DE2160821A1 - PROCESS FOR THE DEPOSITION OF COPPER LAYERS ON MOLDED BODIES MADE OF POLYIMIDES - Google Patents

Description

2080 FP-Dr.N.-ur 29 November 1971

Description for registering the

KALLE AKTIENGESELLSCHAFT Wiesbaden-Biebrich

for a patent

Process for the deposition of copper coats on molded articles made of polyimides

The invention relates to a method for deposition firmly adhering copper layers on molded articles made of polyimides. -

It is known. Molded body made of electrically non-conductive Plastics, ζ. B. made of polystyrene, acrylonitrile-butadiene-styrene copolymers (ABS plastics), polyolefins and polyesters, if necessary after suitable pretreatment, electroless or galvanically provided with thin metal coatings.

309825/0940

In particular, a method has proven itself in which a very thin layer is formed on the plastic surface Precious metal nuclei are deposited by treating the surface with a precious metal salt solution sensitized and activated with a solution of a reducing agent. Leave on the precious metal germs coherent metal layers are then deposited by means of chemical or galvanic metallization baths,

|. Such a pretreatment can be carried out, for example,

by first treating the surface with a palladium salt solution, e.g. B. PdCIp, and then with a hydrazine hydrate solution treated. Small amounts of elemental palladium are deposited on the surface. .

In order to firmly anchor the metal layers to be applied later, it is customary to use the plastic surface before the mentioned pretreatment mechanically or preferably chemically roughening. With ABS plastics

the chemical roughening z. B. with more concentrated Sulfuric acid, which can also contain an oxidizing agent, carried out.

309825/0940

In the older patent application P 20 62 215.5 is already a method for the deposition of metal layers on molded bodies made of polyesters has been proposed, in which the surface of the Pormkörpers

a) sensitized with a precious metal salt solution, if necessary

b) activated with a reducing agent and

c) with a metal _{salt solution a} Z ₉ B. a copper salt solution, chemically metallized

the order of a) and b) can be reversed. This is the first of the steps a) and b) or each of both steps or at least step a) carried out with a solution, which additionally contains a halogenated fatty acid, preferably trichloroacetic acid, and the shaped body directly after treatment with the solution containing halogen fatty acid, dried with heating.

If the previously known metallization processes are applied to the copper-plating of polyimide moldings, in this way no firmly adhering coatings are obtained.

982570940

The object of the invention was to find a method after which one can also deposit firmly adhering copper layers on molded bodies made of polyimides.

The invention is based on the older method for depositing copper layers on shaped bodies .Plastics, in which the surface of the molded body

Sl) sensitized and with a solution of a noble metal salt and a halogenated fatty acid

b) activated with the solution of a reducing agent and

c) chemically metallized with a copper salt solution,

whereby the order of a) and b) are reversed can, and in which the shaped body is dried with heating immediately after step a).

The method according to the invention is characterized in that that a molded body made of a polyimide is used.

It has thus been found that certain embodiments of the prior process for metallizing Polyester moldings-also for copper plating of poly-

30982S / 0940

Imide molded bodies · can be used. The implementation of the The method according to the invention is therefore carried out - apart of the restrictions that emerge from the definition above - largely analogous to that Older registration procedure.

The polyimides whose surface can be metallized according to the invention are essentially all high molecular weight condensation products of aromatic diamines with aromatic dianhydrides Tetracarboxylic acids into consideration. Examples of suitable aromatic diamines are 4,4'-diamino-diphenylpropane, 4,4'-diamino-diphenylmethane, benzidine, 4,4'-diamino-diphenyl sulfide, 4,4'-diamino-diphenyl sulfone, 4,4'-diamino-diphenyl ether, m-phenylenediamine, p-phenylenediamine and the like. More.

The reactants are, for. B. the dianhydrides of the following tetracarboxylic acids are suitable: 2,3,6,7-naphthalenetetracarboxylic acid, 3j3 ^f , 4,4 '-. Diphenyltetracarboxylic acid, bis- (3,4-dicarboxy-phenyl) -propane, bis- (3,4 -dicarboxyphenyl) ether and pyromellitic acid.

'30982670940-

Chlorinated acetic acids, preferably trichloroacetic acid, are used as halogenated fatty acids. However, it is 2,2,3-trichloropropionic acid or trifluoroacetic other halogenated fatty acids, Z ₀ B. be used.

The treatment solution, which contains the halo fatty acid, preferably contains water as solvent,

||, The solvent can also consist of organic liquids, z. B. acetone, butanone, or their mixture with water.

