JPH0247052A - Sheet suitable for iron based printed board - Google Patents

Abstract

PURPOSE:To obtain an excellent effect for peeling resistance of an insulating layer at the time or cutting or pressing a printed board by forming a plated layer of specific amount of Cr, Cu, Ni, Zn, Sn on the surface of a steel plate, and forming a specific amount of chromate layer and further thereon a specific amount of organic coating layer containing as a main ingredient organic polymer compound. CONSTITUTION:A plated layer of 0.5-5g/m<2> of one or more types selected from Cr, Cu, Ni, Zn, Sn is formed of a pickled steel plate 1, electrolyzed as chromating to form a chromate layer 3 of 10-80mg/m<2> by metal chromium conversion. The surface of the chromated steel plate is coated, for example, with aqueous dispersible 3-element copolymer resin by copolymerizing 50% of methylmethacrylate, 20% of ethylacrylate, 20% of dimethylaminomethacrylate, and dried to form an organic coating layer 4 having 0.5-5g/m<2> of thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a steel plate suitable for iron-based printed circuit boards that has excellent adhesion to an insulating layer and punching properties.

[Prior Art] In recent years, iron-based printed circuit boards based on steel plates have been used as having excellent heat dissipation properties and mechanical strength, and as magnetic paths for small motors.

However, in the case of iron-based printed circuit boards, when copper foil is pasted after forming an insulating layer, and etching is performed using chemicals to form a circuit on the copper foil, or when soldering is performed, the copper foil may peel off between the insulating layer and the copper foil. There were problems such as peeling of about 2 to 3 mm from the edges during cutting and pressing, and burrs during cutting.

Additionally, there were problems with the rust resistance of the steel plate on the opposite side to the side to which the copper foil was applied, as well as the rust resistance of the cut end face of the steel plate.

On the other hand, Japanese Patent Application Laid-Open No. 61-142939 proposes a steel plate suitable for printed circuit boards for small precision motors. This content includes Sn and Z on the surface of steel plates (including silicon steel plates).
One or two of the following: n, Ni, Cr, CLI, j61
By plating 5 to 150g/rf of the seed or higher, an insulating layer (approximately 100μ) of epoxy resin or the like is applied to the steel plate in the printed circuit board manufacturing process, and copper foil is pasted on top of it and etched into the desired wiring state. , when various parts are soldered to the copper foil wiring locations, the adhesion between the steel plate and the insulating layer is improved, and the rust resistance is also improved.

[Problem to be solved by the invention]

However, the above-mentioned proposal still leaves unsolved problems such as peeling of the cut surface and the edges of the insulating layer during pressing, and burrs of the steel plate during cutting.

The object of the present invention is to provide a steel plate suitable for iron-based printed circuit boards, which improves the above-mentioned drawbacks and has excellent adhesion with an insulating layer and punching properties.

[Means to solve the problem]

In the present invention, as shown in FIG. 1, the surface of a steel plate 1 is coated with Cr.

A plating layer 2 of a specific amount of one or more types selected from Cu, NirZn, and Sn is formed, a specific amount of a chromate layer 3 is formed thereon, and an organic A specific amount of organic coating layer 4 characterized by a polymer compound is formed.

In manufacturing a printed circuit board using the steel sheet of the present invention, an insulating layer 5 and a copper foil 6 are formed on one side as shown in the figure.

It is desirable that the steel plate 1 has a thickness of 0.2 to 2.0 mm; if the thickness is less than 0.2 mtm, the heat dissipation will not be sufficient;
．． If it exceeds 0, good motor characteristics cannot be obtained when used as a magnetic path for a small motor.

Regarding the composition of the steel plate, if only heat dissipation and mechanical strength are required, ordinary steel is sufficient, but when used as a magnetic path for a small motor, 0.05 mm, which is used for ordinary motors, is sufficient. It is preferable to use a silicon steel plate containing 5 to 3.5% silicon.

The plating layer 2 formed on the surface of these steel plates 1 is made of Cr,
One or more selected from Cu, Nl, Zn, and Sn are plated in an amount of 0.5 to 5 g/I, and the chromate layer 3 thereon has a plating amount of 10 to 80 in terms of metallic chromium.
+++g/rrf chromate amount, and an organic coating layer 4 mainly composed of an organic polymer compound formed thereon.
Is it 0.5~5g/rr? It is essential that the amount of organic film is .

The reason for the limitation will be explained in detail below.

First, regarding the plating layer 2, as the plating metal, Cr,
Cu, Nl, Zn, and Sn are selected, and 1tTi or two or more selected from these are plated at a rate of 0.5 to 5.0 g/d. If the amount of plating is less than 0.5 g/rrf, good adhesion cannot be obtained even under normal conditions, and rust resistance is also insufficient.

