JPS5920495A - Improvement for electroplating to non-metal surface - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION To metallize non-metallic surfaces, the individual surface is first made catalytic to sensitize it to electroless metal deposition, and then the catalyzed surface is subjected to an external power source. It is common to expose the plating bath solution to an easily manipulated plating bath solution for a time sufficient to form a layer of metal, such as Cu or Ni, of desired thickness without use. The first layer is typically provided with additional metal deposits formed by conventional electrolytic plating. Known methods of making plated through holes in printed circuit boards use this metallization concept and variations thereof to metallize the hole walls. In view of starting with a two-sided copper-coated laminate as the base material, first prepare an appropriately sized panel with the required pores and sensitize it as a catalyst by immersing it in a known catalyst solution. do. Thereafter, exposure to a bath solution, commonly known as an electroless plating bath, which produces a metal deposit without an external power source, and for a time sufficient to achieve a thickness of, for example, 0.5 to 2.5μ. causes the formation of metal, usually copper, precipitates. The first conductive metal layer is further plated using conventional electrolytic plating means.

It has developed to a high degree of stability. This mechanism is used to oxidize appropriate components present in the electroless plating bath by reducing the complexed metal ions to metals, which act as internal electron sources to be used in the plating reactants. Thereby, surfaces treated with the above solutions catalytically promote the generation of electroless metal deposits.

Operation of electroless plating solutions requires somewhat careful monitoring of the various components and replenishment of consumed material by controlled chemical additions. Furthermore, the plating solution has a tendency to precipitate indiscriminately, resulting in the formation of metal, eg copper, deposits on the walls and bottom of the tank used when operating the plating bath. As a result, interference with plating operations 1. Remove the plating solution from the tank and clean the walls and bottom of the tank by means of an etching operation.

Therefore, electroless metal plating is quite expensive and complex, and requires highly trained operations.

Despite the above-mentioned essential drawbacks, to date, electrolessly deposited first metal layers have been used to metallize non-metallic surfaces, including the above-mentioned processing processes used in the fabrication of printed circuit boards. It was an essential part of all manufacturing processes.

U.S. Pat. No. 3,099,608 forms a mostly non-conductive film of colloidal or semi-colloidal particles on the walls of holes made in laminates used in the fabrication of printed circuits, and describes the use of palladium-tin-chloride colloids for electrolytic plating of copper.

However, this process has been found to have significant drawbacks and is impractical for practical use. Palladium-tin-chloride colloidal dispersions have unacceptably very short lifetimes. It can be used for only about 9 days as the dispersion solidifies and is quite expensive due to its high palladium content. Furthermore, this method deposits significantly more copper on the surface than on the wall of the through hole, making it untenable for economical use.

This patent describes the appearance of deposits on the surface to be plated.
The use of a "thin, slightly visible film of particles" of "semi-colloidal palladium", the fact that said film has "considerable resistance", and the fact that it still "has the properties of both a catalytic metal and a conductive metal in nature". The teaching that "some palladium has the potential for simultaneous and combined activation and conductive functions" (paragraph 4, lines 53-56), and furthermore, "
After electrolytic plating has started with the conductor, which is clearly activated by the catalytic properties of palladium, the electrolytic deposition processing process continues directly on the film of conductive agent particles.
It is based on the teachings (lines 62 to 66). Column 5, lines 2 to 7 states, ``The colloidal palladium deposits in the through-holes are extremely weak conductors and cannot be useful as substrates for electrolytic plating compared to precipitated graphite. During the plating reaction, one has to take the help of something else, i.e., one has to take the help of a catalyst during the plating reaction.''

This observation began in 1959 and continued with the use of graphite for the metallization of nonconductors 1, and the use of "seeding agents - electroless" for the metallization of plastic parts and the creation of plates with plated through holes (PTH). Although the first application of the "plating method" was made in the same period, no practical process was developed. Seeding Agents - The initial difficulties associated with electroless technology and its improved methods, and even more so, the complex characteristics of operating, controlling and maintaining electroless plating baths have been transformed into a relatively simple electrolytic plating process. In comparison, it was a great surprise that these observations were not shocking as far as the technological improvements of the last 20 years are concerned. This is because these observations did not provide the person skilled in the art with any teachings that would enable their use. Without this teaching, this observation could only be reproduced when using his "conductor solution" and the then present copper pyrophosphate electrolytic plating bath. It is believed that the inventor did not appreciate the importance of the composition of the copper electrolytic plating bath. For example, of the known formulations for pyrophosphate electrolytic plating baths used around the same time as this submission, the simplest did not produce copper of sufficient quality for printed circuit boards, and more complex types of baths Although producing sufficient steel quality, this patent suggests that the process manipulations are suppressed. Therefore, the industry has found that this observation has no practical application. With or without subsequent electrolytic plating, [seeding agent--electroless copper J] was found to be acceptable only as a means of metallizing non-metallic surfaces useful in this technique.

Therefore, the teachings in this patent are far from the invention claimed by the applicant. As a result of the present invention, the misconception proposed in said patent that the characteristics of electrolytic plating baths are non-critical had to be overcome and completely discarded.

The present invention discloses a method for metallizing a non-metallic surface of a substrate by direct electrolytic plating, which method includes the following steps.

(a) forming a number of metal seats on the surface;

This seat comprises or consists of a metal (A) which is different from the metal (B) which is to be deposited on the surface by electrolytic plating.

(b) providing the surface with a portion of the connector; This connector portion (connector electrode) is located outside the non-metallic surface portion to be electrolytically plated.

(C) exposing the surface, including at least a portion of the connector portion, to an electrolytic plating bath solution; The solution with 1 has a specific electrical conductivity and contains the metal (B) to be electrolytically deposited in an ionic state, and further comprises the species of the metal (B) to be electrolytically deposited, or contains the metal (B) to be electrolytically deposited. On said metal sheet comprising or consisting of metal (A), compared to the deposit on the surface formed, said metal (B)
One or more components (
C).

