JPH03224289A - Printed circuit board and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a board in which a wire disconnection in a through hole is prevented by forming a mark printed part by exposing a solder-resist film, curing the film, and then forming it above the bore of the hole and at the peripheral edge of an opening by silk printing. CONSTITUTION:A through hole 901 is opened in a board 9, then a pattern is formed, resist films 4 are cured above the bore of the hole 901 and a part except the peripheral edge of the opening, and a resist film is formed above the bore of the hole 901 and at the peripheral edge of the opening at the time of printing a mark by silk printing. That is, the resist films above the bore of the hole 901 and the part except the peripheral edge of the opening are exposed, cured, and the resist films are formed above the bore of the hole and at the peripheral edge of the opening together with a mark by silk printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention can prevent wire breakage due to solder build-up and corrosion in through-holes when electronic components are mounted. This invention relates to a printed wiring board and its manufacturing method.

(Prior Art) Conventionally, in a printed wiring board, as shown in FIG. 11, electronic components 6 are mounted on a board 9 by inserting two leg parts 61 into through holes 90.

That is, the electronic component 6 has one leg 61 connected to the through hole 90.
The solder 5 is inserted into the through hole 9.
0 and bonded and fixed.

The through hole 90 is generally called an electronic component mounting hole. Note that the through hole 90 has an inner diameter of 0. 5-1. It is a through hole of about 6m+*.

On the other hand, on the printed wiring board there are figures 11, 12, 1
As shown in Figures 3a to 13c, the inner diameter is 0.3 to 1.
A 2 m through hole called a via hole 901 is provided. The via hole 901 is a hole for conduction in a multilayer pattern.

A solder resist film 81 is formed on such a printed wiring board having through holes in order to protect the pattern formed on the surface thereof. Generally, the solder resist film 81 is formed by a photographic method or thermosetting. The above-mentioned photographic method is a method in which a resist film 81 is applied to the front and back surfaces of the substrate 9 by rough printing using liquid resist ink. Thereafter, the resist film 81 is exposed and developed.

In addition to the photographic method described above, there is a method of forming the solder resist layer 11 using thermosetting resin ink. In this method, the ink is heated at about 150'C for several tens of minutes to cure it.

5. After the resist film is formed using the above method, add one character to clarify the electronic component mounting position.

Marks such as patterns are applied by printing. Mark printing for printing the mark is generally performed by silk printing using a pattern mask of the mark.

[Problem to be solved] However, the above conventional method has a first-order problem.

That is, when the electronic component 6 is mounted on the front surface side of the board 9, when the solder flows, the through hole 90° and the via hole 901 are formed as shown in FIGS. 11 and 12.
Melted solder 5 overflows from the inside toward F. in this way,
The phenomenon in which half [115] overflows upward is called 1 and a half lTI uplift. As shown in FIG. 12, the half 15 is (
, flows out to the adjacent land portion 92 and creates an interference (overlapping) portion 51. This causes a short circuit in the pattern.

-.The solder resist film 81 described in J- is the first conventional solder resist film 81.
As shown in Figure 3a, they were formed into five predetermined shapes. That is, on the surface side of the substrate 9, the via balls 9
A resist film 81 is formed in the hole 01 and its periphery. Although it is possible to prevent short circuits in the pattern due to half +1"lfA at the land portion, a closing film 82 is formed on the back side of the substrate 9 that closes the bottom of the via hole 901 indicated by -. Therefore, the closing The acid treatment liquid and the flux treatment liquid 7 remain on the surface of the film 82. The flux treatment liquid 7 has the property of being an antioxidant for the conductive film 910 made of a copper plating film.

As a result, the conductive film 910 is corroded by the acid treatment liquid or flux treatment liquid 7, as shown in FIG. 13b.

Therefore, inside the via hole 901.

As shown in FIG. 13C, a disconnection 912 occurs in the conductive film 910 due to thermal stress H during mounting or operation of electronic components.
may occur.

The present invention has been made in view of such conventional problems, and can simultaneously prevent solder build-up during mounting of electronic components and wire breakage due to corrosion within the through-hole. The present invention aims to provide a printed wiring board and a method for manufacturing the same.

[Means for solving problems]

The present invention is a printed wiring board in which a pattern and a through hole are formed on a substrate, and a resist film is formed on the -F side of the through hole and the periphery of its opening when printing a mark by silk printing. There is a printed wiring board characterized in that:

The most noteworthy feature of the present invention is that a resist film is formed on one side of the through-hole and the periphery of the opening of the through-hole (-h) at the time of printing the mark by silk printing.

