JP2838538B2 - Printed wiring board - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a printed wiring board having a photo solder resist film formed by applying, irradiating, developing, and curing a liquid ink.

(Prior art)

In the case of a printed wiring board, it is necessary to form a solder resist film on the surface of the circuit conductor in order to protect the circuit conductor formed thereon from peeling or oxidation.

In recent years, printed wiring boards have been required to achieve higher densities of circuit conductors and the like in response to demands for smaller and lighter weight and higher performance. For this reason, in order to be able to form the above-mentioned solder resist film with high accuracy, a photo solder resist film is formed.

As the photo solder resist film, a dry film type and a liquid type are commercially available. In the case of the above-mentioned dry film type, as the circuit conductor width and its interval become narrower, there is a problem in the ability of the resist to follow the surface irregularities and the cost is high. For this reason, recently, the liquid type has become the mainstream.

On the other hand, many printed wiring boards have bonding pads and connector terminals for external connection due to the spread of the surface mounting method. In order to enhance connection reliability, nickel-gold plating, tin plating, solder plating, etc. are applied to desired circuit conductors (for example, bonding pads, connector terminals) after forming a photo solder resist film. Required.

Thus, the formation of the photo solder resist film in the conventional method is performed by the method shown in FIGS. 15 to 17B.

First, as shown in the lower part of FIG. 16B, on the base material 3, a printed wiring board having a connector terminal 2 as a circuit conductor at its left end and a pad 25 as a circuit conductor near the center is prepared. I do. Then, the entire surface of the substrate 3 is coated with the liquid photo solder resist ink 90.

Next, as shown in FIGS. 16A and 16B, an exposure mask 8 is disposed above the exposed mask 8 and irradiated with ultraviolet rays 58 to polymerize the ink 90. The exposure mask 8 has an ultraviolet opaque portion 81 covering a portion above the connector terminal 2 and an ultraviolet opaque portion 81 covering above the pad 25.
Having.

After that, development and heat curing are performed to obtain the 17th A
As shown in FIG. 17 and FIG. 17B, a printed wiring board provided with a photo solder resist coating 91 is obtained. That is, one portion on the connector terminal 2 is covered with the tip 911 of the photo solder resist coating 91. The coating 91 is formed around the pad 25 with a gap 912 therebetween.

Thus, the tip 911 is, as shown in FIG.
The upper part of the connector terminal 2 is covered. Also,
The connector terminal 2 has an end 21 for forming a plating film in front of the tip 911, and a plating film 28 is formed on the end 21.

The tip 911 is formed so as to be eroded downward and inward. Therefore, the plated part, which is the contact point between the tip 911 and the connector terminal 2 as the recovery conductor
95 is undercut.

[Problem to be solved]

However, in the case of the photo solder resist film formed using the liquid type, the plating film formed on the end portion 21 of the circuit conductor and the tip portion of the photo solder resist film are formed.
The plating resistance of the plating-attached portion 95 in contact with 911 is poor.

That is, the photo solder resist film is formed on the substrate and the circuit conductor on the surface thereof, and since the photo solder resist film and the substrate are both resins, the adhesion is strong. However, since the circuit conductor and the photo solder resist film are different materials (metal and resin), the adhesion is not so strong. For this reason, conventionally, there is a problem that the plating solution penetrates between the coating and the circuit conductor at the plating-attached portion 95 between the coating and the circuit conductor when the plating film is formed, thereby further weakening the adhesion between the two. That is, the plating resistance is low.

 The reasons are as follows.

That is, the photo solder resist film is formed by applying the entire surface of the ink, drying by touching, exposing through a mask, developing, and thermosetting. Thus, in the case of a photo solder resist film, the longitudinal cross-sectional shape of the tip portion of the film after the development process is as shown in FIG. In other words, the inside of the coating (the one closer to the conductor circuit) is cut into an undercut shape. Further, in the plated portion 95 in FIG. 15, the adhesion between the circuit conductor and the photo solder resist film is weak.

