JPH0567871A - Printed-wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate the generation of a solder bridge and the generation of a defective connection due to a positional deviation by a method wherein steps are respectively formed on pads for electronic component mounting use. CONSTITUTION:A P-type photosensitive resin film is formed on the whole surface of an insulating substrate 2a and thereafter, is dried. Then, a first mask film for intercepting ultraviolet rays from a prescribed through hole 1a, wiring circuit 1b formation parts and pad 1d formation parts is abutted on the resin film and after an exposure is performed exposed parts of the resin film are selectively removed, a P-type photosensitive resin film etching resist 7a is formed, an etching of a conductor layer is performed in a state that the ultraviolet rays are cut and wiring circuits 1b and pads 1d are formed. Then, a second mask film 4b is abutted only on the pads 1d and after an exposure is performed, the etching resist 7a on the pads 1d is selectively removed and the pads 1d are partially etched to form the pads 1d having a step. Thereby, the generation of a solder bridge and the generation of a defective connection due to a positional deviation can be eliminated.

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 and a method for manufacturing the same, and more particularly to a through-hole printed wiring board having a copper foil pad for mounting electronic components for surface mounting and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, a method of manufacturing a through-hole printed wiring board (hereinafter referred to as "T / H PWB") includes a method shown in FIG.
The tenting method shown in (a) to (d) and FIGS. 5 (a) and 5 (b) is often used. According to this method, first, as shown in FIG. As shown in FIG. 4 (b), a photosensitive dry film (hereinafter referred to as a dry film) 6 is attached to both surfaces of the insulating substrate 2a having the through holes 1a formed thereon. A predetermined wiring circuit pattern is printed with ultraviolet rays through the first mask film 4a. Next, the unnecessary portion of the dry film 6 is removed with a developing solution to obtain an etching resist 6a in a tenting state and an etching resist 6b for a wiring circuit portion as shown in FIG. 4B.

Further, as shown in FIG. 5 (a), after the exposed conductor layer 1 is removed by etching, finally, as shown in FIG. 5 (b), the etching resists 6a, 6b are peeled off to remove T / T.
Get HPWB.

Further, FIGS. 6 (a) to 6 (d) and 7 (a) to
In the hole filling method as shown in (c), as shown in FIG.
The through hole 1a of the insulating substrate 2a is filled with the filling ink 3 as shown in FIG. 6 (b) and cured, and the dry film 6 is attached to both surfaces of the insulating substrate 2a as shown in FIG. 6 (c). 6 (d), the first mask film 4a
A predetermined wiring pattern is baked with ultraviolet rays through. Next, as shown in FIG. 7A, an unnecessary portion of the dry film 6 is removed with a developing solution to obtain an etching resist 6a in a tenting state and an etching resist 6b of a wiring circuit portion.
Further, as shown in FIG. 7B, after the exposed conductor layer 1 is removed by etching, finally, the etching resists 6a and 6b are removed.
And the hole-filling ink 3 is removed by peeling to remove T shown in FIG.
/ H PWB.

In this method, an image formed by screen printing can also be used as an etching resist.

Besides this, FIGS. 8A to 8D and FIG.
As shown in FIG. 8A, the conventional positive electrodeposition coating method for the positive photosensitive resin film as shown in FIGS. 8A and 8B is applied to both sides of the insulating substrate 2a on which the conductor layer 1 and the through holes 1a are formed.
As shown in FIG. 8B, the positive photosensitive resin film 7 is electrodeposited on the entire surface, and the first mask film 4 is formed as shown in FIG. 8C.
A predetermined wiring circuit pattern is printed with ultraviolet rays through a. Next, the positive photosensitive resin film 7 of the unnecessary portion with the developing solution.
Is removed to obtain a positive photosensitive resin film etching resist 7a shown in FIG. Further, as shown in FIG. 9A, after the exposed conductor layer 1 is removed by etching, finally, as shown in FIG.
As shown in (b), the positive photosensitive resin film etching resist 7a is peeled and removed to obtain a printed wiring board.

