EP3918884A1

EP3918884A1 - Method for treating metal insert parts

Info

Publication number: EP3918884A1
Application number: EP20701740.1A
Authority: EP
Inventors: Andreas Kugler; Mareen Rosenkranz; Philipp Scheiner; Thomas Dittert; Claudia Kruse; Eduard Reimer; Matthias Mahlich; Emilia SCHWINDT
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-01-28
Filing date: 2020-01-23
Publication date: 2021-12-08
Also published as: WO2020156916A1; DE102019201035A1

Abstract

The invention relates to a method for treating insert parts (40) or printed circuit boards (50) in order to improve the attachment to a soldering material (16) or a plastic material (10). First, the metal insert part (40, 50) is encapsulated with plastic material (10) in order to mechanically fixed the insert part (40) or the printed circuit board (50). Then, the surface (52, 82) of the insert parts (40) or the printed circuit boards (50) is activated using a fluxing agent. The solder material (16) is subsequently applied in order to produce an electric connection (64).

Description

description

title

Process for the treatment of metallic inserts

Technical field

The invention relates to a method for treating metallic inserts to improve a connection to a solder or a

Plastic material. Furthermore, the invention relates to an electrical connection that is produced according to the method for treating metallic inserts.

State of the art

DE 10 2018 208 491 A relates to a contacting system for a modular car battery. A contacting system for a modular battery is disclosed, the battery comprising a plurality of battery cells. The contacting system comprises a carrier element made of a first plastic for arranging at least one functionally essential component for operating the battery, as well as a plurality of electrically conductive conductor tracks for interconnecting the battery cells. The carrier element is coated with the conductor tracks. Furthermore, a method for producing a

Contacting system for a modular battery disclosed, the battery comprising a plurality of battery cells. The contacting system is constructed in such a way that a carrier element made of a first plastic for arranging at least one functionally essential component for operating the battery has a large number of electrically conductive interconnects for interconnecting the battery cells. The carrier element of the contacting system is coated with the conductor tracks.

When connecting metallic inserts with a solder or a plastic, the various materials used may not adhere sufficiently. With mechanical loads, such as vibration or shock, but also with thermal

Loads or at high or low temperatures, at one Changes in temperature or in the event of a temperature shock, the adhesion of various materials can be critical. If there is insufficient adhesion between a solder material and a metallic insert,

for example, the electrical path can be destroyed. In this case the component loses its function.

Presentation of the invention

According to the invention a method for the treatment of metallic inserts is proposed, whereby the improvement of the connection to a solder material or a plastic material can be achieved, and at least

the following process steps are carried out: a) encapsulation of the metallic insert with plastic material

mechanical fixation of the metallic insert, b) activation of a surface of a metallic insert by means of a flux, c) application of the solder material to produce an electrical connection.

By means of the method proposed according to the invention, a pretreatment of the surface or the

Surfaces of the metallic inserts significantly improve the adhesion of the components that form an electrical connection, so that the

Component life can be extended accordingly.

In a development of the method proposed according to the invention, the metallic insert parts are provided with a single or multiple coating comprising copper, tin or nickel / Au and / or other connection partners, such as silver or metallic connection partners.

Further following the method proposed according to the invention, the single / or multiple coating of the mechanical insert parts is carried out by means of a galvanic process. This process is mature and extremely robust against external influences. In a further development of the method proposed according to the invention, method steps a), b) and c) are carried out as part of the process of integrated metal-plastic injection molding.

In one embodiment of the method proposed according to the invention, the metallic inserts are made from Clad material. Clad materials are generally made up of two different metals that are joined together to form a solid bond. In the present context, clad material is understood to mean a composite of aluminum and copper, i. H. two metallic bodies that are put together.

In the method proposed according to the invention, the metal inserts used can be provided with pins made of Cu or Clad material, for example a composite of Al and Cu, which are inserted into the metal

Insert part can be pressed in or can be integrally joined with it. In the method proposed according to the invention, those pins are preferably used which have a small cross-section / length ratio. The cross-section / length ratio is determined from the relationship pa ² / b or a ² / b with a <b (whichever

Cross-sectional area geometry of the pin).

