JPH04217387A - Electroless plating method for conductor pattern and electroless plating jig - Google Patents

Abstract

PURPOSE:To form an equalized conducting layer regardless of the types of conductor patterns or the degree of activity of their surface by further enhancing the equipotential of a conductor pattern to be plated and carrying out plating processing. CONSTITUTION:An equipotential jig 6 is used as an electroless plating jig which produces the uniform potential of each conductor pattern 4 by bringing the jig into contact with the conductor pattern 4 in a circuit board 2. This equipotential jig 6 is designed to project a large number of contactors 10 into a net-like conductor frame 8 where the span of each contactor is set so that it may respond to a minimum span between each conductor pattern 4 or smaller. The circuit board 2 is submerged in a plating solution 14 in a plating tank 12. When it is submerged, each contactor 10 of the equipotential jig 6 is placed into contact with the conductor pattern 4 while the equipotential jig is grounded as well.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electroless plating of conductor patterns and a jig for electroless plating, which are used when electroless plating is applied to circuit conductors.

0002

[Prior Art] In circuit boards used for hybrid integrated circuits, etc., a conductor pattern corresponding to the desired circuit form is formed on a board made of an insulating material by printing or the like, and a conductor resistor is placed on this conductor pattern. For the purpose of reducing this, a Cu layer is formed by electroless plating.

0003

[Problems to be Solved by the Invention] Incidentally, it is known that the formation of a Cu layer on a conductor pattern by electroless plating depends on the form such as the area of the conductor pattern and the activity level of its surface. This causes unevenness in thickness and localized Cu layer formation. To prevent such unevenness, it is possible to immerse the circuit board in the plating solution for a long time.
When the immersion time becomes longer, the thickness of the Cu layer becomes thicker in parts where Cu is well deposited, and the thickness of the Cu layer becomes uneven, which impairs the flatness. Furthermore, if the immersion time in the plating solution becomes longer, the manufacturing time increases accordingly, which also increases the manufacturing cost.

[0004] Accordingly, a first object of the present invention is to provide a method for electroless plating of a conductor pattern, which can form a uniform conductor layer regardless of the form of the conductor pattern or the degree of activity of its surface.

Another object of the present invention is to provide an electroless plating jig that can uniformly equalize the potential of a conductor pattern to be plated in a plating solution, regardless of the form of the conductor pattern or the activity level of its surface. 2 objectives.

[0006]

[Means for Solving the Problem] That is, the electroless plating method for conductor patterns of the present invention provides a method for electroless plating of conductor patterns in a large number of conductor patterns (4
) is characterized in that the plating process is performed by immersing the circuit board (2) on which the plating pattern (2) is formed in a plating solution (14) and equalizing the potential of the conductive pattern to which conductive plating is to be applied.

[0007] The jig for electroless plating of a conductor pattern of the present invention also contacts a conductor pattern (4) formed on a circuit board (2), and also has a plurality of commonly connected contacts (10). It is characterized by having the following.

[0008]

[Operation] The conductor patterns of the circuit board on which the conductor layer is to be formed by electroless plating are equalized in potential in the plating solution, so a conductor layer is uniformly deposited from the plating solution on each conductor pattern, and the conductor layer is The occurrence of uneven formation and uneven thickness is reliably prevented.

[0009] Furthermore, a large number of contacts are formed on the electroless plating jig, and each contact is commonly connected. Therefore, by bringing a contact into contact with the conductor pattern to be plated in a plating solution and equalizing the potential of each conductor pattern through each contact, for example, by grounding, it is possible to uniformize the formation of the conductor layer on the conductor pattern. can.

0010

EXAMPLE FIGS. 1 and 2 show a method for electroless plating of a conductor pattern and a jig for electroless plating. A circuit board 2 is formed of an insulating material such as alumina, and a large number of conductor patterns 4 are formed on the surface of the circuit board 2 with a conductor paste, such as Ag paste, depending on the circuit pattern to constitute the electronic circuit to be mounted. It is formed by printing, etc.

A potential equalization jig 6 is used as an electroless plating jig that contacts the conductor patterns 4 of the circuit board 2 to equalize the potential of each conductor pattern 4. This potential equalization jig 6 has a large number of contacts 10 protruding from a conductor frame 8 on a mesh, and the distance between each contact 10 is a size corresponding to the minimum distance between each conductor pattern 4 or less. It is set to

Then, as shown in FIG. 1, the circuit board 2 is immersed in the plating solution 14 in the plating bath 12, and at this time, each contact 10 of the potential equalization jig 6 is attached to the conductor pattern 4. are brought into contact with each other, and the potential equalization jig 6 is grounded. As a result, each conductor pattern 4 on the circuit board 2 is shared and grounded through the potential equalization jig 6.
The active points and inactive points of each conductor pattern 4 are equalized using a potential equalization jig 6, and in this case, the potential is equalized to the ground potential.

Specifically, the conductor pattern 4 on the circuit board 2 shown in FIG. With the start of this deposition, the potential equalization jig 6 is removed from the circuit board 2. Once plating has started, the plating metal begins to be deposited continuously, as shown in FIG. 3(B).
Depending on the plating metal of the plating solution 14, for example, a Cu layer 16 is deposited as a conductive layer on the surface of the conductive pattern 4,
Layer 16 is formed to have a uniform thickness. The precipitation reaction formula of this Cu layer 16 is shown below.

[0014]

[Chemical formula 1]

[0015] In this way, in the electroless plating process,
By equipotentializing all of the conductor patterns 4 of the circuit board 2 using the potential equalization jig 6, the shape of the conductor patterns 4,
Depending on the size, etc., the electron (e) from the active point to the inactive point
As a result of being suppressed by the movement of (-), unevenness and unevenness in the plating layer caused by differences in surface activity are prevented, and a Cu layer 16 having a uniform thickness is deposited. Moreover, since the plating progresses at the same time by contacting each conductor pattern 4 with the potential equalization jig 6, the processing time required to obtain a predetermined film thickness is shortened.

In addition, the potential equalization jig 6 has an extremely simple structure, and can be handled semi-permanently without having to be replaced every time the plating process is performed, since it can be handled by simply removing it from the circuit board 2 at the time of depositing the plating metal. can.

[0017]

[Effects of the Invention] As explained above, according to the electroless plating method of the present invention, the circuit board on which a large number of conductor patterns to be electroless plated are formed is made to have an equal potential in the plating solution. A conductor layer can be formed uniformly on each conductor pattern, reducing plating time.
It is possible to reduce manufacturing costs while improving quality.

Further, according to the electroless plating jig of the present invention, a circuit board on which a conductor pattern to be electroless plated is formed can be easily and reliably equalized in potential in a plating solution. A conductor layer to be formed on a conductor pattern can be formed uniformly and at high speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a method for electroless plating a conductor pattern and a jig for electroless plating according to the present invention.

FIG. 2 is a perspective view showing a circuit board on which a conductor pattern to be subjected to electroless plating is formed and an electroless plating jig.

FIG. 3 is a cross-sectional view showing a circuit board on which a conductive pattern is formed, showing before and after electroless plating.

[Explanation of symbols]

2 Circuit board 4 Conductor pattern 6 Potential equalization jig 10 Contact 14 Plating solution

Claims (2)

[Claims] 1. Electroless plating of a conductor pattern, characterized in that a circuit board with a conductor pattern formed on its surface is immersed in a plating solution, and the conductor pattern to be subjected to conductor plating is made to have an equal potential to perform the plating process. Plating method. 2. A jig for electroless plating, comprising a plurality of contacts that come into contact with a conductor pattern formed on a circuit board and are connected in common.