Further, as shown in FIGS. 10 (a) to 10 (c), in the additive method, as shown in FIG. 10 (a), after punching the laminated plate 2b with the adhesive layer containing the catalyst, as shown in FIG. 10 (b). After applying the plating resist 5 to the non-wiring circuit portion, electroless copper plating 8 is applied to a predetermined wiring circuit portion to form a through hole and a wiring circuit, as shown in FIG.
Obtain T / HPWB.

[0008]

In recent years, as an effective method for increasing the density of wiring circuits, a wiring circuit pattern and an electronic circuit formed on the surface of the insulating substrate without providing through holes for lead insertion of components on the insulating substrate. Amid the rapid progress of surface mounting in which electrical connection is performed using only component mounting pads, it has been a problem to establish a printed wiring board having a form suitable for this and a manufacturing method thereof.

In a printed wiring board manufactured by a conventional manufacturing method such as a tenting method, a hole filling method, an additive method, etc., as shown in FIGS. 11 (a) and 11 (b), a copper foil pad (hereinafter referred to as a pad) 1d portion for mounting an electronic component is used. Since the surface shape of the pad is smooth, the pad 1 for soldering the leads 9 of the surface mount component
When the parts a are close to each other, the solder bridge 11 is likely to occur due to the flow of the cream solder at the time of reflow, and the connection failure is likely to occur due to the positional deviation at the time of mounting the components.

As a countermeasure against these problems, a method of making a step difference in the thickness of the plating resist and the electroless copper by an additive method has been carried out, but since the step cannot be made inside the pad 1d, the problem of component displacement occurs. was there.

It is an object of the present invention to provide a highly reliable printed wiring board and a method for manufacturing the same, which does not cause a solder bridge and a connection failure due to a position shift when mounting a component.

[0012]

The present invention is characterized in that a step is formed on the electronic component mounting pad in a printed wiring board having a through hole and an electronic component mounting pad.

The method for manufacturing a printed wiring board of the present invention comprises the steps of forming a hole in a copper-clad insulating substrate and then forming a copper plating layer on the hole and the surface of the copper-clad insulating substrate, and a positive photosensitive resin film. A step of electrodeposition coating on the copper clad insulating substrate,
A first mask film having a predetermined wiring circuit and a through-hole copper foil pad pattern is brought into contact with the positive photosensitive resin film to expose it, and then the positive photosensitive resin film in the exposed portion is selected by development. Second step of removing the exposed copper portion by etching, and the second step having a predetermined pattern shape with respect to the obtained copper-clad insulating substrate.
A mask film is abutted, and after selectively exposing the inside of the copper foil pad portion, a step of removing the positive photosensitive resin film in the exposed portion by development and etching the exposed copper portion to a predetermined thickness And a step of removing the remaining positive photosensitive resin film by peeling.

[0014]

Embodiments of the present invention will now be described with reference to the drawings.

1A to 1D and 2A to 2A.
(E) is sectional drawing shown in order of a process explaining one Example of this invention.

First, as shown in FIG. 1A, a hole is drilled in the insulating substrate 2a, and then the conductor layer 1 is formed. As the material of the insulating substrate 2a, for example, a glass cloth base epoxy resin plate or a glass base polyimide resin plate can be used.

Next, FIG. 1 is formed on the entire surface of the insulating substrate 2a.
As shown in (b), the positive photosensitive resin film 7 is formed by electrodeposition coating and then dried.

Next, as shown in FIG. 1 (c), a predetermined through hole, a wiring circuit, and a first mask film 4a for blocking ultraviolet rays in the pad forming portion are brought into contact with each other, and after exposure,
As shown in (d), the positive photosensitive resin film 7 in the exposed portion is selectively removed to remove the positive photosensitive resin film etching resist 7a.
2A, the wiring layer 1b and the pad 1d are formed by primary etching of the conductor layer in a yellow room where ultraviolet rays are cut, as shown in FIG.