The halogenated fatty acid, in particular trichloroacetic acid, in the noble metal salt solution can vary widely. In general, solutions of about 5 to 25% by weight, preferably 10 to 15% by weight, are used. _} used.

The precious metal salts are the salts of platinum, palladium, gold or silver. May% _t preferably between ¹ 0.005 and 0.5 wt .- ^, are present -. The palladium chloride in concentrations of between 0.001 and 5 percent is preferably used.

309825/09

Tin-TI-chloride is usually used as the reducing agent, but organic reducing agents can also be used, ζ. B. hydrazine hydrate can be used. Tin (II) chloride is used in hydrochloric acidic aqueous solution in concentrations between 0.1 and 10 wt .- ^, preferably from 0.5 to 5 wt .- ^, hydrazine hydrate in alkaline aqueous solution in concentrations between 0.1 and 5 % _{By weight 3,} preferably from 0.5 to 1% by weight .

Both the noble metal salt solutions and the reducing agent solutions left at room temperature for 10 seconds to 10 minutes, preferably 30 seconds act for up to 3 minutes.

Before the sensitization or activation of the polyimide moldings these are expediently subjected to cleaning or superficial hydrolysis in order to ensure uniformity To achieve wetting by the treatment solution. The cleaning can be carried out in a known manner with organic Solvents, acids or alkalis.

'% Chromic acid, 30 to 60 wt - - to be particularly convenient treatment has proved with a xväßrigen solution containing 1 to 5 wt..% Phosphoric acid and

3 0 9825/0940

% Of sulfuric acid contains - 30 to 50 wt.. The bath temperature is between 50 and 80 ° C. The exposure time is 5 to 15 minutes.

The acid is rinsed off after the treatment, and the chromic acid residues still adhering to the polyimide body surface are expediently removed with an alkaline sodium thiosulphate solution. This creates a uncontrolled local reaction of the noble metal salt "with adhering chromic acid residues when the

Sensitization solution avoided.

All types of rigid, z. B. manufactured by injection molding, moldings from polyimides into consideration. But it can also z. B. Fibers, threads and foils made of polyimides are copper-plated by the process according to the invention «. In particular in the case of copper-plated foils, which are widely used industrially, this is the one according to the invention A method of particular advantage since, of course, a metal layer adheres to flexible foils poses greater problem than with rigid moldings.

309825/0940

Substances which improve the wetting ability are preferably added to all of the treatment solutions described in a known manner in order to achieve the most uniform possible effect. The sensitizing solution used according to the invention and containing halogen fatty acid is added a small amount, e.g. B. 0 _Ä 01 to 2% _{t of} a water-soluble high molecular substance, e.g. B. polyvinyl alcohol added. The wetting agent content of the solution can generally be about 0.1 to 5 % . If a hydrazine hydrate or tin IT.chloride solution is used as the activating solution, no wetting agent needs to be added to this solution.

After applying the halogen fatty acid containing Sensitization solution becomes the molded body at increased Temperature dried. It is essential that the temperature of the treated surface when using a palladium salt solution containing halogen fatty acid does not exceed 150 ° C. j im 120 to 130 ° C. are generally used. The drying should not be done too quickly, as it appears a certain exposure time for the treatment solution

309825/094

"-Τη -

elevated temperature is required to achieve good adhesion of the copper layer on the substrate. The tracking time can generally be 1 to 3 minutes, e.g. B. 2 minutes. Drying can be in hot air _s can also be done under infrared lamps.

After the deposition of noble metal nuclei on the surface of the polyimide molded body, the copper can P on the surface of the polyimide molded body from a reducing agent-containing copper salt bath electrolessly to be deposited.

After a copper film thickness in the order of O, Z to 0 _a 3 / um has been reached, the further reinforcement can be made of Kupferschieht galvanic or currentless again in known manner.

. The conditions and working method for the described Metallization steps are known per se and not Subject of the present invention ..

After he inventive method, firmly adhering copper layers can be applied to part of the surface or on the entire surface of the body of the mold.

to be brought. So foils z. B. be copper-plated on one and both sides. The adhesion of the copper layer on the substrate increases in the first time after the metal deposition and reaches after 1 to 3 days their final maximum value «,

For galvanic reinforcement of about 0.2 to 0.3 µm thick copper layers deposited according to the invention electroplating baths with and without the addition of leveling and smoothing agents are suitable. The copper deposition In the electroplating baths, current densities between 0.1 and 2 A / qdm occur, the electroplated Copper layers adhere together with the electroless deposited Bottom layer firmly on the polyimide base.