In the method proposed according to the invention, the pins used in addition to the representation of the electrical connection or the electrical contact also serve to represent a mechanical fixation. By creating the electrical connection with the

According to the method proposed according to the invention, a mechanically reliable mounting can be achieved in a plastic material as part of a mechanical fixation, since, for example, the pins or pins used can be cast into this. Heating of the plastic material is also conceivable, the pins or pins used being able to be introduced into the previously heated and thus softened material. If the plastic material cools down again, the pressed-in pins are, as it were, cast in this plastic material.

In a further development of the method proposed according to the invention, the electrical connections can be designed such that between the components to be connected to one another, for example a distance can be maintained between the metallic inserts and a further component. This embodiment variant of the method proposed according to the invention advantageously allows the flexibility of a pin or a pin to be exploited, so that a more flexible mechanical connection is obtained. This is made possible in that, when the two components to be connected to one another by the pin are spaced apart, there is a margin within which the two components connected by the pin can move relative to one another. This scope is limited, but significant, so that

Relative movements can be permitted without the electrical connection itself being damaged.

In a development of the method proposed according to the invention, for example, to improve the connection of a solder material to the

Surface of the metallic insert the surface of the metallic insert can be enlarged. To enlarge the surface of the

Metallic insert, for example, methods such as

Laser structuring, chemical activation and mechanical roughening are available. All methods have in common that the surface of the component treated in this way is enlarged, which improves the connection between the roughened or enlarged surface of the metallic insert and the solder.

Furthermore, the invention relates to an electrical connection between a metallic insert and a solder material, which is produced according to the inventive method.

Advantages of the invention

Through the solution proposed according to the invention, a

Pretreatment, especially that made of metallic material

Insert, an improvement in the connection between the material of the metallic insert on the one hand and the solder processed by means of integrated metal-plastic injection molding can be achieved. If this electrical connection is permanent, the electrical path also remains thermal Stresses and mechanical stresses, such as vibrations or shocks, so that the service life of the component assembly produced in this way is considerably improved.

Due to the various contacts, for example a flat contact or a via (vertical interconnect access), the inserts can be connected in an individual way, so that a reliable electrical connection between the solder material and the

Insert is created. The production of vias in

In terms of process technology, plastic material is easy to implement. Only the injection mold, into which the plastic material is injected, must have corresponding domes with which the insert can be held at the same time. A major advantage of contacting solder material to the insert by means of the integrated metal-plastic injection molding (IMKS) and the previous pretreatment, i. H. A surface activation by a flux is the integration in one and the same process. This allows extremely cost-effective production of components that are also very cost-effective.

Brief description of the drawings

The invention is described in more detail below with reference to the drawings.

It shows:

FIG. 1 shows a first variant of an electrical connection,

Figure 2 shows another embodiment of a contact between

a metallic insert and a solder material,

Figure 3 shows an embodiment of an electrical connection

Maintaining a distance between the components to be connected and

Figure 4 shows a variant of an electrical connection, where

for example on the surface of a metallic insert Vias (vertical interconnect access), that is, vias are present.

Variants of the invention

FIG. 1 shows a variant of an electrical connection 64 in a schematic view.

FIG. 1 shows that a solder material 16 is located on a bottom 14 of a plastic material 10. The plastic material 10 comprises an edge 12 which partially surrounds the solder material 16. On the solder material 16 there is a pin 18 which comprises a first vertical leg 20 and a second leg 22 oriented at right angles to this, a horizontal leg 22. The pin 18 is a part of a connector part 24, which is only schematically indicated here. The connector part 24 with which extends in the vertical direction

extending first leg 20 and the second horizontally extending leg 22 of the pin 18 is contacted by the solder material 16.

FIG. 2 shows a further embodiment variant of an electrical connection 64 proposed according to the invention, in which a plastic material 10 has a recess 36 into which an insert 40 made, for example, of metallic material, for example designed as an aluminum connector or plug or printed circuit board or the like, projects . The insert 40 is provided with a pin 34 on its upper side. The pin 34 can, for example, be pressed into the material, for example aluminum, from which the insert 40 is made. There is also the possibility that the pin 34, be it made of copper or be made of a Clad material, is firmly attached to the top of the insert 40 and protrudes through an opening 30 in the solder material 16.