On the other hand, if it exceeds 5 g/rrF, not only is the manufacturing cost high, but also the adhesion to the insulating layer after soldering is poor. The plating layer 2 in this case includes single-layer plating, multi-layer plating, single-layer plating, or alloying treatment after multi-layer plating.

The chromate treatment layer 3 applied to these surfaces is not particularly limited in the present invention, but in order to obtain a stable chromate film in a short time, Cro3-H, SO4, C
ro3-HCll.

A bath in which an anion is added to chromic anhydride such as Cr Oa HF in an amount of 1 to 3% of Cr Oa ffi as necessary is suitable.

Further, the treatment method may be an electrolytic method or a dipping method. The chromate treatment is carried out in terms of 10 to 80 I1 g/d in terms of metal chromium.

If the amount of chromate is less than 10 mg/rrr, there is almost no effect of improving adhesion even under normal conditions, and 80 mg/rr? If it is more than 100%, the strength of the chromate layer is insufficient, causing defects such as cohesive failure in the chromate film layer and deterioration of adhesion, which is not preferable.

Next, regarding the organic coating layer 4, when a predetermined amount of organic coating layer mainly composed of an organic polymer compound is formed, an insulating layer and copper foil are formed in the printed circuit board manufacturing process, and soldering is performed after etching. It has been found that peeling due to poor adhesion between the metal layer and the insulating layer during punching can be prevented and the burr of the metal layer can be reduced without deteriorating the solder heat resistance (heat-resistant beer strength) of the metal layer.

In this case, if the amount is less than 0.5g1rd, the purpose will not be achieved, and the effect of improving the peeling of the insulating film during punching and the burring of the metal layer during punching and cutting will be small, and the rust resistance will not be sufficient. On the other hand, 5g/rr? In super,
There is a tendency for solder heat resistance (heat-resistant beer strength) to deteriorate.

As the organic polymer compound used as the organic coating layer 4, a water-soluble or water-dispersible organic resin, or a polymer compound dissolved in a common organic solvent can be used.

Examples of these organic resins include: (1) polyalkylene polyamines such as polyethyleneimine and polypropylene imine and their derivatives; (2) polyamide polyamines and their derivatives produced by condensation of polycarboxylic acids and polyamines; and (2) polyglycidyl compounds such as epoxy resins. Cationic epoxy resin obtained by reacting with amine and/or polyamine, ■Cationic urea resin obtained by reacting polyisocyanate compound such as urethane prepolymer with amine and/or polyamine, ■Dialkylaminoalkyl A polymer derived from one or more cationic nitrogen-containing vinyl compounds such as vinyl compounds containing amino ester groups such as (meth)acrylate, vinylpyridine, vinylimidazole, or their salts, or a polymer derived from these. A multi-component copolymer of a cationic nitrogen-containing vinyl compound and other copolymerizable monomers; ■ A multicomponent copolymer derived from one or more monomers selected from the group consisting of diallylamine and its salts. or a copolymer of these monomers with other copolymerizable monomers, ■ chloromethyl group and/or
or hydroxymethyl group-containing polymer and amine and/or
or an aminomethyl group-containing resin obtained by reaction with a polyamine; ■ a polycondensate of polyhaloalkane and/or epihalohydrin and/or polyepihalohydrin with an amine and/or polyamine; ■ cations of the above-mentioned Nos. [Phase] (meth)acrylic resin, alkyd resin, or carboxyl group such as maleated polybutadiene Group-containing resin and ethyleneimine, boropyreneimine, hydroxyethyleneimine, 1,6-hexamethylene diethylene urea, diphenylmethane, 4.4-
Resins with amphoteric ionic groups obtained by reaction with basic nitrogen-containing alkylating agents such as aziridine compounds such as N,N-diethyleneurea, glycidylamine, or its salts, ■Dialkylaminoalkyl (meth)acrylates, vinylpyridine , one or more basic nitrogen-containing vinyl compounds such as vinylimidazole or their salts, and one or two carboxyl group-containing vinyl compounds such as (meth)acrylic acid, crotonic acid, or maleic acid. One or more mixed resins of water-soluble or water-dispersible resins from ■ to ■, such as copolymers with more than one species or multi-component copolymers with other copolymerizable monomers. used.

In addition, silica sol, Ag compound, T
One compound, a silane coupling agent, etc. may be added. These organic resin treatment liquids are applied by roll, spray, etc., and dried by heating with hot air, induction heating, etc.

It is important to design these organic film layers 4 with the primary purpose of adhesion to the steel plate, and as mentioned above, all the resins that can be applied to the present invention have many functional groups including 0°N. This significantly improves the adhesion with the insulating resin layer of the printed circuit board.

Furthermore, these organic resins greatly contribute to improving the mackerel resistance of the plated surface, and the rust resistance of the steel plate on the opposite side of the Cu foil is also significantly improved.

As mentioned above, Cr, Cu, and N1 are on the surface of the steel plate.

