JP2000208910A - Printed circuit board with bump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a bump of a low cost with good production efficiently and to improve productivity of overall component mounting by previously forming the bump on an electrode pad for connecting a bare chip component of a printed circuit board by a plating method. SOLUTION: Electrode pads 2 or the like for connecting an upper surface outer layer conductor 3, a lower surface outer layer conductor 5 and bumps are formed. Bumps 9 of a protrusion shape, a columnar shape, a trapezoidal shape, a hemispherical shape or the like are formed on an electrode pad part 2 higher than the surface of the printed circuit board by a plating method as the board with the bumps. Thus, it is not necessary to form the bump at a conventional bare chip component side and to supply the component to a set maker as a flip-chip component, and the bare chip component can be connected directly to the board with the bump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board with bumps for connecting bare chips (bare chips) of electronic components.

[0002]

2. Description of the Related Art A conventional method for mounting a bare chip component on a printed wiring board shown in FIG. As shown in FIG. 3A, a pad portion for external connection is provided on a lower surface of a bare chip component 10 such as a semiconductor chip component, a resistor, a capacitor or a module component, and a bump 9 is formed at a predetermined position in this portion. And
The flip chip component 20 is used. Next, as shown in FIG. 3B, the conventional printed wiring board 30 includes an upper surface outer layer conductor 3, a lower surface outer layer conductor 5,
Through conduction hole 6, inner conductor 4, and bare chip component 10
Are provided with electrode pads 2 for connecting the bumps 9 formed on the substrate. Next, as shown in FIG. 3C, the flip chip component 20 having the bump 9 formed on the lower surface of the bare chip component 10 of FIG.
The bare chip component 10 is connected to the electrode pad 2 of the conventional printed wiring board 30 by bonding to the electrode pad 2 of the conventional printed wiring board 30 shown in FIG. Components are mounted.

That is, a method of forming the bumps 9 on the bare chip component 10 side and connecting the bumps 9 to the flat electrode pads 2 of the conventional printed wiring board 30 is called a flip chip (FC) method. The flip chip component 20 has a higher density and a smaller size, the number of electrode pads for connecting bare chips has increased, and the so-called terminal pitch interval between electrode pad terminals has become smaller, so that the bumps have become smaller, and the bump 9 has been connected to the bare chip component 10. And the transportation, packing, and delivery of the flip chip component 20 after completion is difficult, and the productivity and quality stability of the flip chip component 20 in which the bumps 9 are formed on the bare chip component 10 are poor due to poor supply. The reality is that things are not going as expected.

[0004]

In the conventional mounting method in which the bumps 9 are formed on the bare chip component 10 side and the flip chip component 20 is connected to a printed wiring board, the productivity of the flip chip component 20 is low, and As described above, various types of handling are problematic. In the present invention, a bump 9 having a convex shape or the like is previously formed on an electrode pad portion 2 for connecting a bare chip component 10 of a printed wiring board by a plating method, thereby forming a printed wiring board with bumps. That is, by forming the bumps 9 in advance on the electrode pads 2 on the printed wiring board side, the bumps 9 are formed on the bare chip parts 10 side, and the bare chip parts 10 are directly formed on the printed wiring board with bumps instead of the flip chip parts 20. This is an implementation method to connect. The bare chip component 10 can be used in the same manner as the conventional one, so that it can be supplied sufficiently, and the bump formation by the plating method of the printed wiring board can be performed with high production efficiency and at a low price. Can be improved.

[0005]

According to the present invention, bumps having a convex shape, a cylindrical shape, a trapezoidal shape, a hemispherical shape, etc. are previously formed on an electrode pad portion for connecting bare chip components of a printed wiring board by a plating method. A bare chip component is connected to a printed wiring board with bumps for component mounting.

Further, a bump is formed higher than the surface of the printed wiring board so as to have a convex shape at a place where the electrode pad portion for connecting bare chip parts of the printed wiring board is depressed into a concave shape. Printed wiring board with a cable. The bumps to be formed in the concave portions of the electrode pad portions are not limited to the bumps formed by the plating method, and the bumps are formed so that the solder or the conductive paste becomes a convex shape in a semi-cured state. May be formed.

[0007] The material of the bump formed by the plating method may be copper, nickel, gold, lead, tin, solder, silver, rhodium, or a multilayer structure of these metals. When bumps are formed by a plating method, a photosensitive film having a predetermined thickness is formed as a plating resist on the entire surface or a part of the printed wiring board, and an electrode pad portion for connecting bare chip components by a photo method or laser processing. The photosensitive film having a small diameter is removed at a predetermined position to form a plating resist film.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to a cross-sectional view for explaining a manufacturing process of the present invention shown in FIG. The printed wiring board 1 may be any of a multi-layered wiring board having an inner conductor formed thereon, a double-sided wiring board, a single-sided wiring board, and the like. As shown in FIG. 2A, a component hole for attaching a component to the double-sided copper-clad laminate, a through hole for connecting layers, and a non-through hole are formed. Then, electroless plating or electrolytic plating is performed to form through conduction holes 6 such as plated through holes and via holes, and non-through conduction holes. In addition, the upper surface outer layer conductor 3, the lower surface outer layer conductor 5, and the electrode pad portion 2 for connecting the bumps are formed by the subtractive method or the additive method.