It can also be seen from the illustration in FIG. 2 that the pin 34, also referred to as a pin, has a pin height 38. The pin 34, which is connected to the metallic insert 40 in the illustration according to FIG. 2, has a small ratio of cross section to length in order to ensure a compensation of the forces which occur in the case of, for example, thermally induced different material expansions at the electrical connection 64 results. FIG. 3 shows an embodiment variant of an electrical connection 64, in which a pin 56, which is also referred to as a pin, is also used. 3 shows that a distance 58 is formed between a surface 52, for example a printed circuit board 50, and an underside 66 of an electrical component 62, however it is designed. This distance 58 gives the assembly of the components 50 and 62 realized via the pin 56 a flexibility, whereby the electrical connection 64 is relieved in mechanical terms. This means that the embodiment variant shown in FIG. 3 allows relative movements between the printed circuit boards 50 or the electrical component which are connected by the pin 56, without the functionality of the electrical connection 64 between the components 62 and 50 suffering. Position 54 denotes an underside of the circuit board 50. The top of the electrical component 62 can be provided with an SN layer 60

In the variants of the formation of an electrical connection 64 shown above in the context of FIGS. 1 to 3, this is used in each case

Insert 40, which is an aluminum connector, a

Cell connector, a connector, see illustration in Figure 1 position 24, or the like can be pretreated. The pretreatment of the inserted parts 40 takes place before application thereof in the integrated metal-plastic injection molding (IMKS) process. In the case of the insert parts 40, these can first be mechanically fixed with the aid of the plastic material 10 or with the formation of a plastic encapsulation.

Subsequently, the connection contacts of the inserts 40 are wetted in the area where the electrical connection 64 is formed. Activation takes place in this surface area of the insert parts 40

for example using a flux. So that this activation is effective and good wetting, i.e. H. a good sealing of the heated solder material 16 used can take place, the insert 40 is first extrusion-coated with plastic material 10, then the flux is applied before the solder material 16 is applied as part of the integrated metal-plastic injection molding. In order to ensure good adhesion on the one hand and on the other hand a low electrical contact resistance, can

for example, the insert 40 can be provided with copper, tin or a nickel / Au single or multiple coating. In addition to the above Components copper, tin, nickel / Au can also be used for other connection partners, for example silver or other metallic

Connecting materials.

The single or multiple coating mentioned above can be carried out by means of a highly robust galvanic process.

Clad materials can also be used, which are preferably composite bodies made of aluminum and copper.

On the one hand, the use of a Clad material can be made directly by the material of the insert 40 being such; However, the pins 34 or 56 used can also be made from a Clad material on the one hand or, for example, from copper and pressed into the heated plastic material 10 of the plastic component. In addition, there is of course also the possibility of producing the pins 34 or 56 from a clad material and of integrally joining them, for example, to the surface 52 of the insert 40.

As already mentioned above in connection with FIG. 3, the pins 34 and 56 can be used in addition to the electrical connection 64 simultaneously for mechanical fixing in the plastic material 10 of the plastic component. In order to take into account various mechanical and thermal loads which act on a component assembly and are to be compensated, a pin 34 or 56 is preferably used which has a small cross-section / length ratio and balances the forces

for example in the case of thermally induced different material expansions. The cross-section / length ratio of the pins 34 is given by a ² / b, with a ² = cross-sectional area of the pins 34, b = length of the pins 34, with a <b.

Depending on the design of the electrical component 62 or the electrical connection 64, there is very good adhesion between the insert 40, which can also be referred to as insert 32, and the

Plastic material 10 of the plastic component is required. Since there is no reliable adhesion over the life cycle seen between the metallic material and the plastic after injection molding, it is like

proposed according to the invention, the metallic material before making the Pre-treat injection molding. A method can also be used for the pretreatment which enlarges the surface 52 of the insert 40 before the application of the integrated metal-plastic injection molding. The surface 52 of the circuit board 50 can be enlarged, for example, by laser structuring, chemical activation or mechanical

Roughening or the like. Through the so achieved

The plastic material 10 can enlarge the surface when

Better connect the injection molding process with the metallic material as part of the integrated metal-plastic injection molding (IMKS) process.

FIG. 4 shows a further version of the electrical connection 64 produced by the method proposed according to the invention. It can be seen from FIG. 4 that one is used, for example, as a cell connector

insert 40 made of metallic material between two

Plastic components made of plastic material 10 is joined. Each of the two plastic components comprises a recess 36, in each of which one end of the insert 40 is embedded. FIG. 4 shows that the plastic material 10 of the plastic component in each case has one end of the insert 40 in the context of a

Enclosure 90 encloses.

