WO2012119789A2

WO2012119789A2 - Method for producing a component

Info

Publication number: WO2012119789A2
Application number: PCT/EP2012/001075
Authority: WO
Inventors: Andreas SEEFRIED; Marcus SCHUCK; Zaneta BROCKA-KRZEMINSKA; Michael Fuchs
Original assignee: Jacob Plastics Gmbh
Priority date: 2011-03-09
Filing date: 2012-03-09
Publication date: 2012-09-13
Also published as: DE102011013372A1; WO2012119789A3

Abstract

The invention relates to a method for producing a component, comprising the steps of providing a plastic workpiece, applying a metal coating to the plastic workpiece, irradiating the plastic workpiece in order to at least partially cross-link the polymer chains of the plastic workpiece, and thermoforming the irradiated plastic workpiece. The invention further relates to a component comprising a metal coated plastic workpiece made at least partially of a radiation cross-linked plastic.

Description

Method for producing a component

The invention relates to a method for producing a component, a component comprising a metallized plastic workpiece, and the use of a component.

Components such as circuit carriers of metallized plastics are known (eg, 3D-MID). Such circuit carriers have, for example, printed conductors and electronic or electrical components. In their application can be dispensed with a separate wiring on or next to the components, which may be undesirable for cost reasons, reasons of work, space and design.

In the prior art, circuit carriers are left, for example, as back-injected foil circuit carriers. In this case, metallic conductor pieces are applied to a plastic film. Examples are flexible interconnects (FPC, FFC). This insert is finally injected behind. In most cases, the finished circuit carrier must also be used for welding and soldering the imple- impregnated conductor tracks are suitable for metallic contacts and therefore resist at least in the short term temperatures of about 270 ° C.

Due to the abovementioned production sequence, special requirements arise for the polymer materials of the plastic film. High-performance plastics such as polyether ketone (PEEK) or polyimides (PI) have therefore been used in the prior art. These are basically processable in the above-mentioned manner and have acceptable but not outstanding properties for all process steps. A major drawback, however, is their cost.

The use of cheaper thermoplastics such as polyamide (PA) or polybutylene terephthalate (PBT) has not been possible. The main reasons were that a sustainable forming by thermoforming was hardly possible and these materials do not have the desired solder resistance.

An object of the invention is therefore to provide a method for producing a component described above, which allows the use of cheaper starting materials.

This object is achieved by a method according to claim 1. Advantageous embodiments emerge from the subclaims.

Accordingly, the invention relates to a method for producing a component, which comprises the following steps, which can be carried out in any meaningful order:

a) provision of a plastic workpiece,

b) metallization of the plastic workpiece,

c) irradiation of the plastic workpiece for the purpose of at least partial crosslinking of the polymer chains of the plastic workpiece, and

d) thermoforming the preferably already irradiated plastic workpiece. The sequence of steps a) to d) is basically arbitrary, with all conceivable sequences of the patent to be included. Only the implementation of step d) is necessarily carried out after step c), as well as from the formulation thermoforming of the "irradiated" plastic workpiece emerges.

Essential to the invention is the step of irradiation, which causes a change in the properties of the plastic workpiece by the at least partial crosslinking of the polymer chains of the plastic workpiece. The irradiation preferably takes place before the thermoforming. The irradiated plastic component serves as a semi-finished product for thermoforming.

The component is preferably a composite component or a metallized plastic component such as a circuit carrier. In one embodiment, the component is a back-injected foil circuit carrier.

In one embodiment, the sequence metallization - irradiation -> thermoforming is relevant. In this case, the metallized plastic workpiece is irradiated. One of the central research topics was precisely the determination of the optimal time for the irradiation within the procedure.

In one embodiment, the plastic workpiece comprises or consists essentially of a thermoplastic. It should be a radiation-crosslinkable thermoplastic. Suitable thermoplastics include, for example, polyamide or polybutylene terephthalate. These thermoplastics are advantageously cheap and easy to process before irradiation. In addition, they can have good metallization adhesion. By the irradiation thermoforming can be made possible. The radiation-crosslinked thermoplastics can also have a soldering resistance of at least short-term up to 270 ° C and have a good long-term use temperature. Without wishing to be bound by the invention, it is assumed that the thermoplastic used has thermosetting properties as a result of the irradiation. As a result of the irradiation, the polymer chains can be crosslinked radically at their points of contact, as a result of which a structure customary for thermosets with 3-dimensionally crosslinked polymer chains is formed. Before the irradiation, the plastics used can be thermoplastically reversibly deformable and weldable. Before irradiation, the plastics can be rigid and have hard, glassy properties. Important criteria for the selection of the plastic include the Metallisierungshaftung, the thermal expansion coefficient, the thermal formability, the adhesion during injection molding and the soldering resistance before and after irradiation.

