KR101344176B1 - Copper foil for printed circuit board and copper-clad laminate for printed circuit board - Google Patents

Abstract

Copper foil for printed circuit boards provided with the layer (henceforth a "copper nickel zinc layer") containing nickel, zinc, and copper on the surface of copper foil, The weight of zinc adhesion per unit area of the said copper nickel zinc layer is 200 It is 1 microgram / dm <^2> or more and 2000 microgram / dm <^2> or less, Ni is 1-50 weight% in the said copper nickel zinc layer, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} Is 0.3 or more and (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.3 or more, The copper foil for printed circuit boards characterized by the above-mentioned.
When laminating | stacking copper foil on a resin base material and soft-etching a circuit using a sulfuric acid-hydrogen peroxide type etching liquid, it is a subject to establish the surface treatment technology of copper foil which can prevent a circuit erosion phenomenon effectively.

Description

Copper foil for printed circuit boards and copper clad laminates for printed circuit boards {COPPER FOIL FOR PRINTED CIRCUIT BOARD AND COPPER-CLAD LAMINATE FOR PRINTED CIRCUIT BOARD}

This invention is the layer which contains nickel, zinc, and copper in the adhesive surface with at least resin of the copper foil for printed circuit boards and the copper clad laminated board for printed circuit boards, especially copper foil excellent in heat resistance and chemical-resistance. (Hereinafter referred to as "copper nickel zinc layer"), a copper foil for printed circuit boards having a chromate coating layer and a silane coupling agent layer on the copper layer, and a copper clad laminate for printed circuit boards manufactured using the copper foil. It is about.

The semiconductor package substrate which is one type of a printed circuit board is a printed circuit board used for mounting a semiconductor IC chip and other semiconductor elements. Since the circuit formed on the semiconductor package substrate is finer than a conventional printed circuit board, a resin substrate different from a general printed circuit board is used for the substrate material.

The semiconductor package substrate is usually manufactured by the following process. First, a copper foil is laminated and adhered to a base material such as a synthetic resin under high temperature and high pressure. This is called a copper clad laminate or simply a laminate. Next, in order to form the target electroconductive circuit on a laminated board, the pattern equivalent to a circuit is printed by materials, such as a etch-resistant resin, on copper foil. And the unnecessary part of the exposed copper foil is removed by an etching process.

After the etching, the printed portion is removed to form a conductive circuit on the substrate. Finally, predetermined elements are soldered to the formed conductive circuits to form various printed circuit boards for electronic devices. Finally, it joins with a resist or a buildup resin substrate.

In general, the quality requirements for copper foil for printed circuit boards are different on the adhesive surface (so-called rough surface) and the non-bonded surface (so-called glossy surface) to be bonded to the resin substrate, and satisfying both at the same time. need.

As a request for a gloss surface, (1) the appearance is good and there is no oxidation discoloration at the time of storage, (2) the solder wettability is good, (3) the oxidation discoloration at the time of high temperature heating, ( 4) Good adhesion with a resist is required.

On the other hand, the roughened surface is mainly (1) no oxidation discoloration at the time of storage, (2) peel strength with the substrate is sufficient even after high temperature heating, wet treatment, soldering, chemical treatment, etc., (3) Lamination | stacking with a base material, what is called a lamination | smal flaw which generate | occur | produced after etching, etc. are mentioned.

In addition, in recent years, with the miniaturization of circuit printed patterns, the roughness of the copper foil surface is required.

In addition, in electronic devices such as personal computers and mobile communication, high frequency of electric signals is progressing with high speed and high capacity of communication, and a printed circuit board and copper foil that can cope with this are required. When the frequency of the electrical signal is 1 GHz or more, the effect of the skin effect that the current flows only on the surface of the conductor becomes remarkable, and the effect of changing the current transmission path due to the surface irregularities and increasing the impedance cannot be ignored. Also from this point, it is desired that the surface roughness of the copper foil is small.

In order to meet these demands, many surface treatment methods have been proposed for copper foil for printed circuit boards.

Although a surface treatment method differs between a rolled copper foil and an electrolytic copper foil, when an example of the surface treatment method of an electrolytic copper foil is shown, there exists a method described below.

That is, first, in order to increase the adhesive force (peel strength) of copper and a resin base material, generally, the fine particle which consists of copper and copper oxide is given to the copper foil surface (harmonic treatment), and in order to have heat-resistant characteristics, such as brass or zinc, A heat resistant layer (barrier layer) is formed.

Finally, in order to prevent surface oxidation during transportation or storage, etc., the product is subjected to rust prevention treatment by immersion or electrolytic chromate treatment or electrolytic zinc chromate treatment.

Among these, the surface treatment method which forms especially a heat resistant layer determines the surface property of copper foil, and has an important key. For this reason, many copper foils which provided coating layers, such as Zn, Cu-Ni alloy, Cu-Co alloy, and Cu-Zn alloy, as a metal or alloy which forms a heat resistant layer are put to practical use (for example, patent document 1 Reference).

Among these, the copper foil in which the heat resistant layer which consists of Cu-Zn alloys (brass) was formed does not have the stain of a resin layer when it uses for the printed circuit board which consists of epoxy resins, etc., and copper foil after maintaining a printed circuit board at high temperature It has been widely used industrially because it has excellent characteristics such as less deterioration in peel strength. The method of forming the heat resistant layer which consists of this brass is explained in patent document 2 in detail.