That is, one aspect of the present invention is to form a resist film for preventing semi-ff lifting at least above the inside of the through-hole and around the opening thereof, and to prevent the lower part of the through-hole from being blocked. For this reason, when printing the mark, we decided to form a resist film on the upper part of the through-hole and the periphery of the opening, but not on the lower part.

The above-mentioned through holes include mounting holes through which the legs of various electronic components such as semiconductor chips, resistors, capacitors, etc. are inserted and bonded and fixed, and holes with a smaller diameter than the mounting holes for mounting electronic components. There are conductive holes such as via holes that cannot be used.

The upper part of the hole means, for example, in the through hole, above approximately half of the through hole.

The opening includes, for example, a land portion extending above the through hole and its periphery.

There is a method of applying solder resist to the opening [1 part of the through hole] using a Tetron screen having a mesh size of about 200 to 300 meshes, for example. . and,
When applying, use a squeegee and doctor knife.
The solder resist on the screen is transferred onto the printed wiring board substrate.Next, the solder resist film thus formed is heated to about 150°C or cured by ultraviolet (UV) irradiation. .

Further, - the above-mentioned mark printing essentially means printing a mark that indicates the mounting position of an electronic component.

Therefore, it is preferable to mix, for example, a white or yellow pigment into the liquid solder resist to make it clear that it is a mark-printed part.

As a result, the mark printed portion exhibits a complementary color effect in contrast to, for example, a green resist film applied on the surface of the printed wiring board by rough printing.

Further, the above-mentioned mark printing is generally used by using a pattern of characters and patterns to identify and display the position of the mounted component by silk printing.

The method for manufacturing the printed wiring board of the present invention includes drilling a hole for forming a through-hole in a substrate, forming a pattern thereon, and then forming a hole in the through-hole of the substrate and a periphery of the opening. 1. After forming a resist film on the parts except for the above-mentioned through hole and curing the resist film, a resist film is applied to one side of the through-hole and the periphery of the opening by silk printing when a mark is printed. This is a method of manufacturing a printed wiring board characterized by forming a printed wiring board.

That is, the most noteworthy point in the two methods is that first, the resist I/coating is hardened and formed by exposing the upper edge of the through-hole and the portion other than the periphery of its opening [ ] to light, and then the through-hole is cured. The purpose of this method is to form a resist film together with a mark by silk printing on the upper part of the hole and the periphery of the opening thereof.

The above-mentioned resist film may be formed by the same method used to form the mark.5 For example, a pattern in the shape of a land portion may be used and silk-screen printed on a desired portion.

[Function] In the printed wiring board of the present invention, the resist coating is applied at least above the inside of the through hole and at the periphery of the opening, in addition to the resist coating for pattern protection, during mark printing by silk printing. is forming. That is, the formation of the resist film marked L is performed by silk printing during mark printing after the formation of the resist film for pattern protection. Therefore, when electronic components are mounted, molten solder as a flow solder does not reach the surface side of the board. It doesn't overflow.

That is, in the through-hole, the molten solder rises to the resist layer III formed above the through-hole when printing the mark. However, the resist film has the role of a dam that prevents the molten solder from rising. Therefore,
The molten solder does not rise above the mark printing area. Therefore, the half m does not overflow onto the surface of the substrate. In other words, no solder build-up occurs.

In addition, the resist film formed when printing the above mark is
It is formed only in the upper part of the through hole.

Therefore, like the solder resist film formed by the conventional hole-filling method (there is no closure film that can cause corrosion below the through-hole, there is no acid treatment solution or flux treatment that can cause corrosion inside the through-hole). No liquid remains.As a result, the conductive film within the through hole is not corroded and does not cause insulation.

2. In the manufacturing method of the present invention, as described above, the resist film is formed during mark printing by exposing the resist film to light in areas other than the inside of the through-hole and the periphery of the opening, and then curing the resist film. Silk printing may be performed on the upper part of the through-hole and the periphery of the opening, or a resist film may be formed on the entire surface of the through-hole without being limited to the upper part of the through-hole and the periphery of the opening.

That is, it is possible to form a resist film on the resist film for pattern protection, and also on the parts other than the peripheral edge of the through hole when printing the mark.

According to the above manufacturing method, a resist film can be easily formed by the same operation as the method of printing marks during mark printing. Therefore, there is no need to provide a separate device, which is economically advantageous.

