JP2003209343A - Printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed circuit board in which an adhesive (closely contact) strength to a base, a wiring and a component mounting pad can be increased without increasing a ruggedness of the contact surface of the conductor with the base. <P>SOLUTION: The printed circuit board comprises a copper foil (circuit conductor) 21 projected and formed on a surface of a resin (base) 1, so that the projected and formed copper foil (circuit conductor) 21 is pressed by an end plate or the like, heated, embedded in a resin (base) 1 and upper surfaces of the resin (base) 1 and the foil (circuit conductor) 21 are made smooth. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having improved adhesion between a base material and a copper foil or a component mounting pad.

[0002]

2. Description of the Related Art Generally, a printed wiring board is arranged by adhering a copper foil, a component mounting pad, etc. to a base material such as a resin, and a large number of unit circuits are arranged in parallel. The unit circuit is cut into a size including one (unit) and used as a unit for use.

In recent years, in order to promote miniaturization of various electronic devices, miniaturization of printed wiring boards has been attempted, and circuit width of printed wiring boards and component mounting pad dimensions have been miniaturized. For example, BGA, CAP. In the printed wiring board for packages such as MCP, the solder ball mounting pad is required to have a manufacturing dimension of 0.15 mm in diameter and a wiring pitch of 40 μm by adopting 0.3 mm pitch CSP in 2005. .

[0004]

However, in the above-mentioned printed wiring board, the adhesion (adhesion) strength between the base material and the conductor such as the copper foil or the component mounting pad depends on the miniaturization of the circuit width and the component mounting pad size. Table 1 in FIG. 10 shows an example of the situation in which the adhesive strength is reduced due to miniaturization. Since the adhesive strength is reduced due to the miniaturization as described above, there is a problem that the base material and the conductor may be separated from each other due to external stress such as external impact or hooking.

In order to solve this problem, it is necessary to increase the adhesive strength between the base material and the conductor, and as shown in FIG. 11, a large number of convex portions B and concave portions C are formed on the surface of the conductor A. Then, it is known that the unevenness of the surface of the conductor A is eroded into the surface of the base material (resin) D to increase the adhesion (adhesion) strength, but the unevenness is small in the formation of fine wiring. There was a problem that it was more advantageous.

The object of the present invention is to solve these problems,
It is an object of the present invention to provide a printed wiring board capable of increasing the adhesion (adhesion) strength between a base material and wiring and component mounting pads without increasing the unevenness of the contact surface between the conductor and the base material.

[0007]

In order to achieve the above object, the printed wiring board according to the present invention has a base material and a circuit conductor forming a circuit. The circuit conductor embedded in the base material has a contact area with the base material that is formed by popping out the circuit conductor on the surface of the As a result, the strength of adhesion (adhesion) between the conductor and the substrate is significantly increased. In particular, the circuit conductor formed by the panel etching method has a trapezoidal cross section, and thus has a large effect of improving the bonding (adhesion) strength obtained by burying the circuit conductor. Furthermore, since the circuit conductor is buried in the base material, it is less likely to be subjected to external physical stress such as bumping or external impact or being caught, and the occurrence of problems such as separation of the conductor and the base material is suppressed. be able to. According to claim 2,
By providing fine irregularities on the outer surface of the circuit conductor formed by projecting on the surface of the base material, the contact area between the buried circuit conductor and the base material is increased, and the contact (adhesion) strength can be increased. .

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention using a panel plating method will be described with reference to FIGS. In FIG. 2, a. A method for forming irregularities on the surface by roughening the surface of the resin (base material) 1 with a chemical or the like, b. The convex portion 11 and the concave portion 12 are formed on the surface of the resin (base material) 1, that is, the contact surface, by a method of forming irregularities on the surface of the resin (base material) 1 by pasting a copper foil on which the roughness is formed on the surface of the resin (base material) 1. Then, copper plating is performed to form a copper foil (conductor) 2, and an etching resist 3 corresponding to the circuit to be created is formed on the surface of the formed copper foil (conductor) 2.
Is provided and etching is performed. In FIG. 3, after removing the excess copper foil by etching, the etching resist 3 is washed away to remove the copper foil (circuit conductor) 21 of the required circuit portion.
A circuit is formed by leaving (the above is the panel plating method).

In FIG. 4, a plate material 4 such as a mirror plate having a smooth surface is placed on the upper surface of the protruding copper foil (circuit conductor) 21 to apply heat and pressure, or a printed wiring board is sandwiched to apply heat and pressure. The copper foil (circuit conductor) 21 is embedded in the resin (base material) 1, and the upper surfaces of the resin (base material) 1 and the copper foil (circuit conductor) 21 are made smooth (see FIG. 1).

