JPS6223196A - Through hole plating method and automatic plating apparatus for printed wiring board - 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] 3-1 Technical Field The present invention relates to a through-hole plating method and an automatic plating apparatus for printed wiring boards (hereinafter referred to as "boards"). It is characterized by obtaining high quality plating through continuous plating treatment.

3-2 Prior Art The conventional through-hole plating process for substrates can be roughly divided into an electroless plating process that imparts conductivity to the hole wall of the drilled board, and an electroless plating process that imparts conductivity to the hole wall. It can be divided into increasing electroplating process.

%, the latter electroplating process requires a special jig (also called a rack) to apply electricity to each board, and usually separate jigs are used for the electroless plating process and the electroplating process. Since it is necessary to change jigs between these processes, it has been difficult to perform through-hole plating in a completely automated manner.

Furthermore, during electroplating, the thickness of the electrodeposited copper film varies depending on the shape of the jig, the electroplating equipment, and the quality of the plating solution, at different positions on a single substrate. It had the drawback of causing so-called variations in film thickness.

3-3 Disclosure of the Invention The applicants of the present invention have been conducting extensive research into a method of performing these through-hole plating processes all at once, and found that by using a removable substrate holding jig, the electroless plating process and the electroplating process can be combined. We have discovered a method and device that can simplify the process.

In other words, in the normal electroless plating process, a substrate with holes drilled is heated with 20 to 50.9μ of an alkali builder such as sodium phosphate, sodium tripolyphosphate, sodium borate, or sodium carbonate, and 5 to 50.9μ of a nonionic surfactant. 101/
1 for 2 to 5 minutes at 30 to 60°C (referred to as degreasing).

■ In the next step, wash with water and add 20 to 30% of the
℃, soak for 2 to 5 minutes (referred to as a conditioner), and rinse with water.

■ Next, sodium persulfate or ammonium persulfate 150-200! ? Dip in μ solution for 1 to 2 minutes at 20 to 30°C (referred to as soft etching) and wash with water.

■ Next, add 10% to 15% (volume) solution of concentrated sulfuric acid at room temperature.
Treat for ~2 minutes to dissolve and remove undissolved matter on the surface generated by soft etching, and wash with water.

■ Next, add 10% to 30% (it volume) of concentrated hydrochloric acid at room temperature.
Soak for ~3 minutes, then palladium chloride 0°2~0.61
/l, stannous chloride 20-601/l, concentrated hydrochloric acid 200-3
00 m/7 for 3 to 10 minutes at 10 to 30° C. to provide the substrate with a catalyst necessary for electroless plating (referred to as a catalyst).

(2) Wash this with water, treat it with a 20-50 gμ solution of borofluoric acid at 15-35°Q for 5-15 minutes, and then wash with water.

■ Next, copper sulfate or chloride steel 8~is i7t, formaldehyde 7~1s Vt, Rossel [30~s
o The solution containing E/l was adjusted to pH 1 with sodium hydroxide.
Electroless copper plating solution adjusted to 1.5 to 12.5 to 15 to
It is immersed at 25°C for 15 to 30 minutes to deposit a copper film of 0.3 to 0.9 μm over the entire surface of the substrate.

■ Next, add 1 to 2 ml of concentrated sulfuric acid to 4 to 10 vol.
Dip for a minute to activate the surface of the substrate, then wash with water.

After the above 8 steps, we move on to the next electroplating step, which is usually performed using potassium birophosphate of 300 to 350%.
'E/l, Copper biruphosphate 65-85 jj/l,
PiH containing 17t of 28% ammonia water 2-3rrL
rCathode current density 1 in copper phosphate plating solution at 45-60°C
Electrolytic copper plating is performed at 5 to 3.5 A/dm''.

Generally, separate jigs are used in the electroless plating process and the electroplating process, and therefore it is necessary to change the jigs between these processes, but this is not possible with the present invention. A rectangular board holding jig (copper-plated iron frame) consisting of two hanger parts, a removably attached frame part, and two horizontal frames (width can be adjusted to any kg) during electrolytic plating. ), after electroless plating is completed, the substrate is transported while being held in the electroplating equipment for the next process.
It is possible to obtain an arbitrary film thickness and a substantially uniform film thickness.

In the electroplating apparatus, the substrate is held and nine jigs are connected to the cathode, and the cathode terminals of the six rectifiers are connected to the cathode bus bar so that they are all common.

On the other hand, the anode terminals of the rectifier are connected to individual anode busbars.

The energized jig moves with a pusher, and the moving speed is 1 to 5 minutes, 8 times per anode, and it is not preferable that this time becomes too long.

The plating film thickness can be controlled by the cathode current density and migration speed.

Embodiments of the method and automatic plating apparatus of the present invention will be described in detail below with reference to the drawings.