Next, as shown in FIG. 2B, a predetermined thickness of an alkali peeling type photosensitive coating film or a positive type photo film is formed on the entire surface or a part of the printed wiring board as a plating resist. . After that, irradiate ultraviolet rays and then develop a small-diameter hole by alkali development using a photo method or a carbon dioxide laser to form a fine-diameter hole reaching the surface of the electrode pad that connects the bare chip components with a photosensitive coating. Alternatively, the photosensitive film or the photo film is removed at a predetermined position of the positive type photo film to form a plating resist film 7 exposing the copper foil surface of the electrode pad portion 2 for connecting the bump. The plating resist film 7 of the electrode pad portion 2 for connecting the bumps forms the upper surface outer layer conductor 3, the lower surface outer layer conductor 5, the through conduction hole 6, and the non-through conduction hole of the printed wiring board. It is preferable to form a film so that plating for the purpose does not precipitate.

Next, as shown in FIG. 2C, electroless copper plating is applied to form a bump of 20 μm.
m to 30 μm, electroless nickel plating 10 μm, electroless gold plating further 0.5 μm, and bumps 9 having a convex shape, a cylindrical shape, a trapezoidal shape, a hemispherical shape, etc. are formed on the electrode pad portion 2 for connecting bare chip components. The printed wiring board is formed to have a height of 30 μm to 50 μm higher than the surface of the printed wiring board by a plating method. After plating for forming the bumps, the plating resist film 7 is peeled off with an alkaline aqueous solution, and the bumps 9 having a small diameter of 30 μm to 40 μm as shown in FIG. To form a printed wiring board with bumps formed on the surface of the copper foil of the electrode pad portion 2. In the plating step of forming the bumps shown in FIG. 2C, the plating resist film 7 is peeled off after electroless copper plating, and then electroless nickel plating and electroless gold plating are performed to form the printed wiring board 1. The surface rust prevention treatment can be omitted. Alternatively, it is also possible to form a permanent film without removing the plating resist film 7.

FIG. 1 is a sectional view of a multilayer wiring board as a printed wiring board with bumps according to the present invention. Upper surface outer layer conductor 3, inner layer conductor 4, lower surface outer layer conductor 5, through conduction hole 6, solder resist film 8, printed wiring board 1,
In addition, a bump 9 having a small diameter for mounting a bare chip component is provided on the electrode pad portion 2. The solder resist film 8 is formed at a predetermined position after forming the upper surface outer layer conductor 3, the lower surface outer layer conductor 5, the electrode pad portion 2, etc. of the printed wiring board 1 of FIG. After that, the plating resist film 7 may be formed, or the plating resist film 7 may be formed after the bumps 9 are formed on the copper foil surface of the electrode pad portion 2 in FIG.

The bumps formed on the electrode pads for connecting bare chip components of the printed wiring board are not limited to the bumps formed by the plating method. For example, the surface of the electrode pad part for connecting bare chip parts of the printed wiring board is depressed into a concave shape and the like, and solder plating is applied to the place where plating is deposited, or a conductive paste is applied and semi-cured state 30 μm to 50 μm from the surface of the printed wiring board so as to have a convex shape.
A printed wiring board with bumps can be formed by forming the wiring board with a height of μm.

[0013]

According to the printed wiring board with bumps of the present invention, bumps for connecting bare chip components are formed on the electrode pads of the printed wiring board in advance by a plating method so that bumps are formed on the conventional bare chip components. This is a mounting method that eliminates the need to form and supply a component to a set maker as a flip chip component, and allows a bare chip component to be directly connected to a printed wiring board with bumps. Accordingly, since the same bare chip components can be used as before, they can be supplied sufficiently, and the bumps can be formed by the plating method of the printed wiring board with good production efficiency and at a low price.
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[Brief description of the drawings]

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

FIG. 2 is a sectional view for explaining a manufacturing process of the present invention.

FIG. 3 is a cross-sectional view illustrating a conventional method for mounting a bare chip component on a printed wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printed wiring board 2 ... Electrode pad part 3 ... Upper surface outer layer conductor 4 ... Inner layer conductor 5 ... Lower surface outer layer conductor 6 ... Through conduction hole 7 ... Plating resist film 8 ... Solder resist film 9 ... Bump 10 ... Bare chip part 20 ... Flip chip component 30: Conventional printed wiring board.

Claims (2)

[Claims] 1. A printed wiring board with bumps, wherein bumps are formed in advance on an electrode pad portion for connecting bare chip components of the printed wiring board by a plating method. 2. A printed wiring board with bumps, wherein a bump is formed in a depressed portion of an electrode pad portion for connecting a bare chip component of the printed wiring board so as to be convex in a semi-cured state.