(d) providing a container containing the electrolytic plating bath solution with a reverse electrode;

(e) applying a sufficient potential difference between a portion of the connector and the counter electrode to initiate preferential deposition of metal (B) on said seat containing or consisting of metal (A), and for a sufficient period of time; This process forms a precipitate with a substantially uniform required thickness.

In one embodiment of the present invention, the deposition rate on the metal sheet is at least one order of magnitude higher than the deposition rate on the plated metal.
Moreover, it is desirably larger by two or more orders of magnitude.

In another embodiment, the metal seat and the metal to be plated are of metals selected from groups Ib, Th, or ■■ of the Periodic Table of the Elements, provided that they are not of the same type.

In yet other embodiments, the components recited above are selected from Dye 9 surfactants, gylating agents, polishing agents or leveling agents.

In still other embodiments, the substrate provided with the metal seat is subjected to one or more of the following treatments: heat treatment; treatment with a detergent conditioning agent; and/or treatment with a reducing agent.

The method of the present invention is an improved method for plating non-metallic surfaces on substrates and is also a highly effective method for plating through holes in metal coated laminates.

A particular advantage obtained in the fabrication of printed circuits with plated through holes is the preservation of the walls of the screen.

Because the copper is electrolytically plated directly onto the non-metallic hole wall substrate without the intervening electroless metal layer, the physical, physical, and adhesion properties of the copper-plastic interface are greatly improved. This is particularly important in the production of highly reliable printed circuits, such as multilayer circuits.

In fact, the method of the present invention for electrolytically plating non-metallic surfaces on a substrate includes the step of forming distinct metal seats on the surface to be plated. This metal seat is of a different metal type from the metal type to be plated.

The present invention then provides a portion of the connector on the substrate to be electrolytically plated, outside of the non-metallic surface portion, and brings at least a portion of the surface to be plated and the connector portion into contact with an electrolytic plating bath solution. let This solution covers the plateable metal to be electrolytically deposited and the plated-out metal to be deposited on the metal sheet, preferentially depositing from the electrolytically deposited metal.

Contains ingredients that make it possible. Further, providing a container containing an electrolytic plating bath with a counter electrode and applying a sufficient potential difference between the electrode formed by the connector and the counter electrode to selectively deposit on the seat prepared surface. is initiated and allowed to occur for sufficient time to form a precipitate of substantially uniform thickness as required.

While not intending to be bound by any particular theory, it is believed that the direct electrolytic plating process of the present invention is based on the following principles.

1. (1) A metal seat provided on a non-metallic surface with a ``connector portion'' provided on said surface by a plating bath electrolyte that forms a ``resistive path'' between the connector portion and the adjacent seat. - electrodes); a similar electrical path is formed between the seats.

(2) In a theoretical electrolyte with infinite electrical conductivity, the higher the electrical conductivity of the electrolyte, the lower the resistance of the "resistive circuit", and all seats would have the same potential difference as a part of the connector, and the opposite is true. In addition, for a theoretical electrolyte of very low electrical conductivity, the resistance between the seat and the connector portion would be such that the potential difference across which the seat was plated would be too high for any practical purpose.

(3) For real electrolytes, a voltage drop appears across the resistive path. Therefore, based on the preamble, ta) the potential difference supplied by the power source between the counter electrode and the connector part is:
A suitable plating potential difference is supplied to the metal seat, compensating not only for the voltage drop between the electrodes, including the deposition overvoltage, but also for the voltage node F in the resistive circuit formed by the electrolyte. (b) The higher the electrical conductivity of the electrolyte, the faster the plating rate on the seat will be (and still the thickness will be more uniform); (C) The electrical conductivity of the electrolyte will be higher than the plating Acceptance for the factor must be chosen as high as possible.

The term electrical conductivity, as used herein, is defined as a function of the concentration of the species-carrying current, ie, it is assumed that in acidic baths, hydrogen ions act as the main species-carrying current.

ml, (11) For all practical purposes, the deposit formed by electrolytic plating is approximately uniform, and its thickness is not substantially a function of the distance to the connector portion. In the case of printed circuit boards with holes,
The deposits on the surface and on the pore walls should not have a substantial and unacceptable difference in thickness.

(2) Non-uniformity problems also commonly exist in electrolytic plating; to overcome them, certain additives, known as, for example, leveling agents, are used in the plating bath.

(3) If a pyrophosphate electrolytic plating bath containing the above additives is used in a standard "seeding, electroless-electrolytic plating" process, satisfactory results are produced.

(4) Copper pyrophosphate baths of the type that sometimes contain helpful additives render the processing process suggested by the aforementioned US patents ineffective. Commonly used additives deposit themselves equally on the finished metal species (copper) and the palladium of the metal seat, or deposit themselves more preferentially on the latter, resulting in the plating on said seat. It is not intended to obstruct or suppress operation. This patent unsurprisingly states that it preferentially adheres to the metal species to be plated, and as a result, compared to the plating action on a metal seat of a suitable dissimilar metal, such as palladium. By using a bath formulation that contains one or more ingredients that reduce the plating action on the surfaces mentioned above, or which preferentially adheres itself to the metal of the metal seat, and which also coats the finished metal. The applicant is interested in the fact that by increasing the plating action on the seat compared to the seed surface, satisfactory results have been obtained both in terms of uniform thickness and excellent quality of the deposit. .

The problems described above with respect to the use of seeding, electroless-electroplating processes as well as the ineffective manufacturing methods described in the aforementioned US patents are completely overcome by the present invention.

As is clear from the mechanism theorized above, the applied potential difference drives the plateable metal onto the distinct seat at a faster rate than onto the plated-out metal. It must be sufficient for electrolytic deposition.