In one embodiment, the matrix of the plastic workpiece additionally comprises a crosslinking agent such as a peroxide, a vulcanizing agent or the like. The addition of the crosslinking agent may be included in step a).

In one embodiment, the semifinished product is brought to a temperature of between about 200 ° C and about 280 ° C, preferably between about 220 ° C and about 260 ° C, prior to thermoforming.

In one embodiment, the plastic workpiece has a thin and planar shape, and is preferably a plastic film. The irradiation of such a plastic film may result in a radiation-crosslinked film with altered properties. The thickness of the workpiece or plastic film may be less than about 1 cm in one embodiment. Other preferred thicknesses include less than about 5 mm, less than about 2 mm, or less than about 1 mm. In one embodiment, the thickness is between about 100 m and about 1 mm.

In one embodiment, the metallization of the plastic workpiece is carried out by hot stamping. In this case, the plastic workpiece is optionally heated Condition with a possibly heated metal component such as a conductor strip hot impregnated. Suitable metal components include, for example, a conductor band, a structured metal plate, and the like. However, other metallization forms such as CVD and the like are conceivable and encompassed by the invention.

In one embodiment, structuring of the surface is associated with metallization. For example, a hot stamp may determine the circuit logic of a resulting circuit carrier. The metallization of the plastic workpiece may include applying a conductor pattern. In the course of the metallization and structuring, conductor tracks and solder joints can be applied to the plastic workpiece or the plastic film.

In one embodiment, the hot stamping occurs at a temperature of the plastic workpiece and / or the metal component of between about 100 ° C and about 250 ° C, preferably at a temperature of between about 170 ° C and about 200 ° C.

In one embodiment, the hot stamping takes place in a press. The embossing pressure may be between about 10 and about 50 N / mm ² , and preferably between about 20 and about 40 N / mm ² . The imprinting time in one embodiment is less than about 5 seconds, preferably less than about 2 seconds.

In one embodiment, the irradiation is an irradiation with electrons. This may be particularly suitable for achieving optimal crosslinking, optionally radical crosslinking of polymer chains.

In one embodiment, the irradiation is at an energy of between about 1 and about 10 MeV, preferably between about 3 and about 7 MeV. In one embodiment, the radiation dose delivered to the plastic workpiece is between about 50 and about 250 kGy, preferably between about 100 and about 200 kGy. The radiation dose can be delivered to the plastic workpiece in several irradiation processes with possibly the same radiation dose. The implementation of individual irradiation processes is possible at several points of the process, for example, after an optionally performed back injection or loading with additional components. In any case, at least one irradiation process should take place before the thermoforming of the plastic workpiece.

In one embodiment, the method according to the invention further comprises the step of injection molding and preferably back-injection of the thermoformed plastic workpiece by composite injection molding. The injection molding can be done with a suitable injection mold whose shape is adapted to the shape of the thermoformed plastic workpiece. The plastic workpiece may also be referred to as an insert in connection with injection molding. This process step results in a back-injected, thermoformed and radiation-crosslinked film, which represents a component according to the invention. The back molding can be done with a thermoplastic, such as PBT or PA. The plastic used for composite injection molding may be the same thermoplastic as used in providing the uncrosslinked film.

In one embodiment, the inventive method further comprises the assembly of the plastic workpiece with additional components, preferably the assembly of electronic or electrical components. This may include the soldering of metal contacts, the creation of electrical solder joints on solder joints, and the like. This step may be done at a convenient location in the process flow, but is preferably done as a last step. The invention further relates to a component according to claim 10. Accordingly, a composite component is provided with a metallized plastic workpiece, wherein the plastic workpiece consists at least partially of a radiation-crosslinked thermoplastic. The component is preferably produced by a method according to the invention.

Preferably, the component is a composite component such as a circuit carrier, and more preferably an automotive part. The plastic workpiece is preferably metallized on the surface thereof. In one embodiment, the metallization has a particular structure, and serves as a trace, as circuit logic, or the like.

