DD283580A5 - METHOD FOR PRODUCING CONTACTED UNIT OR MULTIPLE PCBS AND CONTACTING ONE OR MULTIPLE PCB - Google Patents

Abstract

The invention relates to a method for producing through-contacted single or multilayer printed circuit boards and a plated-through single or multi-layer printed circuit board. A method is described for producing plated-through single- or multilayer printed circuit boards based on a polymeric support material or ceramic optionally provided on both sides with at least one electrically conductive layer by galvanic or electroless plating of a metal layer even on the surfaces which are not coated with a conductive metal layer characterized in that a) the surface of the carrier is pretreated in an oxidizing solution, b) after removal of the solvent residues by rinsing the carrier is brought into a solution containing at least one monomer, in particular pyrrole, furan, thiophene or derivatives thereof, which is electrically conductive in polymeric or copolymeric form, c) the carrier is brought into an acidic solution, wherein an electrically conductive polymre layer, in particular of polymerized or copolymerized pyrrole, furan, thiophene or derivatives thereof ausbi whereupon, if appropriate, residual solvents are removed by rinsing and metallized galvanically or without external current. {through-plated single-layer or multilayer printed circuit board; polymeric carrier material; ceramics; galvanic or electroless application of a metal layer; monomer; Solution residue; Do the washing up}

Description

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Process for the production of plated-through single or multilayer printed circuit boards and plated-through single or multilayer printed circuit board

Field of application of the invention

The present invention is a process for the preparation of plated-through single or multilayer printed circuit boards based on a optionally provided on both sides with at least one electrically conductive layer polymeric carrier material or ceramic by galvanic or electroless plating a metal layer on the surfaces not with a conductive metal layer are coated, and the circuit boards themselves.

Characteristic of the known state of the art

Through-printed circuit boards have hitherto been produced essentially by chemical metal deposition on catalytically activated surfaces of a carrier material. Also multilayer printed circuit boards (multilayer) are produced in this way. The electrolessly deposited metal layers are then optionally reinforced by electrodeposition. This technology allows the production of high quality printed circuit boards. The catalytic activation of the surface is generally carried out by means of noble metal-containing, colloidal, ionic or nonionic catalysts, in particular based on palladium and tin. However, non-noble metal-containing systems, for example based on copper, can also be used. In special cases, the use of physically applied, for example, vapor-deposited, catalytically active layers is known.

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The methods are in the relevant literature, for example Hermann, Handbuch der Leiterplattentechnik, Bugen G-. Leuze Verlag, Saulgau described. In the case of wet-chemical catalysis by means of noble metal-containing or non-noble metal-containing systems, the following procedure is generally used:

1. Cleaning / conditioning

2. coils

3. Activate / etch

4. Rinse

5. Pre-dip solution

6. Applying the catalyst ^э 7. Rinse

8. Addition of an accelerator / reductor

9. Rinse again

10. External electroless metallization

11. Rinse

12. Dry

The quality of the germination (catalysis) and thus the quality of the end product is very much dependent on the pre-treatment methods that precede the catalysis. This is especially true for the conditioning, in which on the one hand the surfaces are cleaned, on the other hand the borehole walls are prepared for the following catalysis. The preparation is carried out by means of special surfactants which cover the entire surface.

gene and have the distinct property of adsorbing the catalyst nuclei. The application of the catalyst is followed by a treatment corresponding to the system, which either removes interfering by-products of the catalytic treatment or converts the catalysts applied in the catalyst into their catalytically active form. Subsequently, the electroless metallization takes place. In general, copper is deposited. Even slight deviations from the prescribed process parameters in one of the process steps usually lead to faulty metallization, so that the end product is useless in many cases.

A major disadvantage of these catalyst systems is accordingly the dependence of the seeding density on the pretreatment, the particle size and the post-treatment step. The higher the seeding density, the better the initial deposition rate or the density of incipient electroless coppering, which is equivalent to high throughput quality. However, there are very easily defects, in the jargon so-called "voids", which greatly reduce the Durchkontaktierungsqualität or make the PCB unusable. But even under optimal conditions, a completely dense nucleated surface can not be achieved. In addition, the existing catalyst systems are susceptible to introduced foreign ions. This will both the reproducibility of their operation as

also severely impaired their stability. Another disadvantage of noble metal-containing catalyst systems is the high price of the metals used.

The state-of-the-art technology using electroless plating, which is optionally enhanced by electrodeposition, has, despite its widespread use, some drawbacks that have heretofore been accepted in the absence of viable alternatives. Above all, the purely chemical deposition of metal from reductive working electrolytes is very expensive and requires accurate analysis and guidance of the electrolyte. These electrolytes also contain by far the most expensive chemicals. Nevertheless, such deposited layers are physically and mechanically of lesser quality than electrodeposited metal layers. Another disadvantage of the previously used technology is the uncertainty in the stabilization of the systems and thus the uncertainty,

whether the deposition rate and layer thickness in the borehole walls are sufficiently reproducible. The electrolytes tend to self-decomposition due to their low stability. In addition, the said electrolysis usually contain formaldehyde as the reducing agent, which is to be avoided under occupational safety aspects. Furthermore, the reductive working electrolytes contain larger amounts of complexing agents that are difficult to biodegrade and therefore represent a significant burden of wastewater.

