JP2625968B2 - Printed wiring board - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board, and more particularly to a printed wiring board having an insulating resin layer without any gap with respect to a conductor pattern of a component mounting pad and a land of a through hole. .

[Prior art] Generally, a component mounting pad of a printed wiring board, and a conductor pattern of a land of a through hole, 0.1 mm to 0.5 mm
An insulating resin pattern (hereinafter referred to as a solder resist) is formed with a certain gap. This is in consideration of the positioning accuracy, and is to prevent the solder resist from being formed on the component mounting pad and the land of the through hole.

In addition, as shown in FIG. 5A, a method of manufacturing a printed wiring board of this type includes, on an insulating substrate 1 having a conductive layer 2 formed on a main surface and an inner wall surface of a through hole 1a, as shown in FIG. As described above, a laminator (not shown) is used to close the upper and lower openings of the through hole 1a with the film-shaped photosensitive resin 4.
Then, the film-shaped photosensitive resin 4 is exposed through a mask film 3 and developed, and then the film-shaped photosensitive resin 4 is etched as shown in FIG. 5 (c). A resist pattern 4a is formed, and the exposed portions of the conductive layer 2 are etched to form desired circuit patterns 2a and 2a ', and the etching resist pattern 4a is peeled off as shown in FIG. 5 (d). I do.

Thereafter, an insulating resin (solder resist ink) is applied to the entire surface of the substrate by screen printing, as shown in FIG. 4 (e) or FIG. Exposure and development are performed to form a desired insulation treatment pattern (solder resist) 5 at a distance of 0.1 to 0.5 mm from the mounting pad 2a 'and the through hole land 2a.

[Problems to be solved by the invention]

In the conventional printed wiring board described above, in order to form an insulating resin pattern by combining a screen plate and a mask film with a mounting pad and a land of a through hole, in consideration of misalignment and expansion and contraction of the screen plate and the mask film, 0 for mounting pads and land of through hole.
It is made to be formed at a distance of 1 mm to 0.5 mm,
Since the distance between the mounting pad and the adjacent mounting pad has become smaller, it is difficult to form the insulating resin pattern between the mounting pads without covering the mounting pads. Can not. For this reason, there is a disadvantage that a solder bridge is easily generated at the time of mounting. On the other hand, when the circuit is formed by the landing method and the insulating resin forming method is employed, the insulating resin layer is dented at the through hole and the via hole, and during the polishing step of the insulating resin layer, poor polishing of the through hole and the via hole occurs. This is disadvantageous in that it is difficult to form through holes and via holes of landless.

[Means for solving the problem]

According to the structure of the present invention, a through hole,
In a printed wiring board formed with a via hole and a circuit pattern, the through hole and the via hole are formed in a landless manner, and the insulating resin is formed in a thickness greater than that of a conductor layer of a component mounting pad of the circuit pattern. It is formed on the main surface, and the insulating resin is formed on the main surface except for the conductor pattern of the component mounting pad without any gap.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (h) are cross-sectional views showing a process of manufacturing a printed wiring board according to a first embodiment of the present invention in the order of steps. First, as shown in FIG. 1 (a), a printed wiring board according to this embodiment has an insulating substrate 1 on which a main surface and an inner wall layer 2 of a through hole 1a are formed.
Then, as shown in FIG. 1 (b), the photocurable resin 7 is filled by means such as screen printing or a roller coating method, and then irradiated with ultraviolet rays at about 1 J / cm ^{2 to 3} J / cm ² and cured. Next, as shown in FIG. 1 (c), the film-shaped photosensitive resin 4 is laminated on the insulating substrate 1 using a laminator or the like, and the film-shaped photosensitive resin 4 is exposed through a mask film and developed. Then, as shown in FIG. 1 (d), an etching resist pattern 4a of the film-like photosensitive resin 4 and circuit patterns 2a, 2a 'are formed by etching, and thereafter, as shown in FIG. 1 (e), An ultraviolet-curing or thermosetting insulating resin 6 is uniformly applied to the entire main surface of the substrate and cured. Thereafter, as shown in FIG. 1 (f), the insulating resin layer 6 is polished flat to expose the etching resist pattern 4a.
As shown in FIG. 1 (g), the etching resist 4a and the photocurable resin 7 are peeled off with dichloromethane. Next, as shown in FIG. 1 (h) and FIG. 4, an insulating resin (solder resist ink) is applied to portions where soldering is unnecessary by screen printing, and a desired insulating resin pattern (solder resist) 5 is formed.
To obtain a desired printed wiring board.

