JPH0691308B2 - Partial plating method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a partial plating method, and more particularly to a method of performing partial plating without coating an unnecessary portion of plating.

[Background of the Invention]

To perform gold plating on the plug portion (connector tag) of the printed wiring board by the conventional partial plating method, the following (a),
It was performed in the step (b).

(A) A contact portion that holds a printed wiring board under pressure between opposing elastic belts, and a contact portion that comes into contact with a plating solution by a boundary line of a mask formed by the belt being brought into pressure contact; and a wiring portion that does not come into contact with the plating solution. And (b) the plating solution is sprayed onto the plug portion from below the boundary line. (Japanese Patent Laid-Open No. 55-16499) However, the above method has a problem that the plating solution penetrates between the belt as a mask and the printed wiring board by a capillary phenomenon, and a gold plating film is formed even on an unnecessary plating area. there were.

[Object of the Invention]

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to selectively form a plating film only on a portion to be plated, without forming a mask by directly pressing a portion not requiring plating with a belt or the like. An object is to provide an improved partial plating method.

[Outline of Invention]

The purpose of the above is to arrange the upper shield plate at a right angle in the upper space of the plating tank by forming a gap with respect to the object to be plated and the boundary line between the object to be plated that is held vertically and the plating unnecessary. A step of forming a smooth inclined surface that is inclined at a predetermined angle in the plating tank from the horizontal plane that intersects the object to be plated on the tip portion and the inner wall surface of this upper shielding plate, and below the upper shielding plate, the lower shielding plate. The plate is arranged perpendicularly to the upper shield plate so that a predetermined gap is formed between the plate and the upper shield, and the plating solution is held in the upper space of the plating tank from this gap. And a step of spraying the portion to be plated of the object to be plated.

The above-mentioned predetermined angle refers to θ in FIG. 1 which will be described later, and is practically 10 ° to 65 °, preferably 30 ° to 45 °.
In addition, the portion where the plating solution is ejected may be located at a position that does not hinder the movement of the object to be plated, usually 1 mm from the object to be plated.
~ 4mm apart, but 1m ~ 2mm apart is even better.

The spraying speed of the plating solution is preferably such that the plating solution is uniformly sprayed near the boundary between the part to be plated and the part not to be plated, and is usually 21.0 l / mm to 212 l / mm per 1 m of the plating tank, preferably It is 35.7 l / mm to 71.4 l / mm.

Further, when jetting the plating solution to the portion to be plated of the object to be plated from the gap portion provided between the upper shield plate and the upper end portion of the lower shield plate, as described later with reference to FIG. , Where W is the distance between these spaces and L is the length of the terminal (the length of the plugging part) for plating the object to be plated that is held in the upper space of the plating tank. Is 0.3
/ 10 to 10/10 (that is, 0.03 to 1). This value is 0.
When it is smaller than 3, plating is locally formed on a part of the plug portion, and when it is larger than 1, the partial plating effect is reduced.

Further, when the upper shielding plate is arranged at a right angle to the object to be plated, a gap is provided between the two, which has the following two effects.

One of them is similar to the well-known continuous plating method described as a conventional example in the section of "Background of the Invention", but the configuration is different, but the object to be plated is in a non-contact state in the plating tank with the upper shielding plate. The function is to move and move easily.

The other one is an important function of the present invention, which enables a maskless partial plating method. It is preferable that when the plating solution is sprayed from the above-mentioned interval to the portion to be plated, the upper shield plate and the plating target are plated. It is that the outside air is taken in from the gap between the object and the negative pressure is generated near the boundary line based on the well-known Bernoulli's theorem, and as a result, the plating solution leaks to the upper part from the gap between the upper shielding plate and the object to be plated. Therefore, the plating solution can be reliably supplied only to the portion below the boundary line that requires plating. When the length of the plated terminal is 16 mm, it is 0.5 mm to 16 mm, preferably 1 mm to 13 mm.

Example of Invention

 Hereinafter, the present invention will be described in detail with reference to examples.