It has long been attempted to dispense with the chemical metallization and instead carry out a direct galvanic metal deposition. Sin such method has been described for example in US Patent 3,099,608 and in DE-OS 33 04 004. The methods described there, however, have found no input into practice. Only with freshly prepared electrolytic electrolytes reasonably usable results can be achieved. Very soon after their commissioning, the quality of the resulting metal deposition decreases so much that only unusable results are achieved. In addition, quite long times are necessary for the metal deposition. When using the method described in US Pat. No. 3,099,608, at least 20 minutes are required for the metal deposition. Furthermore, defects in the metallization occur very rapidly to an increasing extent. This results in the perforated metal layers that adhere insufficient.

Object of the invention

The aim of the invention is to largely avoid the aforementioned disadvantages.

Explanation of the essence of the invention

The invention is first based on the object to develop a method for producing plated-through single or multilayer printed circuit boards, which ensures a secure, adherent and closed activation of the

allows a direct metallization of the activated surfaces by electroplating, reduces the number of process steps and thereby quickly and inexpensively leads to products that are qualitatively excellent. The process should ensure high security with regard to a reproducible procedure. The subsequent metallization should not only be as usual without external power, but also directly be carried out by electroplating.

The object underlying the invention has surprisingly been achieved in that, for activation, intrinsically electrically conductive polymers are used as a guide surface which are produced from monomers by certain oxidative pre- and post-treatment steps.

The inventive method is characterized in that

a) the surfaces of the support are pretreated in an oxidizing solution,

b) after removal of the solvent residues by rinsing the

Carrier is brought into a solution containing at least one monomer, in particular pyrrole, furan, thiophene or derivatives thereof, in the polymeric or

copolymeric form is electrically conductive, contains, 25

c) the carrier is then placed in an acidic solution,

wherein an electrically conductive polymeric layer, in particular of polymerized or copolymerized pyrrole, furan, thiophene or their derivatives, is formed, whereupon, if appropriate, residual solutions are removed by rinsing and metallized galvanically or without external current.

It is particularly advantageous to precede steps a) with processes in which the pierced conductor

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plate is subjected to an etching process and a surface pre-treatment of the non-conductive areas of the circuit boards. The etching is done by an acid, oxidative solution. The treatment of the wellbore surfaces, which are non-conductive, by means of organic, preferably nitrogen-containing solvents or their aqueous, alkaline solutions.

The solution used for process step a) contains salts of the permanganate, the manganate, the periodate and / or a cerium-IV compound. The oxidative pretreatment to be described in more detail below can be carried out in a pH range of <1 to 14 and at temperatures of 20 to 95 ° C. The addition of ionic or nonionic surfactants in an amount of 0.1 to 10 g / l improves the quality

Did the oxidative pretreatment, but is not essential. The oxidative agents are present at a concentration of 0.1 g / l up to their solubility limit. The pretreatment time can be between

0.5 and 20 minutes are

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The solution used for step b) preferably contains in addition to 1 to 50% of pyrrole (or furan, thiophene, pyrrole derivatives or mixtures thereof) the complementary amount of solvents or solvents.

middle and possibly also alkalizing additives. Of course, mixtures of solvents or solubilizers can be used. As solvents or solubilizers, e.g. Water, methanol, ethanol, n-propanol, isopropanol, higher alcohols, polyalcohols, DMF (dimethylformamide), ketones, in particular methyl ethyl ketone, cumene sulfonate, N-methylpyrrolidone, triglyme, diglyme, alkali salts of toluenesulfonates or their ethyl esters and aqueous alkaline solutions or mixtures the same usable.

Subsequent to process step b), the objects to be metallized, such as printed circuit boards, are subjected to activation in process step c). The activation can be carried out with oxidatively active substances such as, for example, alkali persulfates, alkali peroxodisulfates, hydrogen peroxide, iron (III) salts such as iron chloride, iron sulfate, potassium hexacyanoferate (III), alkali per iodates or similar compounds in an acidic medium. It is also possible to allow the activation to take place only in an acidic medium, wherein as acids hydrochloric acid, sulfuric acid, phosphoric acid, etc. can be used. The activation can take place both in the acidic, oxidizing medium and in the acidic medium with permanent air injection.

The following subsequent to the process steps a), b) and c) subsequent galvanic processing of the objects to be metallized such. Circuit boards are explained in more detail in the following sections.

In a preferred embodiment of the process according to the invention, metals such as copper, nickel, gold, palladium, tin, lead, tin / lead are used for producing the metal layer.

By means of the method according to the invention, a through-plated single-layer or multilayer printed circuit board is obtained on the basis of a polymeric carrier material or ceramic, optionally provided with at least one electrically conductive layer on both sides. This plated-through printed circuit board is characterized in that a layer of polymerized, electrically conductive plastic is present between the metal layer on the inner surface of the plated-through holes and the carrier material or the ceramic. The

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Layer of electrically conductive plastic consists in particular of polymerized or copolymerized pyrrole, furan, thiophene or derivatives thereof. The layer of polymerized plastic is preferably 0.1 to 10 μm thick. The intermediate product is a perforated single- or multi-layered plate based on a polymeric support material or ceramic optionally provided on both sides with at least one electrically conductive layer, wherein a layer of polymerized, electrically conductive plastic is disposed on the surface surrounding the borehole, preferably of polymerized or copolymerized pyrrole, furan, thiophene or derivatives thereof.