2 (a) and 2 (b) are sectional views showing a method of manufacturing a printed wiring board according to a second embodiment of the present invention in the order of steps.
First, as shown in FIG. 2 (a), the printed wiring board of this embodiment is formed on an insulating substrate 1 having a conductive layer 2 formed on a main surface and an inner wall surface of a through hole 1a, as shown in FIG. 2 (b). Curable resin 7
Was charged by a means such as screen printing or roller coating, followed irradiating ultraviolet radiation of about 1 J / cm ² to 3J / cm ^2, curing. Next, as shown in FIG. 2 (c), the liquid photosensitive resin 8 is uniformly coated with 10 to 10
50 μm is applied, dried, and the liquid photosensitive resin 8 is exposed to light through a mask film and subjected to a developing treatment.
As shown in FIG. 2, an etching resist pattern 8a of the liquid photosensitive resin 8 is formed, and an exposed portion of the conductive layer is etched to form desired circuit patterns 2a and 2a '. Thereafter, FIG. As described above, an ultraviolet-curing or thermosetting insulating resin 6 is uniformly applied to the entire surface of the substrate and cured. Thereafter, as shown in FIG. 2 (e), the insulating resin layer 6 is polished flat to expose the etching resist pattern 8a, and as shown in FIG. 2 (g), the etching resist 8a and the photocurable resin 7 are mixed with dichloromethane. Peel and remove. Next, as shown in FIG. 2 (h) and FIG. 4, an insulating resin (solder resist ink) is applied by screen printing to a portion where soldering is not required, and a desired insulating lubricating grease pattern (solder resist) 5 is formed.
To obtain a desired printed wiring board.

As described above, the printed wiring board of the present invention is such that the insulating resin is formed in a thickness greater than that of the component mounting pad and the conductor layer of the through hole land, and the insulating resin is formed on the component mounting pad and the through hole land. Because it can be formed without any gaps, even if the distance between the mounting pad and the adjacent mounting pad becomes smaller, the mounting pad does not need to be covered with insulating resin (overlapping), and even between narrow mounting pads. A printed wiring board on which an insulating resin pattern is formed and which has a landless through hole is obtained.

The production of the printed wiring boards of the first and second embodiments is a process of forming a through hole and a via hole on the main surface of an insulating substrate, and plating the insulating substrate with inner wall surfaces of the through hole and the via hole. Forming a conductive layer on the main surface of the insulating substrate, filling the through holes and via holes with a photosensitive or thermosetting resin, exposing the conductive layer on the conductive layer using an etching resist pattern as an etching mask; Forming a circuit pattern by selectively removing portions by etching, and embedding and curing the circuit pattern and the etching resist pattern formed on the insulating substrate with an insulating resin to form an insulating resin layer Polishing the insulating resin layer smoothly so that the etching resist pattern is exposed; and A step of dissolving and removing the photoresist pattern or the thermosetting resin filled in the through holes and the via holes to expose the circuit pattern, and a step of selectively applying a solder resist to the exposed circuit pattern. It is characterized by having.

〔The invention's effect〕

As described above, according to the present invention, the following effects can be obtained.

(I) Even if the space between the circuit patterns 2a and 2a 'becomes narrow, the insulating resin pattern can be formed between the circuit patterns without requiring the positioning accuracy of the insulating resin pattern with respect to the circuit pattern. Efficiency is improved.

(Ii) Even in places where it is difficult to form an insulating resin pattern without covering the circuit patterns 2a and 2a 'with the current construction method, the circuit pattern can be easily formed without covering the circuit pattern with the insulating resin. improves.

(Iii) Since an insulating resin pattern having a thickness equal to or greater than the circuit pattern thickness can be reliably formed between the circuit patterns, solder bridges between the circuit patterns during mounting can be prevented.

(Iv) Since the through-hole is formed by a resin filling method, a landless through-hole can be formed, and the mounting density can be improved.

[Brief description of the drawings]

1 (a) to 1 (h) are sectional views showing a method of manufacturing a printed wiring board according to a first embodiment of the present invention in the order of steps, and FIGS. 2 (a) to 2 (h) are FIG. 3 is a sectional view showing a method of manufacturing a printed wiring board according to a second embodiment of the present invention in the order of steps, FIG. 3 is a plan view of a printed wiring board manufactured by a conventional method of manufacturing a printed wiring board, and FIG. 5 (a) to 5 (e) are cross-sectional views showing a conventional method of manufacturing a printed wiring board in the order of steps. 1 ... insulating substrate, 1a ... through hole, 2 ... conductive layer, 2a
…… Circuit pattern (through hole land), 2a ′ …… Circuit pattern (mounting pad), 3 …… Mask film, 4
... film-shaped photosensitive resin, 5 ... insulating resin pattern (solder resist), 6 ... insulating resin (photocurable),
6 ': an insulating resin (thermosetting); 7: a photocurable resin;
8: Liquid photosensitive resin.

Claims (1)

(57) [Claims] In a printed wiring board having a through hole, a via hole and a circuit pattern formed on a main surface of an insulating substrate, the through hole and the via hole are formed in a landless manner, and a conductor layer of a component mounting pad of the circuit pattern is provided. In contrast, an insulating resin is formed on the main surface with a thickness greater than that, and the insulating resin is formed on the main surface except for a conductor pattern of the component mounting pad without a gap. Printed wiring board.