JPH0458196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. OBJECTS OF THE INVENTION a. Field of Industrial Application The present invention relates to a method for electrodepositing a photosensitive resist film during the manufacture of printed wiring boards, and an apparatus for carrying out the method.

b. Prior Art When manufacturing printed wiring boards, the method of applying a photosensitive resist film to a copper-clad laminate board in order to form a circuit pattern using the copper or solder through-hole method has conventionally been to use, for example, screen printing after filling the through-holes. There are the screen printing method, which applies liquid resist, and the tenting method, which laminates dry film.

However, the above-mentioned screen printing method requires time and effort to fill all the through holes, so productivity is not good. In addition, the tenting method is uneconomical as it may cause considerable loss in the dry film depending on the combination of dimensions of the copper-clad laminate board and the dry film, and if there are scratches on the copper foil surface, they will not be covered. There were problems such as wire breaks and short circuits occurring during etching.

Therefore, recently, a method of forming a photosensitive resist film by electrodeposition coating has been developed, as shown in, for example, Japanese Patent Application Laid-Open No. 61-206293. The electrodeposition coating method has traditionally been developed as an undercoating method for automobiles, but the aim is to make it applicable to the formation of photosensitive resist films for printed wiring boards. The purpose is to uniformly apply a photosensitive resist film to the surface and cover even scratches on the surface, eliminate loss of resist film material, and aim for complete automation to improve productivity.

c Problems to be Solved by the Invention However, the electrodeposition coating methods used in the conventional undercoating of automobiles, etc., involve dipping the object to be coated in an electrodeposition bath containing electrodeposition paint by moving it up and down, or The object to be coated is moved diagonally by a conveyor and immersed in an electrodeposition tank. If this electrodeposition coating method was used as is for printed wiring boards,
The liquid does not fully enter the small diameter through hole and bubbles remain.
It is impossible to reliably electrodeposit a photosensitive resist film.

Particularly in recent years, as electronic devices have become smaller, lighter, and more sophisticated, printed wiring boards as well as semiconductor elements are required to have higher density, finer circuits, and higher reliability. There is a problem in that bubbles remain in the small diameter and large number of through holes of such a substrate using the conventional electrodeposition coating method described above, making it impossible to reliably electrodeposit a photosensitive resist film.

The present invention relates to a method and apparatus used for electrodepositing a photosensitive resist film on a printed wiring board, and is intended to solve the above-mentioned conventional problems. That is, the purpose of the present invention is to make it possible to reliably electrodeposit a photosensitive resist film without creating bubbles by imparting hydrophilicity to the small diameter and large number of through-holes of the substrate, and to make use of the advantages of the electrodeposition coating equipment. , high density
The goal is to make it possible to manufacture printed wiring boards with fine circuitry and high reliability.

B. Structure of the Invention (a) Means for Solving Problems The method for electrodepositing a resist film for a printed wiring board according to the present invention is such that a copper-clad laminate board 1 with through holes 2 is coated with an electrodeposition paint in a main electrodeposition tank B. photosensitive resist solution 3
Before the electrodeposition process is performed in the substrate 1, the substrate 1 is passed through a pretreatment tank A in which the same resist solution 3 flows under pressure, so as to block the flow, and the solution 3 is poured into the through holes 2 of the substrate 1. By passing through the through hole 2, the air inside the through hole 2 is expelled and hydrophilicity is imparted.

Further, the resist film electrodeposition apparatus for printed wiring boards according to the present invention is provided with a pretreatment tank A in front of the main electrodeposition tank B, and a photosensitive resist liquid 3 converted into an electrodeposition paint is continuously supplied to both of them. The pretreatment tank A
is a copper-clad laminated substrate 1 with a through hole 2 that allows the resist solution 3 to flow under pressure, and an opening 4 that can block the flow of the solution 3.
It is made up of the following.

In the above configuration, the shape of the main electrodeposition tank B is
As shown in Figures, Figures 2, 3, and 5, main tank B
In the case where the liquid 3 filled with water is supplied to the pretreatment tank A, a pressure tank type with a lid plate is used. Further, as shown in FIGS. 6, 7, and 8, when the liquid 3 is directly supplied to the pretreatment tank A from the reserve tank 5 described later, a non-pressure tank without a lid plate may be used. The photosensitive resist liquid 3 can be supplied to the main tank B, for example, by providing it separately or by continuously supplying it from a reserve tank 5 using a pump 6. The front and rear side walls 7 and 8 of the main tank B are provided with slits 9 and 10 for substrate passage.
As shown in FIGS. 1 to 7, 10 is formed horizontally when the substrate 1 is transferred horizontally, and the 8th
When the transition is vertical as shown in the figure, it is formed vertically.

The photosensitive resist solution 3 to be supplied to the main electrodeposition tank B and the pretreatment tank A may be an anionic type, for example, a carboxylic acid resin neutralized with an organic amine to be water-solubilized or water-oxidized.

Reference numeral 11 denotes a cathode plate provided in the main tank B, which is provided on both sides on the same plane as the slits 9 and 10. Further, as shown in FIGS. 1, 2, 3, and 5, when the liquid 3 overflowing from the main tank B is to be supplied to the pretreatment tank A, a liquid outlet 12 is provided.

As shown in FIGS. 1 to 7, the pretreatment tank A has an opening 4 that is shielded by the substrate 1 passing therethrough, and a slit 9 in the main tank B. The substrate passage 13 provided on the same plane as 10 is also horizontal, and if the substrate 1 is vertical as shown in FIG. 8, these passages 4 and 13 are also provided vertically. The pretreatment tank A has a liquid inlet 1 for the resist liquid 3.
4, and as shown in FIGS. 1, 2, 3, 4, and 6, if the substrate 1 passes through the upper surface of the opening 4, the substrate passage 13 Installed in the lower position. However, Figures 5, 7, and 8
If the substrate 1 passes through the lower surface or side surface of the opening 4 as shown in the figure, it is provided above or on the side of the substrate passage 13.

