KR950000293B1 - Printed wiring board and manufacturing method thereof - Google Patents

Abstract

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Description

Printed wiring board and its manufacturing method

1 is a cross-sectional view for each step showing a method for manufacturing a printed wiring board according to the present invention.

2 is a cross-sectional view showing the structure of the foot pattern portion of the printed wiring board manufactured according to the present invention.

Explanatory drawing which compares the dimensional relationship of the spacer between conductors in the conventional printed wiring board and the printed wiring board by this invention.

6 is a cross-sectional view showing a structure of a foot pattern portion of a conventional printed wiring board.

7 is a cross-sectional view for each step showing a conventional method for manufacturing a printed wiring board.

* Explanation of symbols for main parts of the drawings

10: glass epoxy substrate 20: copper foil

40: electroless copper plating layer 60: electrolytic copper plating layer

70, 110: solder plating layer 80, 85: solder resist

90: foot pattern part 100: FT pattern conductor

120: wiring conductor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board and a manufacturing method thereof, and more particularly, to a structure of a foot pattern formed on a printed wiring board and a manufacturing method thereof.

On the surface of a printed wiring board (printed board), a foot pattern for component mounting is usually provided in addition to the wiring pattern.

6 shows an example of a foot pattern in a conventional printed board.

A foot pattern 100 made of copper foil is formed on an insulating substrate 10 such as a glass epoxy substrate, and a solder plating layer 110 is formed thereon. Copper foil is the wiring layer 120 in parts other than this foot pattern, and this wiring layer 120 is covered with insulating materials, such as soldering resist 80. As shown in FIG.

7 is a cross-sectional view for each process illustrating a manufacturing process of a printed circuit board having such a foot pattern.

First, as shown in Fig. 7 (a), a glass epoxy material (copper laminate) 10 whose surface is covered with copper foil 20 is prepared, and drilling is performed as shown in Fig. 7 (b). The electroless copper plating 40 is performed after the activation process is performed by opening the through hole 30.

Next, the resist 50 is applied and patterned so that the foot pattern and the wiring formation region are exposed, and then the electrolytic copper plating 60 and the electrolytic solder plating 70 are performed to form the wiring and the foot pattern.

Next, as shown in Fig. 7 (c), a resist is applied to the entire surface so that the resist 50 remains on portions other than the foot and wiring portions, and patterned, and then electrolytic copper plating (60) on the portion without a resist. ) And solder plating 70 are performed.

Next, while removing the resist, the solder plating layer is masked to etch the copper plating layer 60 to obtain the structure of FIG.

Finally, solder plating is peeled off and the solder resist 80 is applied. Thereafter, the solder resist of the foot pattern forming unit 90 is removed, and the solder layer 110 is formed by solder plating only on the surface of the foot pattern.

In general, in a high density mounted printed circuit board, wiring is often performed between the solder foot patterns. However, in a printed circuit board having a foot pattern created by the above-described conventional foot pattern creation method, the wiring may be exposed from the solder resist due to the misalignment of the mask registration between the solder resist and the foot pattern, the precision of the solder resist, and the like.

In this case, there is a problem that shortages such as solder bridges or migration due to use in high humidity conditions occur between adjacent wirings due to solder paste applied during mounting or solder by solder immersion.

In particular, since the lead pitch of components to be mounted is gradually narrowed to 1.27 mm, 0.6 mm, 0.5 mm, and 0.4 mm, the pitch between the foot patterns is also narrowed, so that the patterning of the solder resist between the foot patterns is also disturbed. For this reason, the above-mentioned solder bridge and the movement problem also arise between the foot patterns.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and since a wiring is reliably covered with a solder resist, a printed wiring board having a foot pattern suitable for mounting on a high density wiring or manufacturing a highly reliable fine pitch device, and a method of manufacturing the same The purpose is to provide.

According to the present invention, a printed wiring board having a wiring conductor and a component mounting conductor formed on a surface of a desired pattern with a first metal material, wherein the printed wiring board is formed so as to cover the periphery of the surface of the component mounting conductor and the wiring conductor. A soldering resist layer applied to a surface and a component fixing conductor layer formed of a second metal material except for the periphery on the component mounting conductor surface are provided.

In addition, the method for manufacturing a printed wiring board according to the present invention includes the steps of etching the first metal material layer formed on the insulating substrate, selectively forming the wiring conductor and the component mounting conductor, and applying the solder resist to the entire surface; And a step of forming a component fixing conductor layer of a second metal material on a portion from which the solder resist is removed only on the periphery of the component mounting conductor.

In this invention, copper is preferable as a 1st metal material, and solder is preferable as a 2nd metal material.

The printed wiring solder resist of the present invention covers all of the wiring conductor and the layer and covers the periphery of the foot pattern conductor. Therefore, the area actually covered with the solder layer in the foot pattern is smaller than the area of the foot pattern conductor layer. Moreover, since the area | region outside a foot pattern is covered with soldering resist all, including a wiring conductor, the short circuit or movement between a foot pattern conductor, a wiring conductor, and a foot pattern conductor can be suppressed.

Moreover, in the manufacturing method of the printed wiring board which concerns on this invention, a soldering resist is formed so that the periphery part of a component mounting conductor and a wiring conductor may be formed, and a solder layer is formed on the exposed component mounting conductor, and it is surely reliable printed wiring board. Can be obtained.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of a printed wiring board according to the present invention.

A copper layer is selectively formed on the glass epoxy substrate 10, and the foot pattern 100 and the wiring 120 are formed. On these, a solder resist layer 85 is formed, and the wiring 120 is completely covered with a solder resist. On the other hand, the solder resist exists only in the periphery part on the foot pattern 100, and the solder layer 115 is formed in the copper foil inside.