However, in recent years, in order to improve the adhesiveness of the resist or build-up resin substrate and the gloss surface of copper foil which is a circuit surface, in the manufacturing process of a printed circuit board, especially a package board | substrate, soft etching is performed by the liquid mixture of sulfuric acid and hydrogen peroxide, and copper foil glossiness. When the surface roughening process is used, soft etching of the copper foil circuit gloss surface of the printed circuit board using the copper foil which provided the well-known heat-resistant layer described in patent document 1 etc. with the liquid mixture of the said sulfuric acid and hydrogen peroxide is carried out. There exists a problem that the erosion (circuit erosion) phenomenon of the circuit pattern both sides edge part formed previously arises, and the peeling strength with a resin base material deteriorates.

This circuit erosion phenomenon refers to a phenomenon in which the adhesive boundary layer between the copper foil circuit and the resin substrate is eroded by the mixed solution of sulfuric acid and hydrogen peroxide, whereby the peel strength of the copper foil in the portion is significantly degraded. When this phenomenon occurs on the entire circuit pattern surface, the circuit pattern is peeled off from the base material, which is a serious problem.

Therefore, it is generally known that a nickel-zinc-copper layer in which nickel is added to brass is effective as a surface treatment layer excellent in preventing circuit erosion. However, although the circuit erosion phenomenon can be prevented by the addition of nickel, the Cu-Zn alloy (brass) may be reduced depending on the amount of nickel added, such as a decrease in heat resistance (heat peel strength) or generation of pool residues during circuit formation. The inventors found out that the surface layer may be lower than the surface layer formed of the same.

Japanese Patent Publication No. 51-35711 Japanese Patent Publication No. 54-6701

The subject of this invention is the various characteristics of the surface layer which consists of a Cu-Zn alloy (brass) (state peeling strength of the copper foil of the printed circuit board manufactured by laminating | stacking copper foil and a resin base material, and a printed circuit board predetermined | prescribed at high temperature). It is to develop a copper foil suitable for a semiconductor package substrate which reduces the above-described circuit erosion phenomenon without deteriorating the peel strength (hereinafter referred to as a heat resistant peel strength) and chemical resistance (hydrochloric acid) after the time retention.

In particular, when copper foil is laminated on a resin substrate to greatly improve the heat-resistant peeling strength, and the circuit is soft-etched using a sulfuric acid-hydrogen peroxide-based etching solution, the circuit erosion phenomenon by the copper etching solution can be effectively prevented. (Hereinafter, it is called "chemical resistance" as needed.) It is in establishing the surface treatment technology of copper foil.

In order to solve the said subject, as a result of earnestly examining about the conditions etc. which this inventor performs surface treatment on copper foil, the heat-resistant peeling strength improvement and chemical-resistance of the following copper foil, ie, the copper foil glossiness surface by the sulfuric acid-hydrogen peroxide type etching liquid, At the time of soft etching, it turned out that it is effective for the corrosion resistance (circulation corrosion resistance) of a roughening surface.

From the above, this invention,

1) Copper foil for printed circuit boards provided with the layer containing nickel, zinc, and copper on the surface of copper foil (henceforth a "copper nickel zinc layer"), and the weight with zinc per unit area of the said copper nickel zinc layer. It is 200 micrograms / dm <^2> or more and 2000 micrograms / dm <^2> or less, Ni is 1-50 weight% in the said copper nickel zinc layer, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%) )} Is 0.3 or more and (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.3 or more, The copper foil for printed circuit boards is provided.

Further, according to the present invention,

2) A copper foil for a printed circuit board according to 1, comprising a chromate coating layer on the copper nickel zinc layer.

3) Said chromate coating layer WHEREIN: The chromium adhesion weight is 30 microgram / dm <^2> or more and 100 microgram / dm <^2> per unit area, The copper foil for printed circuit boards of said 2 characterized by the above-mentioned.

4) Copper foil for printed circuit boards as described in said 2 or 3 which further comprises a silane coupling agent layer on the said chromate coating layer,

5) Copper foil is an electrolytic copper foil, The said copper nickel zinc layer is formed in the rough surface at the time of electrolytic plating, or the gloss surface of an electrolytic copper foil, The copper foil for printed circuit boards in any one of said 1-4 characterized by the above-mentioned.

6) Copper foil is rolled copper foil, Copper foil for printed circuit boards in any one of said 1-4 characterized by the above-mentioned,

7) The copper clad laminated board for printed circuit boards which attached and manufactured the copper foil for printed circuit boards and resin for a printed circuit board as described in any one of said 1-6 are provided.

As shown above, the copper foil for printed circuit boards of this invention uses a copper nickel zinc layer in order not to deteriorate the peeling strength of copper foil after maintaining a printed circuit board at high temperature. Thereby, the heat resistant peeling strength of copper foil can be improved remarkably.

In addition, this prevents the erosion of the circuit caused by chemicals, and in particular, has given new characteristics to improve sulfuric acid-hydrogen peroxide resistance. Copper foil for printed circuit boards (in particular, copper foil for semiconductor package substrates) and copper foil It is very effective as a copper clad laminated board (especially copper clad laminated board for semiconductor package board | substrates) manufactured by adhering to a resin base material. Naturally, it can be used also as a copper foil for general printed circuit boards.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the composition area | region suitable for this invention of Cu-Ni-Zn ternary alloy.

Next, in order to make understanding of this invention easy, this invention is demonstrated concretely and in detail.

The copper foil of this invention can use either an electrolytic copper foil and a rolled copper foil, but in the case of an electrolytic copper foil, it can apply to the rough surface at the time of electroplating, or the gloss surface of an electrolytic copper foil. In addition, you may perform a roughening process further on these surfaces. For example, in order to improve the peeling (fill) strength of the copper foil after lamination with a resin substrate, an electrolytic treatment in which the electrodepositing of, for example, a "hog" shape of copper is performed on the surface of the copper foil after degreasing is performed. With copper foil, this can be used as it is.