This is because the liquid photo-solder resist ink is photo-curable, so that photo-curing of the ink starts at the surface layer where ultraviolet light is first applied, and proceeds sequentially inside. However, once the photocured portion is hard to pass ultraviolet rays, the amount of ultraviolet irradiation of the ink inside is reduced, and sufficient photocuring is not performed. In addition, the plated portion 95 is eroded by the developer.

As described above, there is a problem of an undercut shape and weak adhesion at the leading end of the film after the development process.

The developing solution is heated by a thermosetting process at a temperature higher than the Tg point (100 ° C. to 120 ° C.) of the skeleton resin (generally, epoxy resin) constituting the liquid photo solder resist ink. At this time, first, there is a large difference between the coefficient of thermal expansion of the resin forming the ink and that of the metal forming the circuit conductor. Second, the curing strain (internal stress) of the coating is
In FIG. 15, the undercut shape is applied to the plated portion 95 and the plated portion 95 has a larger amount of ink per unit area than the other portions. For this reason, large hooves are applied to the plating-attached portion 95. For the above two reasons, in the thermosetting step, minute peeling on the order of several μm occurs between the photo solder resist film and the circuit conductor.

Therefore, when the liquid photo-solder resist film after curing is subjected to electrolytic plating and electroless plating, the plating solution penetrates from the minute peeling portion that has already occurred at the plating-attached part, and the film and the circuit Adhesion between conductors is reduced in a fatally wide range.

On the other hand, various attempts have been made to add an adhesion improver to the ink in order to improve the plating resistance after the formation of the film.

However, these adhesion improvers themselves have high reactivity with the circuit conductor and cannot be completely removed during development. Further, the ink has poor compatibility with the ink, and it is necessary to use a solvent having a strong dissolving power to be dissolved in the ink, which causes problems such as deterioration of the screen printing plate and the squeegee rubber.

As described in detail above, the use of a liquid type photo solder resist film has the above-mentioned advantages, but has the above-mentioned problems in plating resistance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a printed wiring board which is excellent in plating resistance at a portion where plating is applied.

[Means for Solving the Problems] A printed wiring board according to the present invention is a photo solder resist obtained by applying, irradiating, developing, and curing a liquid ink, which is a liquid solder resist used for a photographic method, on a circuit conductor on a substrate surface. In the printed wiring board on which the coating is formed, the photo solder resist coating is formed by applying the liquid ink on the circuit conductor excluding an end for forming a plating film, and irradiating at least the coating applied in contact with the end with light. A printed wiring board, characterized in that the coating has a slanting state in which the film thickness gradually decreases toward the end portion on the circuit conductor.

The most remarkable thing in the printed wiring board of the present invention is that a liquid ink, which is a liquid solder resist used for a photographic method, is printed on a circuit conductor excluding an end for forming a plating film, and is printed at least in contact with the end. By irradiating the coating with light, the tip of the coating has a photo solder resist coating in an inclined state in which the thickness gradually decreases toward the plating film forming end of the circuit conductor. In other words, the thickness of the photo solder resist coating is reduced while the tip of the photo solder resist film is inclined toward the surface of the circuit conductor at the portion where the tip contacts the circuit conductor. Such a shape of the tip portion is formed when the liquid ink for the photo solder resist film is applied.

The angle of inclination of this tip is 30 to
Preferably it is 80 degrees. If it is less than 30 degrees, the performance (heat resistance) as a resist film is insufficient. On the other hand, if the angle exceeds 80 degrees, the irradiation light does not sufficiently reach below the tip of the coating (a portion close to the circuit conductor), so that the plating resistance of the plating-attached portion may be reduced. That is,
Light is difficult to reach below the printed liquid ink.