Such techniques involve the measurement of current-potential relationships for metal electrode positions on various substrates, as well as the presence or absence of component (C). Potential ranges applicable to standard electrolytic deposition solutions (e.g., about O to -200 mV for copper sulfate and sulfuric acid plating solutions versus saturated carmel electrodes, and about -300 to -1 for copper pyrophosphate plating solutions) ooomv vs. saturated Carmel electrode), the plating rate on various substrates (e.g., those containing metal seats) is significantly lower when the plating solution contains component (C) than on other substrates,
For example, they discovered that the plating speed is faster than the plating speed on the metal that is being plated.

The absorbent component (component (C)) of the electrolytic plating solution has a power value made of the electrolytically plated metal (e.g. copper) and a power value made of the metal used to form the metal seat (e.g. palladium). The selection can be made based on the current-potential difference curve obtained. Current-potential curves are recorded using a three-electrode system consisting of a test article, a counter, and a reference electrode. Polarization of the electrodes can be carried out either by applying a linearly varying potential difference and recording the current (voltage current method) or by applying a constant current and recording the potential difference (potentiostatic method). The three-electrode system, voltage-current method and constant-potential method are listed in "Modern Electrochemistry" published by Plenum Publishing Co., Ltd., 19'70, pages 891-893 and 1019-1026.

A rapid method of selecting bath compositions for the process of the present invention uses current-potential curves to determine the value of the difference, delta (B), defined below.

Delta (E), = E', -E'.

where E'1 and Ell are the potential differences at a current density of 1 in the metals used to form the electrolytically plated metal electrode and metal seat, respectively (FIG. 1). Current density!
is within the range of 30 to 50% of the peak current I (first
figure). With the current density selected in this way, the metal electrodes used to form the metal seat are hardly covered by the plated metal at the potential difference E1. The current density i in the potentiostatic method is still selected in such a way that the metal electrode used to form the metal seat is hardly coated with the metal to be plated.

The absorbent component selection method consists of the following steps.

(+) Two types of test electrodes, electroplated metal (and
(Cu) and the metal used to form the metal seat (e.g. Pd)
v) Record the curve.

(2) Select a current density within the range of 30 to 50% of the peak current.

(3) Read the potential differences E'1 and E'1 for the selected current from the current-potential difference curve (l-■).

(4) Calculate the difference in potential difference.

delta(E)i = E', -Ei (5) The absorbent component that yields the highest delta(E)I value is the proper component, i.e. the bath with the highest value of the difference delta(E) is the proper one. It's a nice bath.

The same methods and criteria are used to select the appropriate concentration of absorbent component.

Another rapid method for selecting bath compositions for the process of the present invention also uses current-potential curves, but in this case the function delta (E)dep is determined and defined as:

Delta (E)dep = E'dep - E"dep where E'dep and B'dep are the analytical values for the plateable metal on the electrolytically plated metal substrate and the metal used to form the metal seat, respectively. .

It is the specific gravity position difference (ie, the potential difference extrapolated from the current-potential difference curve to zero current) (FIG. 2).

The experimental method is the same technique as the method described above. However, E'dep and E'dep are calculated by extrapolating the current-potential curve to zero current and then reading the values of E'dep and E'dep. In the present method of selecting bath compositions for the process of the present invention, the bath with the highest delta Edep value is the suitable bath. The absorbent component that produces the highest delta Edep value is the appropriate concentration of absorbent component.

Both of the above rapid methods of selecting bath compositions for galvanostatic plating can be modified for use with other techniques of metal plating, such as pulse plating, galvanostatic or galvanostatic plating.

In addition to the rapid method described above for selecting bath compositions for the process of the present invention, other methods used in electrochemical academic research (see pages 1017 et seq. of the above-mentioned book) are available. Can be used in the same way.

Therefore, all components that seek to achieve faster plating rates on metal seats than on plateable metals as described above are within the scope of this invention.

In one embodiment of the invention, component (C) preferentially attaches itself to the surface of the metal (B) seeds compared to the surface of the metal (A) seeds, so that the seat metal (A) Effectively suppresses preferential deposition by almost suppressing or reducing the plating reaction on the surface formed by the metal (B) while hardly suppressing the plating reaction on the surface formed by the metal (B). Make it. In another embodiment, component (C) preferentially attaches itself to the seeds of the seat metal (A) such that said deposited component (C) reduces the overpotential difference and as a result the metal (B
) increases the plating reaction compared to the above reaction on the surface of the seeds.

According to a suitable embodiment of the invention, the electrical conductivity of the electrolytic plating bath solution and the potential difference applied between the connector part and the counter electrode are selected to be sufficiently high to outpace the rate of deposition of metal (B) species on the surface. Also, less.

Both achieve deposition rates of one order of magnitude, and preferably two orders of magnitude, on the seed surface of the seat metal (A). It has been found that the maximum electrical conductivity suitable for the process of the present invention is as high as is acceptable with respect to other plating factors for all practical purposes.

Select the potential difference still applied to the electrodes to compensate for the potential drop across the resistive conductor formed by the metal bath solution between the connector portion and the metal seat made of metal (A), and between said adjacent seats. I also discovered what I needed to do.

Furthermore, it is desirable to choose the potential difference to be the highest value allowed with respect to other meshing factors.

The metal (A) and similarly the metal (B) can be selected from the groups Ib and II of the periodic table of elements provided, and both are different types.

Suitable metals (A) and (B) are selected in such a way that metal (A) exhibits a lower plating potential difference than metal (B) - under the conditions provided by the crab plating operation.

Suitable metals for (A) are radium and platinum.

It is selected from silver and gold, with palladium being the most preferred.

Suitable metals CB) are selected from copper and 2-ykelsica.

Suitable electrolytic plating bath solutions are acidic.

Component (C) is a dye, a surfactant, a chelating agent, which acts by preferentially adhering itself to the surface made of metal (B) and reducing or suppressing the plating reaction.
It can be selected from polishing agents and leveling agents, and alternatively from bipolar agents which preferentially adhere themselves to the surface made of metal (A) and increase the plating reaction on said surface.