As described above, an excellent printed wiring board can be easily obtained.

(Effects) Therefore, according to the present invention, semi-I when mounting electronic components
It is possible to prevent wire breakage due to n lift and corrosion inside the through hole. A printed wiring board and a method for manufacturing the same can be provided.

〔Example〕

First Embodiment A printed wiring board according to this embodiment will be explained with reference to FIGS. 1 and 2.

First, in the printed wiring boards of the two examples, a pattern 93, via holes, and through holes 901 and 90 as holes for mounting electronic components are formed on a mounting board 9, as shown in the figure.

And through hole 901 which is L via hole.
A resist coating part (hereinafter referred to as a mark printing part) I is formed by printing a mark by silk printing on the upper part B of the hole and the opening part C thereof.

As shown in FIG.
In the −F side 13 of the through hole 901, which is a hole, it is formed in a substantially streamlined state and adhered to the first through hole plating film 91. Therefore, the mark printing section 1 has a taper 11 toward the bottom.

That is, - the mark printed portion l is made of epoxy resin and exhibits yellow color. The mark printed portion 1 is made of a durable film that is cured by heating.

In addition, the mark printing part l is formed by a through-hole plating film 9.
1, and forms a coating having an annular shape on the surface. That is, as shown in FIG. 1, the mark printed portion I has a substantially donut shape or is in a completely closed state at the opening C of the through hole 901.

That is, as shown in FIG. 1, the mark printing part 1 has a hollow part 110 in the center or is completely closed, and the periphery thereof has a net-like surface covering 1191o extending in a substantially circular shape. It's true. In addition, the mark printing part 1 has a through hole 9
It is formed integrally with the mark printing part l formed above in 01.

The through hole 901 is a via hole with an inner diameter of about 0.4 mm. Then, the through hole 9 (11
Inside, a conductor 119910 made of copper plating is formed so as to be continuous with the land portion 92.

1. The substrate 9 is made of a glass boxy resin substrate with a thickness of 0.5 to 1.61. Then, the substrate 9'
A pattern 93 of a copper plating film is formed on the surface. Further, the pattern 93 has a through hole 90 for mounting electronic components at the end. Also.

” 2. On the surface of the substrate 9, there is a green solder resist film 4 which is coated on the surface other than the mark printed portion l.
has.

Next, each action and effect will be explained.

In the printed wiring board according to this example, a mark printing part l is formed by silk printing on the upper part B of the through hole 901 and the periphery of the opening part C thereof.

Therefore, when electronic components are mounted, the molten solder of the flow solder does not overflow to the front surface of the board 9.

That is, the molten solder rises to the mark printing portion l formed above the one above-mentioned through hole. but.

The mark printed portion I has the role of a dam that prevents the molten solder from rising. Therefore, the 78 melted solder does not rise above the taper 11 of the mark printing portion l. Therefore, the solder does not overflow onto the surface of the substrate 9. In other words, soldering does not occur.

Further, the mark printing portion I is formed only in the upper part B within the nine through holes 901.

Therefore, like the conventional solder resist film, there is a closing film (
(see FIG. 12a) does not exist. Therefore, no acid treatment liquid or flux treatment liquid remains in the through hole 901, which causes corrosion.

As a result, the conductive film 910 within the through hole 901 is not corroded and does not cause heat insulation.

Therefore, according to one example, in a printed wiring board,
Half [L] lift and through hole 90 when mounting IT child parts
It is possible to prevent wire breakage due to corrosion inside 1.

Second example Regarding the method for manufacturing a printed wiring board according to this example.

This will be explained using FIGS. 3 to 7.

First, the printed wiring board of this example is as shown in Fig. 3.
A hole 90 for forming a through hole 901 is made in the substrate 9.

The board 9 has a thickness of about 0. It consists of a glass epoxy substrate with a diameter of 5 to 1.6 degrees.

Next, as shown in FIG. 4, - a copper plating film 91 for forming a pattern 93 is formed on the substrate 9; Then, a conductive film 91O is formed on the inner wall of the hole 90. As a result, a through hole 901 as a via hole is formed.

Next, as shown in FIG. 5, a pattern 93 is formed by etching. Then, a conductive film 910 and a copper plating film as a land portion 92 are formed on the inner wall of the through hole 901 and the periphery of its opening.