Electrically conductive polymers have been available for some years.

They have been the focus of scientific interest, but have so far failed to achieve industrial application. The development and the current state of the art are presented in several reviews, for example Herbert Naarmann, "Elektrisch leitfähige PpIymere" in "Chemische Industrie", 6/87, pages 59 to 64; Klaus Menke and Siegmar Roth, "Metallisch leitfähige Polymere I and II "in" Chemistry in our Time ", 1/86, pages 1 to 10 and 2/86, pages 33 to 43. Among the large number of different conductive polymers, the systems with delocalized π-electron systems are chosen in particular The systems based on furan, thiophene, pyrrole or derivatives thereof It is known from the prior art that conductive polypyrrole can be prepared by electrochemical polymerization, but also by purely chemical means (KC Khulke and RS Mann, "Journal of Polymer Science, Vol. 20 (1982), pages 1089 and 1095).

EP-A-0 206 133 discloses a process for applying layers of electrically conductive polymers,

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in particular polypyrrole, described on other materials. The coating of various substrates takes place chemically. Thus, the surface of a polyester film is coated with a thickness of 42 μπι with a 10 wt .-% ethanolic solution of iron perchlorate. After evaporation of the solvent, the film thus treated is exposed to an atmosphere containing 10% by volume of pyrrole vapor in nitrogen at a temperature of 150 ° C. for 30 seconds, forming a black layer on the surface of the film within a few seconds Insoluble polypyrrole layer has a specific conductivity of 10 S / cm It is also mentioned in EP-AO 206 133 that the polypyrrole layers are suitable for the production of printed conductors and the possibility of removing the monomers from a solution by using an additional oxidation step However, the advantageousness of the reaction in the gas phase is emphasized, information about the adhesive strength of the layers obtained is not given, and in particular no subsequent metallization of the layers produced is suggested in any way.

However, the procedure described in the prior art is completely unsuitable for the production of plated through single- or multilayer printed circuit boards. In particular, a useful deposition of the polypyrrole film on the inner surfaces of the boreholes could not be achieved. Only by adhering to the parameters of the process of the invention can be practically useful

Results are achieved. In particular, the Metallab-30

Divorce on the previously deposited layer of conductive polymers in realistic process time is made possible only by the inventive method.

As carrier materials are in particular glass fiber reinforced epoxy resin, polyimide and other solid polymers in question. In principle, all materials are suitable which can be coated with a metal layer by being treated according to the inventive process steps. The plated-through printed circuit boards according to the invention can in principle be produced in various ways by the method according to the invention.

The metal deposition can be carried out initially with the aid of polymerized, electrically conductive, heterocyclic compounds such as pyrrole, thiophene and furan with the concomitant use of electroless, reductive working electrolytes.

A printed circuit board pretreated according to the pretreatment method according to the invention, which will be described below, from a carrier material such as glass-fiber-reinforced epoxy resin is introduced into a reductively operating electrolyte, so that metal, preferably copper, is deposited for deposition by chemical means.

Another type of metal deposition is carried out with the aid of polymeric, electrically conductive, heterocyclic compounds, in particular pyrrole, thiophene and furan, without the use of electroless, reductive working electrolytes. In this case, copper is preferably brought to the deposition. A printed circuit board pretreated according to the pretreatment method according to the invention, which will be described below, of a carrier material such as glass-fiber reinforced epoxy resin is introduced into a galvanic copper electrolyte, so that a copper deposition takes place both on the pretreated copper cladding of the printed circuit board and on the pretreated borehole walls.

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A variation of this procedure is an altered aftertreatment. In this case, the conductive polymer film is formed only on the pretreated borehole walls and not on the Kupferkaschierung.

In a third procedure, the metal deposition takes place with the aid of polymerized, electrically conductive, heterocyclic compounds such as pyrrole, thiophene and furan with the concomitant use of electroless, reductive working electrolytes or without application of electroless, reductive working electrolytes on non-metal-clad base materials (additive process) , A pre-treated, pretaminated, non-laminated circuit board of a carrier material such as glass fiber reinforced epoxy resin according to the pretreatment method according to the invention, which will be described below

is introduced into a reductive working copper electrolyte, so that copper is deposited by chemical means. It is also possible to introduce the correspondingly pretreated, unbacked printed circuit board directly into a galvanic copper electrolyte and to bring about a copper deposition on the entire printed circuit board surface.

The method according to the invention thus makes it possible to manufacture plated-through printed circuit boards in subtractive, semi-additive and additive technology.