A suitable dye is for example Victoria Pure Glue F80
．． Methylene blue, methyl violet, acid blue 161. Alcian Blue 8GX, and other N-heterocyclic compounds 1, triphenylmethane type dyes selected from amines, imines and diazo compounds, including fused ring amines, imines and diazo compounds. be. Suitable surfactants include nonionic surfactants such as alkylphenoxypolyethoxyethanols, such as octylphenoxypolyethoxyethanol, and nonionic fluorocarbon surfactants such as Zonyl FSN from E.I. DuPont. Contains.

Among the many surfactants, including wetting agents and water-soluble organic compounds, that may be proposed for use in electrolytic plating solutions are surfactants and polymers, including polyoxyethylene.

It has been found that compounds with as few as 4 polyoxyethylene groups and as many as 1 million polyoxyethylene groups are effective. Preferred groups of such compounds include polymers with as few as 20 polyoxyethylene groups and as many as 15.0. Polyoxyethylene and polyoxypropylene block copolymers containing 10 to 400 oxyethylene groups are also preferred. Among these, preferred block copolymers are those containing 7 to 250 oxyethylene groups. In general, it has been found that these polyoxyethylene compounds, when added to electrolytic plating baths, particularly acidic electrolytic plating baths, will significantly enhance the growth of electrolytically plated metal onto the non-conductive surface that provided the metal seat. There is. These polyoxyethylene compounds are most often used in electrolytic plating solutions in a concentration range of 0.1 to 11//l. The optimum concentration depends on the composition of the electrolytic plating solution and the polyoxyethylene compound chosen. In some cases, 0.1
less than 111 g or more than 111/l and 10
0! j, /l ma is sometimes preferred.

Typical chelating agents are riboflavin, 2,4.6-(
Contains 2-pyridyl\S-) riazine and -pyrophosphate anions.

Suitable polishing and leveling agents include N-heterocyclic compounds, triphenylmethane type dyes, thiourea and thiourea derivatives. Among the thiourea derivatives suitable for use are tetramethylthiuram disulfide and allylthiourea.

For example, a suitable commercially available example is Electrochem.

Cal's Electro-Brite PC-667
and Leeronard's Copper Gleam
I have a PC. Other suitable additives include saccharin and O-benzaldehyde sulfonic acid derivatives which are particularly useful in Watts' nickel plating baths.

In a suitable embodiment of the invention, the respective metals (A) are treated in solution as compounds or complexes, such as dimetal halides, metal halide chlorides, as exemplified by palladium-tin chloride. A metal seat is formed by treating the surface. Reference examples of the above dimetal halides are U.S. Pat. No. 3,011,920 i 3,
532°518.3,672,923 and 3,672
, 938.

It has been found that to form a metal seat of metal (A) it is advantageous to expose the surface to a reducing agent after the above treatment.

In the case of seat-forming compounds consisting of tin, it has been found that it is further advantageous to remove the tin compound from the surface on which the seat was provided. This is accomplished with tin-removal solvents that allow the formation of soluble alkali stannites, such as dilute aqueous tetrafluoroboric acid solutions or strongly basic solutions.

In order to improve the shelf life of the seating provided surface, the surface treated with the seating providing solution may be subjected to a thermal processing treatment, e.g.
We have found that exposure to temperatures between 5 and 1200C for 10 minutes or longer is advantageous. It has been discovered that surfaces treated as described above immediately after removal from the seating solution can be stored for extended periods of time, for example 9 months, without deleterious effects. After long-term storage, the seat is treated with an acidic solution,
For example, exposure to 1 molar sulfuric acid for 15 to 20 minutes is advantageous.

Suitable reducing agents mentioned above can be selected from sodium borohydride, formaldehyde, dimethylamineporane or hydroxylamine.

It has also been found advantageous to pre-treat the non-metallic surface prior to the seating process by exposing it to an aqueous solution containing a detergent conditioning agent, such as a mixture of non-ionic and cationic wetting agents. The above detergent conditioning agents are widely used for plating printed circuits and plastic products.

Next, I will briefly explain the drawings.
The figures have already been described in detail.

Figures 3a to 3f show the state of electrolytic deposition in an electrolytic plating bath, and Figure 3a is a photograph taken one minute after electrolytic deposition. The substrate was a copper-clad laminate that provided a palladium metal seat to the wall of the through-hole. The metal being deposited is copper.

Figure 3b is a photographic representation of the same substrate captured 2 minutes after electrolytic deposition.

Figure 3C is a photographic representation of the same substrate captured 3 minutes after electrolytic deposition.

Figure 3d is a photographic representation of the same substrate captured 4 minutes after electrolytic deposition.

Figure 3e is a photographic representation of the same substrate captured 5 minutes after electrolytic deposition.

Figure 3f is a photographic representation of the same substrate captured 20 minutes after electrolytic deposition.

The above series of drawings shows that the metal deposition on the surface of the pores is uniform and continuous.

EXAMPLE 1 This example describes the metallization of the walls of holes drilled into a copper-coated insulating sheet of the type used in the fabrication of Print 1 circuits. Panel is 1.6ffm thick copper coated FR-4
Cut from epoxy glass sheet.

Holes were drilled into the copper coated epoxy-glass PR-4 panel.

The apertured panel is then treated with a pepoxy resin containing a cationic surfactant, a nonionic surfactant and a plucanolamine.
Treatment with a solution adjusted to below H4 cleanses and conditions the pore wall surfaces for subsequent treatment steps.

Subsequently, the panel was placed in a 1% sulfuric acid aqueous solution for 5 minutes.

Soak, rinse with water, and soak in sodium persulfate solution (120 g
The copper surface is deoxidized by treatment at 4o0C for 45 seconds at pH 2 or below, and washed again with water.

