JPH0444292A - Printed wiring board and its manufacture - Google Patents

Abstract

PURPOSE:To improve the reliability of connection by installing a spotting device with projected shape or recessed shape on a pad for mounting parts, thereby preventing from dislocation of packaging parts on the surface of a printed wiring board. CONSTITUTION:A prescribed mask pattern is formed with the use of a dry film, etc., and a land 2' for surface packaging is formed by applying selective etching. Then, a through-hole land 11 and a pad 2 are removed, and an epoxy solder resist 3 with chemical copper plating resistance if formed, by printing, on the zone etched in prior process and other circuit pattern. After that, a resist pattern 7, which has chemical copper plating resistance and capability to strip plating, is selectively formed with precision of less than + 30mum on the pad 2 in exposed condition as a frame surround ing the pad 2 by using exposure method. Next, a conductor 8 is formed in the recessed part 1 of the pad 2 and a through hole 9 by applying chemical copper plating with a coating thickness of 30 to 50mum. By eliminating the plated resist pattern 7 with solution for stripping, it is made possible to manufacture a printed wiring board incor porating a frame-type pad with a recessed part 1 measuring 50 to 120mum in width and 30 to 50mum in height in the pad 2. The height and width of the recessed part 1 shall be within the range from 10 to 200mum each.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printed wiring board for mounting surface-mounted components and a method for manufacturing the same.

[Prior Art] The shape of a pad in a conventional printed wiring board for mounting surface-mounted components is flat, as shown in a cross-sectional perspective view in FIG. 10, for example. In order to prevent the position of the mounted components from shifting, there is a method of making the isolation pattern 12 formed by the solder resist 3 between the pads 2 higher than the pads, and, although not shown in the drawing, a recess is formed in the base material 1 to position the main body of the mounted component. Methods such as doing this were used.

For example, Japanese Patent Laid-Open No. 1-217994 can be cited as an example of a printed wiring board for mounting surface-mounted components of this type.

[Problems to be Solved by the Invention] In the above-mentioned conventional technology, in order to increase the height of the solder resist between the pads, it was necessary to perform coating multiple times or provide a pattern between the pads. The former has the problem of increasing the number of steps, and the latter has the problem of not being able to cope with higher density.

Furthermore, when a solder resist is used as a guide, there is a problem that accurate positioning cannot be performed because the guide is located outside the pad.

In addition, the method of forming recesses in the base material requires a large number of processing steps, cannot be positioned without strict precision between the main body of the component and the lead, and cannot absorb bending of the lead.
Since wiring patterns cannot be placed in the recessed portions, there are problems such as not being suitable for high density.

The purpose of the present invention is to solve the above-mentioned conventional problems, and the first purpose is to provide a printed wiring board that prevents displacement of surface-mounted components and has high connection reliability. The objective is to provide manufacturing methods for each.

Means for Solving Problem 18] The first object of the present invention is (1) a printed wiring board for mounting surface mount components, which is provided with a pad for mounting zero components, the pad having a positioning means having an uneven shape; (2) The above pad is a frame-shaped pad having a continuous convex portion on its periphery and a concave portion formed on its inner principal surface, according to (1) above. (3) The printed wiring board according to (2) above, in which the inner wall surface of the concave portion of the pad is roughened, and (4) The pad has a continuous peripheral edge. By the printed wiring board according to (1) above, which comprises a picture frame-type pad which forms a convex part and whose inner main surface forms a bottomless part where an underlying insulating base material is exposed, and (5), a concave part of the pad. The printed wiring board according to any one of (2) to (4) above is filled with solder, and (6) the height of the convex portion forming the frame of the pad is 10 to 10.
By using the printed wiring board according to any one of (1) to (5) above, which is a frame-shaped pad having a width of 200 μm and a width of 10 to 200 μm, and (7), the degree of roughening of the inner wall surface of the pad recess is 5. ~3
This is achieved by the printed wiring board described in (3) above, which has concavities and convexities of 0 μm.

The second object of the present invention is to: (8) form a through hole at a predetermined position of a double-sided steel-clad insulating substrate; a step of applying a plating catalyst including the inside of the through hole; and a step of applying a plating catalyst to the inside of the through hole. a step of forming a component mounting pad and a conductor circuit pattern connected thereto by etching through a predetermined mask, leaving a land at the opening of the through hole while holding a catalyst applied to the through hole; A step of printing an insulating layer made of solder resist on the substrate except on the lands and pads, a step of forming a resist mask on the main surface with the periphery of the pad exposed, and an electroless copper plating process. depositing copper on the periphery of the pad and in the through hole to form a plated conductor layer, and forming a convex portion made of the plated conductor layer on the periphery of the pad;
By the method for manufacturing a printed wiring board according to (1) or (2) above, which comprises the step of removing the resist mask, and (9) forming through holes at predetermined positions in the double-sided mesh insulating substrate. a step of applying a plating catalyst including the inside of the through hole, and a step of forming a picture frame on which parts are mounted by leaving a land at the opening of the through hole while holding the catalyst applied in the through hole. A step of forming a pad having a bottomless part of the mold and a conductive circuit pattern connected thereto by etching through a predetermined mask, and printing an insulating layer made of solder resist on the substrate except at least on the through hole land and the pad area. By the method for producing a printed wiring board according to (4) above, the method includes the steps of: achieved.