Next, as a method of manufacturing a printed wiring board, a photo solder resist film is formed on a circuit conductor on a substrate surface,
A method for manufacturing a printed wiring board, further comprising: providing a plating film on an end portion of the circuit conductor, wherein a screen printing method is provided in which an ink impermeable portion is provided inwardly from a tip portion of a photo solder resist film to be formed on the circuit conductor. Using a printing plate, print the liquid ink for the photo solder resist coating on the circuit conductor, flow the leading end toward the plating-attached part by the fluidity of the liquid ink, and set the leading end to the film thickness. Is gradually reduced, and then light is irradiated using an exposure mask that has an exposed part formed outside the tip of the printed part, followed by development and curing, and then the circuit conductor There is a method for manufacturing a printed wiring board, characterized in that a plating film is formed on an end of the printed wiring board.

This manufacturing method relates to a series of methods of forming a photo solder resist film as described above, performing light irradiation, development, and curing, and then forming the plating film.

What should be noted in the present invention is the positional relationship between the tip of the photo solder resist film in the inclined state, the screen printing plate, and the exposure mask, and the method of forming the tip of the inclined body.

In other words, the screen printing plate is provided with an ink impermeable portion to the inside of the tip of the photo solder resist film to be formed. In other words, the penetrating portion of the ink in the screen printing plate is not provided up to the tip of the photo solder resist film to be formed, but is formed only to the inside. The ink impermeable portion is formed by applying an emulsion or the like.

In the formation of the photo solder resist film in the inclined state, as shown in the embodiment, the tip of the photo solder resist film is caused to flow toward the plated portion by the fluidity of the liquid ink.

Further, with respect to the exposure mask, an exposed portion is formed outside the tip of the ink printed on the circuit conductor. In other words, the exposure mask is configured such that the tip of the coating can sufficiently receive light such as ultraviolet rays. The distance between the tip and the exposed end is 0.1
It is preferable to set it to 0.2 mm.

After the above-mentioned light irradiation, a development process for removing unnecessary portions of the film which has not been irradiated with light and a curing process (heating) for the photo solder register film are performed by a conventional method, and then a plating film is formed on the end of the circuit conductor. I do.

As a liquid ink for coating the photo solder resist, there is a liquid ink based on a thermosetting resin having a photosensitive group such as an acrylic-modified epoxy resin. In addition, it is preferable to use a material having a viscosity of 100 ps to 1000 ps. When the thickness is less than 100 ps, the thickness of the printed portion becomes thinner. When the thickness is more than 1000 ps, a problem occurs in embedding the liquid photo solder resist film between adjacent circuit conductors. Note that the speed is more preferably 300 ps to 500 ps.

Further, it is desirable that the ink be a non-Newtonian fluid. In the case of a Newtonian fluid, since the leveling property is large, the amount of ink flowing into the plating-attached portion is affected by the undulation of the circuit conductor (variation in the height of the circuit conductor). For this reason, it is difficult to control the amount of inflow, and it is difficult to set a clearance between the emulsion-coated portion of the screen printing plate and the light-impermeable portion of the exposure mask in the plating-attached portion.

As a material of the screen printing plate for ink application, a synthetic resin, a metal, or the like can be used.

As an exposure mask, a silver halide film, a diazo film, or the like can be used.

Plating films applied to the present invention include electrolytic nickel-gold plating, electroless nickel-gold plating, electrolytic copper plating, electroless copper plating, electrolytic tin plating, electroless tin plating,
There are electrolytic solder plating and the like.

In the photo solder resist coating and the method of manufacturing the same according to the present invention, the configuration relating to the shape of the tip of the photo solder resist coating in the plating-attached portion and the relationship between the tip and the screen printing plate and the exposure mask are described. As shown in the examples, the shape of the front end portion other than the plating-attached portion and the relationship between the front end portion, the screen printing plate, and the exposure mask are arbitrary. In other words, the portions other than the plating-attached portions may be the same as those of the present invention or may be the same as the conventional ones.