1 is a cross-sectional view for each step showing a method for manufacturing a printed wiring board according to the present invention. In the same drawing, the same code | symbol is attached | subjected to the 7th diagram and the same part which show a prior art.

First, as shown in Fig. 1 (a), a glass epoxy material (copper laminate) 10 having a surface coated with a copper foil 20 is prepared, and as shown in Fig. 7 (b), drilling is performed to form a through hole. After opening 30 and performing an activation process, electroless copper plating 40 is performed. Next, the resist 50 is applied to the entire surface and patterned so that the foot pattern and the wiring forming region are exposed, and then the electrolytic copper plating 60 and the electrolytic solder plating 70 are performed only on the region where the foot pattern and the wiring are to be formed. A layer of electrolytic copper plating 60 and electrolytic solder plating 70 is formed (Fig. 7 (c)).

After removing the resist, the copper foil 20 is etched using the solder plating layer 70 as an etching mask to obtain the structure of FIG.

Next, the solder plating is peeled off, and the solder resist 85 is applied to the whole surface. Thereafter, the solder resist is patterned to expose the copper plating layer 60 in the foot pattern forming portion 90. At this time, the solder resist 85 remains on the periphery of the copper plating layer 60 (FIG. 1 (e)).

Next, the solder is plated on the exposed portion of the copper plating layer to form the solder layer 115 (FIG. 1 (f)).

Thus, the solder layer 115 of a foot pattern part is formed inward rather than the edge part of a copper foil pattern, and since the soldering resist is apply | coated to the peripheral part of this copper foil pattern, it is isolate | separated from other foot patterns and wiring layers. Therefore, even when mounting parts, no bridges or movements are caused by solder.

3 to 5 are cross-sectional views illustrating the structure of a conventional printed wiring board and a printed wiring board according to the present invention. (A) shows a conventional case, and (b) shows a case according to the present invention, respectively. have. In these cases, the minimum line width of the conductor pattern and the space between the conductors are 0.2 mm, respectively, and the mask misalignment of the solder resist is 0.15 mm.

3 shows a case in which two wiring conductors pass through a neighbor of the foot pattern, and when the component mounting width of the foot pattern is 0.6 mm, the mask misalignment and the total width of the spaces between the conductors are 0.35 mm between the adjacent wiring layers. In addition to half of the width of the foot pattern, 0.65 mm is needed between the end faces of the wiring conductors adjacent at the center of the foot pattern.

On the other hand, in the case of the present invention, since the periphery of the foot pattern conductor is covered by the solder resist, the distance between the end face of the copper foil buried in the solder resist and the wiring conductor adjacent to it becomes a problem. When the copper foil width of the foot pattern portion is 0.6 mm, the distance required between the center portion and the end face of the wiring conductor adjacent to the center portion is 0.5 mm by adding 0.3 mm, which is half of the copper foil width of the foot pattern portion, and the distance 0.2 mm from the end face of the copper foil to the end face of the wiring conductor. It can be reduced by 0.15 mm than the conventional one. Thus, it turns out that the structure of the printed wiring board by this invention can improve a density more.

4 shows a case where one wiring conductor is passed between two foot patterns.

Similarly, in the conventional case shown in FIG. 4 (a), the distance required between the foot patterns becomes 0.7 mm even when the wiring conductor width is suppressed to 0.1 mm, whereas in the case of the present invention shown in FIG. Even if a 0.1 mm wide wiring conductor is used, 0.65 mm is sufficient.

Therefore, not only the mounting density can be improved but also the wiring resistance can be reduced to improve the characteristic impedance.

5 shows a case where a plurality of foot patterns are continuous, and shows that the sum of the widths of the foot patterns and the interval between the foot patterns is set to 0.6 mm.

In the conventional case of Fig. 5 (a), the space between conductors is 0.3 mm with respect to the conductor width of 0.3 mm, but considering the misalignment of the solder resists, the solder resist cannot be applied between the conductors. On the other hand, according to the present invention shown in Fig. 5, the solder resist can be interposed between the conductors, so that the reliability can be remarkably improved.

As described above, in the printed wiring board according to the present invention, since the periphery of the foot pattern conductor and the wiring conductor are covered with a resist, reliability can be improved without shorting or moving between adjacent foot patterns or between the foot pattern and the wiring conductor. Become.

According to the method of manufacturing a printed wiring board according to the present invention, after forming a foot pattern conductor or a wiring conductor, a resist is applied to the entire surface, and the resist on the foot pattern conductor is removed so that the resist remains on the periphery of the foot pattern conductor, Since the conductor layer for component fixing is formed, it becomes possible to reliably manufacture a highly reliable printed wiring board.

Claims (3)

A printed wiring board having a wiring conductor 120 and a component mounting conductor 100 formed on a surface of a first metal material in a desired pattern, wherein the printing is performed so as to cover the periphery of the surface of the component mounting conductor and the wiring conductor. A solder resist layer 85 applied to the surface of the wiring board; And a component fixing conductor layer (115) having a second metal material formed on the surface of the component mounting conductor except for the peripheral portion. The printed wiring board according to claim 1, wherein the first metal material is copper and the second metal material is solder. Etching the first metal material layers 20, 40, and 60 formed on the insulating substrate 10 to selectively form wiring conductors and component mounting conductors; Applying the solder resist 85 to the entire surface; Selectively removing the solder resist on the component mounting conductor such that the solder resist layer remains only at its periphery; And forming a component fixing conductor layer (115) using a second metal material at a portion where the solder resist on the component mounting conductor is removed.