DE102018214982A1 - Process for producing a circuit and circuit - Google Patents

Abstract

The invention relates to a method for producing a circuit (1), comprising a substrate (3) and at least one electrical circuit element (5), comprising the following steps: a) providing a thermoforming tool (7) with at least one molded part (9), b ) Applying at least one circuit element (5) to a surface (11) of the molded part (9), c) heating a semi-finished plastic product (13) and placing and molding the heated semi-finished plastic product (13) onto the surface (11) of the molded part (9) and the at least one circuit element (5), d) demolding the semi-finished plastic product (13) to obtain the circuit (1) with the cooled and demolded semi-finished plastic product (13) and the at least one circuit element (5).

Description

The invention relates to a method for producing a circuit, comprising a substrate and at least one electrical or electronic circuit element.

Furthermore, the invention relates to a circuit which is manufactured or can be produced by the method according to the invention.

State of the art

Methods for producing a circuit are already known from the prior art. In particular, it is known that flexible circuit carriers - also referred to as flex foils - can be produced, wherein flat semi-finished foils are printed by means of screen printing, jetting, gravure printing and / or hot stamping. The disadvantage of this is that these flexible circuit carriers are not stretchable, which is why no further deformations are possible afterwards, since the conductor tracks necessary for the circuit break when stretched. Another disadvantage is that the flexible circuit carriers cannot be back-injected. Rigid circuit carriers are also known - also referred to as printed circuit boards or printed circuit boards (PCBs) - printing on the rigid circuit carriers using different methods, this also permitting a multilayer circuit structure. However - as the term "rigid" suggests - the rigid circuit carriers are not flexible. A disadvantage of the flexible circuit carriers as well as the rigid circuit carriers is that only flat geometries are possible due to the lack of deformability. Furthermore, due to the small thickness of the printed structures, only flat circuit structures are usually possible. Also known are “Molded Interconnect Device (MID)”, whereby MIDs allow the production of three-dimensional plastic components with applied structuring and components. There are various variants of this, one variant being laser direct structuring (LDS), the component being structured with a laser after injection molding. As a rule, an activator additive is exposed, on which metallic layers can grow in an electroplating process. An alternative variant is the two-component injection molding variant. In this process, galvanizable and non-galvanizable plastic components are injected and then metallized. The conductor tracks are only created where there is galvanizable plastic on the component surface. The Molded Interconnected Devices can only be obtained by a process with many process steps and in order to create the structuring an expensive plant technology is necessary. Furthermore, from the German Offenlegungsschrift DE 198 12 880 A1 a method is known in which a primer is printed on the semi-finished product to be formed, on which, after the forming, conductor tracks are galvanically deposited in a further step. The semi-finished product is then back-injected, thus protecting the structure. Furthermore, from the German Offenlegungsschrift DE 10 2011 013 372 A1 a method is known in which a metallization is first applied to a semi-finished plastic product by hot stamping, then this metallization is crosslinked by an irradiation process and then reshaped. The shell structure produced is also back-injected and then equipped with electronic components and soldered. The disadvantage here is the low degree of deformation, which is limited by the metallization already applied.

In principle, three process steps are always required for all of the methods mentioned, these being the production of the conductor tracks, the assembly and the soldering. Furthermore, the circuits must always be additionally protected against media contact. In addition, large-scale metallizations are usually uneconomical.

Disclosure of the invention

1. a) Bereitstellen eines Thermoformungswerkzeugs mit zumindest einem Formteil, insbesondere einem Formteil mit einer dreidimensional geformten Oberfläche,
2. b) Aufbringen von mindestens einem Schaltungselement auf eine Oberfläche des Formteils und vorzugsweise Fixieren des mindestens eines Schaltungselements auf der Oberfläche des Formteils,
3. c) Erwärmen eines Kunststoffhalbzeugs und Auflegen und Anformen des erwärmten Kunststoffhalbzeugs an die Oberfläche des Formteils und das mindestens eine Schaltungselement,
4. d) Entformen des Kunststoffhalbzeugs, wenn das Kunststoffhalbzeug vorzugsweise eine Entformungstemperatur erreicht hat, zum Erhalt der Schaltung mit dem abgekühlten sowie entformten Kunststoffhalbzeugs und dem mindestens einen Schaltungselement.