Further, as shown in FIG. 6, a greenish color solder resist film 4 is formed on the surface of the substrate 9 other than the through holes 901 and the land portions 92. The solder resist film 4 is formed on portions other than the through holes 901 by 5-screen printing. That is, in the screen printing, an ink containing a modified epoxy resin mixed with a green pigment, an antifoaming agent, and a filler 1 solvent is used. Note that the solder resist film 4 has a pattern 9
Formed to protect 3.

Next, the solder resist film 4 is exposed to light to harden it.

Thereafter, as shown in FIG.
A mark printed portion 1 is formed by silk printing on the upper part B of one hole and the periphery of its opening C. The mark printing part l is
Formed by silk printing using epoxy resin ink. What should be noted here is that a white or yellow pigment is mixed into the ink. That is, in the green solder resist film 4,
Colored to make it more noticeable. A mark printing portion l is formed.

The mark printing part 1 has a hollow part in the center and is formed to extend approximately circularly around the periphery of the land part 92 (see FIG. 1).

Next, the effects will be explained.

In this example, after the solder resist film 4 is exposed to light and the solder resist film 4 is cured, the mark printing part 1 is silk-printed (mark printed) on the upper part B of the through hole 901 and the periphery of the opening C. ) formed by

According to this example, an excellent printed wiring board as shown in the first embodiment can be manufactured.

Third Embodiment Regarding the printed wiring board according to this example, as another example, the eighth
This will be explained using FIGS.

That is, the printed wiring boards of the two examples are printed wiring boards on which a quad flat package (QFP) is mounted instead of the printed wiring board of the first embodiment. Other configurations.

This is the same as in the first embodiment.

The printed wiring board has a structure as shown in FIG.

Bands 2 for terminals are formed in four directions in order to mount an IC card. A via hole 950 is formed in the Ic card mounting portion 95 surrounded by the pad 2. Then, the whole area including the upper part B in the hole of the via hole 950 and the periphery of the opening C thereof is printed in 5-macro printing part 1.
5, it is formed by silk printing.

The via hole 950 is formed by making a through hole in the substrate 9 with an inner diameter of about 0.4 m, as shown in FIG.

Then, an IC card (not shown) is mounted on the pad 2. In addition, around the periphery of the via hole 950,
Mount IC component 3. The IC component is used for bonding during its mounting.

Use a flow solder of molten solder.

At this time, in the upper part B and the opening C of the via hole 950, as shown in Figures 8 to 1O,
Since the mark printed portion 15 is formed, solder splatter does not occur. Furthermore, a resist film 4 is formed by rough printing prior to the mark printing portion 15.

Further, a closing film is not formed below the via hole 950 by the conventional hole-filling method.
Therefore, no flux treatment liquid that causes corrosion remains in the via ball 950.

Therefore, according to this example, effects similar to those of the first example can be obtained.

[Brief explanation of drawings]

1 and 2 show a printed wiring board according to the first embodiment, FIG. 1 is a plan view thereof, and FIG. 2 is an A-A in FIG. 1.
3 to 7 are cross-sectional views showing the manufacturing process of the printed wiring board according to the second embodiment, and FIGS. 8 to 10 show the printed wiring board according to the third embodiment, FIG. 8 is a sectional view thereof. Fig. 9 is a plan view thereof, Fig. 10 is a sectional view taken along the line IE-E in Fig. 9, Figs. 11 to 13c show conventional examples, and Fig. 1
FIG. 1 is a sectional view thereof, FIG. 12 is a plan view thereof, and FIGS. 13a to 13c are sectional views showing the state of occurrence of corrosion in the through hole. 1 29. . 3. 4. 91. . 90, 90 Mark printing part 5° band IC parts. Solder register base material. ■,. Through hole. Tocoat. 92,...Land part 93...Pattern. 95, Beyer Hall applicant IBIDEN Electronics Industry Co., Ltd. IBIDEN Co., Ltd.

Claims (2)

[Claims] (1) A printed wiring board in which a pattern and through holes are formed on a substrate, characterized in that a resist film is formed at least above the inside of the through hole and at the periphery of the opening thereof during mark printing by silk printing. printed wiring board. (2) Drill holes for forming through-holes in the substrate, then form a pattern, and then form a solder resist film above the through-holes of the substrate and in areas other than the periphery of the openings, and Manufacturing a printed wiring board characterized in that, after exposing the resist film to light and curing the resist film, a resist film is formed above the inside of the through hole and on the periphery of the opening thereof by printing a mark by silk printing. Method.