In the subtractive technique, copper-clad substrate materials, for example glass fiber reinforced epoxy resin, are processed. The perforated printed circuit board is pretreated by the method according to the invention and contacted without external current or preferably directly by electrodeposition by electroplating. The plated-through printed circuit boards produced in this way can then be screen-printed or photo-printed in a known manner in order to obtain, after the exposure and development, the film.

generate a picture. Then the conductor pattern is formed by galvanic deposition of metallic layers. The other necessary process steps are carried out in a conventional manner, as described for example in Hermann, Manual of printed circuit board technology. According to the so-called tenting technique, the printed circuit boards through-contacted by the method according to the invention can also be galvanically metallized directly on a flat surface with the necessary layer thickness. In the positive pressure, a photoresist is applied, the conductor pattern and the holes in the later necessary etching process

protects.

In the semi-additive technique, unbacked carrier material can be used, which is pretreated, activated and then metallized according to the invention. Subsequently, in a known manner, the photoprocess and the structure of the conductor pattern. But it can also be copper-clad substrate, preferably with copper foils of 5 to 12 μπι thickness, are used, which is pretreated by the novel process, activated and dried. Subsequently, photoresist is applied and, after exposure and development, the pattern is generated negatively. Subsequently, the pattern is selectively amplified. Furthermore, one proceeds in a conventional manner.

The methods according to the invention open up completely new methods of printed circuit board production by variation within the operation, so that it is possible to selectively carry out the track construction and the through metallization of the boreholes.

The metallization of the support materials is carried out, for example, so that the conductor track construction and the through metallization of the appropriately prepared materials on already coated with photoresist carriers.

For a further process variant, the drilled and copper-clad substrate materials are etched, conditioned and then fed to the oxidative pretreatment (step a). After removal of the solvent residues by rinsing, the support is brought into a solution which contains a monomer, in particular pyrrole or pyrrole derivatives or mixtures of furan, furan derivatives, thiophene, thiophene derivatives with pyrrole (step b).

Subsequently, the carrier is introduced into an acid solution, so that the electrically conductive polymer layer is formed (step c).

Thereafter, the carrier is rinsed, dried and coated with a photoresist, exposed to the corresponding pattern and developed, the holes and the circuit pattern are exposed. The thus treated carrier can then be brought into a suitable copper electrolyte for galvanic reinforcement of the conductor tracks and for the through-hole of the boreholes, so that a galvanic deposition takes place only in the resist channel or in the boreholes.

The additive technique is based on unbacked carrier material. The surfaces to be metallized, interconnects, etc. are selectively activated and then metallized chemically and / or galvanically. In this case, a direct structure of the conductor pattern is achieved.

A variation of the above additive technique is characterized by the following process steps:

The drilled backing plate is treated to provide an optimum prepared surface for lamination

a photoresist. The thus prepared support is coated with photoresist, exposed to the appropriate circuit pattern and then developed, the holes and the circuit pattern are exposed. Then the support is etched, conditioned and fed to the oxidative pretreatment (step a). After removal of the solvent residues by rinsing, the carrier is introduced into one of the abovementioned heterocyclic-containing solutions (step b).

Subsequently, the carrier is placed in an acid solution, so that the electrically conductive polymer layer can form (step c).

The carrier pretreated in this way is freed from polymer layers adhering to the photoresist by intensive rinsing, brushing, mechanical cleaning with suitable auxiliaries or a combination of the abovementioned cleaning methods. Subsequently, the carrier is treated in a conventional pickling and then fed to the galvanic metallization, wherein only metallized in the resist channel and in the boreholes.

The method steps of the method according to the invention are explained in more detail below.

The process according to the invention can be characterized by the following general operations:

1. Oxidative Pretreatment (a)

0 2. Rinse

3. Catalysis (b)

4. Activation (c)

5. Rinse

6. External electroless metallization

7. Rinse

8. Picking

9. Copper preamplification (galvanic)

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If the plated-through printed circuit board is to be produced by direct galvanic copper plating, the following procedure can be used:

1. Oxidative Pretreatment (a)

2. Rinse

3. Catalysis (b)

4. Activation (c)

5. Rinse

6. Picking

7. Galvanic copper plating

In a preferred embodiment of the process according to the invention, the step a) of the oxidative pretreatment can be preceded by an etching process, a rinsing process, a cleaning step and a cleaning and surface treatment of the drilled holes, followed by a further rinsing process.

If the support materials already have an electrically conductive layer of copper, the etching of the circuit board is carried out in a commercially available acidic, provided with oxidative substances solution so that all accessible copper areas receive a uniform finely textured surface.

After treatment, the surface should be free of oxi-25

areas of fingerprints and other contaminants and have a uniform light color.

The process step of cleaning and surface pretreatment of the non-conductive areas of the printed circuit board (borehole walls), which in addition to the cleaning also causes the activation and conditioning of the non-conductive regions of a printed circuit board, by means of an organic solvent, preferably with a nitrogen-containing solvent or with a

aqueous alkaline solution of the corresponding solvent. In addition to activation and conditioning of this process step leads in multi-layer circuits that any existing impurities of the copper inner layers are prepared on the borehole walls for a subsequent removal of the impurity. The treatment time should generally be between 1 and 20 minutes and be carried out at temperatures of 20 to 80 ° C. The upstream steps provide optimal pre-treatment of the printed circuit boards for the subsequent process.