[Operation: The concavities and convexities provided on the surface mounting pads act as guides for the component leads to be mounted, and prevent component misalignment, thereby preventing connection failures.6 The concave portions of the pads serve as guides for the component leads to be mounted, and this prevents connection failures. By filling, the amount of solder supplied can be made constant, so it is possible to prevent solder bridging, unconnected solder, etc. due to insufficient solder, and improve connection reliability.

In addition, by providing minute irregularities on the surface of the pad,
Since the contact area of the solder can be increased, the adhesive strength of the solder can be improved and the connection reliability can be improved.

[Example code] An embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a plan view of the area around a pad in a printed wiring board for mounting surface mount components according to the present invention.

FIG. 2 is a sectional view taken along line 1-1 of FIG.

In this example, in the surface mounting pad 2 with a radius of 0.6 to 0.65 m+, the width around the pad 2 is 50 to 120 μm.

A frame-shaped pad was formed with a convex portion 1 having a height of 30 to 50 μm and having a bottom portion 20. Further, a solder resist 3 was formed on the outer periphery of the convex portion 1.

FIG. 3 shows a cross-sectional view after surface mount components are mounted on this printed wiring board and the leads 4 are soldered 5 to the pads 2.

Since the leads 4 of this component do not come out of the pad using the convex portion 1 as a guide, positional shift can be prevented. Furthermore, soldering could be performed with lead bends and the like corrected.

As a result of the above, it was possible to form the fold 5 having a normal fillet shape, and to significantly reduce connection failures due to positional deviations.

Regarding the manufacturing method of the printed wiring board in this example,
This will be explained in detail later in Example 3.

Example 2゜ Next, a sectional view of the second embodiment is shown in FIG.

Note that this figure corresponds to FIG. 3 of the first embodiment, but in FIG. 3, the pad 2 had a bottom 20, but in this FIG. Material 6 is exposed.

In other words, in this example, the surface mount pad 2 was constructed in a frame shape with only the convex portion 1, and the same effect as in Example 1 was obtained.

Example 3 Next, the manufacturing method of Example 1 will be explained using the process diagram shown in FIG.

As shown in FIG. 5(a), a predetermined through hole 9 was provided in a double-sided copper-clad laminate consisting of an insulating base material 6 and a copper foil 2', and a catalyst for electroless copper plating was applied inside the hole.

Next, as shown in FIG. 5(b), a predetermined mask pattern was formed using a dry film or the like, and selective etching was performed to form lands 2 for surface mounting.

Next, as shown in Figure 5 (C), the through-hole land]
An epoxy-based solder resist 3 having resistance to chemical copper plating was formed by a printing method or the like on the area etched in the above process and other circuit patterns except for the pads 1 and 2.

Note that, at this time, although a predetermined groove 10 was provided on the outer periphery of the pad 2 to form the solder resist 3, this groove is not necessarily necessary. It is important to prevent the resist 3 from being placed on the pad 2 during printing, and this groove was created as a result of creating a printing pattern with a margin for this purpose.

Thereafter, as shown in FIG. 5(d), a plating resist pattern 7 that is resistant to chemical copper plating and can be peeled off after plating is applied to the pad 2 using an exposure method with an accuracy of ±30 μm or less.
It was selectively formed on top of the frame with its periphery exposed like a picture frame.

It is important to form a continuous edge with such precision; if this is exceeded, the convex portion can only be formed on one side.

Next, as shown in Figure 5(e), chemical copper plating is applied to
A conductor 8 was formed within the convex portion 1 of the pad 2 and the through hole 9 by applying a thickness of 50 μm.

Finally, as shown in FIG. 5F, the plating resist 7 provided in FIG. A printed wiring board having a frame-shaped pad having a convex portion of 50 μm was manufactured.

According to this manufacturing method, the convex portion 1 can be easily formed.

Although a detailed explanation of the method for forming the pad 2 shown in FIG. 4 of Example 2 will be omitted, the pattern shape of the pad 2 was changed as shown in FIG. 5(d) during the etching process shown in FIG. 5(b).
The portion corresponding to the resist 7 may be etched to form a picture frame-like empty bottom.

Example 4゜ Next, a fourth embodiment will be explained using FIGS. 6 and 7.

FIG. 6 is a plan view of the concave surface of the surface mounting band 2 in which irregularities of about 5 μm are formed using means such as polishing.

FIG. 7 is a cross-sectional view taken along the line ■--■ after the component glue 4 has been soldered 5 thereto.

Since the contact area between the solder 5 and the pad 2 was increased, the adhesive strength was improved by about 1.5 times compared to Example 1. This made it possible to improve connection reliability.

Example 5゜ Next, a fifth embodiment will be explained using FIG. 8.