[Action]

In the printed wiring board of the present invention, the tip of the photo solder resist film formed by applying, irradiating, developing, and curing the liquid ink is inclined toward the plating-attached portion. Therefore, when the light such as ultraviolet rays is irradiated, the tip is sufficiently irradiated with light. Therefore, the tip is also sufficiently photo-cured, and the tip and the lower surface thereof are not etched by the developing solution during development. Therefore, when forming the plating film, the plating solution does not enter between the coating and the circuit conductor from the portion where the plating is applied.

Further, in the manufacturing method of the present invention, the screen printing plate has an ink-impermeable portion provided from the front end of the photo solder resist film to be formed to the inside. Therefore, the leading end of the liquid ink printed by the screen printing plate is not provided to the leading end of the coating immediately after printing.

However, since the liquid ink has fluidity, it flows toward the tip and reaches the desired tip of the coating. The size of the ink impermeable portion is determined in consideration of the fluidity of the liquid ink used.

As a result, due to the above-mentioned flow, the leading end of the coating ink has an inclined shape in which the film thickness decreases toward the plating-attached portion.

Next, the printed liquid ink is irradiated with light using the exposure mask. In the exposure mask, the exposed portion is provided outside the tip of the ink-printed portion, and the tip of the ink-printed portion has the above-mentioned inclined shape. Light irradiation is performed.

After the light irradiation, development, curing, and plating film formation are performed by a usual method.

〔effect〕

According to the present invention, since the thickness of the tip portion of the photo solder resist film decreases toward the portion to which plating is applied, light irradiation during exposure reaches sufficiently below the tip portion. Therefore, the tip is sufficiently photo-cured, and the adhesion between the film and the circuit conductor is strong.

In addition, since the thickness of the coating on the plating portion at the tip portion is small, the amount of ink per unit area in this portion is smaller than in other portions. For this reason, peeling between the coating and the circuit conductor does not occur at the time of thermosetting or the like.

Therefore, when the plating film is formed on the end of the circuit conductor after curing, the plating solution does not enter between the photo solder resist film and the circuit conductor.

Further, even when ink adheres to an unnecessary portion of the coating due to bleeding or scattering of the ink at the time of ink application, such ink can be easily removed at the time of development because it is covered with the exposure mask and is not exposed.

Therefore, according to the present invention, it is possible to provide a printed wiring board having excellent plating resistance at a portion where plating is applied.

〔Example〕

First Embodiment A printed wiring board and a method of manufacturing the same according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6B.

The printed wiring board of this example is a printed wiring board for a memory module (FIGS. 3A and 3B). Before the formation of the photo solder resist film, the printed wiring board is formed of a base material 3 and a circuit conductor provided at the end (left side) on the surface, as shown in FIGS. 3A and 3B. And a pad 25 as a circuit conductor provided near the center of the surface of the substrate 3. The connector terminal 2 is a terminal to which a Ni-Au plating 28 is applied after the photo solder resist film 1 is cured as shown in FIG. on the other hand,
The pad 25 is a surface mounting pad of a package for mounting a semiconductor, and this portion is a portion on which Ni-Au plating is not performed.

Next, a process of forming a photo solder resist film on the printed wiring board and thereafter forming a plating film will be described. Hereinafter, the photo solder resist coating is simply referred to as “coating”. Further, the liquid photo solder resist ink for forming the coating is referred to as “liquid ink”, and a portion on which the liquid ink is printed is referred to as a printed portion. Therefore, the printed portion exposed, developed and cured forms a coating, and the contact portion between the coating and the circuit conductor is a plating-attached portion.

Thus, a screen printing plate 4 for printing liquid ink on the printed wiring board shown in FIGS. 3A and 3B.
4A and 4B, as shown in FIGS. 4A and 4B.
And an ink passage section 42 for printing by transmitting ink. Then, as shown in FIG. 4B, the ink impermeable portion 41 is located above the connector terminal 2 provided on the base material 3.
It is configured to be located on a portion. That is, an ink impermeable portion 41 is provided to the inside of the tip portion 12 (FIG. 2) of the coating to be formed on the connector terminal 2, and an ink passage portion 42 is provided inside the portion.

