 or 4a. A part of the peninsula-shaped contact surfaces 2c, 2d and / or elastic regions would then be recognizable through these openings.

It is expressly pointed out that FIGS. 1 to 4a merely represent exemplary embodiments which can be varied within wide limits without leaving the scope of the invention.

Claims

claims 1. Metal-plastic composite component (1) with - A conductor comb (2) which is equipped with at least one electronic component, the at least one electronic component comprising at least one SMD component (3) and wherein the conductor comb (2) has at least two electrically conductive carrier strips (2a, 2b) which Each have at least one peninsula-shaped contact surface (2c, 2d) for mechanical fastening and electrical contacting of the SMD component (3), characterized in that the carrier strips (2a, 2b) have an area in their area adjacent to the peninsula-shaped contact surfaces (2c, 2d) have elastic structure (2e, 2f), which has a higher elasticity than the rest of the conductor comb (2). 2. Method for producing a metal-plastic composite component (1), in which a conductor comb (2) is equipped with at least one electronic component, the at least one electronic component comprising at least one SMD component (3), and wherein the conductor comb (2) has at least two electrically conductive carrier strips (2a, 2b), each having at least one elastic structure or peninsular contact surface (2c, 2d) for mechanical fastening and electrical contacting of the SMD component (3), with the following steps: Equipping the conductor comb (2) with the at least one electronic component, arranging the assembled conductor comb in an injection molding tool, the conductor comb (2) being supported against the injection mold in the region of the peninsula-shaped contact surfaces (2c, 2d) or the elastic structures, Injection molding of parts of the assembled conductor comb and at least one SMD component (3) with a plastic. 3. The method according to claim 2, characterized in that the at least one support element is removed from the molded plastic part, in particular the injection mold has a support element which is arranged such that it is the metal-plastic composite component in the region of the peninsula-shaped contact surfaces or supports the elastic structures. 4. The method according to claim 2, characterized in that the metal-plastic composite component in the region of the peninsula-shaped contact surfaces (2c, 2d) or the elastic structures (2e, 2f) has a support element. 5. Arrangement of an injection mold, a conductor comb and a support element between the conductor comb and injection mold, and equipping the conductor comb with at least one electronic component, the at least one electronic component comprising at least one SMD component (3) and the conductor comb (2) at least has two electrically conductive carrier strips (2a, 2b), each having at least one peninsula-shaped contact surface (2c, 2d) for mechanical fastening and electrical contacting of the SMD component (3), characterized in that the conductor comb in the region of the peninsula-shaped contact surfaces (2c , 2d) is supported with at least one support element (6a, 6b) against the injection molding tool. 6. Arrangement according to claim 5, characterized in that the injection mold and / or the conductor comb have a supporting element with which the conductor comb can be supported against the injection mold in the region of the peninsula-shaped contact surfaces or the elastic structures. 7. Metal-plastic composite component (1) with a conductor comb (2) for equipping with at least one electronic component, the at least one electronic component comprising at least one SMD component (3) and the conductor comb (2) having at least two electrically conductive components Carrier strips (2a, 2b) each having at least one peninsular contact surface for mechanical fastening and electrical contacting of the SMD component (3) and with a plastic injection molded part with which at least the SMD component (3) and partially the conductor comb ( 2) are extrusion-coated, characterized in that in the area of the peninsula-shaped contact surfaces (2c, 2d) at least one support element (6a, 6b) is arranged on the peninsula-shaped contact surfaces (2c, 2d) and is mechanically fixed to the conductor comb (2), that that Support element (6a, 6b) rises above the peninsula-shaped contact surfaces (2c, 2d). 8. Metal-plastic composite component according to claim 7, characterized in that the support element (6a, 6b) is only partially covered by the plastic injection part (5).