Example work A 60 crn x 40 crn 35 μm glass epoxy printed circuit board with holes of approximately 2,000 mm in diameter was held in place by a jig with a removable part and a frame part, and the following processing was performed. .

50.9μ, 50'Q, in 0PC-250 cleaner
Treat for 4 minutes, then wash with water. Next, immerse in 0PC-350 container at 20xl/125℃ for 4 minutes,
After washing with water, it was immersed in sodium persulfate 200.9μ, 25C for 2 minutes, and then washed with water.

Next, it was immersed in a 10% (by volume) concentrated sulfuric acid solution, washed with water, and treated with a solution of concentrated hydrochloric acid 50g/l and 0PC-8ALI701/at room temperature for 2 minutes.

Next, 0PC-80 Kiyakrist ao*z/zOP C
-S A L 1701/l, concentrated hydrochloric acid 30g/l solution for 8 minutes at room temperature, and washed with water.

Next, 0PC-5557 Kusereku 200TIL/ was immersed in 1c25" (1.8 minutes). After washing with water, 0PC-5557
750 Electroless copper plating A solution 100rd/1OPC-75
0 Electroless copper plating B solution 100i1/l mixed solution at 20℃
It was immersed in water for 17 minutes to perform electroless plating.

After washing with water, hold the board and move the jig as it is to the electroplating equipment.

Next, the jig was connected to the cathode, and the cathode terminals of each rectifier were connected to the cathode busbar, making them all common. On the other hand, the anode terminals of the rectifier were connected to individual anode busbars.

Inside the plating equipment, potassium birophosphate 31511/l
, pyrophosphate chain s 3E/l, 28% ammonia water 3y/l, Pirurite (trade name) 2d/z bipj
Cathode current density 3.0A/drrX with J-acid copper plating solution
Electroplating was performed for 55 minutes.

Furthermore, the nine jigs that were energized were moved by a push button, and the moving speed was adjusted to 3 minutes per anode.

After plating, the film was washed with water and dried, and the film thickness was measured using an electromagnetic non-destructive film-forming measuring device called Fischerscope. The results are shown in Table-1. Note that the film thickness side feet are the upper left, upper right, and
Measure at five locations: lower left, lower right, and center, and indicate the thickness.

Example 2 The same process as in Example 1 was carried out, and the cathode current density was 3. O
Electrical steel plating was performed at A/am' for 110 minutes. The film thickness is shown in Table-2.

Comparative Example 1 The same substrate as in Example 1 was used, set in a stainless steel substrate holder, and subjected to electroless copper plating in the same manner as in Example 1.

Next, the substrate was attached to an ordinary electroplating jig made of stainless steel coated with resin, and immersed in a 5% sulfuric acid solution (volume jt) for 1 minute. After washing with water, viroline having the same composition as in Example 1 was attached. Cathode current density 3. Using an ordinary carrier-type plating device using an acid silver plating solution. Electroplating was performed at OA/dm for 55 minutes.

After plating, washing with water and drying, the film thickness was measured using the same film thickness measuring device as in Example 1. The results are shown in Table-1.

Comparative Example 2 Conducted under the same conditions as Comparative Example 1, cathode current density 3°OAla
Electroplating was performed for 110 minutes at m.

The results are shown in Table-1.

Effects of the Invention The present invention enables continuous through-hole plating of substrates by using a common substrate holding jig for electroless plating and electroplating processes. be.

Further, since the film thickness is uniform, it has the advantage that the manufacturing process, especially the work of dissolving (etching) unnecessary portions of copper, can be carried out smoothly.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the automatic plating apparatus of the present invention, and FIG. 2 is a sectional view. Explanation of symbols 1, Cathode busbar λ Anode busbar 3,
Rectifier 4. Plating solution 5, jig carrier (butsusha) 6. Insulator 7, plating bath
8. Anode Figure 2

Claims (2)

[Claims] (1) Use a movable iron board holding jig to give the printed wiring board to be plated electrical conductivity in the hole wall using the normal electroless copper plating method, and then connect the jig holding the board to the cathode side. At the same time, the cathode terminals of each rectifier are connected to a cathode busbar so that they are all common, while the anode terminals of the rectifiers are individually connected to independent anode busbars, and the energized board holding jig is moved continuously using a pusher. A through-hole plating method for printed wiring boards characterized by plating. (2) A rectifier was arranged in parallel on one side of the plating tank, and independent anode busbars were installed on both sides of the plating tank and connected to the anode terminal, and a single cathode busbar was passed through the center to sandwich the substrate. An automatic plating device for printed wiring boards, in which a jig is connected to a cathode, the cathode terminal of each rectifier is connected to a cathode busbar, and the jig is moved by a pusher to perform plating continuously.