Generally, in the manufacturing apparatus of the drum type electrolytic copper foil, one side (drum side) is a gloss surface, and the other side is a rough surface. In a rolled copper foil, both become a glossy rolling surface. In the present invention, the electrolytic copper foil has a rough surface and a glossy surface, but in the case of the rough surface, it can be used as it is. About the gloss surface of an electrolytic copper foil, in order to raise a peeling intensity | strength, a roughening process can be performed and it can be set as a roughening surface.

Also in a rolled copper foil, a roughening process is performed similarly. In any case, the roughening process can use a well-known roughening process, and there is no restriction | limiting in particular.

The roughening surface of this invention means the electrolytic copper foil which has the roughening surface at the time of electrolytic plating, or the electrolytic copper foil and rolled copper foil which performed the roughening process, and is applicable to any copper foil.

As mentioned above, the copper foil for semiconductor package substrates of this invention consists of a copper nickel zinc layer formed on the surface of the copper foil used as an adhesive surface with resin, a chromate coating layer, and a silane coupling agent layer as needed. As copper foil, said rolled copper foil or electrolytic copper foil can be used.

As the chromate coating layer, an electrolytic chromate coating layer or an immersion chromate coating layer can be used.

As mentioned above, this invention forms a layer (henceforth a "copper nickel zinc layer") containing nickel, zinc, and copper on the surface of copper foil, for example.

In order for copper foil not to deteriorate the peeling strength after high temperature heating, it is necessary to make zinc adhesion amount per unit area of copper foil in the said copper nickel zinc layer into 200 microgram / dm <^2> or more. Regardless of the composition of the copper nickel zinc layer, when the zinc adhesion weight is less than 200 µg / dm ² , the deterioration of the peel strength after high temperature heating becomes large without the effect of layer formation. On the other hand, when zinc adhesion weight exceeds 2000 microgram / dm < ² >, erosion of the circuit edge by a sulfuric acid-hydrogen peroxide type etching liquid becomes remarkable. Therefore, the zinc adhesion amount per unit area of copper foil in the said copper nickel zinc layer is preferably 200 µg / dm ² or more and 2000 µg / dm ² or less.

And the inventors of the copper nickel zinc layer, the balance of the composition of each metal is important, and by forming a copper nickel zinc layer of the region X shown in the composition region of the Cu-Ni-Zn ternary alloy of Fig. 1, after the high temperature heating It was found that the peel strength and the chemical resistance (hydrochloric acid resistance, sulfuric acid-hydrogen peroxide resistance) were excellent. It describes concretely below.

Nickel addition is inevitable for chemical resistance, and the nickel ratio in a copper nickel zinc layer should just be 1% or more. If it is less than 1%, circuit erosion cannot be prevented effectively. However, when the nickel ratio in a copper nickel zinc layer exceeds 50%, since the balance of zinc and copper in a copper nickel zinc layer mentioned later will fall, heat-resistant peeling strength will fall and the pool residue at the time of circuit formation will become unpreferable. not. Therefore, as for the nickel ratio in a copper nickel zinc layer, 1% or more and 50% or less are preferable.

And when the nickel ratio in a copper nickel zinc layer is 1% or more and 50% or less, the ratio of the adhesion amount of zinc and copper in a copper nickel zinc layer affects heat-resistant peeling strength and chemical-resistance (hydrochloric acid). Specifically, it is necessary to satisfy the following equation. That is, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} (formula 1) is 0.3 or more, (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%) )} (Formula 2) needs to be 0.3 or more (the area | region of X of FIG. 1). Moreover, (Equation 1) and (Equation 2) were added to the said Formula, respectively, so that it might be easy to understand.

For example, when there is too much zinc adhesion amount, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} (formula 1) becomes 0.3 or more, but since copper adhesion amount becomes small, copper adhesion amount ( Mass%)) / {100- (zinc adhesion amount (mass%))} (Formula 2) may be less than 0.3 (region c of FIG. 1). In this case, since copper adhesion amount becomes small with respect to zinc adhesion amount, chemical-resistance (hydrochloric acid) falls.

On the other hand, when there is too much copper adhesion amount, (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} (formula 2) becomes 0.3 or more, but (zinc adhesion amount (mass%)) / {100 -(Copper adhesion amount (mass%))} (Formula 1) may be less than 0.3 (region b of FIG. 1).

In this case, since zinc adhesion amount becomes small with respect to copper adhesion amount, heat-resistant peeling strength falls. Therefore, about the ratio of the adhesion amount of zinc and copper in a copper nickel zinc layer, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} (Formula 1) is 0.3 or more, (copper adhesion amount (mass %)) / {100- (zinc adhesion amount (mass%))} (Formula 2) preferably satisfies both equations of 0.3 or more (region of X in FIG. 1).

A copper nickel zinc layer is normally formed on condition of the following. However, zinc adhesion weight per unit area of a copper nickel zinc layer is 200 microgram / dm <^2> or more and 2000 microgram / dm <^2> or less, and Ni is 1-50 weight% in the said copper nickel zinc layer, (zinc adhesion amount (mass%) ) / {100- (copper adhesion amount (mass%))} (formula 1) is 0.3 or more, (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} (formula 2) is 0.3 or more If it is an electroplating condition which can achieve | attain, it will not specifically limit, Other electroplating conditions can also be used.

(Plating amount furtherance)

Ni: 0.1 g / l to 30 g / l, Zn: 0.1 g / l to 12 g / l, Cu: 0.1 g / l to 2 g / l, sulfuric acid (H ₂ SO ₄ ): 0.1 g / l to 10 g / l, is taken as the basic bath. In addition, other inorganic acids or organic carboxylic acids (citric acid, malic acid, etc.) may be used instead of sulfuric acid.