To prepare the printed circuit boards for galvanic or chemical metallization, they must undergo oxidative pretreatment, a). The oxidative pretreatment can be carried out in a pH range of <1 to 14 and at temperatures of 20 to 95 * C. The addition of ionic or nonionic surfactants in an amount of 0/1 to 10 g / l improves the quality of the oxidative pretreatment, but is not essential. The oxidative agents are present at a concentration of 0.1 g / l up to their solubility limit. The pretreatment time can be between 0.5 and 20 minutes. As the oxidizing agent, for example, cerium (IV) sulfate, alkali metal manganates, alkali permanganates and alkali per iodates can be used. Preferably, potassium permanganate is used.

As an oxidative medium for the pretreatment of the objects to be metallized in an alkaline medium, an aqueous solution consisting of 20 g / l potassium permanganate and 10 g / l sodium hydroxide is prepared. It is advantageous to add about 0.1 g of nonionic fluorosurfactant to the mixture. The printed circuit boards are preferably left in the tempered solution for 10 minutes with slight movement. After pretreatment, the circuit boards are rinsed with water.

As the oxidative medium for pretreatment of the objects to be metallized in the neutral medium, an aqueous solution consisting of 12 g / l potassium permanganate, 0.1 g / l nonionic fluorosurfactant using pH correcting substances (sodium hydroxide, sulfuric acid, etc.) is so adjusted so that the solution has a pH of about 7. The printed circuit boards to be treated are preferably left for 5 minutes with slight agitation in the solution heated to about 65 ° C. After the oxidative pretreatment, the circuit boards are rinsed with water.

As an oxidizing medium for the pretreatment of the objects to be metallized in an acidic medium, an aqueous solution consisting of 10 g / l potassium permanganate, 0.1 g / l non-ionic wetting agent and sulfuric acid is prepared which has a pH of about 2. The printed circuit boards to be treated are preferably left in the solution for about one minute with slight movement. The temperature of the solution is preferably from 2 0 to 30'C. Following the oxidative pretreatment, the circuit boards are rinsed with water. As the oxidizing medium, an aqueous solution of 50 g / l of cerium (IV) sulfate, nonionic wetting agent and sulfuric acid is prepared so that the pH is <1.

The printed circuit boards to be treated are preferably left for about 5 minutes with slight pivoting movements in the preferably tempered at 20 to 30'C solution. Following the oxidative pretreatment, the circuit boards are rinsed with water.

As another oxidizing medium, an aqueous solution of 50 g / l of sodium periodate, a nonionic wetting agent and sulfuric acid is prepared so that the pH of the solution is <1. The printed circuit boards to be treated are left in the tempered solution for 5 minutes with slight swiveling movements. In connection to

the oxidative pretreatment, the circuit boards are rinsed with water.

For the process step of catalysis, b), a solution consisting of a heterocyclic compound, in particular pyrrole, thiophene or furan, a water-miscible organic solvent such as methanol, ethanol, n-propanol, isopropanol, higher alcohols, polyalcohols, DMF ( Dimethylformamide), ketones, cumene sulfonate, N-methylpyrrolidone, triglyme, diglyme, alkali metal salts of toluenesulfonates or their ethyl esters and aqueous alkaline solutions or mixtures thereof as solubilizers for the heterocyclic compound and water. In this solution, the substrates to be metallized (printed circuit boards) are introduced. Due to the high reactivity of the oxidatively pretreated articles such as printed circuit boards, the concentration of the heterocyclic catalyst solution can be kept within wide ranges, so that solutions with a heterocyclic content of 0.1 to 50% can be used. However, it has been found that such solutions, which have a heterocyclic content of 5 to 35%, have optimal catalyzing properties. The residence time of the objects such as printed circuit boards in the catalyst solution can be between a few seconds and 20 minutes. Residence times between 1 and 5 minutes have proven to be optimal. During the treatment of substrates such as printed circuit boards in the catalyst solution, they may be subjected to a slight agitation. The listed table shows a summary of the preferably usable catalyst solutions.

Following catalysis, the articles to be metallized, such as printed circuit boards, are subjected to activation, c), in preparation for the subsequent metal deposition.

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deposition. The activation can be carried out with oxidatively active substances such as, for example, alkali persulfates, alkali peroxodisulfates, hydrogen peroxide, iron (III) salts such as iron chloride, iron sulfate, potassium hexacyanoferate (III), alkali per iodates or similar compounds in an acidic medium. It is also possible to allow the activation to take place only in an acidic medium, wherein as acids hydrochloric acid, sulfuric acid, phosphoric acid, etc. can be used. The activation can also be done in acidic medium with permanent Lufteinblasung.

To activate the objects to be metallized in an acidic, oxidizing medium, the catalyzed substrate is left for 5 minutes in an aqueous solution consisting of 50 g / l of sodium peroxodisulfate and 10 ml / l of sulfuric acid with slight pivoting movements. It forms on the surface of the circuit board and on the borehole walls a dark brown to black colored film. Following activation, rinse under running water

 20

A catalyzed substrate is left for four minutes in an aqueous solution consisting of 40 g / l potassium hexacyanoferate (III) and 20 ml / l sulfuric acid with gentle rocking movements. On the entire PCB surface, a dark, voluminous film forms. Following activation, the substrate is rinsed under running water.