0.5 of one or more selected from Zn and Sn
~5.0g/rf plating, and on top of that, 1O~80mg/rr in terms of metallic chromium? Chromate treatment of
Furthermore, according to the steel sheet of the present invention, on which an organic coating containing an organic polymer compound as a main component is coated in an amount of 0.5 to 5.0 g/g, the adhesiveness with the insulating layer formed in the manufacturing process of the printed circuit board is improved. Not only does it have excellent rust resistance, but it also has excellent punching characteristics, such as no peeling of the edges of the insulating layer when cutting printed circuit boards or pressing, and less burring of the metal layer when cutting. .

〔Example〕

Example 1 Ordinary low carbon cold rolled steel plate (plate thickness 0.5m+w) and 2.
A silicon steel plate (plate thickness 0.5 sm) containing 0% silicon was treated in the following process.

First, as a pretreatment, a 3% caustic soda solution (liquid temperature: 40°C) was used.
) was electrolytically degreased at 2 A/dm2 x 2 seconds. Next, the surface of the steel plate was ground with a commercially available abrasive-containing grinding brush (product name: Sungrid), and then heated at 2 A/d with a 5% sulfuric acid solution (liquid temperature 20°C).
Electrolytic pickling was carried out using I12X for 1 second.

Using this steel plate 1, plating was performed under the following conditions to form a plating layer 2.

Plating condition 1, Zn plating: Z n S Oi, 7 H202
00sr / 1゜H2So415g/ff DK (current density) 50A/dm2 Bath temperature 50℃ 2, Cu plating: CCu2P2O72H2080/gN
H40H1g/fl.

K　2　P　207　300　g　/　D　.

KNO38g/D pH8~9°DK (current density) 8A/c1m2 Bath temperature 50°C Plating: Ni5O46H20250g/fl.

H2SO415g/g DK (current density) 8A/dn+2 Bath temperature 50℃ 4.3n plating: phenolsulfonic acid 200g/Ω.

Sn”30sr/N Bath temperature 40℃ DK (?!S flow density) 15A/dff12 After that,
As the chromate treatment, electrolytic treatment was performed to form a chromate layer 3. Chromate treatment conditions are Cr03-H2
SO4 bath (Cr Oa50g/fl, H2S O4
0.5g/N), DK (current density) 30A
/da2 (bath temperature 50°C).

A water-dispersible terpolymer resin obtained by copolymerizing 50% methyl methacrylate, 20% ethyl acrylate, and 20% dimethylamino methacrylate on the surface of these chromate-treated steel sheets was added to Ig/rr?
, 3g/rrf, 7g/rrr and dried to form an organic coating layer 4 to obtain a steel plate suitable for printed circuit boards.

On top of that, a glass epoxy resin prepreg (film thickness 100 um) is layered as an insulating layer 5, and copper foil is further layered as a metal foil layer 6, and the mixture is pressurized at 170° C. and a pressure of 20 kg/c for 20 minutes. Thereafter, a printed circuit board was manufactured by heating at 170° C. for 2 hours under pressure.

Table 1 shows the evaluation of iron-based printed circuit boards manufactured under various conditions (
Shown in 1) and (2).

Normal beer strength...After adhesion, after storage at room temperature for 24 hours, evaluated according to the peel strength measurement method of JISC6481.Heat-resistant beer strength...After adhesion, after storage at room temperature for 24 hours, in a solder bath at 260℃
After floating for 0 seconds, cool to room temperature, and evaluate the JIS C6481 peel strength tF1 determination method. Peeling status during shearing... After adhesion, after storage at room temperature for 24 hours, and after punching with a press. Peeling status of the adhesive layer ○: No peeling of the film, good △; Partial peeling at the insulating layer and metal interface ×: Peeling at the insulating layer and metal interface Situation of burrs during shearing... After adhesion, at room temperature After storage for 24 hours, observe the condition of burrs after punching with the same mold using a microscope. O: Good if the burrs are less than 30μ. ×: Poor if the burrs are 30μ or more. Salt spray rust resistance... JIS Z-23711:? Visually judge the occurrence of rust after 2 hours of testing. (No rust - no rust observed; white - white rust, red - red rust) [Effects of the invention] The steel plate of the present invention not only has excellent adhesion with the insulating layer and rust resistance, but also In particular, it has excellent peeling resistance of the insulating layer during cutting and pressing of printed circuit boards, and also has effects such as less burring of the metal layer.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the present invention.

Claims (1)

[Claims] The surface of the steel plate is plated with 0.5 to 5 g/m^2 of one or more selected from Cr, Cu, Ni, Zn, and Sn, and then 10 to 80 mg/m in terms of metallic chromium. ^2
A steel plate suitable for iron-based printed circuit boards, characterized in that it has been subjected to a chromate treatment and further coated with an organic coating containing an organic polymer compound as a main component at a rate of 0.5 to 5 g/m^2.