Example 1 As shown in the cross section of the plating tank in FIG. 1, the printed circuit board 1 is vertically held between the upper shielding plates 2-1 and 2-2 of the plating tank, and its plug portion and its connection are connected. A very small part of the prepared lead is located in the upper space in the plating tank. The tips C and D of the upper shield plates 2-1 and 2-2 are separated from the printed circuit board by forming a gap of 2 mm. Plating bath 5-1
The plating solution in 5-2 flows out from the gap W between the gaps formed between the upper shield plates 2-1 and 2-2 and the lower shield plates 4-1 and 4-2, and the tip portion C, The length of the printed circuit board 1 is 50 cm at a rate of 70 l / mm per 1 m of plating tank from the inclined surface of D (θ = 30 °)
The plating solution sprayed on the boundary line of No. 2 was circulated from the plating solution discharge unit 6 to the plating tanks 5-1 and 5-2. The term "per meter of plating bath" means the unit length of the plating bath, and corresponds to the length of the depth of the interval W shown in the figure. The length of the printed circuit board 1 corresponds to the depth of the illustrated circuit board 1, that is, the width of the printed circuit board 1. Then, the printed circuit board 1 is used as a cathode, and a DC voltage (DC4 to 20V, DA = 5 to 20A / dm ² ) is applied between the anode 3 and the printed circuit board 1, although a power circuit diagram is omitted. Aurobrite HS-5 (gold concentration: 5-10 g /
1, specific gravity: 10 to 16 Baume degree, PH: 4.0 ± 0.2, additive: aurobrite HS-5), and gold plating was performed on the copper pattern at the plug portion of the printed circuit board 1.

The result of partial gold plating on the plugging portion is shown in FIG. As shown in the figure, in the upper space of the plating bath, a plug portion at one end of the printed circuit board 1 and some of the leads connected to the plug portion are arranged as boundaries.

FIG. 2 (a) shows a plug portion (terminal) that is one end portion of the printed circuit board 1 held in the plating tank located below the boundary line and a partial region of the lead connected to the plug portion. It is a plan view, and the wide portion shows the shape of the plug portion.

In FIG. 2B, the spray angle θ of the plating solution is 30 °, and
The distribution of plating thickness is shown when the distance W between the lower shielding plates is adjusted to 1.0 mm. However, in this example, when the length of the plug portion (terminal) is L, L = 10 mm, so
The relationship of the interval W of the lower shield plate / terminal length L, that is, W / L is 1.0 mm / 10 mm = 0.1. As shown in the figure, the gold plating state was thick near the contact portion with the contact, which is the upper region of the tangent portion, and extremely thin at the lower end portion. In such a condition, (upper and lower shield plate spacing ÷ terminal length = W / L) is 0.1 to 0.2
It was seen between. The results when the above W / L relationship is set to 0.5 and 1.0 are shown in FIGS. 2 (c) and 2 (d). Second
Figure (c) shows the upper and lower shield plate spacing ÷ terminal length = 0.5 W / L.
The thickness around the contact part becomes thicker and the other parts are
It is about 1/2 the thickness.

Further, as shown in FIG. 2 (c), if the ratio W / L of the upper and lower shield plate spacing W and the terminal length L is set to 1.0, a uniform gold plating thickness can be obtained on the entire surface of the plug portion. Was given.

Supplementing the shape of partial plating, plating of noble metal such as gold is expensive. Therefore, as shown in (c) and (d) of FIG.
As shown in (b) of the figure, the purpose can be sufficiently fulfilled only by locally arranging the contact portion of the terminal necessary for connection with the external terminal and performing partial plating. Further, when uniform plating is desired on the entire surface of the terminal, the plating conditions as shown in (c) and (d) of FIG. 2 may be selected.

Example 2 The distance between the tip of the upper shielding plate and the printed circuit board was 1 mm,
The jet speed is 50l / mm per 1m of plating tank, the distance W between the upper and lower shields is fixed at 1mm, and the spray angle θ is 10 ° ~ 65
The contact portion of the printed circuit board was plated in the same manner as in Example 1 except that the temperature was changed to °.

FIG. 3 shows the result of forming the partial gold plating on the plug portion in the same manner as in FIG. 2 of Example 1.

FIG. 3 (a) shows the case where the injection angle (θ) is 30 °.
Gold was partially plated, that is, only in the vicinity of the contact portion with the contact. Such a condition was observed between the injection angles of 30 ° and 45 °. It was also confirmed that the spraying speed of the plating solution and the distance between the tip of the upper shielding plate (C and D in FIG. 1) from which the plating solution is sprayed and the printed circuit board similarly occur within the range described above.