The activation of the objects to be metallized, such as printed circuit boards in an aqueous solution of 20 g / l Alkaliperjodat and 40 ml / 1 sulfuric acid takes place with slight pivoting movements within two minutes. On the entire surface forms a black film.

_ ₂₁ _

Furthermore, the activation can be carried out in an aqueous solution of 50 g / l ferric sulfate and 30 ml / l sulfuric acid. In this solution, a catalyzed substrate is left under gentle rocking movements, preferably for 5 minutes. It forms on the entire surface of a dark colored coating. Following activation, rinse with water.

The activation of the objects to be metallized, such as printed circuit boards, takes place within approximately 5 minutes in an acidic medium, consisting of an about 20% strength sulfuric acid solution, with slight pivoting movements and permanent air injection. Following activation, rinse under running water.

When a 5% hydrochloric acid solution is used for activation, the appropriately pretreated substrate is preferably left in the solution for 10 minutes with slight swaying. Even after the activation with 5% hydrochloric acid, the substrate is rinsed with water

 20

When 8% phosphoric acid is used, the substrate to be activated is left in the appropriate solution for 10 minutes with gentle rocking movements and permanent air injection. Following the action

tivierung is rinsed with water.

The activation can also be carried out by leaving a substrate pretreated according to the invention for about 10 minutes in an aqueous solution consisting of 60 g / l of sodium peroxodisulfate and 40 ml / l of H ₃ SO ₄ with slight pivoting movements and permanent air injection. Also following this type of activation is rinsed with water.

M3 SSO

In a further preferred embodiment, a catalyzed substrate is left for about 3 minutes in an aqueous solution consisting of 100 ml / 1 sulfuric acid and 25 ml / 1 hydrogen peroxide (30% strength) with permanent air injection and slight pivoting movement. Following the activation is also washed here with water.

The above quantities, both grams and milliliters, each refer to 1 liter of total solution.

The articles treated by the method described above, such as circuit boards, may be subjected to an electroless reductive metal deposition immediately after activation. It is also possible to carry out a galvanic metal deposition immediately after activation. In addition, the activated objects, such as printed circuit boards, can later be electroplated with metals.

For electroless metallization, commercially available electrolytes, preferably copper electrolytes, e.g. METALYT CU NV, used under the usual conditions known to any person skilled in the art.

The galvanic metal deposition takes place by means of known galvanic electrolytes. In principle, all metals or alloys can be deposited, which are to be deposited by electroplating. However, copper electrolytes are preferably used. Particularly preferred are sulfuric acid copper electrolytes having a content of 50 to 300 g / l of free sulfuric acid and a metal content of 5 to 50 g / l. But also fluoroboric, hydrochloric, thiosulfate or pyrophosphate-containing or cyanide-containing electrolytes and electrolytes

Basis of sulfamines and organic sulfonic acids have been found to be suitable. These electrolytes are used under the usual conditions, namely in temperature ranges between 20 and 70 ° C. with current densities between 0.1 and 20 A / dm. Surprisingly, the time of the galvanic deposition can be galvanically plated directly after the activation according to the invention. be significantly shortened, namely in particularly favorable cases to 2 to 5 minutes. This gives uniform, closed and moreover firmly adhering metal layers, which also have no defects in the so-called transillumination test. Exemplary embodiments

In the following examples, the inventive method is explained in more detail:

example 1

Eirt double-sided copper-clad carrier material made of glass fiber reinforced epoxy resin is drilled in the usual way and mechanically cleaned. Subsequently, the substrate is pretreated by oxidation. This is carried out in an aqueous solution of 50 g / l of cerium-IV-sulphate in sulfuric acid solution using a nonionic fluorosurfactant. The circuit board remains for 5 minutes with slight movement in the 20 to 30 ⁰ C warm solution and is then rinsed. It is then immersed in an aqueous catalyst solution consisting of 20% pyrrole and 20% isopropanol, and the plate is left for 5 minutes at room temperature with slight movements in this solution. Then it is left for a further 5 minutes in an aqueous solution consisting of 50 g / l of sodium peroxodisulfate and 10 ml / 1 sulfuric acid with gentle agitation. On the surface and the borehole walls, a dark brown to black colored conductive polymer film forms, which is subsequently under running water

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is rinsed. Now it is decanted with 20% sulfuric acid and copper-plated with a commercial copper electrolyte bath. The electrolyte used is the commercial product of the arabian CUPROSTAR LP-I. This electrolyte has the following composition:

Copper: 18-22 g / l

Sulfuric acid: 180-250 g / l

Sodium chloride: 60-100 mg / 1 supplement

Base of a polyether: 4-8 ml / 1

The temperature is 20-30 ⁰ C and the current density 2-4 A / dm. After only 8 minutes, all holes are completely metallized, evenly and firmly adhering.