The panels were then treated for 5 minutes in a presoak solution containing tin chloride + 1159/l i sodium chloride 22511/e and sufficient hydrochloric acid to obtain a pH below 0.5. After the pre-soaking step, the panels were exposed to a palladium-tin-chloride solution for 5 minutes at 55°C.

The panels were continuously stirred in the palladium-tin-chloride solution. The palladium-tin-chloride solution was formulated as follows. That is, by mixing the solution of Example 3 of U.S. Pat.
Dilute to a palladium concentration of mg/71. After immersion in the palladium-tin-chloride solution, the panels were washed with water and
Heat treated in an oven for 60 minutes at 'c and then brushed.

Several points on the panel: 0.3 mol of copper sulfate; 1.8 mol of sulfuric acid;
and electrolytic plating in an electrolytic plating solution consisting of 1.3 mmol of hydrochloric acid. The current density was 3.8V (.squared). Prior to electrolytic plating, the copper surface was deoxidized by immersion in a sodium persulfate solution for 5 seconds. After 5 minutes of electrolytic plating, only 10% of the hole walls were coated. After 1 hour of electrolytic plating, the panels were removed and the holes were inspected. Copper is electrolytically plated partially on the hole wall, but no plating is done in the middle, leaving a gap in the center of the hole.

Additional panels were electrolytically plated after adding 5 Vl of a nonionic surfactant, octylphenoxypolyethoxyethanol, to the copper plating solution. In less than 5 minutes, the hole walls were completely covered with a continuous film of copper metal, with no gaps.

Example ■ An additional panel prepared by the method of Example I was
Electrolyte in the same copper electroplating solution as in Example 1, except containing 5 Fl/1 methyl violet in place of the nonionic surfactant.

I was lucky. After 5 minutes of electrolytic plating, the hole walls were covered with a completely continuous film of copper metal.

Example ■ The procedure of Example ■ was repeated except that methyl violet was replaced with methylene blue. Here too, 5
After a minute of electrolytic plating, the hole walls were covered with a completely continuous film of copper.

Example ■ The process of Example ■ was repeated, except that the copper electroplating bath was replaced with a Watts nickel electroplating bath. Watts nickel bath is nickel sulfate 300f;
l/71! 30 I/A of boric acid. There was only incomplete penetration on the hole wall. A saccharin polish was added to the Watts nickel bath and the other panels were plated. A completely continuous film of electrolytically plated nickel quickly covered the pore walls.

Example■ Wafts nickel plating bath is 20ml/l Lec
tro-Nic 1O-03 (commercially available from Cellex, Hooker Chemical, & Plastic Co., Ltd.)
The preparation of Example 2 was repeated, except that a polishing agent containing benzaldehyde sulfonic acid was included. A completely continuous film of electrolytically plated nickel was obtained on the hole walls.

Example ■ The procedure of Example ■ was repeated, except that Copper Gleam PC (a polish consisting of a triphenylmethane dye used in a copper sulfate/sulfuric acid electrolytic plating bath) was added to the Watts nickel bath. A completely continuous film of electrolytically plated nickel is obtained on the hole walls.

EXAMPLE ■ This example describes the fabrication of a printed circuit using the metallization techniques of the present invention.

PR-4 or CEM-3 grade copper-clad insulating sheets are cut into panels of a size convenient for the fabrication process. Drill the holes necessary for the plated through-hole short circuit,
and the copper surface of the panel.

Remove burrs. The panel is then treated with a cleaning and conditioning solution as in Example I.

Sulfuric acid solution, wash, sodium persulfate solution, wash.

Presoak solution, and process in palladium-tin-chloride solution. The panels are then cleaned and placed in the oven for 20 minutes.
Heat treatment at 0'C and brush. The panels may be stored on this R floor or processed immediately without interrupting the processing process.

At this stage, the panel is provided with a mesh resist mask created by well-known photo printing, screen printing or other suitable processing processes.

The panel is then placed in an alkaline detergent for 45 seconds at 3A/(10
cm square) is subjected to reverse current electrolytic plating method, washed and 5
Do dtrium persulfate treatment for seconds (as above) and rewash.

The panel was then heated for 5 minutes at 3A/(
Electrolytic plating is performed with 10CIn square).

Copper sulfate 75 g/l sulfuric acid
1909/1 Chloride ion
70ppm Electro-Brite (P
C-667) The finished panels were then washed with 5ml/1 and 3A/(Loa) for 40 minutes in a bath containing:
Copper electrolytic plating is applied (m square).

Copper sulfate 75 El/1 sulfuric acid
1909/1 Chloride ion
50 ppmCopper Glea
m PC 5 ml/1 Alternatively, without going through the two-step electrolytic plating step described above, the panels are plated in one step in the first electrolytic plating bath described above at 3 A/(10° square) for about 45 minutes.

The panel is then cleaned and then converted into a printed circuit board by a well known solder plating process at 2A/(10cm square) for 18 minutes, cleaned, resist stripped, etched in a copper chloride solution containing ammonia and soldered. melt and
Apply solder paste and cut to the dimensions of the circuit board.

Example v■ Example ■ still includes the above steps up to the step of exposing the copper coated panel to a palladium-tin-chloride solution.
Process the panel according to the following. After this step, it is washed and then immersed in a 5% tetrafluoroboric acid solution, which is a solvent for the tin component of the palladium-tin-chloride seat deposited on the pore walls. The panels are then plated at 3 A/(10 Tan square) in a copper electrolytic plating bath formulated according to the invention and having the following composition:

Copper sulfate 75g/l sulfuric acid
100g/l chloride ion
50ppmCopper Gleam P
After depositing the C5ml/7!35μ thick copper layer, the panel is cleaned, dried, and a positive photoresist etching mask is applied using known techniques to cover the desired circuit features, including the through-holes to be plated. do. The copper is etched and the resist is then removed using standard processing steps, resulting in a finished printed circuit board.