(Current Density) 3 to 25 A / dm ²

Next, in the chromate treatment, any of the electrolytic chromate treatment, the immersion chromate treatment, and the zinc chromate treatment containing zinc in the chromate bath can be applied to the production of the chromate coating layer.

In any case, when the chromium adhesion weight is less than 30 µg / dm ² , the chromium adhesion weight is 30 µg / dm ² or more because the effect of enhancing acid resistance and heat resistance is small. In addition, when the chromium adhesion weight exceeds 100 µg / dm ² , the effect of the chromate treatment is saturated so that the chromium adhesion weight no longer increases. Taken together, it can be said that the chromium adhesion weight per unit area in the chromate treated layer is preferably 30 to 100 µg / dm ² .

Examples of the conditions for forming the chromate film layer are described below. However, it is not necessary to be limited to this condition as mentioned above, Any known chromate treatment can be used.

Generally in the case of immersion chromate treatment, 30-40 microgram / dm <^2> of chromium adhesion weights per unit area can be achieved. Moreover, in the case of the electrolytic chromate treatment, 30-100 microgram / dm <^2> of chromium adhesion weights per unit area can be achieved.

This rust prevention treatment is one of the factors affecting the acid resistance and heat resistance of the copper foil, and is effective because the chemical resistance and heat resistance of the copper foil are further improved by the chromate treatment.

(a) Example of immersion chromate treatment

CrO ₃ or K ₂ Cr ₂ O ₇ : 1-12 g / L, Zn (OH) ₂ or ZnSO ₄ .7H ₂ O: 0-10 g / L, Na ₂ SO ₄ : 0-20 g / L, pH 2.5-12.5, Temperature: 20-60 ℃, time: 0.5-20 seconds

(b) An example of electrolytic chromate treatment

CrO ₃ or K ₂ Cr ₂ O ₇ : 1-12 g / l, Zn (OH) ₂ or ZnSO ₄ · 7H ₂ O: 0-10 g / l, Na ₂ SO ₄ : 0-20 g / l, pH 2.5-12.5, temperature: 20-60 ° C., current density 0.5-5 A / dm ² , time: 0.5-20 seconds

As a silane coupling agent used for the copper foil for printed circuit boards of this invention, it is preferable that at least 1 type of alkoxysilanes provided with the functional group which has at least tetraalkoxysilane and reactivity with resin, for example is preferable. Although the selection of this silane coupling agent is also arbitrary, the selection which considered adhesiveness with resin is preferable.

delete

Next, the silane coupling agent process (after application | coating and drying) was performed on this rust prevention layer.

The conditions of a silane coupling agent process are as follows.

An aqueous solution containing 0.5 volume% of epoxysilane was adjusted to pH 7 and applied, and then dried.

(Test Methods)

The following two types of things were used for copper foil and the resin base material laminated | stacked.

FR-4 Resin (Glass Cross Base Epoxy Resin)

BT resin (triazine-bismaleimide resin, trade name: GHPL-830 manufactured by Mitsubishi Gas Chemical)

Moreover, BT resin is high in heat resistance and is a material used for the printed circuit board for semiconductor packages.

(1) Measurement of state peel strength and heat resistant peel strength using FR-4 substrate

The copper foil on the laminated board which laminated | stacked the surface which formed the copper nickel zinc layer of copper foil, and FR-4 resin base material is etched, and the copper foil circuit of 10 mm width is formed on a laminated board.

This circuit is peeled off and the state peel strength is measured. Next, the peel strength (henceforth heat-resistant peeling strength) and the relative deterioration rate (loss%) from the state peeling strength after heating the laminated board in which the said 10 mm width copper foil circuit was formed at 180 degreeC in air | atmosphere for 2 days. Measured. FR-4 substrates are inferior in heat resistance compared to BT substrates.

Therefore, when it has favorable heat resistant peeling strength and low deterioration rate when using a FR-4 board | substrate, it has sufficient heat resistant peeling strength and deterioration rate even when using a BT board | substrate.

(2) Measurement of state peel strength and sulfuric acid hydrogen peroxide resistance using BT substrate

Copper foil on the laminated board which laminated | stacked the surface which formed the copper nickel zinc layer of copper foil, and BT resin base material is etched, and the copper foil circuit of 0.4 mm width is formed on a laminated board. This circuit is peeled off and the state peel strength is measured. Next, the sulfuric acid-hydrogen peroxide test and the hydrochloric acid test were implemented using the laminated board in which the said 0.4 mm width copper foil circuit was formed.

In the sulfuric acid-hydrogen peroxide test, the copper foil circuit on the laminated sheet was immersed in an etching solution containing 5-20% by volume of sulfuric acid and 1-10% by volume of hydrogen peroxide, and the copper foil circuit thickness was etched by 2 µm. The relative deterioration rate (loss%) from is measured.

In this case, the peel strength can be said to be in a harsh environment, which is a harsher condition than the evaluation of chemical resistance that is generally performed when using a FR-4 substrate.

Therefore, when the BT substrate is used, if it has good sulfuric acid-hydrogen peroxide resistance, the FR-4 substrate also has sufficient chemical resistance (particularly sulfuric acid-hydrogen peroxide resistance).

In a hydrochloric acid resistance test, the peel strength after immersing a copper foil circuit on a laminated board in 60 degreeC liquid containing 12 weight% of hydrochloric acid for 90 minutes, and the relative deterioration rate (loss%) from the state peeling strength are measured.

(3) Measurement of plating adhesion weight of nickel and zinc per unit area

It laminates with FR-4 resin base material so that the surface which formed the copper nickel zinc layer in copper foil is exposed to the surface, and a laminated board is manufactured. Next, the copper nickel zinc layer exposed on the surface of the laminated plate and copper of the mother layer were dissolved with hydrochloric acid or nitric acid, and the adhesion weight of zinc per unit area was measured by performing a chemical analysis of the zinc concentration in the solution.

