DE19736093A1 - Production of conductive metallized three-dimensional polymer article - Google Patents

Abstract

Production of conductive metallized three-dimensional polymer article involves coating with an activator containing primer, drying and at least partially leveling by filling between ribs by injection molding. Production of a conductive metallized three-dimensional polymer article comprises injection molding to give the article, coating with an activator containing primer, drying, at least partially leveling by filling between ribs by injection molding, chemically metallizing and optionally galvanizing.

Description

The present invention relates to a method for producing a in the form of Conductor tracks metallized three-dimensional plastic molding and its Ver Use as a printed circuit board in the form of an electrical or electronic housing Apparatus.

In electrical engineering, three-dimensional circuit boards win, for example wise housing parts in the three dimensions of their dimensions directly as a circuit carriers can be used are becoming increasingly important. Such housing parts with Integrated circuit boards can be manufactured using various methods. A process that is already used technically is the two-component Injection molding. Here, a metallizable plastic is ge in a first shot splashes. In a second shot, a non-metallizable plastic is so around first molded part that only the desired conductor tracks are exposed. Then the molded parts are conventional and known to the person skilled in the art metallized method, in the present case only the exposed structures of the metallizable plastic can be metallized.

This method is disadvantageous the fact that the three-dimensional housing thus produced with integrated Printed circuit boards always consist of different plastics and therefore not can be easily recycled by type.

Another method uses only one type of plastic. Here in a first shot, the conductor pattern as above made of a plastic, in previously a metallization activator, for example based on palladium, was incorporated, injected. Then the same plastic, but without Activator, so injected around the first molding in a second shot that only the conductor track image formed by the activator-containing plastic is exposed; after that is also used here in conventional metallizing baths known to those skilled in the art is working. The proportion of plastic used in the activator is not just that Surface of the molded parts, but evenly distributed in mass in the plastic. Of the The disadvantage of this method is therefore that it is uneconomically high  Amounts of catalyst. Both of these procedures are in the journal Galvanotechnik 85 (1994), p. 1314.

It has now been found that the disadvantages mentioned, due to the following described method according to the invention can be overcome.

The invention relates to a method for producing a three-dimensional plastic molded part that is metallized in the form of conductor tracks and is characterized by the method steps:

• a) Production of a three-dimensional molded plastic part by injection molding drive that with the elevated pattern in the form of ribs intermediate recesses;
• b) coating the conductor track image with one for electroless metallization suitable primer containing an activator;
• c) drying the primer;
• d) partial or complete leveling of the raised in the form of ribs with Intermediate depressions present conductor pattern through Filling the depressions between the ribs of the plastic molding by injection molding again so that the activated conductor tracks are exposed stay;
• e) chemical metallization of the activated conductor tracks; and
• f) optionally subsequent galvanic reinforcement of the chemically metalli based conductor tracks.

The invention further relates to the use of the metallized three-dimensional Plastic molded part as a printed circuit board in the form of the housing or inner part of a electrical or electronic apparatus.  

Plastic moldings in the sense of the present invention are regular or un regularly shaped molded parts, the housing or housing (inner) parts of an electri or electronic equipment. In any case, such housings wear or housing parts conductor tracks in the three dimensions of the dimensions of such Housing or housing parts. In a rectangular housing, the Conductors therefore follow the right angle; instead of the right angle any other angle. Furthermore, the conductor tracks can be any Bulges follow and so any fashionable design and technical applications combine. Such conductor tracks serve as circuits or parts of circuits of the electrical or elec accommodated in such housings or housing parts tronic apparatus. Examples of such housings that tra traces at the same time gen, are: Housings of televisions or radios, computers or telephones telephone devices of both the handset and the telephone base; further analog poss are known to those skilled in the art.

In a first step a) of the method according to the invention, the Injection molding technology produces a plastic molded part (housing or housing part), which is a conductive pattern at the intended location in the form of raised Ribs with recesses in between.

In a second method step b), these ribs, which form the conductor track image are covered with a primer suitable for electroless metallization, the contains an activator for electroless metallization. Coating the conductor web image with the primer can, for example, by printing, stamping, Dipping, painting, knife coating or spraying can be carried out.

In a further process step c) the primer is dried.