"At least partially" in the sense of the claim may mean that at least one thin layer on the surface of the component, which is subject to the metal component, consists of a radiation-crosslinked thermoplastic.

In one embodiment, the composite component is a component which has a film circuit carrier made of a radiation-crosslinked thermoplastic. In one embodiment, the film circuit carrier is back-injected with plastic.

As thermoplastics PA and / or PBT are used in one embodiment.

The invention further relates to the use of the components according to the invention for the production of plastic components with printed conductors or the use of the inventive method for sensor attachment to plastic components or for the production of plastic components. Suitable plastic components include, for example, automotive components such as steering column switches, windows, center consoles, fittings, and the like.

Further details and advantages of the invention will become apparent from the figures and embodiments described below. In the figures show: FIG. 1: a graphic representation of the task underlying the invention,

FIG. 2 is a flowchart illustrating an embodiment of a method according to the invention; and FIG

FIG. 3 shows perspective views of a component according to the invention from the metallized front side and the rear side with an injection-molded structure.

FIG. 1 graphically depicts the task underlying the invention. The FIGURE shows a diagram with five axes, each axis representing a property of possible plastics for use in a plastic workpiece of a method according to the invention.

The properties are the continuous service temperature, the price, the workability, the metallization adhesion, as well as the soldering resistance.

The continuous service temperature is a material property that gives information about the temperature resistance. It is standardized according to DIN 53476 and indicates which temperature a material can withstand in the long term without significantly changing its properties, or in other words at which operating temperatures the finished component can be used permanently without material fatigue occurring. For example, the thermal expansion coefficient and the flexibility of the material can be decisive.

The term workability includes, for example, how easy the plastic workpiece, such as a plastic sheet, can be provided with the polymer of choice. The thermoplastic properties may play a role in the extrusion process. Furthermore, it is understood, for example, how the mathematical material during thermoforming and back injection, for example, whether it is dimensionally stable at the desired temperatures.

The metallization adhesion indicates how well an embossed on the material, or otherwise applied metal structure adheres to the surface.

Solder resistance indicates the property of the material to remain stable during the possible soldering of additional components or electrical contacts to the metallized surface. During soldering typically temperatures of about 270 ° C are needed, which should withstand the material in the short term. For example, the thermal expansion coefficient, the melting point and the thermoplastic / thermosetting properties of the material can be decisive for this.

The price refers to the purchase price of the raw material.

The properties of the polymers PEEK (dark line) and PI (light line) used in the prior art were shown in the diagram. These have good solder resistance and long-term use temperature, but have deficits in terms of processability, metallization adhesion and price.

The object of the invention is shown by the dotted line. Thus, processability, metallization adhesion and price should be significantly improved and the soldering resistance should be maintained. Losses in the continuous service temperature compared to the high-performance plastics can be accepted as long as the continuous service temperature remains within an acceptable range.

This objective can be achieved in the present invention, in particular by changing the material properties during the process. The plastics used can be, for example, thermoplastic and can be extruded well into the film. After irradiation, however, the properties are changed so that they have a very good dimensional stability during and after thermoforming. The metallization adhesion to the exemplary As a result, thermoplastic starting material can be very good, while the soldering resistance is achieved only after the irradiation (this is also needed only in the final phase of the process).

FIG. 2 shows a flow chart which represents the sequence of an embodiment of a method according to the invention. First, after suitable choice of material, a radiation-crosslinkable film is produced, for example by film extrusion of PBT.

This film is then metallized and patterned by hot stamping to attach a conductor pattern.

This is followed by electron irradiation with a predetermined irradiation dose of, for example, 150 kGy at an electron energy of 5 MeV. As a result, the metallized and structured film changes its material properties, presumably due to the crosslinking of the polymer chains, and is transformed from thermoplastics to thermosetting plastics.

Subsequently, the cutting and the shaping takes place, wherein the shaping can be done three-dimensionally by thermoforming. The resulting molded part or insert is dimensionally stable due to the thermosetting properties of the irradiated and therefore radiation-crosslinked plastic film.

This is followed by a step of assembly injection molding, wherein the insert is injection-molded, injection-molded or preferably back-injected with the aid of suitable injection-molded parts.

This creates a component that can be provided in a final step with various components such as electrical or electronic components. These can be mechanically mounted or soldered to the metal structure of the component. FIG. 3 a shows an embodiment of a component according to the invention in a perspective view from the metallized front side. The three-dimensionally shaped component has, on the surface facing the viewer, a very thin (smaller 1 mm) thick layer of a radiation-crosslinked plastic, on which printed circuit traces of metal are embossed, which can represent a circuit logic, for example. Furthermore, electronic components are welded on, such as microcontrollers, LEDs, passive SMDs or capacitive touch sensors.