(4) Analysis of abundance of zinc, nickel and copper

The abundance ratio of nickel, zinc, and copper contained in a copper nickel zinc layer was measured using XPS (X-ray photoelectron spectroscopy). The measurement was intermittently carried out from the outermost surface to the copper layer which is the base of the copper nickel zinc layer while etching the copper foil thickness with an argon ion sputter, and the abundance ratios of nickel, zinc and copper obtained at each depth were determined from the outermost surface. By integrating to the depth of, the average abundance ratio of nickel, zinc, and copper in the whole copper nickel zinc layer was calculated.

The instrument used for the measurement is AXIS-HS manufactured by KRATOS, and the output of the argon ion sputter is 52.5 W. In this condition, the copper foil thickness is etched at about 20 kPa in one minute. Sputter time was performed on 15-100 minutes conditions.

Example

Next, examples and comparative examples will be described. The results are shown in the following tables. This embodiment shows a preferable example, and the present invention is not limited to these embodiments. Accordingly, all modifications, other embodiments or aspects included in the technical idea of the present invention are included in the present invention.

Further, for comparison with the present invention, a comparative example was published.

(Examples 1-9)

A copper nickel zinc layer was formed by electroplating on the rough surface (surface average roughness: 3.8 micrometers) of this copper foil on the conditions shown below using the electrolytic copper foil of thickness 12micrometer. Table 1 shows the abundance ratios of nickel, zinc and copper.

(Electric Plating Solution Composition of Example 1)

Ni: 3 g / l, Zn: 6 g / l, Cu: 0.5 g / l, sulfuric acid (H ₂ SO ₄ ): 7.5 g / l

(Electric Plating Solution Composition of Example 2)

Ni: 20 g / l, Zn: 3 g / l, Cu: 0.2 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 3)

Ni: 13 g / l, Zn: 1 g / l, Cu: 2 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 4)

Ni: 10 g / l, Zn: 12 g / l, Cu: 0.2 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 5)

Ni: 28 g / l, Zn: 8 g / l, Cu: 0.5 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 6)

Ni: 10 g / l, Zn: 5 g / l, Cu: 1.0 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 7)

Ni: 0.3 g / l, Zn: 0.3 g / l, Cu: 2.0 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 8)

Ni: 28 g / l, Zn: 1 g / l, Cu: 0.8 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electric Plating Solution Composition of Example 9)

Ni: 7 g / l, Zn: 10 g / l, Cu: 0.5 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Current density) 5 A / dm ² or 10 A / dm ²

Moreover, the chromate treatment was performed on this copper nickel zinc layer, and the rust prevention layer was formed. The processing conditions are shown below.

CrO ₃ : 4.0 g / l, ZnSO ₄ · 7H ₂ O: 2.0 g / l, Na ₂ SO ₄ : 15 g / l, pH: 4.2, temperature: 45 ° C., current density 3.0 A / dm ² , time: 1.5 second

(Example 1)

In Example 1, zinc (Zn) adhesion amount in a plating film is 924 microgram / dm <^2> , Ni: 9 mass%, Zn: 42 mass%, Cu: 49 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.83, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.85, and all It was in the range of the condition of invention. As a result, in this Example 1, the peel strength after aging for 1.47 kN / m, 2 days was 1.20 kN / m, and the deterioration rate was 18% in the FR-4 board | substrate.

In addition, the state peel strength in the state BT substrate (under severe environment) is 1.05 kN / m, the peel strength after hydrochloric acid treatment is 0.85 kN / m, the deterioration rate is 20%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.98 kN / m and the deterioration rate became 7%, and all brought favorable results.

Table 1 shows the above results.

(Example 2)

In Example 2, zinc (Zn) adhesion amount in a plating film is 320 micrograms / dm <^2> , Ni: 31 mass%, Zn: 34 mass%, Cu: 36 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.52, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.54, and all It was in the range of the condition of invention. As a result, in this Example 2, the peel strength after aging for 1.56 kN / m and 2 days was 1.42 kN / m, and the deterioration rate was 9% in the FR-4 board | substrate.

In addition, the state peel strength in a state BT substrate (under severe environment) is 0.99 kN / m, the peel strength after hydrochloric acid treatment is 0.89 kN / m, the deterioration rate is 10%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.86 kN / m and the deterioration rate became 14%, and all brought favorable results.

The above result is shown in Table 1 similarly.

(Example 3)

In Example 3, zinc (Zn) adhesion amount in a plating film is 465 microgram / dm <^2> , Ni: 18 mass%, Zn: 12 mass%, Cu: 70 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.39, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.79, and all It was in the range of the condition of invention. As a result, in this Example 3, the peel strength after the aging of 1.55 kN / m and aging for 2 days was 1.53 kN / m, and the deterioration rate was 2% in the FR-4 board | substrate.

In addition, the state peel strength in a state BT substrate (under severe environment) is 0.99 kN / m, the peel strength after hydrochloric acid treatment is 0.93 kN / m, the deterioration rate is 6%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.88 kN / m and the deterioration rate became 11%, and all showed favorable results.

The above result is shown in Table 1 similarly.

(Example 4)

In Example 4, zinc (Zn) adhesion amount in a plating film is 390 microgram / dm <^2> , Ni: 2 mass%, Zn: 93 mass%, Cu: 5 mass% in a plating film, Formula 1 (Zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.98, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.77, and all It was in the range of the condition of invention. As a result, in this Example 4, the peel strength after aging for 1.46 kN / m and the aging for 2 days was 1.28 kN / m, and the deterioration rate was 12% in the FR-4 board | substrate.