The plastic molded part treated in this way is then through for further treatment d) Injection molding technology ready, creating the recesses between the ribs of the Plastic molded part to be filled so far that the originally raised conductor web image is partially or completely leveled so that the activated  Conductors remain exposed. This shows an advantage of the invention Process in which in the coating of the conductor pattern according to Ver step b) no great care needs to be taken, since everyone next the ribs in the form of the conductor track image coated areas of the wells of the molded plastic part are covered in process step d) and thus the after following chemical metallization in the desired sense no longer available stand by.

In a further step e), the plastic molding is then everywhere where the activated traces have remained free, chemically metallized. This chemical Finally, if desired, metallization can subsequently be carried out in step f) be galvanically reinforced.

As plastics for the molded plastic parts to be metallized according to the invention are basically all that can be processed by injection molding. These are at for example: acrylonitrile-butadiene-styrene (AB S) polymers, polycarbonate (PC), their Mixtures and flame-retardant types, also polyamide (PA), at for example polyamide 6, polyamide 66, polyester types such as polyethylene terephthalate, Polybutylene terephthalate, polyethylene naphthalate, aromatic, liquid crystalline Polyester, polyvinyl chloride (PVC), polyethylene, polypropylene, polyphenylene sulfide, Polyphenylene oxide, polyurethanes, polyimides, polyamideimides, polyetherimide, poly sulfones, polyacetals, polystyrene and their copolymers or blends.

Preferred plastics for injection molding in the context of the Ver are aryl nitrile butadiene styrene copolymers, polycarbonate, polyamide, poly etherimide, polysulfones, their copolymers and blends.

These plastics and their processing by injection molding as well as the related set machines are known to the expert. For injection molding comes in Ab dependence on the softening range and the thermal resistance of the above Plastics in the general range of 150 to 400 ° C in question. A lot of this art substances can also be used as matrix formers described below; It is now  advantageous, plastics for injection molding and those used as matrix formers to coordinate that they have comparable thermal resistance.

The width of the ribs on the plastic molded parts is very variable and ranges from about 100 µm to a few centimeters (e.g. 5 cm), preferably from 200 µm to 5 mm. The distance between the ribs is also very variable and ranges from 100 microns up to a few centimeters (z. B. 5 cm), preferably from 200 microns to 1 cm, be particularly preferably from 400 μm to 0.8 cm. The depressions between the ribs have a size of 200 µm up to a few centimeters (e.g. 5. cm), preferably from 500 µm to 1 cm, particularly preferably from 1 mm to 0.8 cm. With the second injection molding Step 2) the wells can be completely filled so that the ribs are out the injection molding a) with the conductor tracks and the plastic of injection molding d) full are always on one level. But it is equally possible, the deepening only partially fill up so that the ribs are still, but at a lower height than previously, are shown.

The primer consists essentially of (i) a polymer as a film or matrix formers, (ii) a metallization catalyst (activator), (iii) optionally orga African and / or inorganic fillers, (iv) other stocks if necessary share and (v) solvents.

Depending on the solvent system (organic or watery) various in question. For primers with an organic solution agent systems may be mentioned, for example: paint systems, such as alkyd resins, unsaturated Polyester resins, polyurethane resins, epoxy resins, modified fats and oils, polymers sates or copolymers based on vinyl chloride, vinyl ether, vinyl ester, styrene, (Meth) acrylic acid, acrylonitrile or acrylic esters, cellulose derivatives or those at higher Temperature-curing stoving enamels, such as polyurethanes hydroxyl-containing polyethers, polyesters or polyacrylates and capped Polyisocyanates, melamine resins from etherified melamine-formaldehyde resins and hydroxyl-containing polyethers, polyesters or polyacrylates, epoxy resins Polyexpoxides and polycarboxylic acids, carboxyl-containing polyacrylates and polyesters containing carboxyl groups, stoving lacquers made of polyesters, polyesterimides,  Polyester amide imides, poly amide imides, polyamides, polyhydantoins and polypara bic acids.