Example 2

A substrate as in Example 1 is subjected to oxidative treatment in an aqueous solution consisting of 20 g / l potassium permanganate, 10 g / l sodium hydroxide and 0.1 g / l nonionic fluorosurfactant at 90 ° C. with agitation. After a rinsing process is immersed for 10 minutes in an aqueous solution consisting of 10% pyrrole, 15% isopropanol and 0.1 g / l fluorinated surfactant at room temperature. The substrate is moved slightly to ensure good fluid exchange in the holes. The mixture is then treated in an aqueous solution containing 20 g / l of hydrogen peroxide and about 20% sulfuric acid. At room temperature, the substrate is exposed to movement for about 8 minutes. It forms a dark brown to black conductive polypyrrole film, which is then rinsed under running water. Subsequently, as described in Example 1, directly electroplated copper.

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After about 5 minutes, all holes are completely, uniformly and adherently metallized throughout.

The continuously metallized printed circuit boards are galvanically applied to a copper layer thickness of 25 μτα. reinforced in the hole. A thermal shock test according to MIL Spec.-P-SSllO-C is easily passed.

Example 3

A substrate as in Example 1 is left to undergo an oxidative treatment in an aqueous solution consisting of 20 g / l potassium permanganate, 10 g / l sodium hydroxide and 0.1 g / l nonionic fluorosurfactant at 90 ° C. with agitation. After a rinsing process is immersed for 10 minutes in an aqueous solution consisting of 10% pyrrole, 10% furan, 15% isopropanol and 0.1 g / l fluorosurfactant at room temperature. The substrate is moved slightly to ensure good fluid exchange in the holes. The mixture is then treated in an aqueous solution containing 20 g / l of hydrogen peroxide and about 20% sulfuric acid. At room temperature, the substrate is exposed to movement for about 8 minutes. It forms a dark brown to black conductive polymer film, which is then rinsed under running water. Subsequently, as described under Example 1,

directly galvanically coppered.

After about 8 minutes, all holes are fully metallised, evenly and firmly adhering. The so metallized printed circuit boards are galvanically reinforced to a copper layer thickness of 25 μπι in the hole. A thermal shock test according to MIL Spec.-P-55110-C is easily passed.

Example 4

Non-copper-clad base material of glass fiber reinforced epoxy resin is pretreated, catalyzed and activated according to the procedure of Example 2. Subsequently, it is directly galvanically coppered. After approx. 10 minutes, the entire surface and the holes are completely coppered, evenly and firmly adhering.

Example 5

A double-sided copper-clad substrate made of glass fiber reinforced epoxy resin is drilled in the usual way and mechanically cleaned. Subsequently, the substrate is pretreated by oxidation. This is carried out with gentle rocking movements in an aqueous solution of 25 g / l potassium permanganate and 10 g / l potassium hydroxide at 70 ° C. within 10 minutes, followed by rinsing and 5 minutes in a solution consisting of 25% butanol, 50% H ₂ %, 10% pyrrole, 2% NaOH (30%), and 13% cumene sulfonate (40%).

This is then left for 5 minutes in a solution consisting of 300 ml / 1 sulfuric acid and 20 g / l sodium peroxodisulfate. On the surface and the borehole walls, a dark brown to black, conductive polymer film is formed, which is rinsed with running water. Before the subsequent galvanic copper plating in LP-I (see Example 1) is dekapiert in 20% sulfuric acid. After 10 minutes, all holes are completely, uniformly and adherently metallized throughout.

Example 6

A printed circuit board as in Example 1 is subjected to an oxidative treatment in an aqueous solution

- 27 - «2 * 3 SW

from 20 g / l potassium manganate and 20 g / l KOH, at 80 * C for 10 minutes with gentle rocking movements. Then it is rinsed under running water. The mixture is then left for 10 minutes in a solution consisting of 25% glycerol, 25% triglyme, 35% H ₃ O and 15% pyrrole with gentle rocking movements. The plate is removed from the bath and the liquid is drained for 2 minutes and the plate is transferred into an aqueous solution of 50 g / l sodium peroxodisulfate and 100 ml / l sulfuric acid. With permanent air injection with slight pivoting movements, it is left in it for 5 minutes. On the entire plate surface, a dark brown to black film forms, which is rinsed under running water. It is decanted in 20% sulfuric acid and galvanized in a copper electrolyte (see Example 1). After 8 minutes, all borehole walls are evenly covered with copper.

Example 7

Following the alkaline oxidative pretreatment (see Example 6), the printed circuit board is left in a solution consisting of 10% H 2 O, 20% triglyme, 30% N-methylpyrrolidone, 20% pyrrole and 20% DMF for 5 minutes with gentle rocking movements , After catalysis, the treated circuit board is left for 5 minutes in an aqueous solution consisting of 5 g / l sodium peroxodisulfate and 50 ral / 1 sulfuric acid, with permanent air injection with slight pivoting movements. The subsequent plate treatment is carried out as already described in Example 6.

Example 8

A multi-layer circuit (8 indoor units) is drilled in the usual way and mechanically cleaned. On-

2 <S3

Finally, it is pretreated alkaline oxidatively. This is done in an aqueous solution of 30 g / l potassium permanganate and 30 g / l sodium hydroxide at a temperature of 75 ° C with gentle rocking movements for about 7 minutes. It is then rinsed and left for 5 minutes in the catalyst solution consisting of 66% glycerol, 27% N-methylpyrrolidone and 7% pyrrole at room temperature. The catalyzed multilayer is left in catalysis for 5 minutes in an approximately 3 0 VoI.-ligen sulfuric acid with air injection and slight pivoting movement. The further treatment is carried out as already described in Example б.