The present invention provides a method for producing a circuit which has the advantage over the method known from the prior art that three-dimensional circuit geometries with high degrees of deformation are possible. Furthermore, assembly, structuring and contacting can be integrated in a single process and electrical or electronic components can be protected by back injection. It is also advantageous that electronic components are covered by the circuit carrier resulting from the semi-finished plastic product, in other words, are not visible from the outside. It is also advantageous that both flexible and rigid components can be produced, and thus variable wall thicknesses are possible. It is particularly advantageous about the method according to the present invention that even large components with integrated circuits can be manufactured inexpensively. The method according to the invention has the following method steps:

1. a) providing a thermoforming tool with at least one molded part, in particular a molded part with a three-dimensionally shaped surface,
2. b) applying at least one circuit element to a surface of the molded part and preferably fixing the at least one circuit element to the surface of the molded part,
3. c) heating a semi-finished plastic product and laying and molding the heated Plastic semi-finished product to the surface of the molded part and the at least one circuit element,
4. d) demolding the plastic semi-finished product when the plastic semi-finished product has preferably reached a demolding temperature, in order to maintain the circuit with the cooled and demolded plastic semi-finished product and the at least one circuit element.

The method for producing a circuit according to the present invention is particularly characterized in that simple electrical or electronic circuits can be produced inexpensively and quickly and their integration into a complex component by means of the thermoforming method. Reshaping semi-finished plastic products using thermoforming makes it possible to produce shell structures with complex shapes in a very cost-effective manner, the circuit elements being transferred to the component surface or the semi-finished plastic product. There is no additional soldering process. Furthermore, it is preferably provided that in process step c) the application and, in particular, the shaping are carried out by means of a vacuum or an overprint. By means of the present method, it is possible to implement thermoforming, for example of a housing cover, with functional integration (EMC, antenna or strain gauge) being possible, in particular by means of transfer printing.

In a development of the invention it is provided that after method step b) in method step b1) at least one conductor track is applied, in particular printed, to the surface of the molded part and / or to at least one area of a surface of the at least one circuit element. Applying the at least one conductor track means in particular application or printing and preferably drying the applied conductor track. It is particularly preferably provided that the application or printing is carried out by means of a pad printing process. Furthermore, it is preferably provided that after the at least one conductor track has been applied in accordance with method step b1) in a method step b2), the at least one printed conductor track is hardened on the surface of the molded part and / or on the at least a region of the surface of the at least one circuit element . This embodiment has the particular advantage that electrically conductive connections can be integrated into the circuit in a simple manner without having to insert them subsequently by soldering. In other words, conductor tracks and electrical / electronic components can be integrated into the circuit by means of transfer printing during the forming process. In the simplest case, the circuit can already function as a component, such as a housing cover.

In a development of the invention, it is provided that the at least one circuit element has at least one contacting element, in particular a contacting pad or contacting plate, the at least one contacting element preferably being applied to a surface of a first side of the at least one circuit element and the first side of a second side opposite, with the second side, the circuit element is in contact with the molded part. Furthermore, it is preferably provided that the at least one circuit element with the at least one contacting element is arranged on the surface of the molded part in such a way that the at least one circuit element with the at least one conductor track applied during method step b1) is electrically, in particular cohesively, by means of the at least one contacting element. is connected. It is preferably provided here that the at least one contacting element is flush with the surface of the molded part. This embodiment has the particular advantage that an electrical connection between the at least one conductor track and the at least one electrical / electronic circuit element is achieved particularly reliably.

In connection with the present invention, the term “substrate” is to be understood to mean a carrier which carries out the circuit, i.e. the at least one circuit element and the optional at least one conductor track. The substrate is formed by the semi-finished plastic product which is heated, placed on and molded on in method step c).

In a further embodiment it is provided that the at least one circuit element has at least one engaging elevation and / or depression, and in method step c) the semi-finished plastic product is placed on the surface of the molded part and the at least one circuit element is pressed, in particular pressed on, that the at least one circuit element is gripped or can be gripped behind by the molded plastic semi-finished product. This embodiment has the particular advantage that a non-positive and / or positive connection between the circuit, in particular the semi-finished plastic product, and on the other hand the at least one circuit element can be achieved.

In a further development of the invention it is provided that during hardening according to the method step b2 ) curing is activated with ultraviolet radiation. This has the particular advantage that hardening is locally selective and / or can also be carried out in a time-controlled manner.