FIGS. 3B and 3C show the case where the injection angle (θ) is 60 ° and 80 °. As shown in FIG. 3 (b), the thickness of the gold plating film in the vicinity of the contact portion with the contact becomes thicker, and the thickness of the gold plating film in other portions becomes thinner.
Greater than ° to less than 65 °. It was also confirmed that such a state occurs similarly in the range where the jetting speed of the plating solution, the distance between the jetting parts of the plating solution (C and D in FIG. 1) and the printed circuit board are within the above-mentioned range. Fig. 4 is an example of that, and shows the case where partial gold plating is performed under the same conditions as in Fig. 3 (b) except that the distance between the tip of the upper shielding plate from which the plating solution is ejected and the printed circuit board is 4 mm. Yes, the same result as in FIG. 3 (b) is obtained.

〔The invention's effect〕

As described above, partial plating according to the present invention is (a) economical because it is thick only in the vicinity of the required portion.

(B) Since it is not necessary to press the non-plating portion with the elastic body, the plating facility is simplified.

(C) The plating process is simplified because it is not necessary to mask with a tape to hide the unnecessary portions of the plating. Further, the step of removing the adhesive remaining after peeling the tape is also unnecessary.

Further, the present invention can be applied to the case of performing connector and other partial plating.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a plating tank used in the present invention, and FIGS. 2, 3, and 4 are diagrams showing the finish of a plated film when partial plating is performed by the method of the present invention. 1 ... Printed circuit board, 2-1, 2-2 ... Upper shield plate, 3 ... Anode, 4-1, 4-2 ... Lower shield plate, 5-1, 5-2 ... Plating bath , 6 ... Plating solution discharge part.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhiro Enmoto 2-26-7 Minamiikebukuro, Toshima-ku, Tokyo Japan High-Purity Chemical Co., Ltd. (72) Akihito Kawakami 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address Stock Company Hitachi Co., Ltd. Totsuka Factory (72) Inventor Shigeru Fujita Address 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Company Hitachi Ltd. Totsuka Factory

Claims (3)

[Claims] 1. An upper shielding plate is formed at a right angle in the upper space of a plating tank by forming a gap with respect to an object to be plated at a boundary line of the object to be plated held vertically and a plating-free boundary. A step of forming a smooth inclined surface that is inclined at a predetermined angle in the plating tank from the horizontal plane that intersects the object to be plated at the inner wall surface of the tip of the upper shielding plate, and below the upper shielding plate. In addition, the lower shield plate is arranged vertically to the upper shield plate so that a predetermined gap portion is formed between the upper shield plate and the upper end portion of the lower shield plate, and the plating solution is supplied from this gap portion. And a step of spraying onto a portion to be plated of an object to be plated held in the upper space in the plating tank. 2. An upper shield plate is formed at a right angle in the upper space of the plating tank by forming a gap with respect to the object to be plated at a portion to be plated that is held vertically and a boundary line that does not require plating. A step of forming a smooth inclined surface that is inclined at a predetermined angle in the plating tank from the horizontal plane that intersects the object to be plated at the inner wall surface of the tip of the upper shielding plate, and below the upper shielding plate. In addition, the lower shield plate is arranged vertically to the upper shield plate, and a predetermined gap is formed between the upper shield plate and the upper end portion of the lower shield plate. When W is W and the length of the terminal for plating the object to be plated held in the upper space of the plating tank is L, the relationship between the two is W / L = 0.03 to 1, and the plating solution is supplied from this space. The plating of the object to be plated held in the upper space of the plating tank. The method of partial plating, which comprises: 3. An upper shielding plate is formed at a right angle in the upper space of the plating tank by forming a gap with respect to the object to be plated at a portion to be plated that is held vertically and a boundary line that does not require plating. In addition to being installed, the inner wall surface of the tip of this upper shielding plate is placed in the plating tank from a horizontal plane that intersects the object to be plated at a right angle.
The process of forming a smooth inclined surface inclined at an angle of 10 ° to 65 °, and the lower shield plate below the upper shield plate, perpendicular to the upper shield plate, and the upper shield plate and the lower shield plate. Arranged so that a predetermined gap is formed between the upper end,
And a step of spraying a plating solution from the gap portion onto a portion to be plated of the object to be plated held in the upper space of the plating tank.