Since the other portions of the screen printing plate 4 form a coating including the portion of the pad 25, the ink impermeable portion 41 is not provided.

Next, a screen printing plate 4 is placed on the printed wiring board as shown in FIG. 4B, and then screen printing is performed using liquid ink. As a result, FIG.
As shown in FIG. 5B, a printed wiring board whose upper surface is covered with the printed portion 10 of the liquid ink except for the end 21 of the connector terminal 2 is obtained. The end 21 is an end for plating film formation.

Next, above the printed wiring board, see FIGS. 5A and 5B
As shown in FIG. 1 and FIG. 1, an exposure mask 5 is arranged.
The exposure mask 5 has an ultraviolet opaque portion at the left end and the center.
51,54. The ultraviolet opaque portion 51 is provided so as to be located outside the tip portion 12 of the printing portion 10 of the liquid ink. The ultraviolet opaque portions 54 are located above and around the six pads 25 provided at the center of the printed wiring board. Others form an exposure part 523.

FIG. 1 shows the positional relationship between the screen printing plate 4, the exposure mask 5, and the leading end 12 of the printed portion 10 on the printed wiring board. As shown in FIG. 1, the inside of the ink impermeable portion 41 and the leading end 12 of the print portion 10 have a length l1.
Of the inside of the ultraviolet opaque part 51 and the tip of the printed part 10
There is a distance of length l2 from 12. Here, l1 is about 0.3 mm and l2 is about 0.45 mm.

Then, the exposure mask 5 is positioned as shown in FIGS.
Is photopolymerized. Then, a developing process is performed (not shown). As a result, the liquid ink in the portion not irradiated with light is removed. Thereafter, the printed portion 10 is thermally cured by heating to form a coating, and a plating mask is formed on the coating by a conventional method.

6A and 6B show the printed wiring board obtained in this manner. That is, the printed wiring board is provided with a plating mask 60 on the entire upper surface thereof, except for an end portion 21 for forming a plating film of the connector terminal 2 and a tip portion of the coating film 1 adjacent thereto. The coating 1 is formed between the pads 25, 25, 25 at intervals.

In the printed wiring board configured as described above, a Ni-Au plating film 28 was applied to the end 21 of the connector terminal 2 by electrolytic plating (see FIG. 2).

In the above, as shown in FIGS. 1 and 2, the coating 1 provided on the connector terminal 2 as a circuit conductor has its tip 12 reduced in thickness toward the plated portion 15. Therefore, the ultraviolet rays sufficiently reach the lower surface of the distal end portion 12. Therefore, the leading end portion 12 of the printing portion 10 of the liquid ink is not eroded during development, and
The coating 1 and the connector terminal 2 adhere firmly. Further, since the end portion 12 has a slope 11 to reduce the thickness of the film, the thickness of the end portion 12 is small, and the connector terminal 2 is hardened during thermosetting.
No more peeling.

Therefore, it is possible to obtain a printed wiring board having excellent plating resistance of the plated portion 15.

In the above, a solvent developing type PSR-1000 (manufactured by Taiyo Ink Co., Ltd.) was used as the liquid ink.
The touch drying after forming the printed portion 10 was performed at about 80 ° C. The exposure amount was 800 mj / cm ² . Development was performed by spray development, and curing was performed at 150 ° C for 60 minutes. The film thickness of the Ni—Au plating was about 5 μm for Ni and about 0.5 μm for Au.

Next, after the plating film is formed, a cellophane adhesive tape specified in JIS-Z1522 is completely adhered in the direction of the plated part to check the bonding strength of the plated part. It was kept perpendicular to the surface of the printed wiring board and pulled instantaneously. Then, the adhesive surface of the adhesive tape was observed with a microscope (40 ×). As a result, no adhesion of the coating was observed, and it was confirmed that the adhesion between the coating 1 and the connector terminal 2 was extremely good.