In addition, the state peel strength in a state BT substrate (under severe environment) is 1.01 kN / m, the peel strength after hydrochloric acid treatment is 0.86 kN / m, the deterioration rate is 15%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.92 kN / m and the deterioration rate became 9%, and all brought favorable results.

The above result is shown in Table 1 similarly.

(Example 5)

In Example 5, zinc (Zn) adhesion amount in a plating film is 378 microgram / dm <^2> , Ni: 40 mass%, Zn: 36 mass%, Cu: 24 mass% in a plating film, Formula 1 (Zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.47, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.37, and all It was in the range of the condition of invention. As a result, in this Example 5, the peel strength after the aging of 1.48 kN / m and aging for 2 days was 1.43 kN / m, and the deterioration rate was 3% in the FR-4 board | substrate.

In addition, the state peel strength in the state BT substrate (under severe environment) is 1.04 kN / m, the peel strength after hydrochloric acid treatment is 0.91 kN / m, the deterioration rate is 13%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.93 kN / m and the deterioration rate became 11%, and all brought favorable results.

Table 1 shows the above results.

(Example 6)

In Example 6, zinc (Zn) adhesion amount in a plating film is 617 microgram / dm <^2> , Ni: 18 mass%, Zn: 12 mass%, Cu: 70 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.39, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.79, and all It was in the range of the condition of invention. As a result, in this Example 6, the peel strength after the aging of 1.45 kN / m and aging for 2 days was 1.42 kN / m, and the deterioration rate was 2% in the FR-4 board | substrate.

In addition, the state peel strength in the state BT substrate (under severe environment) is 1.10 kN / m, the peel strength after hydrochloric acid treatment is 0.87 kN / m, the deterioration rate is 21%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.98 kN / m and the deterioration rate became 11%, and all showed favorable results.

The above result is shown in Table 1 similarly.

(Example 7)

In Example 7, zinc (Zn) adhesion amount in a plating film is 1860 microgram / dm <^2> , Ni: 7 mass%, Zn: 9 mass%, Cu: 84 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.56, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.92, and all It was in the range of the condition of invention. As a result, in this Example 7, the peel strength after state aging of the FR-4 board | substrate was 1.48 kN / m, aging for 2 days was 1.40 kN / m, and the deterioration rate was 5%.

In addition, the state peel strength in the state BT substrate (under severe environment) is 1.02 kN / m, the peel strength after hydrochloric acid treatment is 0.98 kN / m, the deterioration rate is 4%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.96 kN / m and the deterioration rate became 2%, and all brought favorable results.

The above result is shown in Table 1 similarly.

(Example 8)

In Example 8, zinc (Zn) adhesion amount in a plating film is 746 microgram / dm <^2> , Ni: 47 mass%, Zn: 30 mass%, Cu: 23 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.39, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.33, and all It was in the range of the condition of invention. As a result, in this Example 8, the peel strength after aging of 1.47 kN / m and aging for 2 days was 1.46 kN / m, and the deterioration rate was 1% in the FR-4 board | substrate.

In addition, the state peel strength in a state BT substrate (under severe environment) is 1.03 kN / m, the peel strength after hydrochloric acid treatment is 0.95 kN / m, the deterioration rate is 8%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.95 kN / m and the deterioration rate became 0%, and all showed favorable results.

Table 1 shows the above results.

(Example 9)

In Example 9, zinc (Zn) adhesion amount in a plating film is 220 microgram / dm <^2> , Ni: 20 mass%, Zn: 69 mass%, Cu: 11 mass% in a plating film, Formula 1 (zinc adhesion amount) (Mass%)) / {100- (copper adhesion amount (mass%))} is 0.78, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.35, and all It was in the range of the condition of invention. As a result, in this Example 9, the peel strength after the aging of 1.45 kN / m and aging for 2 days was 1.42 kN / m, and the deterioration rate was 2% in the FR-4 board | substrate.

In addition, the state peel strength in the state BT substrate (under severe environment) is 1.06 kN / m, the peel strength after hydrochloric acid treatment is 0.92 kN / m, the deterioration rate is 13%, and the peel strength in sulfuric acid-hydrogen peroxide is 0.98 kN / m and the deterioration rate became 11%, and all showed favorable results.

The above result is shown in Table 1 similarly.

As mentioned above, in the plating layer of the Example, the adhesion weight of zinc per unit area is 220 µg / dm ² to 1860 µg / dm ² , and the state peel strength on the FR-4 substrate is 1.45 kN / m to 1.56 kN / m. The heat resistant peel strength was 1.20 kN / m to 1.53 kN / m, and the deterioration rate was 18% or less, and both exhibited good state peel strength and heat resistant peel strength.

In addition, the state peeling strength in BT board | substrate became the range of 0.99 kN / m-1.10 kN / m. Peel strengths after treatment in hydrochloric acid and sulfuric acid permeate are 0.85 kN / m to 0.93 kN / m and 0.86 kN / m to 0.98 kN / m, respectively, and the deterioration rates are 4% to 21% and 0% to 14%, respectively. And good properties.

(Comparative Example 1-10)

The plating bath composition was changed on condition shown below, and the copper nickel zinc layer was formed. Table 2 shows the zinc adhesion amount per unit area and the abundance ratio of nickel, zinc and copper in the plated film.