According to this structure, the contact area between the copper foil (circuit conductor) buried in the resin (base material) and the resin (base material) increases, so that the adhesive strength is significantly increased. In particular, the circuit conductor formed by the panel etching method has a trapezoidal cross section, and thus has a great effect of improving the bonding strength obtained by burying the circuit conductor. Furthermore, since the copper foil (circuit conductor) is buried in the resin (base material), it is less likely to be subject to external physical stress such as bumping or catching, and the occurrence of problems such as separation of the conductor and the base material is suppressed. be able to.

A second embodiment of the present invention using the pattern plating method will be described with reference to FIGS. In FIG. 5, a convex portion 51 and a concave portion 52 are formed on the surface of a resin (base material) 5, a plating resist 6 is arranged on the surface, copper plating is performed, and then the plating resist 6 is washed off and popped out. (Circuit conductor) 7 is formed (see FIG. 6), and a circuit is formed by the copper plating layer.

In FIG. 7, the outer surfaces 71, 72 of the protruding copper foil (circuit conductor) 7 are provided with minute irregularities having a depth of 1 to 2 μm by chemical treatment or physical treatment. Figure 8
Then, a plate material 4 such as a mirror plate having a smooth surface is placed on the upper surface of the copper foil (circuit conductor) 7 to apply heat and pressure, or a printed wiring board is sandwiched to apply heat and pressure to the copper foil (circuit conductor). ) 7 is embedded in the resin (base material) 5 (see FIG. 9).
reference).

It is to be noted that the outer surface of the protruding copper foil (circuit conductor) formed by the panel plating method or the panel etching method as in the first embodiment is not limited to the pattern plating method but is chemically treated. Or 1 to 1 by physical treatment
Fine irregularities having a depth of 2 μm may be provided.

According to this structure, by providing fine irregularities on the outer surface of the protruding copper foil (circuit conductor), the contact area between the buried copper foil (circuit conductor) and the resin (base material) increases, The contact (adhesion) strength can be increased.

In the first and second embodiments described above,
The circuit conductor formed by projecting on the surface of the base material is pressed and heated to be completely embedded in the base material, but more than half (50%) of the thickness of the circuit conductor is embedded in the base material. It would be nice. By embedding more than half of the thickness of the circuit conductor in the base material, the pressing operation can be simplified and the manufacturing process can be simplified.

[0016]

Since the present invention is constructed as described above, it has the following effects. According to the first aspect of the present invention, a circuit conductor is formed by popping out on the surface of the base material, and the circuit conductor is pressed and heated to be embedded in the base material. Because the contact area with
The adhesive strength between the conductor and the base material is significantly increased. In particular, since the circuit conductor formed by the panel etching method has a trapezoidal cross section, it has a large effect of improving the adhesion (adhesion) strength obtained by burying the protruding circuit conductor. is there. Further, since the circuit conductor is buried in the base material, it becomes difficult to receive external physical stress such as bumping or catching, and it is possible to suppress the occurrence of defects such as separation of the conductor and the base material. According to a second aspect of the present invention, by providing fine irregularities on the outer surface of the circuit conductor formed by projecting on the surface of the base material, the contact area between the buried circuit conductor and the base material increases, and contact (adhesion) occurs. The strength can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view of a printed wiring board according to a first embodiment of the present invention.

FIG. 2 is a drawing explaining the manufacturing process of the first embodiment of the present invention.

FIG. 3 is also a manufacturing process explanatory view of the first embodiment of the present invention.

FIG. 4 is also a manufacturing process explanatory diagram of the first embodiment of the present invention.

FIG. 5 is a drawing explaining the manufacturing process of the second embodiment of the present invention.

FIG. 6 is also a manufacturing process explanatory diagram of the second embodiment of the present invention.

FIG. 7 is also a manufacturing process explanatory diagram of the second embodiment of the present invention.

FIG. 8 is also a manufacturing process explanatory diagram of the second embodiment of the present invention.

FIG. 9 is a sectional view of a printed wiring board according to a second embodiment of the present invention.

FIG. 10 is Table 1 showing an example of a situation in which the adhesive strength is reduced due to miniaturization.

FIG. 11 is an explanatory diagram of a printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 resin (base material), 11 convex part, 12 concave part, 2 copper foil (conductor) 21 copper foil (circuit conductor), 3 etching resist, 4
End plate 5 Resin (base material), 51 Convex part, 52 Concave part, 6 Plating resist 7 Copper foil (circuit conductor), 71, 72 (of circuit conductor) outer surface

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[Procedure amendment]

[Submission Date] January 16, 2002 (2002.1.1
6)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5E343 AA02 AA12 AA36 AA39 BB24                       BB67 BB71 CC61 DD43 DD76                       DD80 EE17 EE52 ER11 ER50                       GG04

Claims (2)

[Claims] 1. A printed wiring board comprising a base material and a circuit conductor forming a circuit, wherein a circuit conductor protruding from the surface of the base material is formed, and the circuit conductor formed by pressing out is pressed and heated to form a base. A printed wiring board characterized by being buried in a material. 2. The printed wiring board according to claim 1, wherein fine irregularities are provided on the outer surface of the circuit conductor formed by projecting on the surface of the base material.