Second Embodiment In this embodiment, as shown in FIGS. 7A to 10B, the present invention is applied to a surface mount type printed wiring board of a semiconductor mounting package.

First, as shown in FIGS. 10A and 10B, the printed wiring board in the state where the coating in this example is formed has a pad 26 as a circuit conductor for semiconductor surface mounting on the base material 3 as shown in FIGS. 10A and 10B. The coating 1 is provided on the outside and inside of the pad 26. The outer distal end 261 of the pad 26 is covered by the distal end 12 of the coating 1, and the contact between the two forms the plated part 15. The inside of the pad 26 has the coating 1 at a distance 262 from the pad 26.

Next, as shown in FIGS. 7A and 7B, the basic printed wiring board for forming the printed wiring board has three pads 26 in four directions on the base material 3 as shown in FIGS. 7A and 7B.

The screen printing plate 4 for printing liquid ink on the basic printed wiring board has an ink impermeable portion 43 and an ink passage portion 42 as shown in FIGS. 8A and 8B. The ink impermeable portion 43 is configured to be located above the outer end 261 of the pad 26. Then, the inner side surfaces 432, 432 and the outer side surfaces 431, 431 of the ink impermeable portion 43 are located inside the coating 1 to be formed (FIGS. 10A and 10B). Thus, the printing portion 10 to be printed by the screen printing plate 4 is formed leaving a part of the outer end portion 261 of the pad 26 as shown in FIG. 9B. That is, there is an interval between the leading ends 12, 12 of the print portion 10.

Thus, as shown in FIGS. 9A and 9B, the exposure mask 5 has an ultraviolet opaque portion 55 and an exposure portion 52. The ultraviolet opaque section 55 is configured to be located above the pad 26. Further, the inner side surface 552 of the ultraviolet ray opaque portion 55 is located inside the pad 26, and the outer side surface 551 is located above the outer end portion 261 of the pad 26, and the intermediate portion between the leading end portions 12 and 12 of the printed portion 10. It is located in.

Therefore, the printed wiring board obtained by performing ultraviolet irradiation using the exposure mask 5 and developing and thermosetting has a shape as shown in FIGS. 10A and 10B (see above). Other components and operations are the same as those of the first embodiment.

Thus, the printed wiring board obtained according to the present embodiment has the same effects as the first embodiment.

Third Embodiment In this embodiment, as shown in FIGS. 11A to 14B, the present invention is applied to a printed wiring board by the partly additive method.

That is, the printed wiring board is formed into a conductor by forming an outer layer circuit conductor by a subtractive method, printing liquid ink, and then performing electroless copper plating only on the through-hole portion.

First, as shown in FIGS. 14A and 14B, a printed wiring board having a coating film obtained in this example is provided with a through hole 35 in the substrate 3 and an annular circuit conductor 27 above the through hole. A similar circuit conductor 29 is provided below. Then, the coating 1 is coated on the end 271 side of the circuit conductor 29 except for the end 270 for plating.
The coating 1 is coated on the base material 3 with a gap 272 around the annular body. The contact portion between the plating-forming end portion 270 and the tip portion 12 of the coating film 1 has a plating-attached portion 15.

Next, as shown in FIGS. 11A and 11B, the basic printed wiring board for forming the printed wiring board
The circuit conductor 27 is provided above the through hole 35, and the circuit conductor 29 is provided below the through hole 35. Circuit conductor 2
9 has a tip 291.

Next, the screen printing plate 4 for liquid ink printing is
As shown in FIGS. 12A and 12B, an ink impermeable portion 44 is provided at a part above the circuit conductor 27. The left side 441 of the ink impermeable portion 44 is located on the tip 271 of the circuit conductor 27, and the right end 442 is located above the circuit conductor 27 main body. The printing portion 10 of the liquid ink formed by the screen printing plate 4 has a tip portion as shown in FIG.
Reference numeral 12 covers the front end portion 271 of the circuit conductor 27, and the main body of the circuit conductor 27 is covered with the printed portion 10.