FIG. 3b shows the same component according to the invention from the rear-injected rear side. The component has an injection-molded (here: honeycomb-shaped) structure on its rear side, which gives the component the required strength, since the plastic film used and thus the layer of radiation-crosslinked plastic can be very thin. The reinforcing structure can be cast onto the metallized plastic film by means of a suitable (here: honeycomb) injection molding tool.

A concrete exemplary embodiment of a method according to the invention is given below:

The raw material used is PBT V-PTS-Createc-B3 granulate containing 1% by weight of the dye Lifocolor COLCOLOR E40 / 60. The kilogram price of this source material is currently about € 6. This raw material is extruded using a Collin ESE E30M film, with the slot die at a temperature of 250 ° C and the chill roll at a temperature of 80 ° C. The take-off speed is 1.8 m / min. This results in a radiation-crosslinkable PBT film in a thickness of 300 μητι and a film width of 220 mm.

Hot-stamping is used to impregnate a circuit logic on this film. The hot stamping is carried out in a Blue Tiger press at an embossing temperature of 183 ° C, an embossing pressure of 33 N / mm ² and an embossing time of 0.5 sec. The hot stamp includes 18 μιη thick copper with black oxides and a Sn surface finish. The metallized film is then irradiated with electrons. The electron energy is 5 MeV. The irradiation takes place in five individual irradiation processes, wherein in each case a dose of 33 kGy is delivered to the metallized foil. The film assumes thermosetting properties.

The radiation-crosslinked film is now thermo-formed in a Berg Mini M3 under vacuum at a semi-finished product temperature of 240 ° C and a tool temperature of 40 ° C. This creates an insert that has the shape of a blunt, irregular pyramid.

This insert is placed in an injection molding machine Ferromatik Millacron 110 t. The film is fixed by ionized air. The injection mold is a honeycomb tool with a film gate. For back molding, the PBT plastic Ultradur B4300 G4 is used. The melt temperature is 295 ° C, and the mold temperature 80 ° C.

The result is a component which consists of a back-injected, thermoformed and radiation-crosslinked metallized film. Then a complex circuit with microcontrollers, LEDs and capacitive touch sensors was applied.

In summary, it can be seen that a component and in particular a circuit carrier can be provided with the aid of the method according to the invention, whereby the manufacturing process and the costs compared to the prior art have been significantly improved.

Claims

claims

1. A method for producing a component, characterized in that the method comprises the following steps:

a) provision of a plastic workpiece,

b) metallization of the plastic workpiece,

c) irradiation of the plastic workpiece for the purpose of at least partial crosslinking of the polymer chains of the plastic workpiece, and d) thermoforming of the plastic workpiece, preferably after its irradiation according to step c).

2. The method according to claim 1, characterized in that the plastic workpiece at least one preferably radiation-crosslinkable thermoplastic preferably polyamide and / or polybutylene terephthalate, or consists thereof.

3. The method according to any one of the preceding claims, characterized in that the plastic workpiece has a thin and planar shape, and is preferably a Kunsstoffolie.

4. The method according to any one of the preceding claims, characterized in that the metallization of the plastic workpiece is preferably carried out by hot stamping.

5. The method according to any one of the preceding claims, characterized in that the metallization of the plastic workpiece comprises the application of a conductor structure and or an electrical component.

6. Method according to one of the preceding claims, characterized in that the irradiation is electron irradiation.

7. Method according to one of the preceding claims, characterized in that the irradiation takes place with an energy of between 1 and 10 MeV, preferably between 3 and 7 MeV, and / or that the irradiation dose is between 50 and 250 kGy, preferably between 100 and 200 kGy lies.

A method according to any one of the preceding claims, further comprising a step

e) injection molding and preferably injection molding of the thermoformed plastic workpiece by composite injection molding.

A method according to any one of the preceding claims, further comprising a step f) assembly of the plastic workpiece with additional components, preferably electronic or electrical components.

Component comprising or consisting of a metallized plastic workpiece, characterized in that component is manufactured according to one of the preceding claims and / or that the plastic workpiece at least partially consists of at least one radiation-crosslinked plastic, preferably thermoplastics.