In the pad 2 having the same shape as that described in Example 1,
Solder paste 5 was filled into the flat part 20 of the concave part so as to be flush with the convex part 1. As a result, the amount of solder paste 5 supplied could always be made uniform. Conventional screen printing methods are largely affected by protrusions on the surface of the substrate, but in this embodiment, defects due to excess or deficiency of solder can be significantly reduced since this is not affected.

The same applies to FIG. 4 of Example 2, and although the drawing is omitted here, the same result as Example 5 can be obtained by filling the recessed portion of band 2 with solder paste 5.

Embodiment 6 Next, a sixth embodiment will be explained using the sectional view of FIG. 9. A concave portion is provided on the surface mount component glue 4, and a convex portion 1 is provided on the pad 2, so that the two engage with each other. This made it possible to further improve the positional shift prevention effect.

By providing unevenness on the component lead 4 and interlocking with the unevenness on the pad 2, the effect of preventing misalignment can be improved.

[Effects of the Invention] According to the present invention, misalignment of components can be significantly prevented, and connection failures caused by this can be dramatically reduced.

Further, by roughening the surfaces of the four parts of the pad, the solder adhesion strength can be improved to about 1.5 times that of the conventional one, so that connection reliability can be significantly improved.

Furthermore, by filling the concave portions of the pads with solder paste in advance, the amount of solder paste supplied can be made uniform, which can significantly reduce connection failures caused by too much or too little paste, such as solder bridges and unsoldered connections. .

Furthermore, by using a structure in which one component lead and a pad are interlocked, positional displacement can be further prevented.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the printed circuit board of the present invention, FIG. 2 is a sectional view taken along line I-1 in FIG. FIG. 4 is a sectional view showing another embodiment of the present invention, also showing a state in which component leads are soldered. FIG. 5 is a process cross-sectional view showing an example of the manufacturing process of the printed circuit board of the present invention, FIG. 6 is a plan view of yet another embodiment in which the surface of the pad recess is roughened, and FIG. 7 is a - ■A line cross-sectional view after parts are mounted and connected. FIG. 8 is a sectional view showing an embodiment in which the concave portion of the pad is filled with solder paste, FIG. 9 is a sectional view showing another embodiment in which the butt and component lead have an interlocking structure, and FIG. 10 is a cross-sectional perspective view of a conventional imprinted printed circuit board. <Explanation of symbols> 1... Pad unevenness, 2... Surface mounting pad, 2'... Copper foil, 3... Solder resist, 4... One component lead, 5... Solder , 6...#! Edge material 7...Resist mask, 8...Copper plating, 9...Through hole, 10...Groove, 11...Through hole land, 2o...Bottom 6

Claims (9)

[Claims] 1. 1. A printed wiring board for mounting surface-mounted components, which is equipped with pads for mounting components, the printed wiring board comprising positioning means having an uneven shape arranged on the pads. 2. 2. The printed wiring board according to claim 1, wherein the pad is a frame-shaped pad having a continuous convex portion on its periphery and a concave portion formed on its inner principal surface. 3. Claim 2, wherein the inner wall surface of the recess of the pad is roughened.
The printed wiring board described. 4. The pad forms a continuous convex portion on its periphery,
2. The printed wiring board according to claim 1, wherein the internal principal surface comprises a frame-shaped pad forming a bottomless portion with an underlying insulating base material exposed. 5. Claim 2, wherein the concave portion of the pad is filled with solder.
4. The printed wiring board according to any one of 4 to 4. 6. The height of the convex part forming the frame of the above pad is 10 to 20
6. The printed wiring board according to claim 1, wherein the printed wiring board is a frame-shaped pad having a width of 0 .mu.m and a width of 10 to 200 .mu.m. 7. The degree of roughening of the inner wall surface of the pad recess is 5 to 30 μm.
4. The printed wiring board according to claim 3, wherein the printed wiring board has an unevenness of m. 8. A step of forming a through hole at a predetermined position of a double-sided copper-clad insulating substrate, a step of applying a plating catalyst including the inside of the through hole, and a step of applying a plating catalyst to the through hole while holding the catalyst applied in the through hole. A process of leaving a land in the opening and forming a component mounting pad and a conductive circuit pattern connected thereto by etching through a predetermined mask, and an insulation made of solder resist on the board except at least on the through-hole land and the pad. a step of printing a layer, a step of forming a resist mask on the main surface with the periphery of the pad exposed, and a step of depositing copper on the periphery of the pad and in the through hole by electroless copper plating, and plating. Claim 1 comprising the steps of forming a conductor layer and forming a convex portion made of a plated conductor layer around the periphery of the pad, and removing the resist mask.
Or the method for manufacturing a printed wiring board according to 2. 9. a step of forming a through hole at a predetermined position of the double-sided copper-clad insulating substrate; a step of applying a plating catalyst including the inside of the through hole; and a step of applying a plating catalyst to the inside of the through hole; a step of leaving a land in the opening of the through hole and forming a pad having a frame-shaped bottomless part on which the component is mounted and a conductor circuit pattern connected thereto by etching through a predetermined mask; Claim comprising the steps of: printing an insulating layer made of solder resist on the substrate, and depositing copper in the pads and through holes by electroless copper plating to form a plated conductor layer. 4. The method for manufacturing a printed wiring board according to 4.