On a surface 82 of the insert 40 are perpendicular to

Various vias extending across the drawing plane. Vias (vertical interconnect access) 84 represent plated-through holes. These are used, for example, in printed circuit boards for the electrical connection 64 of individual conductor track levels and are thus designed as bores which are provided with an electrically conductive coating. In the present case, 10

Bores or recesses placed so that the solder material 16 can flow into them and thus the electrical contact to

Inserts 40 or to the circuit board 50. The insert 40 or the circuit board 50 in turn can also contain vias 84.

In the left part of the illustration according to FIG. 4 there is another via 86, which is partly filled with the solder material of the solder 16, see reference number 88, which indicates the amount of solder. The vias 84 are delimited by a number of structures 94 which are located on the surface 82 of the insert 40. It can be seen from the illustration according to FIG. 4 that each of the structures 94 on the surface 82 of the insert 40 has two bevels 92 has, so that the structures have a frustoconical cross section.

The bevels 92 shown on the vias 84 in the plastic material 10 serve to ensure that the liquid solder material 16 can flow optimally into the interspaces during the process, thus ensuring optimal contact with the insert 40 or the printed circuit board 50. This also ensures reliability during use, since with a hard edge of 90 °, for example, strains caused by heat and mechanical stress also cause the connection between solder material 16,

Plastic material 10 and insert 40 or circuit board 50 could tear faster. The vias 84 in the plastic material 10 can be placed in such a way that the solder material 16 contacts the insert 32 or the printed circuit board 50 only at desired locations, and the remaining area is protected from the solder material 16 and environmental influences below the

Plastic material 10 is. For improved connection of the individual

Materials with one another could also be carried out in the course of plated-through holes.

The invention is not restricted to the exemplary embodiments described here and the aspects emphasized therein. Rather, a large number of modifications are possible within the scope specified by the claims, which are within the scope of professional action.

Claims

Expectations

1. A method for treating inserts (40) or printed circuit boards (50) to improve the connection to a solder material (16) or a plastic material (10) with at least the following

Process steps:

a) overmolding the insert (40) or the circuit board (50) with

Plastic material (10) for mechanically fixing the insert parts (40) or printed circuit boards (50),

b) activation of a surface (52, 82) of the inserts (40) or the printed circuit boards (50) by means of a flux and

c) applying the solder material (16) to produce an electrical connection (64).

2. The method according to claim 1, characterized in that the

Inserts (40) or the printed circuit boards (50) are provided with a single or multiple coating comprising copper, tin or nickel / Au or silver or metallic connection partners.

3. The method according to claim 2, characterized in that the

Single or multiple coating of the insert parts (40) or the printed circuit boards (50) is carried out by means of a galvanic process.

4. The method according to claim 1, characterized in that the

Process steps a), b), c) are carried out as part of the process of integrated metal-plastic injection molding.

5. The method according to claim 1, characterized in that the

Inserts (40) or the printed circuit boards (50) are made from Clad material.

6. The method according to claim 1, characterized in that the insert parts (40) or the printed circuit boards (50) are provided with pins (34, 56) made of Cu, oxide, Clad material, which in the insert part (40) or the printed circuit boards (50) are pressed in or integrally joined with it.

7. The method according to claim 1, characterized in that the pins (34, 56) have a small cross-section / length ratio.

8. The method according to claim 1, characterized in that the pins (34, 56) form an mechanical connection in the plastic material (10) in addition to an electrical connection (64).

9. The method according to claim 1, characterized in that the

electrical connection (64) while maintaining a distance (58) between the insert (40) or the printed circuit board (50) on the one hand and a further electrical component (62) on the other.

10. The method according to claim 1, characterized in that a surface (52, 82) of the insert (40) or the printed circuit board (50) is enlarged.

11. The method according to claim 10, characterized in that the surfaces (52, 82) of the inserts (40) or the printed circuit boards (50) are increased by laser structuring, chemical activation or mechanical roughening.

12. The method according to claim 1, characterized in that after the completion of process steps a) - c) a final

Injection molding of the composite obtained with plastic material (10) takes place.

13. Electrical connection (64) between an insert (40) or a printed circuit board (50) and a solder material (16), produced according to the method according to one of claims 1 to 12.