Furthermore, it is preferably provided that in an additional method step b3 ), which after the process step b1 ) and possibly after b2 ) is carried out, the at least one conductor track is pretreated by means of a plasma and / or corona treatment. This embodiment makes it possible in particular to achieve improved adhesion of the semi-finished plastic product to the preferably dried and / or hardened conductor tracks in a simple manner. Furthermore, this form of treatment is particularly precise, ie can be controlled precisely locally, which is why particularly critical treatment can be carried out at particularly critical points, so that the adhesion can be increased in a targeted manner.

Furthermore, it is preferably provided that at least one side of the at least one circuit element, which the plastic semi-finished product is placed on and molded on according to the method step c ) facing at least one pretreatment process before the process step c ), the pretreatment process is selected from a group consisting of coating with adhesive, structuring, heating and plasma treatment. This embodiment ensures good adhesion of the circuit element to the semi-finished plastic product.

Furthermore, it is preferably provided that for the application according to the method step b1 ) a printing paste is used, which is selected from the group consisting of conductive adhesives, conductive inks, conductive varnishes, conductive screen and pad printing pastes. This has the particular advantage that printing pastes that are already available can be used, which is why the method according to the present invention can be carried out particularly easily and inexpensively.

Furthermore, it is preferably provided that the material for the semi-finished plastic product according to the method step c ) is selected from a group consisting of partially crystalline thermoplastics, amorphous thermoplastics and foam films. This has the particular advantage that appropriate materials can be selected for the semi-finished plastic product in accordance with the properties required in relation to the circuit.

In a further embodiment it is provided that the partially crystalline thermoplastics are selected from a group consisting of polyethylene (PE), polypropylene (PP), polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS) and polyether ether ketone ( PEEK). This embodiment has the particular advantage that, depending on the temperature stability or chemical stability required for the circuit, a corresponding semi-crystalline thermoplastic can be selected.

Furthermore, it is preferably provided that the amorphous thermoplastic is selected from a group consisting of polycarbonate (PC), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), polystyrene / acrylonitrile-butadiene-styrene blends (PC / ABS blends ), Polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylate copolymer (ASA) and polysulfone (PSU). This has the particular advantage that, depending on the temperature stability or chemical stability that is required for the circuit, an appropriate amorphous thermoplastic can be selected.

Furthermore, it is preferably provided that the foam films are selected from a group consisting of expanded polypropylene (EPP) and expanded polyethylene (EPE). This has the particular advantage that particularly light foam foils can be used.

In a particularly preferred embodiment, it is provided that in a further method step e), a back injection of the circuit is carried out on a circuit obtained according to method step d). This has the particular advantage that the back injection, in particular in an injection molding process, makes it possible to integrate further mechanical functions, the functions being selected from a group consisting of mechanical fastenings, in particular screw-on eyes, snap hooks, stiffeners, in particular ribbing, and film hinges. Furthermore, the function can be integrated that a simultaneous encapsulation of the electrical / electronic circuit elements is possible. Furthermore, this embodiment has the advantage that the injection molding creates a form-fitting and possibly material bond, in particular between the semi-finished plastic product and the circuit element. Furthermore, this embodiment makes it possible to integrate circuits or functional layers which are protected from media in the circuit.

The invention further relates to a circuit, produced or producible by a method according to the invention. This results in the advantages already mentioned.

Further advantages and preferred features and combinations of features result in particular from what has been described above and from the claims.

• 1 eine schematische Darstellung eines vorteilhaften Verfahrens,
• 2 eine schematische Darstellung, in welcher gezeigt wird wie ein Schaltungselement mittels des Kontaktierungselements mit der mindestens einen gedruckten Leiterbahn und dem Kunststoffhalbzeug verbunden wird,
• 3 eine mit 2 vergleichbare Ausführungsform des Verfahrens, wobei das Schaltungselement eine hintergreifbare Erhebung aufweist.

The invention will be explained in more detail below with reference to the drawing. This shows:

• 1 a schematic representation of an advantageous method,
• 2 2 shows a schematic illustration, in which it is shown how a circuit element is connected to the at least one printed conductor track and the semi-finished plastic product by means of the contacting element,
• 3 one with 2 Comparable embodiment of the method, wherein the circuit element has an elevation that can be reached behind.