Film or matrix formers based on polyurethane systems that are made up of the following components are particularly suitable:

• 1. Aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyc lische Polyisocyanate, as for example in Justus Liebigs Annalen der Chemie, 362, pp. 75-136. Are particularly preferred in usually the technically easily accessible polyisocyanates, for example that 2,4- and 2,6-tolylene diisocyanate and mixtures of these isomers (TDI); Poly phenyl-polymethylene-polyisocyanates such as those obtained from aniline-formaldehyde con densation and subsequent phosgenation are produced (MDI) and Carbodiimide groups, urethane groups, allophanate groups, isocyanurate polyisocyanates containing groups, urea groups or biuret groups.
• 2. Compounds with at least two isocyanate-reactive Hydrogen atoms with a molecular weight usually from 400 to 10,000, preferably 1000 to 6000, particularly preferably 2000 to 6000. Reactive hydrogen atoms are those from amino groups, thiol groups, carboxyl groups and preferably hydroxyl groups.
• 3. If necessary, further compounds with isocyanate-reactive capable hydrogen atoms, which can serve as chain extenders, and Auxiliaries and additives, such as catalysts, surface-active additives and Response delay. Such polyurethanes are known and for example in EP-485 839.

In the case of primers with a predominantly or completely aqueous solution In principle, all dispersible polymers come, for example Polyacrylates, polybutadienes, polyesters and melamine resins, in question. Prefers Polyurethanes or polyurethane ureas, such as those used in the  Angewandte Chemie 82, 1970, pp. 53-63, in DE-A 23 14 512 or DE-A 23 14 513 are described. Particularly preferred dispersible polyurethanes have essentially a linear molecular structure and are characterized by a) end permanent polyalkylene oxide polyether chains containing ethylene oxide units 0.5 to 10 wt .-%, based on the total polyurethane, and b) a content of quaternized nitrogen, tertiary sulfur, carboxyl groups or sulfonic acid groups of 0.1 to 15 milliequivalents per 100 g. The composition of such be Preferred dispersible polyurethanes and their manufacture are also known and described for example in DE-A 2 651 506.

Ionogenic and / or colloidal noble metals or theirs come as activators organometallic covalent compounds or complex compounds with orga African ligands in question. The precious metals come from subgroups I and VIII of the Periodic Table of the Elements (Mendeleev) and are for example Pd, Pt, Au and Ag.

Organic and / or inorganic fillers for such primers are, for example Oxides of the elements Mn, Ti, Mg, Al, Bi, Cu, Ni, Sn, Cn and Si, also silicates, Bentonite, talc and chalk. Individual examples are still: Powdered high melting plastics, disperse silica, Russian, other carbon powders, Clay minerals, titanium oxide.

Solvents for primers which can be used according to the invention are those used in printing or Painting technology known substances, such as aromatic and aliphatic carbons hydrogen, for example toluene, xylene, gasoline; Glycerin; Ketones, for example Methyl ethyl ketone, cyclohexanone; Esters, for example butyl acetate, phthal acid dioctyl ester, glycolic acid butyl ester; Glycol ethers, for example ethylene glycol monomethyl ether, diglyme, propylene glycol monomethyl ether; Esters of glycol ethers, for example ethylene glycol acetate, propylene glycol monomethyl ether acetate; Diacetone alcohol, N-methylpyrrolidone, N-methylcapolactan. Of course can also use mixtures of these solvents and their blends with others Solvents are used.  

In the case of aqueous-based primers, water is alone or a mixture of Water with water-soluble solvents can be used. Miscible with water Examples of solvents are alcohols, such as methanol, ethanol, propanol, Butanol; Ketones such as acetone, methyl ethyl ketone, cyclohexanone; Glycol ethers, like Ethylene glycol monomethyl ether, diglyme, propylene glycol monomethyl ether; water soluble ethers such as tetrahydrofuran, dioxane.

Other constituents for the primers are, for example, surfactants, leveling agents, ent foaming agents and dyes in small concentrations up to 5% by weight, preferably up to 2% by weight, based on the total amount of primer. Such ingredients are basically known to the expert.

Examples of such primer formulations are in EP-A 48 58 39 and EP-A 50 33 51 described.

Preferred primers based on organic solvents consist essentially of, for example

• a) a film or matrix former in an amount of 3-30% by weight,
• b) an ionogenic and / or colloidal noble metal or its organo-me metallic covalent compounds or complex compounds with orga African ligands in an amount of 0.05-2.5% by weight, calculated as metal,
• c) organic and / or inorganic fillers in an amount of 0.5-35% by weight and
• d) organic solvents in an amount of 50-90 wt .-%, all based on the total amount of primer.

In a particularly preferred manner, such primers are based on organic solvents with an additional content of

• e) an organic polymeric or prepolymeric additive with a molecular weight 500-20,000 from the group of polyoxazolines, polymethacrylic acid or their esters, polyacrylates, polyamides, polyesters, polyalcohols and poly amines in an amount of 0.1-15 wt .-%, based on the total formu the primer.