(Electroplating Solution Composition of Comparative Example 1)

Ni: 13 g / l, Zn: 5 g / l, Cu: 0 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electroplating Solution Composition of Comparative Example 2)

Ni: 13 g / l, Zn: 0 g / l, Cu: 6.5 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electroplating Solution Composition of Comparative Example 3)

Ni: 0 g / l, Zn: 5 g / l, Cu: 0.5 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electroplating Solution Composition of Comparative Example 4)

Ni: 13 g / l, Zn: 15 g / l, Cu: 0.9 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electroplating Solution Composition of Comparative Example 5)

Ni: 15 g / l, Zn: 0.1 g / l, Cu: 3 g / l, sulfuric acid (H ₂ SO ₄ ): 8.5 g / l

(Electroplating Solution Composition of Comparative Example 6)

Ni: 3 g / l, Zn: 16 g / l, Cu: 0.1 g / l, sulfuric acid (H ₂ SO ₄ ): 1 g / l

(Electroplating Solution Composition of Comparative Example 7)

Ni: 13 g / l, Zn: 3 g / l, Cu: 0.5 g / l, sulfuric acid (H ₂ SO ₄ ): 1 g / l

(Electroplating Solution Composition of Comparative Example 8)

Ni: 40 g / l, Zn: 3 g / l, Cu: 0.1 g / l, sulfuric acid (H ₂ SO ₄ ): 1 g / l

(Electroplating Solution Composition of Comparative Example 9)

Ni: 32 g / l, Zn: 0.05 g / l, Cu: 3.4 g / l, sulfuric acid (H ₂ SO ₄ ): 1 g / l

(Electroplating Solution Composition of Comparative Example 10)

Ni: 25 g / l, Zn: 16 g / l, Cu: 0.05 g / l, sulfuric acid (H ₂ SO ₄ ): 1 g / l

(Current density)

^{2.5 A / dm 2 ~ 30 A} / dm 2

(Comparative Example 1)

In the comparative example 1, copper did not exist in a plating film, and the abundance ratio of nickel in the plating film exceeded 50 mass%, and deviated from this invention. Moreover, although Formula 1 (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} is 0.49, Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%) )} Is 0.00, and is not in the range of the conditions of the present invention.

In this comparative example 1, the peel strength after the aging of 1.50 kN / m and aging for two days was 1.47 kN / m, and the deterioration rate was 2% in the FR-4 board | substrate. In addition, while the state peeling strength in the state BT substrate (under severe environment) was 0.98 kN / m, the peeling strength after hydrochloric acid treatment was 0.15 kN / m, and the deterioration rate was markedly reduced to 85%. Furthermore, in sulfuric acid-hydrogen peroxide The peel strength of 0.75 kN / m and the deterioration rate became 24%, and the chemical resistance of all significantly decreased. The above result is shown in Table 2.

(Comparative Example 2)

In the comparative example 2, zinc did not exist in a plating film, and the abundance ratio of nickel in the plating film exceeded 50 mass%, and deviated from this invention. Moreover, although Formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.45, Formula 1 (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%) )} Is 0.00, and is not in the range of the conditions of the present invention.

In Comparative Example 2, the state peel strength of the FR-4 substrate was 1.51 kN / m, the peel strength after aging for two days was 1.06 kN / m, and the deterioration rate was 30%. Was greatly reduced. Table 2 shows the above results.

(Comparative Example 3)

In the comparative example 3, although the amount of zinc (Zn) adhesion in a plating film is 620 microgram / dm <^2> , nickel did not exist in a plating film and it deviated from this invention. Formula 1 (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%)) is 1.00, and formula 2 (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 1.00.

In Comparative Example 3, the state peel strength on the state BT substrate (under severe environment) was 0.96 kN / m, but the peel strength after hydrochloric acid treatment was 0.65 kN / m, and the deterioration rate was significantly lowered to 32%. The peeling strength in sulfuric acid-hydrogen peroxide was 0.69 kN / m, and the deterioration rate was 28%, and the chemical resistance of all significantly decreased. Table 2 shows the above results.

(Comparative Example 4)

In Comparative Example 4, the deposition amount of zinc per unit area was 2564 µg / dm ² , which deviated from the present invention. In this Comparative Example 4, the state peel strength on the state BT substrate (under severe environment) was 1.02 kN / m, but the peel strength after hydrochloric acid treatment was 0.20 kN / m, and the deterioration rate was significantly lowered to 80%. The peeling strength in sulfuric acid-hydrogen peroxide was 0.62 kN / m, and the deterioration rate was 39%, and all of them significantly reduced chemical resistance.

Table 2 shows the above results.

(Comparative Example 5)

In Comparative Example 5, the amount of copper present in the plated film was 80% by mass, 4% by mass of zinc, and 16% by mass of nickel, resulting in (zinc deposition amount (mass%)) / {100- (copper adhesion amount (mass% ))} Deviated from 0.2 by the scope of the present invention. In this Comparative Example 5, the state peel strength on the FR-4 substrate was 1.50 kN / m, but the peel strength after aging for 2 days was 1.12 kN / m, and the deterioration rate became 25%. Peel strength was greatly reduced.

Table 2 shows the above results.

(Comparative Example 6)

In Comparative Example 6, since the amount of zinc present in the plated film is large at 70% by mass and the copper is small at 6% by mass, (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%)) is 0.20. In Comparative Example 6, the state peel strength on the BT substrate was 1.04 kN / m, but the peel strength after hydrochloric acid treatment was 0.16 kN / m, and the deterioration rate was large at 85%. Chemical resistance (hydrochloric acid) fell significantly, The same result is shown in Table 2.

(Comparative Example 7)

In Comparative Example 7, the adhesion amount of zinc per unit area was 150 μg / dm ² , which deviated from the present invention. In this comparative example 7, the peeling strength after aging for two days in the FR-4 substrate was 1.01 kN / m, the deterioration rate was increased to 31%, and the heat resistance greatly decreased.

Table 2 shows the above results.

(Comparative Example 8)

In the comparative example 8, the abundance ratio of nickel in a plating film exceeds 50 mass%, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} is 0.27, deviating from the scope of this invention. It was. In this comparative example 8, the peeling strength after aging for two days in an FR-4 board | substrate was 1.10 kN / m, the deterioration rate became 23%, and the heat resistant peeling strength in FR-4 board | substrate fell significantly. Table 2 shows the above results.