1. a) Bereitstellen eines Thermoformungswerkzeugs 7 mit zumindest einem Formteil 9, vorzugsweise einem Formteil 9 mit einer dreidimensional geformten Oberfläche.
2. b) Aufbringen von mindestens einem Schaltungselement 5 auf eine Oberfläche 11 des Formteils 9 und vorzugsweise Fixieren des mindestens einen Schaltungselements 5 auf der Oberfläche 11 des Formteils 9.
3. c) Erwärmen eines Kunststoffhalbzeugs 13 und Auflegen und Anformen des erwärmten Kunststoffhalbzeugs 13 an die Oberfläche 11 des Formteils 9 und das mindestens eine Schaltungselement 5. In 1 sind die in Schritt c) durchgeführten Teilschritte Erwärmen sowie Auflegen und Anformen getrennt schematisch dargestellt. Der Teilschritt Erwärmen wird als c_TS1) und der Teilschritt Auflegen und Anformen als c_TS2) bezeichnet. Es ist aber auch möglich, dass zunächst das Kunststoffhalbezugs 13 aufgelegt wird, anschließend erwärmt und daran anschließend am die Oberfläche 11 des Formteils 9 angeformt wird.
4. d) Entformen des Kunststoffhalbzeugs 13 beziehungsweise des Substrats 3, wenn das Kunststoffhalbzeug 13 vorzugsweise eine Entformungstemperatur erreicht hat, zum Erhalt der Schaltung 1 mit dem abgekühlten sowie entformten Kunststoffhalbzeugs 13 und dem mindestens einen Schaltungselement 5.

1 shows schematically a method for producing a circuit 1 , having a substrate 3 (see process step c), in particular process step c_TS2 ) in 1 ) and at least one electrical / electronic circuit element 5 (see for example process step b) in 1 ), the method comprising the following steps:

1. a) Providing a thermoforming tool 7 with at least one molded part 9 , preferably a molded part 9 with a three-dimensional surface.
2. b) applying at least one circuit element 5 on a surface 11 of the molded part 9 and preferably fixing the at least one circuit element 5 on the surface 11 of the molded part 9 ,
3. c) heating a semi-finished plastic product 13 and placing and molding the heated semi-finished plastic product 13 to the surface 11 of the molded part 9 and the at least one circuit element 5 , In 1 the sub-steps heating, laying on and molding are carried out separately in step c). The heating step is called c_TS1 ) and the sub-step laying on and molding as c_TS2 ) designated. But it is also possible that the plastic half-cover first 13 is placed, then heated and then on the surface 11 of the molded part 9 is molded.
4. d) demolding the plastic semi-finished product 13 or the substrate 3 if the plastic semi-finished product 13 preferably has reached a demolding temperature to maintain the circuit 1 with the cooled and demolded plastic semi-finished product 13 and the at least one circuit element 5 ,

Furthermore, in 1 to recognize that after step b) in an optional step b1 ) at least one conductor track 15 to the surface 11 of the molded part 9 and / or on at least one area of a surface 17 (in 1 not shown) of the at least one circuit element is applied or printed. It is preferably provided here that the application or printing is carried out by means of a tampon printing process, with the aid of a tampon 12 the order is placed. This is preferably followed by drying and / or hardening of the at least one printed conductor track 15 on the surface 11 of the molded part 9 and / or on the at least one area of the surface 17 (in 1 not shown) of the at least one circuit element 5 instead of.

Furthermore, in 1 shown that according to process step d ) circuit obtained 1 in a further process step e ) back injection of the circuit 1 is carried out so that, for example, mechanical fastenings, in particular screw-on eyes, snap hooks, stiffeners 16 , in particular ribbing, and film hinges can be integrated into the circuit.

In method step f) after an optional back injection, a circuit is created 1 get which already as part 14 , for example as a housing cover or vehicle door 14 , can act.

Same reference numerals in 2 denote the same or similar parts as in 1 , which is why in this regard in particular to the 1 made statements.

In 2 it is further shown that the at least one circuit element 5 at least one contacting element 19 - sometimes referred to as a contacting pad or contacting plate - has, wherein the at least one contacting element 19 preferably on a surface 20th a first page 21 of the at least one circuit element 5 is applied and the first page 21 a second page 23 lies opposite, with the second side 23 the circuit element 5 with the molding 9 is in contact. Furthermore, in 2 shown that the at least one circuit element 5 with the at least one contacting element 19 like that on the surface 11 of the molded part 9 is arranged that the at least one circuit element 5 with that during the process step b1 ) at least one applied conductor track 15 by means of the at least one contacting element 19 is connected and preferably the at least one contacting element 19 flush with the surface 11 of the molded part 9 is.