Preferred primers based on aqueous formulations consist essentially of

• a) a water-dispersible polymer, preferably a poly urethane, in amounts of 5-60% by weight, preferably 15-45% by weight,
• b) a metallization catalyst in the form of an ionic or complex Precious metal compound in amounts of 0.02-3.5 wt .-%, preferably 0.05-0.5% by weight,
• c) optionally fillers in amounts of 0-70% by weight, preferably 5-35% by weight,
• d) if necessary, other constituents of the type mentioned in quantities of 0-5 wt .-%, preferably 0-2 wt .-% and
• e) water in amounts of 20-88% by weight, preferably 25-50% by weight, each based on the total amount of the primer.

Optionally used water-soluble organic solvents of the ge named type replace a maximum of 1/3, preferably a maximum of 1/4, particularly preferred maximum 1/10 of the stated amount of water.

The layer thickness of the primer can range from 0, 1-200 µm before trains can be varied in the range of 5-50 µm. For solvent-based primers there is a particularly preferred range of 5-30 µm; for aqueous primers particularly preferred range of 10-50 µm. After the primer has dried  at 0 to 250 ° C, preferred and depending on the plastic used 50 to 200 ° C, the dry layer thickness of the primer is about half the layer thickness of the wet applied primer. The drying time depends on the applied temperature between a few minutes and several hours, preferably between 5 and 90 minutes.

After drying, the plastic molding is used to level the raised conductor tracks again using injection molding technology with the same plastic treated like the first spraying around the rib-shaped raised conductor tracks level. This leaves the one applied to the highest points of the ribs Primer on the surface and is available for subsequent chemical metallization Available while roughly on the flanks of the ribs or the original reason of the plastic molding between the ribs primer placed by the second Injection molding is covered and can not be metallized, so short conclusions between the individual conductor tracks can be reliably prevented. It is an advantage adheres to organic solvents or water before the second injection molding process remove the primer carefully by drying to remove any blistering to avoid in the second injection molding process.

The metallization baths used for electroless metallization are on the market common and known to the expert. Suitable for the production of the conductor tracks Metals are, for example, Cu, Ni, Ag, Au, Pd, preferably Cu.

In the event of a subsequent galvanic reinforcement of the chemically metal lized conductor tracks, the metal layer thickness can be increased up to 500 µm Question.

Examples example 1

An aqueous-based primer solution 1 was prepared by combining 26% by weight of a water-dispersible polymer based on an essentially linear aliphatic polyurethane containing polyether groups with carboxyl groups and sulfonic acid groups, 1% by weight AgNO ₃ , 30% by weight. % Talc and TiO ₂ and 43% by weight water, all based on the total weight of the aqueous primer.

Example 2

A primer solution II based on organic solvents was prepared by combining 5% by weight of a polyurethane composed of poly [(butanediol adipate) - (neopentylglycol)] and 4,4-diphenylmethane diisocyanate, 0.5% by weight. AgNO ₃ , 10% by weight of talc and TiO ₂ , 82.85% by weight of solvent mixture of diacee alcohol, i-propanol and toluene, 1% by weight of a polyamide hot melt adhesive and 0.65% by weight of wetting agent and Dyes.

Example 3

From an acrylonitrile-butadiene-styrene copolymer, a ge curved track structure made with raised ribs. On the so produced The metallizable primer solution I from Example 1 was sprayed onto the molded part. The The layer was dried at 70 ° C. for 60 minutes and gave a dry layer thickness about 9 µm. Thereafter, the molded part with the same copolymer in the Overmoulded that only the desired conductor structure with the metallizable primer layer I exposed. Thereafter, with a chemical copper bath (from Shipley, type CP 78) metallized at 43 ° C. The Copper thickness of the conductor tracks was 2 µm; after galvanic amplification to 35 µm Copper had an adhesive strength of 0.8 N / mm.  