(Comparative Example 9)

In Comparative Example 9, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} was 0.25 and deviated from the scope of the present invention. In this Comparative Example 9, the peel strength after aging for two days in the FR-4 substrate was 1.19 kN / m, the deterioration rate was increased to 22%, and the heat resistant peel strength in the FR-4 substrate was greatly reduced. Table 2 shows the above results.

In addition, in Comparative Example 10, the copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%)} became 0.28 and deviated from the scope of the present invention. Although the intensity | strength was 1.01 kN / m, the peeling strength after hydrochloric acid treatment became 0.71 kN / m, the deterioration rate was 30%, and chemical resistance (hydrochloric acid) fell large.

Table 2 shows the above results.

As mentioned above, the conditions of the plating bath in manufacturing the copper nickel zinc layer of this invention are Ni: 0.1g / L-30g / L, Zn: 0.1g / L-12g / L, Cu: 0.1g / ℓ ~ 2 g / ℓ, sulfuric acid (H ₂ SO _4): to a 0.1 g / ℓ ~ 10 g / ℓ as the primary bath is preferred.

If the concentration of nickel, zinc, or copper increases beyond the range of these concentrations, the treatment of wastewater will be impaired, which is not preferable under the conditions of the plating bath. In addition, when the component concentration is lowered, the management of the plating bath becomes difficult due to factors such as the concentration change due to plating, and the current efficiency is extremely lowered. Therefore, the condition of the plating bath is not preferable.

In the above, although the case where it applied to the roughening surface of an electrolytic copper foil was demonstrated, it is needless to say that it is the same also in the electrolytic copper foil which performed the roughening process to the glossy surface. And also in the rolled copper foil which performed the roughening process, it is the same. If the rough surface of the electrolytic copper foil and the rolled copper foil is used, a difference may occur in the absolute value of the state peel strength due to the difference in shape and surface roughness of the roughening treatment, but the peel strength after heat-resistant peel strength and sulfuric acid / hydrogen peroxide treatment The relative deterioration rate from the state fill of can be made small.

In the copper foil for printed circuit boards of this invention, selecting the optimal conditions of a copper nickel zinc layer especially makes it the central subject of this invention. This significantly improves the heat-resistant peeling strength of the copper foil, effectively prevents circuit erosion, and exerts a stable effect of sulfuric acid and hydrogen peroxide constantly.

Therefore, it should be easily understood that the selection of the electrolytic copper foil and the rolled copper foil or the selection of the roughened surface can be arbitrarily selected according to the purpose.

Industrial availability

As shown above, the copper foil for printed circuit boards of this invention uses a copper nickel zinc layer, in order not to deteriorate peeling strength with resin after high temperature heating, and can significantly improve the heat-resistant peeling strength of copper foil. . In addition, this effectively prevents the circuit erosion phenomenon, and has been given a new characteristic that can effectively effect the chemical resistance (sulfuric acid-hydrogen peroxide-based) always stable, fine patterning and high frequency of the recent printed circuit It is useful as copper clad board for printed circuit boards (especially copper foil for semiconductor package board | substrates), and the copper clad laminated board for printed circuit boards (especially semiconductor package board | substrate) manufactured by adhering copper foil and a resin base material.

Claims (12)

Copper foil for printed circuit boards provided with the layer (henceforth a "copper nickel zinc layer") containing nickel, zinc, and copper on the surface of copper foil, The weight of zinc adhesion per unit area of the said copper nickel zinc layer is 200 It is 1 microgram / dm <^2> or more and 2000 microgram / dm <^2> or less, Ni is 1-50 weight% in the said copper nickel zinc layer, (zinc adhesion amount (mass%)) / {100- (copper adhesion amount (mass%))} Is 0.3 or more and (copper adhesion amount (mass%)) / {100- (zinc adhesion amount (mass%))} is 0.3 or more, The copper foil for printed circuit boards characterized by the above-mentioned. The method of claim 1,
A copper foil for printed circuit boards is provided on the copper nickel zinc layer. 3. The method of claim 2,
The said chromate coating layer WHEREIN: The chromium adhesion weight is 30 microgram / dm <^2> or more and 100 microgram / dm <^2> per unit area, The copper foil for printed circuit boards. 3. The method of claim 2,
A copper foil for printed circuit boards, further comprising a silane coupling agent layer on the chromate coating layer. The method of claim 3, wherein
A copper foil for printed circuit boards, further comprising a silane coupling agent layer on the chromate coating layer. 6. The method according to any one of claims 1 to 5,
Copper foil is an electrolytic copper foil, and the said copper nickel zinc layer is formed in the rough surface at the time of electroplating, or the gloss surface of an electrolytic copper foil, The copper foil for printed circuit boards. 6. The method according to any one of claims 1 to 5,
Copper foil is a rolled copper foil, Copper foil for printed circuit boards characterized by the above-mentioned. The method according to claim 6,
Copper foil is a rolled copper foil, Copper foil for printed circuit boards characterized by the above-mentioned. The copper clad laminated board for printed circuit boards which attached and manufactured the copper foil for printed circuit boards, and the resin for printed circuit boards of any one of Claims 1-5. The copper clad laminated board for printed circuit boards which attached and manufactured the copper foil for printed circuit boards of Claim 6, and the resin for printed circuit boards. The copper clad laminated board for printed circuit boards which attached and manufactured the copper foil for printed circuit boards of Claim 7, and resin for a printed circuit board. The copper clad laminated board for printed circuit boards which attached and manufactured the copper foil for printed circuit boards of Claim 8, and the resin for printed circuit boards.

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