As shown in FIGS. 13A and 13B, the exposure mask 5 has a circular ultraviolet opaque portion 56 and a circuit conductor 27.
Has an outer periphery slightly larger than the annular main body. The left side of the ultraviolet ray opaque portion 56 is the tip of the printed portion 10.
It is located outside (in the direction of through-hole 35) than 12.

Therefore, by irradiating ultraviolet rays with the above-mentioned exposure mask 5 and performing development and thermosetting treatment, the 14th A
A printed wiring board having the shape shown in FIG. 14 and FIG. 14B can be obtained. Others are the same as the first embodiment.

In this embodiment, the same effects as in the first embodiment can be obtained.

[Brief description of the drawings]

1 to 6B show a first embodiment, FIG. 1 is an explanatory view showing a positional relationship between a printing portion, a screen printing plate, and an exposure mask, and FIG. 2 is a photo solder resist coating, a plating film, and the like. 3A is a plan view of the printed wiring board before the film is formed, FIG. 3B is a cross-sectional view taken along line AA of FIG. 3A, and FIG. 4A is a plan view of a screen printing plate. 4B is a sectional view taken along line BB of FIG. 4A, FIG. 5A is a plan view of an exposure mask, FIG. 5B is a sectional view taken along line CC of FIG. 5A, and FIG.
The figure is a plan view of a printed wiring board with a plating mask,
FIG. 6B is a sectional view taken along line DD of FIG. 6A, and FIGS. 7A to 10B.
FIG. 7A is a plan view of the printed wiring board before the film is formed, FIG. 7B is a cross-sectional view taken along line EE of FIG. 7A,
8A is a plan view of a screen printing plate, FIG. 8B is a cross-sectional view taken along line FF of FIG. 8A, FIG. 9A is a plan view of an exposure mask,
9B is a sectional view taken along the line GG of FIG. 9A, FIG. 10A is a plan view of the printed wiring board after the coating is formed, FIG. 10B is a sectional view taken along the line HH of FIG. 11A to 14B show a third embodiment, FIG. 11A is a plan view of a printed wiring board before a film is formed, FIG. 11B is a cross-sectional view taken along the line II of FIG. 11, and FIG. 12B is a plan view of the screen printing plate, and FIG.
13A is a plan view of an exposure mask, and FIG.
FIG. 13A is a cross-sectional view taken along the line KK of FIG. 13A, FIG. 14A is a plan view of the printed wiring board after the film is formed, and FIG.
FIG. 15 to FIG. 17B are cross-sectional views taken along the line L, and FIG.
The figure is a cross-sectional view showing the state of the photo solder resist film.
16A is a plan view of an exposure mask, FIG. 16B is a cross-sectional view taken along line MM of FIG. 16A, FIG. 17A is a plan view of a printed wiring board after a film is formed, and FIG. 17B is FIG. 17A. 3 is a sectional view taken along line NN of FIG. 1 ... Photo solder resist coating, 10 ... Printed part, 12 ... Tip, 15 ... Plating part, 2 ... Connector terminal, 21 ... Plating film forming end, 25,26 ... Pad , 27 ... circuit conductor, 28 ... plating film, 3 ... base material, 4 ... screen printing plate, 41, 43, 44 ... ink-impermeable part, 42 ... ink-permeable part, 5 ... exposure Mask, 51,54,55,56 …… UV opaque part, 60 …… Plating mask,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 3/00

Claims (1)

(57) [Claims] A printed wiring board having a photo solder resist film formed by applying, irradiating, developing, and curing a liquid ink which is a liquid solder resist used for a photographic method on a circuit conductor on a substrate surface, The photo solder resist film is a film formed by applying the liquid ink on the circuit conductor except for an end portion for forming a plating film, and irradiating at least a coating film in contact with the end portion, wherein the circuit A printed wiring board having an inclined state on a conductor, the thickness of which gradually decreases toward the end.