Example 4

The copolymer used in Example 3 again became a curved one Circuit structure with raised ribs made by injection molding. On the Ribs of the molded part produced in this way became the metallizable primer solution II Example 2 sprayed on. After drying for 70 min at 70 ° C, a Dry layer thickness of approximately 18 µm. The sprayed primer solution II was on also in the recesses between the conductor ribs. Then that was Injection molded part with the same copolymer in such a way that only the Desired trace structure with the primer solution II on the surface free day. Thereafter, the same chemical ver copper bath as in Example 3 metallized at 43 ° C. The thickness of the copper layer was 3 µm; after galvanic reinforcement on 35 µm copper an adhesion became Strength of the conductor tracks measured at 0.8 N / mm.

Claims (10)

1. Process for producing a three-dimensional molded plastic part metallized in the form of conductor tracks, characterized by the process steps:

• a) production of a three-dimensional plastic molded part using the injection molding process, which carries the conductor track image in raised form in the form of ribs with recesses in between,
• b) coating of the conductor track image with a suitable for the electroless metalization containing an activator primer;
• c) drying the primer;
• d) partial or complete flattening of the raised conductor pattern in the form of ribs with intervening depressions by filling the depressions between the ribs of the plastic molding by renewed injection molding, so that the activated conductor tracks remain exposed;
• e) chemical metallization of the activated conductor tracks; and
• f) optionally subsequent galvanic reinforcement of the chemically metallized conductor tracks.

2. Use of the metallized three-dimensional plastic molding as Printed circuit board in the form of the housing or inner part of an electrical or electronic apparatus. 3. The method according to claim 1, characterized in that as plastics for Injection molding acrylonitrile-butadiene-styrene polymers, polycarbonate, polyamide, Polyester, polyvinyl chloride, polyethylene, polypropylene, polyphenylene sulfide,  Polyphenylene oxide, polyurethanes, polyimides, polyamideimides, polyetherimide, Polysulfones, polyacetals, polystyrene, their copolymers or blends before adds acrylonitrile-butadiene-styrene polymers, polycarbonate, polyamide, poly etherimide, polysulfones, their copolymers or blends are used. 4. The method according to claims 1 and 3, characterized in that the ribs a width of 100 microns to 5 cm, preferably in a width of 200 microns to 5 mm can be produced. 5. The method according to claims 1, 3 and 4, characterized in that the Ribs with a distance of 100 µm to 5 cm, preferably with a distance of 200 microns to 1 cm, particularly preferably 400 microns to 0.8 cm getting produced. 6. The method according to claims 1 and 3 to 5, characterized in that the Indentation between the ribs with a dimension of 200 µm to 5 cm before pulls 500 microns to 1 cm, particularly preferably 1 mm to 0.8 cm become. 7. The method according to claims 1 and 3 to 6, characterized in that the Primer after step b) from (i) a polymer as film or matrix former, (ii) a metallization catalyst as an activator, (iii) optionally organic or inorganic fillers, (iv) other stocks if applicable share and (v) solvents. 8. The method according to claims 1 and 3 to 7, characterized in that those are used as primers which consist essentially of

• a) a film or matrix former in an amount of 3-30% by weight,
• b) an ionogenic and / or colloidal noble metal or its organometallic covalent compounds or complex compounds with organic ligands in an amount of 0.05-2.5% by weight, calculated as metal,
• c) organic and / or inorganic fillers in an amount of 0.5-35 wt .-% and
• d) organic solvents in an amount of 50-90% by weight, all based on the total amount of primer,

which preferably have an additional content

• e) an organic polymeric or prepolymeric additive with a molecular weight of 500-20,000 from the group of polyoxazolines, poly methacrylic acid or their esters, polyacrylates, polyamides, polyesters, polyalcohols and polyamines in an amount of 0.1-15 wt .-%, based on the total formulation of the primer.

9. The method according to claims 1 and 3 to 7, characterized in that those are used as primers based on aqueous formulations, which consist essentially of

• a) a water-dispersible polymer, preferably a polyurethane, in amounts of 5-60% by weight, preferably 15-45% by weight,
• b) a metallization catalyst in the form of an ionic or complex noble metal compound in amounts of 0.02-3.5% by weight, preferably 0.05-0.5% by weight,
• c) optionally fillers in amounts of 0-70% by weight, preferably 5-35% by weight,
• d) optionally other constituents of the type mentioned in amounts 0-5% by weight, preferably 0-2% by weight and
• e) water in amounts of 20-88 wt .-%, preferably 25-50 wt .-%, each based on the total amount of the primer.

10. The method according to claims 8 and 9, characterized in that as a film or Matrix former a polyurethane is used.