Example■ This example describes the preparation of a multilayer printed circuit board.

A multilayer composite is formed by assembling each layer of circuitry on an insulating carrier and forming it into a laminate using well-known manufacturing techniques. After making the through holes and removing dirt from the copper layer forming part of the hole walls, the laminate is then processed as described in Examples 1 or 2.

Example X This example describes the preparation of a printed circuit board on a neat or uncoated laminate without providing copper foil on the surface.

The surface of the panel is provided with an adhesive layer and holes are formed by the method of US Pat. No. 3,625,75 B. The panel is mounted on electrolytic plating equipment to provide suitable conductive edges to form part of a suitable connector. The process of the US patent enhances the adhesion of the panel. The panel is then processed as described in Example 3.

Example M Copper-coated PR-4 epoxy glass panels were drilled through holes, cleaned, and treated with conditioning solution, presoak solution, and palladium-tin-chloride solution Example I It was processed as follows. palladium
After the tin-chloride solution and washing, the copper coated panels were dried and immersed in each of the following reducing agents (dissolved in 1.5 molar aqueous sodium hydroxide solution):

Both panels were electroplated for 2 minutes in the copper electroplating bath of sodium borohydride hydroxylamine Example 1. A completely continuous film of copper was obtained on the pore walls.

Example 2 The procedure of Example M is repeated, except that the palladium-tin-chloride solution is replaced by an aqueous solution of potassium hexachloroplatinate (IV) and tin (II) chloride. The reducing agent used was 1 g/l of sodium borohydride. The holes were covered with a continuous film of copper by electrolytic plating in less than 5 minutes.

Example ■ The process of Example ■ was repeated except that the copper sulfate/sulfuric acid bath was replaced with a copper pyrophosphate electrolytic plating bath. The copper pyrophosphate bath had the following formulation.

Copper 321/
A pyrophosphate ion 2459/A ammonia 225g/l temperature
The 52°C pyrophosphate anion serves the function of component C.

After 5 minutes of plating at 4.5 A/(10 crn square), copper completely covered the hole walls. A conventional polishing agent for copper pyrophosphate plating baths, dimercaptothiadiazole compounds (
Other panels were plated in the same plating bath with the addition of 1 mt/1 of RY61H (commercially available as RY61H from M.T. Chemical Co.). After 5 minutes in copper pyrophosphate using conventional RY61H polish, the hole walls were not plated. Dimercaptothiadiazole is strongly adsorbed onto palladium metal seats and prevents preferential deposition on palladium metal seats.

EXAMPLE After the palladium-tin-chloride solution and cleaning step, the copper-coated panels were treated without drying with a solution containing fluoroboric acid (100 mt/l) and hydroxyethylenediamine-1-lyacetic acid (4ill). The nonionic activator is Pluronic F-127 (commercially available from BASF-Wyandotte Corporation Kara), a monoblock copolymer of propylene oxide and ethylene oxide. 0,2 as component C in
The procedure of Example 2 was repeated, but electroplated according to the invention in the same copper electroplating solution as Example I except present at a concentration of g/β. After electrolytic plating for 5 minutes at a potential difference giving a current density of 3.8 A/d m', the pore walls were covered with a completely continuous film of copper.

EXAMPLE The method of Example XIV was repeated. In all cases, the result after electrolytic plating was a continuous coating of copper covering the hole walls, completely free of defects.

Example Compound Concentration CD Plating (9
/β)(A/dm) Time (9) A Pluronic F-1270, 23, 85B Pluronic F-127025, 9230 Carbowax 1540, 0.3 3.8 5D Carbowax 1540 0.3 5.92
3E Pluronic F-681,0385F
Chill o-tsuk F 68 1.0 5.92
3G Pluronic L-421,03,s
5H poliopress WSRso 1.0
3.8 15■ Carpowax 4000
0.5 3.8 15J Olin 10(
) 0.5 3.8 15K Olin 6G O,53,8'15L Carbowax 20M O,53,815M Pluronic L-640,53,8'15Np-di)-L MinFoamIX0.5 3.8 150
Carbo Wax 600 1.0 3.8
15 Pluronic is a trade name of BAS F-Wyandts F Co., Ltd. for polyoxyethylene and polyoxypropylene block copolymer, and Pluronic F-1zt is
It is a polyoxypropylene base of about 70 oxypropylene units connected to two polyoxyethylene chains containing a total of about 300 oxyethylene groups. In Pluronic F-68, the polyoxypropylene portion contains about 160 units. Pluronic L-42 has approximately 20 polyoxypropylene units and 15 polyoxyethylene units.

Polyopres WSR80 is a polyoxyethylene compound with an average molecular weight of 200,000 commercially available from Union Force-Noxoid.

Orlin 6G and LOG are 6 and 10, respectively.
An alkylphenylpolyoxyethylene compound with oxyethylene groups.

These are commercially available from Orlin.

Tergitol Min Foam is a linear alcohol polyoxypropylene-polyoxyethylene compound commercially available from X Honey Union Carbide Company.

Example ■ The method of the Examples section was repeated, except that the electrolytic plating solution was a nickel bath consisting of:

N i S O6H201951/7! N 1C1l
6 H201759/IIH3BO34 (1/7 PH1・5 Temperature 46°C The nonionic activator added to this solution as component C had a concentration of 0.1 f//l
It was Carbowax 1540. 3.8A/drr
After electroplating for 15 minutes at a potential difference of i', the pore walls were covered with a completely continuous coating of nickel.

EXAMPLE PART In order to more fully illustrate the effectiveness of polyoxyethylene groups in practicing the present invention, anionic activity widely used in the electrolytic plating industry and recommended for use in acidic copper sulfate electrolytic plating baths is presented. The agent sodium lauryl sulfate was tested as follows.