Next, as shown in FIG. 2B, the second mask film 4b having a predetermined shape is brought into contact with only the pad 1d, and after exposure, the positive type photosensitive resin film etching resist 7a on the pad 1d is selectively selected. After the development process to remove
As shown in (d), the pad 1d is partially etched by about 5 to 30 [mu] m for secondary etching to form a pad 1d having a step.

Finally, as shown in FIG. 2E, the remaining positive type photosensitive resin film etching resist 7a is removed to obtain the T / H PWB of this embodiment.

[0021]

As is apparent from the above, according to the present invention, it is possible to manufacture a printed wiring board having a pad 1b having a step as shown in FIGS. 3 (a) and 3 (b). There is an effect that the conventional soldering failure at the time of surface mounting can be greatly improved.

Conventionally, the main cause of this type of soldering failure is due to the variation in the thickness of the cream solder printed in the solder paste printing process at the time of surface mounting and the solder flow in the reflow process. It was a cause of poor contact. On the other hand, in the printed wiring board having the stepped electronic component mounting copper foil pad according to the present invention, solder flow at the time of reflow can be prevented, and further, a highly reliable surface mounting capable of solving the problem of displacement of mounted components There is an effect that a printed wiring board having a suitable form can be manufactured.

[Brief description of drawings]

1A to 1D are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

2A to 2D are cross-sectional views showing a process sequence for explaining an embodiment of the present invention.

3A and 3B are configuration diagrams in which a lead of an electronic component is connected to a pad according to an embodiment of the present invention. FIG. 3A is a perspective view and FIG.
Is a sectional view taken along line AA ′.

4A to 4C are cross-sectional views showing a method of manufacturing a printed wiring board by a conventional tenting method in order of steps.

5A to 5D are cross-sectional views showing a method of manufacturing a printed wiring board by a conventional tenting method in order of steps.

FIG. 6 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional hole-filling method in the order of steps.

7A to 7C are cross-sectional views showing a method of manufacturing a printed wiring board by a conventional hole filling method in order of steps.

FIG. 8 is a cross-sectional view showing the order of steps for explaining a conventional method for producing a printed wiring board by positive-type photosensitive resin electrodeposition coating.

9A to 9D are cross-sectional views showing a method of manufacturing a conventional printed wiring board by positive-type photosensitive resin electrodeposition coating in the order of steps.

FIG. 10 is a cross-sectional view showing a method of manufacturing a printed wiring board by a conventional additive method in the order of steps.

FIG. 11 is a configuration diagram in which leads of an electronic component are connected to pads of an example of a conventional printed wiring board, FIG. 11 (a) is a perspective view,
FIG. 11B is a sectional view taken along the line AA '.

[Explanation of symbols]

 1 Conductor Layer 1a Through Hole 1b Wiring Circuit 1c Through Hole Land 1d Pad 2a Insulating Substrate 2b Laminated Plate with Adhesive Layer with Catalyst 3 Hole Filling Ink 4a First Mask Film 4b Second Mask Film 5 Plating Resist 6 Dry Film 6a, 6b Etching resist 7 Positive type photosensitive resin film 7a Positive type photosensitive resin film resist 8 Electroless copper plating 9 Lead 10 Solder 11 Bridge

Claims (2)

[Claims] 1. A printed wiring board having a through hole and an electronic component mounting pad, wherein a step is formed on the electronic component mounting pad. 2. A step of forming a copper plating layer on the hole and the surface of the copper-clad insulating substrate after forming a hole in the copper-clad insulating substrate, and a positive photosensitive resin film on the copper-clad insulating substrate. Coating step, exposing a first mask film having a predetermined wiring circuit and a copper foil pad pattern of through holes on the positive type photosensitive resin film, and then exposing the positive type photosensitive resin film to develop the positive type A step of selectively removing the photosensitive resin film, a step of removing the exposed copper portion by etching, and a step of bringing a second mask film having a predetermined pattern into contact with the obtained copper-clad insulating substrate. A step of selectively exposing the inside of the copper foil pad portion and then removing the positive photosensitive resin film in the exposed portion by development; and a step of removing the exposed copper portion by a predetermined thickness by etching. , The rest And a step of peeling and removing the existing positive photosensitive resin film.