The same reference numerals in the figure denote the same or similar parts as in 1 or 2 , which is why in this regard to the corresponding statements 1 or 2 is referred.

In 3 it is shown that the at least one circuit element 5 at least one behind-the-scenes survey 25th and / or depression (not shown in the figures), and in the method step c ) (see. 1 ) the plastic semi-finished product 13 so on the surface 11 of the molded part 9 and the at least one circuit element 5 is placed, or pressed or pressed, that the at least one circuit element 5 through the molded plastic semi-finished product 13 is attacked.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 19812880 A1 [0003]
• DE 102011013372 A1 [0003]

Claims (15)

Method for producing a circuit (1), comprising a substrate (3) and at least one electrical circuit element (5), comprising the following steps: a) providing a thermoforming tool (7) with at least one molded part (9), b) applying at least one circuit element (5) to a surface (11) of the molded part (9), c) heating a semi-finished plastic product (13) and placing and molding the heated semi-finished plastic product (13) on the surface (11) of the molded part (9) and the at least one circuit element (5), d) demolding the plastic semi-finished product (13) to obtain the circuit (1) with the cooled and demolded plastic semi-finished product (13) and the at least one circuit element (5). Procedure according to Claim 1 , characterized in that after method step b) in a method step b1) at least one conductor track (15) on the surface (11) of the molded part (9) and / or on at least a region of a surface (17) of the at least one circuit element (5 ) is applied. Procedure according to Claim 2 , characterized in that after the application of the at least one conductor track (15) according to method step b1) in a method step b2), hardening of the at least one printed conductor track (15) on the surface (11) of the molded part (9) and / or on the at least a region of the surface (17) of the at least one circuit element (5) is carried out. Method according to one of the preceding claims, characterized in that the at least one circuit element (5) has at least one contacting element (19), and in that the at least one circuit element (5) with the at least one contacting element (19) in this way on the surface (11) the molded part (9) is arranged such that the at least one circuit element (5) is connected to the at least one conductor track (15) applied during method step b1) by means of the at least one contacting element (19). Method according to one of the preceding claims, characterized in that the at least one circuit element (5) has at least one engaging elevation (25) and / or depression, and in method step c) the semi-finished plastic product (13) is thus applied to the surface (11) of the molded part (9) and the at least one circuit element (5) is placed such that the at least one circuit element (5) is engaged behind by the molded plastic semi-finished product (13). Procedure according to one of the Claims 3 to 5 , characterized in that in a hardening according to method step b2) a hardening activated with ultraviolet radiation is carried out. Procedure according to one of the Claims 2 to 6 , characterized in that in an additional method step b3), which is carried out after method step b1) and optionally after b2), the at least one conductor track (15) is pretreated by means of a plasma and / or corona treatment. Method according to one of the preceding claims, characterized in that at least one side of the at least one circuit element (5), which faces the semi-finished plastic product (13) during laying and molding in accordance with method step c), undergoes at least one pretreatment method before method step c), the pretreatment process being selected from a group consisting of coating with adhesive, structuring, heating and plasma treatment. Procedure according to one of the Claims 2 to 8th , characterized in that a printing paste is used for the application according to method step b1), which is selected from the group consisting of conductive adhesives, conductive inks, conductive lacquers, conductive screen and pad printing pastes. Method according to one of the preceding claims, characterized in that the material for the semi-finished plastic product (13) according to method step c) is selected from a group consisting of partially crystalline thermoplastics, amorphous thermoplastics and foam films. Procedure according to Claim 10 , characterized in that the partially crystalline thermoplastics are selected from a group consisting of polyethylene (PE), polypropylene (PP), polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyphenylene sulfide (PPS) and polyether ether ketone (PEEK). Procedure according to Claim 10 or 11 , characterized in that the amorphous thermoplastic is selected from a group consisting of polycarbonate (PC), polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), polystyrene / acrylonitrile-butadiene-styrene blends (PC / ABS blends) , Polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylate copolymer (ASA) and polysulfone (PSU). Procedure according to one of the Claims 10 to 12 , characterized in that the foam sheets are selected from a group consisting of expanded polypropylene (EPP) and expanded polyethylene (EPE). Method according to one of the preceding claims, characterized in that the circuit (1) is back-injected in a further method step e) on a circuit (1) obtained according to method step d). Circuit (1), manufactured or producible according to a method according to one of the Claims 1 to 14 ,

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