1. instead of Pluronic F-127 in the first copper electrolytic plating bath. , Og/l of sodium lauryl sulfate (E.
(commercially available as Duponol C from I DuPont) was added as a surfactant, and the second and third electrolytic plating baths each contained 1.09/l of polypropylene in place of Pluronic F-12'7. The procedure of Example 2 was repeated, except that ammonium ether sulfate and 1.0 g/l of ammonium lauryl polyether sulfate (commercially available as Cybo/EA from Alcolac) were used. After a plating time of 5 minutes, the electrolytic plating bath containing polyether sulfate and lauryl polyether sulfate formed a completely continuous film of copper covering the pore walls, whereas the electrolytic plating bath containing lauryl sulfate formed a completely continuous film of copper covering the pore walls. Electrolytic plating is 1
It did not cover the hole walls even after 5 minutes of plating time.

This experiment shows that lauryl sulfate, a simple linear anionic activator, is ineffective for purposes of the present invention. In order to modify the structure of lauryl sulfate with polyether groups,
If the surfactant is selected according to the teachings of the present invention, it becomes effective as component C.

EXAMPLE Copper()leam The procedure of Example 2 was repeated except that substituted thiourea was used in place of PC.

The first electrolytic plating solution used 5~/l of tetramethylthiuram disulfide, and the second solution iK used 0.8 &/l of allylthiourea as component C. 3
．． After electroplating for 15 minutes at a potential difference of 8 amp/sqdm, the hole walls of printed circuit boards plated in both solutions were covered with a continuous coating of copper.

[Brief explanation of drawings]

Figure 1 shows the difference delta (E) , , , E', -E'
, a graph showing the current-potential difference relationship defined by , Figure 2 is the difference delta (E)dep = E'dep ""de
Graphs showing the current-potential difference relationship defined by p, FIGS. 3a to 3f are a series of explanatory diagrams showing changes over time in electrolytic deposition according to the method of the present invention. A: i for an electrode made of metal (e.g. Pd)
-v curve B: i for an electrode made of metal 2 (e.g. Cu)
-v curve patent applicant Kollmorgen Technologies Corporation Agent Kenbu Niimi and 1 other person FIG, 1 FIG, 2゛ Procedural amendment (2) 1937 [', August 4, 1982, Case description 1982 Patent Application No. 120927 2
, Title of the invention Improving method for electrolytically plating non-metallic surfaces 3, Relationship with amendment A'1 Name of patent applicant Kollmorgen Technology I
John Corbore I John 4, Agent 604 6. Number of inventions increased by amendment 7 Subject of amendment Full text of the specification 8. Contents of the amendment 11) Engraving of the specification. (No change in content) List of 9 attached documents

Claims (1)