At game 9

Under the same conditions as in Example 2, a printed circuit board is pretreated and catalyzed. As activation, however, a 20% sulfuric acid solution is used, in which the air was blown. Residence time of the substrate with 5 minutes of movement. It forms a dark brown to black conductive Polypyrrolfilra, which adheres only in the holes. The copper-clad surface is not covered. Now it is rinsed and dried. The circuit board is coated with a commercially available photoresist and exposed and developed so that subsequently the circuit pattern is exposed. Then, the substrate is selectively amplified in the resist channel and in the bore in the galvanic copper electrolyte to a layer thickness of 25 / am. The continuously metallized circuit board can then be further processed in the usual way.

Comparative Example

A drilled and mechanically cleaned circuit board is placed in a solution consisting of 66% glycerol, 27%

5 <Sö

Leave N-methylpyrrolidone and 7% pyrrole for about 3 minutes. The treated circuit board is then treated for 5 minutes in 30% sulfuric acid with air injection and gentle pivoting motion. After rinsing and pickling in 20% sulfuric acid is for one hour in a commercial

^э 2

Copper electrolytes at a current density of 4 A / dm

galvanized. On the borehole walls no copper deposition can be detected.

Examples 1 to 9 inclusive and the comparative example undergo the process steps after mechanical cleaning: etching, rinsing, cleaning and surface pretreatment of the borehole walls, and rinsing again.

All quantities in g or ml refer to 1 liter of solution.

The following table gives some more examples of preferred bath compositions of step b) according to claim 1 for catalyzing the substrate including the preferred residence time.

- зо - c? 23

Table e

No. 10 11 12 13 14 15 16 17 18 19 20 21 in ml

g Pyrrole 5 10 10 10 20 30 5 30 3 15 30 20

Water 55 65 50 50 45 20 55 - 47 35 10 30

Glycerol 40 -----------

Glycol - зо ------ so 25--

aq. cumolsul-

fonat (40%) ---- зо -------

aq. NaOH (30%) ---- 5 -------

Triglynva - 40 ------ 25 20-

Diglyme ___ 40 --------

EMF ----- 50 ---- 10-

N-methyl-

pyrrolidone - - - - - - 40 20 20 - 30

Methyl ethyl ketone ----------- like this

Q residence time

min 3 10 2 2 5 10 15 3 1,5 1 1,5 1

Claims (12)

- 31 claims 2SS 5І0 1. A process for the preparation of plated-through single or multilayer printed circuit boards based on a optionally provided on both sides with at least one electrically conductive layer polymeric carrier material or ceramic by galvanic or electroless plating a metal layer on the surfaces that are not coated with a conductive metal layer, characterized characterized in that a) the surfaces of the carrier are pretreated in an oxidizing solution, b) after removal of the solvent residues by rinsing the carrier in a solution containing at least one monomer, in particular pyrrole, furan, thiophene or derivatives thereof which is electrically conductive in polymeric or copolymeric form, c) "the carrier is then brought into an acidic solution, which forms an electrically conductive polymeric layer, in particular polymerized or copolymerized pyrrole, furan, thiophene or derivatives thereof, whereupon, if appropriate, residues of the solution are removed by rinsing and metallized galvanically or without external current , 2. The method according to claim 1, characterized in that the step a) precedes an etching process and a surface pretreatment step of the non-conductive regions of the printed circuit boards. 3. The method according to any one of claims 1 or 2, characterized characterized in that the etching of the circuit board is carried out in an acid, oxidatively acting solution. -32 - ЖЪ ВЯО 4. The method according to any one of claims 1 to 3, characterized in that organic solvents or their aqueous alkaline solutions are used for surface pretreatment. 5. The method according to claim 4, characterized in that the organic solvents contain nitrogen. 6. A process for the preparation of plated through single- or multi-layer printed circuit boards according to one of claims 1 to 5, characterized in that the metal layer consists of one of the metals copper, nickel, gold, palladium, tin, lead, tin / lead. 7. The method according to any one of claims 1 to 6, characterized in that in the solution of step a) oxidizing salts of permanganate, manganate, periodate and / or cerium (IV) sulfate are located. 8. The method according to any one of claims 1 to 7, characterized in that the pH of the oxidizing solution is between <1 and 14. 9. The method according to any one of claims 1 to 8, characterized in that the oxidizing solution a Contains surfactant.
25 10. A plated through or multilayer printed circuit board based on a optionally provided on both sides with at least one electrically conductive layer polymeric support material or ceramic, characterized in that between the metal layer of the borehole surrounding surface and the support material or the ceramic, a layer of polymerized, electrically conductive Plastic is available. 283 11. A plated through or multilayer printed circuit board according to claim 10, characterized in that the layer of electrically conductive plastic consists of polymerized or copolymerized pyrrole, furan, thiophene or derivatives thereof. 12. A plated through or multilayer printed circuit board according to claim 10 or 11, characterized in that the layer of electrically conductive plastic is 0.1 to 10 pm thick ·