The copper layers obtained according to the invention adhere so firmly on the surface that they, even if the copper-plated moldings have been in a steam bath for weeks stored in a saturated atmosphere, retain their good adhesion.

Is a polyamide film using the same treatment process subjected like the film treated according to the invention, however, the noble metal salt solution is not

3Q982-B / 0940

Halogen fatty acid is added, then either in the electroless bath there is no copper deposition at all (if the foil has been treated first with palladium chloride and then with reducing agent) j or es copper is deposited in the electroless bath (if the foil has been treated first with reducing agent and then ■ with palladium chloride), but after Reinforcement of the electrolessly deposited layer in the

ψ In the galvanic bath, the reinforced copper layer can be easily separated from the base. In air saturated with water vapor, the adhesion of the galvanically reinforced layers then decreases sharply within three days.

Because of the extremely good heat resistance of the polyimide foils, copper-plated polyimide foils z. B. used for the production of printed circuits. You can use the galvanic Copper reinforced foils or emanating from the foils, which are only the electrolessly deposited thin copper layer wear.

The method of the invention is illustrated by the following

■ Examples explained. Percentages are if nothing otherwise indicated, percentages by weight.

3 09 825/0940

example 1

A 100 .mu.m thick polyimide film made from the polycondensate of diaminodiphenyl ether and pyromellitic dianhydride was bathed for 7 minutes in an aqueous solution at 70 ° C. which contained 1.7 % chromic acid, 49.0 % phosphoric acid, 40.0 % sulfuric acid and 9 contained> 3 % water and 0.005 % perfluorooctanecarboxylic acid as a wetting agent.

The film was rinsed with water for 1 minute and bathed for 5 minutes in a 40 ° C. aqueous solution containing 3 % sodium hydroxide and 1 % sodium thiosulfate. '

The film was again sprayed with water for 1 minute and then bathed for 30 seconds at room temperature in an aqueous solution containing 0.15 % palladium chloride, 0.25 % hydrogen chloride, 0.5 % polyvinyl alcohol with a K value of 30 and 12 % residual acetyl group content ( Mowiol N 30-88 from Farbwerke Hoechst AG), 0.4 % sodium dodecylbenzenesulfonate and 13 % trichloroacetic acid. '■■ ·. ·

The bathed film was dried at 130 ° C. for 2 minutes. The dried film was bathed for 30 seconds at room temperature in an aqueous solution containing 0.6 %

309825 / 09AO

- IJLf -

Hydrazine hydrate and 1.25 % sodium hydroxide. The foil was sprayed off and placed in a 49 ° C electroless copper bath for 2 minutes, which had the following composition:

6.2 g CuSO ₄ . 5 H ₂ O

0.1 g NiSO ^. 7 H ₂ O 15 g formaldehyde 18.5 g sodium hyposulfite 13.5 g sodium hydroxide

6 g sodium tartrate

8.5 g of N, N-, N ¹ , N ^t -Tetra- (2-hydroxypropyD-ethylenediamine

0.25 g adduct of ethylene oxide with isopropanol, made up to 1 liter with water.

On the film surface an O, 29 ^micron thick copper layer was deposited. When a cross pattern of fine lines about 1 mm apart was carved into this with the razor blade and then the

Pattern was pasted over with a pressure-sensitive adhesive tape, peeled off with a jerk no copper from the surface of the adhesive tape.

3 09825/094

The copper layer was applied at room temperature in the following electroplating bath at 1 A per square decimeter Current density increased to 30 µm in 3 hours.

Bath composition:

250 g CuSO ^. 5 H ₂ O

50 g sulfuric acid (98 $ ig), made up to 1 liter with water.

For peeling off the copper layer from a 1 cm wide foil strip of the polyimide film was in the peel test DIN 40 802 a pull-off force cannot be measured, since the Try to separate the copper foil from the polyimide foil, it split before the copper layer tore.

If the electrodeposited copper layer only 10, in order to be strong, it could not be detached from the base either,

Example 2

The as in Example 1 defatted and treated with alkaline Natriumthiosulfi-t-purged solution film was initially for 5 minutes at room temperature in solution einer.wäßrigen activated, the 0.5 wt -.%

309 8 2 5/0 9AO

Tin-II-chloride and 0 ,? Wt .- ^ hydrogen chloride contained. .