[Scope of Claims] (1) A non-metallic surface is coated with a metal by electrolytic plating in a container having a reverse electrode and containing an electrolytic plating bath solution containing the metal (B) to be electrolytically plated in ionic form. said surface has a connector portion, said connector portion is located outside the non-metallic surface to be electrolytically plated, the method comprising: (a) forming a plurality of metal seats on the non-metallic surface; step, the seat is made of metal (A), said metal (A) is deposited on said surface by electrolytic plating, said metal (B)
); (b) exposing said surface, including at least a portion of a connector portion, to an electrolytic plating bath solution, said solution having a defined electrical conductivity, and further comprising a species of electrolytically deposited metal (B); one or more causing preferential deposition of said metal (B) on said metal sheet consisting of or comprising metal (A) compared to deposition on a surface consisting of or produced thereby; A part of the connector (C) containing component (C) and a metal (C) on the seat are placed on the opposite electrode.
B) applying a potential difference sufficient to initiate and cause preferential deposition of the non-metallic surface for a time sufficient to form an essentially uniform deposit of the required thickness. Metallization method. (2) The above acid/min (C) attaches itself preferentially to the surface of the metal (B) seeds compared to the surface of the metal (A) seeds, resulting in formation by the seat metal (A) seeds. Claim 1, characterized in that the plating reaction on the surface formed by the metal (B) is almost suppressed or reduced while hardly suppressing the plating reaction on the surface formed by the metal (B). the method of. (3) A method according to claim 2, characterized in that the component (C) increases the overpotential difference on the surface formed by the metal (B). (4) The component (C) preferentially attaches itself to the seed of the seat metal (A), and the attached component (C) becomes the metal (B).
2. A method according to claim 1, characterized in that the plating reaction on the surface formed by the sheet metal (A) is increased considerably compared to the plating reaction on the surface of the species. (5) The attached component (C) reduces the overpotential difference,
5. A method according to claim 4, characterized in that as a result, the plating reaction is increased compared to the plating reaction on the surface of the metal (B) seed. (6) Component (C) is Dye 9 surfactant and chelating agent. 2. A method according to claim 1, characterized in that the brightener is selected from brighteners and leveling agents. (7) A method according to claim 6, characterized in that component (C) is a dye selected from methylene blue and methyl violet. (8) Component (C) is a surface active material selected from alkylphenoxy-polyethoxyethanols, nonionic fluorocarbon surfactants, polyoxyethylene compounds, and block copolymers of polyoxyethylene and polyoxypropylene. 7. The method according to claim 6, wherein the method is a drug. (9) A method according to claim 8, characterized in that component (C) is selected from compounds containing 4 to 1,000,000 oxyethylene groups. 10. Process according to claim 9, characterized in that component (C) is selected from compounds containing 20 to 150 oxyethylene groups. 9. A process according to claim 8, characterized in that the Uυ component (C) is selected from ethylene oxide-propylene oxide copolymers containing from 10 to 400 oxyethylene groups. H component (C) Ka2.4.6-(2-P!J Sill)-
8-1-li. 7. A method according to claim 6, characterized in that the chelating agent is selected from azine and pyrophosphate anions. (13) Component (C) is an N-heterocyclic compound, a triphenylmethane dye, thiourea, allylthiourea, tetramethylthiuram disulfide, a thiourea derivative, saccharin, and 1. 7. The method according to claim 6, characterized in that the brightener and/or leveling agent is selected from O-benzaldehyde sulfonic acid derivatives. (14) The electrical conductivity of the electrolytic plating bath solution and the potential difference applied to the connector portion and the opposite electrode result in a rate at least one order of magnitude greater, preferably two orders of magnitude greater than the rate of deposition of the metal (B) species on the surface. , selected to be of sufficient height to achieve a rate of deposition of the seeds on the surface of the sheet metal (A). α5) The conductivity is adjusted to the highest value allowed in relation to other plating factors.
The method described in Section 4. θ6) that the potential difference is adjusted to compensate for the potential difference F on the resistive conductor caused by the plating bath solution between the metal seat of metal (A) and the connector portion and between such adjacent seats; 15. The method of claim 14, characterized in: 07) Claim 1, characterized in that the potential difference is adjusted to the highest value allowed with respect to other plating factors.
The method described in Section 6. Group 0 Metal (A) and metal (B) are lb of the periodic table of elements
and group V, and the metal (A) is a metal (B
) The method according to claim 1, characterized in that the method is different from: α0 Component (C) is Dye 9 surfactant and chelating agent. 19. A method according to claim 18, characterized in that it is selected from brighteners and leveling agents. (20) Under the conditions provided by the plating operation, the potential difference between the pools of adhesion of metal (B) onto metal (Δ) is less negative than the potential difference between the pools of adhesion of metal (B) to itself. 2. Process according to claim 1, characterized in that metal (A) and metal (B) are selected. Cυ Component (C) is dye 9, a surfactant, and a chelating agent. 2o. Process according to claim 2o, characterized in that it is selected from brighteners and leveling agents. - (221) A method according to claim 18, characterized in that the metal (A) is selected from palladium, platinum, silver or gold. (23) The metal (B) is selected from copper and nickel. (24) A method according to claim 18, characterized in that the seat forming step consists of using the metal (A) in solution as a compound or a complex compound. (25) Claim 24, wherein the compound is a metal halide or a metal halide double salt.
The method described in section. (26) The method according to claim 25, wherein the metal halide double salt is palladium-tin-chloride. (271) A method according to claim 24, characterized in that the solution consists of metal (A) and a tin halide and that the treated surface is then exposed to a solvent for the tin compound. (28) Claims characterized in that a plurality of metal seats of metal (A) are formed by treating a non-metallic surface with a solution consisting of metal (A) and then exposing said surface to heat or a reducing agent. The method of claim 25. (29) The method of claim 28, wherein the heat treatment is carried out at a temperature in the range of 65 to 120'C for at least 10 minutes. (30) The reduction 29. A method according to claim 28, characterized in that the agent is selected from sodium borohydride, formaldehyde, dimethylamineporane and hydroxylamine. (B)
terminating the deposition of the metal (B) after completing the continuous film, characterized in that one or more metal layers are electrolytically deposited on said film or part thereof. A method according to claim 1. (32) at least two electrolytic plating bath solutions of different compositions are used, and the first solution used consists of components that maximize the rate of deposition on the metal (A); and the subsequently used electrolytic plating bath solution is formulated to optimize the properties of each metal deposit produced.
The method described in Section 1. (33) In a method of manufacturing a printed circuit board comprising forming a hole in a copper-coated insulating sheet, or in a laminate formed by a plurality of such sheets, and providing the walls of the hole with a metal layer ( a) forming a number of metal seats on the wall of said hole, said seats consisting of metal (A), said metal (A) being a metal (B) which is to be deposited on the surface of said wall by electrolytic plating; and (b) in a subsequent step, the sheet or laminate contains the metal (B) to be electrolytically deposited in a dissolved form; The layer also contains one or more of the components (C) which cause preferential adhesion of the metal (B) compared to the adhesion on the surface consisting of or produced by the species. (C) exposing a copper coated sheet or laminate and a counter electrode placed in said plating bath solution to a preferential transfer of metal (B) to said seat; a sufficient potential difference to initiate and cause deposition for a sufficient time to form a desired deposit of essentially uniform thickness;
Giving; a printed circuit board manufacturing method with full features. (34) further comprising the step of providing a negative resist layer on the surface of the copper-coated sheet or laminate, the layer leaving exposed portions corresponding to the desired conductor shapes including the holes; defines the hole provided by the seat of metal (A), and after the electrolytic plating process, removes the first layer of resist and etches away the metal covered by the resist layer. 34. The method of claim 33, characterized in: (351 Further, following the electrolytic plating step, the copper-coated sheet still includes a step of applying a positive resist layer to the surface of the laminate, the resist layer covering the portion corresponding to the desired circuit figure including the hole, and applying a positive resist layer to the surface of the laminate. Claim 3, characterized in that metal not covered by the resist layer is etched away to form a printed circuit board figure.
The method described in Section 3. (36) A method of forming a hole in an insulating sheet and providing a printed circuit board having a metal layer of a desired thickness on the hole wall and a portion corresponding to a desired printed circuit conductor shape, a) forming a number of metal seats on the walls of said hole and in said portions corresponding to said conductor shapes; and (b) in a subsequent step, said sheets are attached to the metal to be electrolytically deposited ( B) in dissolved form, and furthermore, the preference of said metal (B) on said metal seat growing from metal (A) compared to the deposit on the surface produced by the electrolytically deposited species of metal (B). Ingredients that cause target adhesion (
d) exposure to an electrolytic plating bath solution of a predetermined conductivity, also comprising one or more of Place a metal (
B) applying a sufficient potential difference to initiate and effect the preferential deposition of B) for a sufficient time to produce the desired deposition of essentially uniform thickness. (37) Claim 36, wherein a portion of the connector is characterized in that a small portion of the surface of the insulating sheet along its edge is shaped like a window frame. the method of.