The film was rinsed with water for 1 minute, then bathed at room temperature for 30 seconds in an aqueous solution containing 0.15 % palladium chloride. 0.25 % hydrogen chloride, 0.5 % polyvinyl alcohol as in Example 1, 0.4 % sodium dodecylbenzenesulphonic acid and 13 % trichloroacetic acid. The bathed film was dried at 130 ° C. for 2 minutes. It was placed in the 49 ° C. copper bath of Example 1 for 2 minutes.

The copper layer thickness was 0.24 μm. The layer inseparably adhered to the one described in Example 1 Adhesive tape test,

The galvanic reinforcement of this layer was carried out as in Example 1 up to a layer thickness of 30 μm

^ψ carried out.

The same procedure as in Example 1 was used to remove the copper layer a force not measurable.

309825/094

If the galvanically deposited copper rachieirl Üür lOyUrii was strong, left them sidh 'vöfi the documents flees solve i

example 3

8 Pdlyiiiiidfoiien would be treated in the manner described iri deri Öeispi§ie'fi ^ 2;

The table shows the tersüejBs'grgebMsse 'in the order of the Sensibiiisierun'is'-iJÖstirig äj and the Redüktiohs-Dösüh'g b) iiiit ttn'd öh'rie ¹ additions of ¹ triehlöressigsäure (TCBj to the ijösüh'geh ^: a ) ilrid 'bj.

1- = copper ate see idüfigeri ifli stroiiilbäert Mpferbad (Ö | 2 to 0 ^ 3 vtini) and liability of the currentless apart from copper heights *

B = reinforcement 'der Seiicht i ifü gäiMfiiSe'iriifi' copper bath "on iÖ pM üfid Hlf ^ üni dei? Vefstarkkteö KÜp'ferseiiieiili

BAD ORiGINAL

- 10 -

I from e 11 e

search 1 * step 2i step Ä B. i Pälladiüiri- Tin-il-chiorid no ___ chTöi'id. or hydrazine Cu-Abschei- hydrate manure ii Tin-ii- Palladittm CÜ-Äbschei- trenii- ehiorid desolate chiörid poorly more 'or' bear' Hydr'äzih- less treriii- hydrate bear iii Pa-liädiüüi- Zinri-ii-chidrid Cti-abschei- itrttr'enn- ähldrid / TCE . dreary hydraulic fertilize fear hydrate - inseparable ΐν Zihh-il- Paliadiiim- Cü-separation ün'trerih- chiörid ode'r öhlOrid / TÖE. dting bar Hydration Urit racing bear Hydrate if. Päiiädiüin- Ziriri ^ li- keiüä Θιί- M ^ H -eniörid chiör ^; id / $ Ci Äbsöhe idttilg VT Zirin-Ii- Päiiädiiüä- tr'enii- efiidr ^; id / Töi öhidrid ' cjiing Bear' trerihb'är

fit Pallädiiiifi-

Zififi ^ li- k & irie cü-

siiiQr'id / TCE Päiiäditini-

Üü ä ö ^ B / Ü 9 u ü

scrawny

tr'Önfi-

BATH ORIGINAL

Inseparable liability is only achieved as.Q if when the trichloroacetic acid alone is the palladium chloride solution is added.

3U ^ 825/0940

Claims (6)

Patent a η s ρ r ü c h e IJ Process for the deposition of copper layers on molded articles made of plastics in the. one the surface of the molding a) with a solution of a noble metal salt and ^ sensitized to a halogenated fatty acid and b) activated with the solution of a reducing agent and c) chemically metallized with a copper salt solution, where the order of a) and b) can be reversed, and in which the molded body is immediately after the step a) drying with heating, characterized in that a molded body made of a polyimide | used. 2. The method according to claim 1, characterized in that that the halogenated fatty acid is trichloroacetic acid used. 3. The method according to claim 2, characterized in that the trichloroacetic acid in aqueous Solution used .. 3U9825 / 094Q. 4. The method according to claim 3, characterized in that a solution is used which contains 5 to 25 wt -% trichloroacetic acid contains.. 5 · Method according to claim 1, characterized characterized in that a palladium salt is used as the noble metal salt. 6. The method according to claim 5, characterized in that one uses a Pallädiumehloridlösung containing 0.005 to 0.5 wt -.% of palladium chloride. 7 ·. Method according to claim I ₉ thereby characterized in that the .Drocknung at a below 150 ° C temperature. 9825/0940 ORiGlNAL INSPECTED