Further, the size of the opening 4 of the pretreatment tank A is set to be approximately the same size as the substrate 1 so that it can be shielded by the substrate 1 passing therethrough. For example, because the board 1 is narrow,
It is preferable to allow adjustment auxiliary plates to be installed on both sides of the opening 4. The resist solution 3 may be supplied to the pretreatment tank A by supplying the solution 3 overflowing from the main electrodeposition tank B, as shown in FIGS. 1, 2, 3, and 5. As shown in FIGS. 6 to 8, the main tank B may be supplied from the reserve tank 5 with a pump 16, or both of the above may be used together. Reference numeral 15 denotes a guide portion, which is formed with, for example, a groove that can lock both side edges of the substrate 1 so that the shielding state will not be released even if the substrate 1 is pressurized by the liquid 3 at the opening 4.

In the pre-treatment tank A, the substrate 1 passes through the opening 4 and then passes through the slit 9 in the front wall 7 to the main tank B.
However, it is also possible to immerse the material in a tact manner so as to cover the opening 4, then lift it out of the pretreatment tank A, and then put it into the main tank B. Further, although not shown, an ultrasonic generator may be attached to the pretreatment tank A.

b. Effects The resist film electrodeposition method and apparatus having the above structure are used as follows.

A copper-clad laminate substrate 1 with through-holes 2 is passed through a pretreatment tank A before being sent to a main electrodeposition tank B. There, main tank B
The same photosensitive resist liquid 3 made into electrodeposition paint is
The liquid 3 flows through the opening 4 under pressure, and the substrate 1 blocks the flow of the liquid 3 at the opening 4. Therefore, the liquid 3 flows into each through hole 2 of the substrate 1 under a higher pressure, and flows out from there. Therefore, air is completely expelled from each through hole 2 of the substrate 1, and the inner wall of each through hole 2 is rendered hydrophilic.

When the substrate 1 is sent to the main electrodeposition tank B in this state,
No air bubbles are formed in each through-hole 2, and even if air bubbles are formed, the inner wall of the through-hole 2 has hydrophilic properties, so the liquid 3 can easily penetrate into the small through-holes 2 and expel the air bubbles, preventing them from leaving behind. .

Therefore, in the main electrodeposition tank B, each through hole 2 is completely filled with the resist solution 3, and sufficient current and reaction are carried out to ensure that the photosensitive resist film is coated on the inner wall of each through hole 2. It is worn and formed.

C. Effects of the Invention As is clear from the above, according to the resist film electrodeposition method and apparatus for printed wiring boards according to the present invention, by passing the resist film through the pre-treatment tank, it is possible to expel the air from the through hole,
Moreover, it is possible to impart hydrophilicity to the inner wall. Therefore, in the main electrodeposition tank, each through hole is completely filled with the liquid, and a photosensitive resist film can be reliably formed by electrodeposition. Therefore, it becomes easier to achieve the high density, fine circuitry, and high reliability that will be increasingly required of printed wiring boards in the future.

[Brief explanation of the drawing]

The figures show embodiments of the present invention.
The figure is a partially enlarged longitudinal sectional front view of the main parts of Fig. 1, Fig. 3 is a partially omitted longitudinal sectional front view of the pre-treatment tank of the electrodeposition apparatus shown in Fig. The vertical side views, and FIGS. 5, 6, 7, and 8 are partially vertical front views showing main parts of other embodiments. Drawing code A...Pretreatment tank, B...electrodeposition main tank, 1...
Copper-clad laminate board, 2... Through hole, 3... Photosensitive resist solution, 4... Opening, 14... Liquid inlet.

Claims (1)

[Claims] 1. Before electrocoating a copper-clad laminate substrate 1 with through-holes 2 in a photosensitive resist solution 3 converted into an electrodeposition paint in a main electrodeposition tank B, the substrate 1 is The resist solution 3 is passed through the pretreatment tank A under pressure so as to block the flow, and the resist solution 3 is passed through the through holes 2 of the substrate 1.
A resist film electrodeposition method for a printed wiring board, characterized in that air in the through holes 2 is expelled and hydrophilicity is imparted by flowing a liquid 3 into the through hole 2. 2 A pretreatment tank A is provided in front of the main electrodeposition tank B,
Photosensitive resist liquid 3 made into electrodeposition paint in both cases
can be continuously supplied, and the pretreatment tank A allows the resist solution 3 to flow under pressure,
Copper-clad laminate board 1 with through holes 2 when passing through it
A resist film electrodeposition apparatus for a printed wiring board, characterized in that an opening 4 is provided so that the flow of a liquid 3 can be blocked. 3 The main electrodeposition tank B is provided with slits 9 and 10 through which the copper-clad laminate substrate 1 with through-holes 2 can pass horizontally, and the main tank B is shaped like a pressure tank to prevent the liquid flow of the resist solution 3 filled with the main tank B. The pretreatment tank A is provided with an outlet 12, a liquid inlet 14 at a position below the substrate passage 13 at the same height as the slits 9 and 10, and an opening slightly below the substrate passage 13 through which the liquid 3 overflows. 4 and a guide portion 15 for preventing floating of the substrate 1 passing over the opening 4. The resist film electrodeposition apparatus for a printed wiring board according to claim 2. 4 The main electrodeposition tank B is provided with slits 9 and 10 through which the copper-clad laminate substrate 1 with through-holes 2 can pass horizontally, and the main tank B is shaped like a pressure tank so that the overflowing resist solution 3 The pretreatment tank A has a liquid inlet 14 above the substrate passage 13 at the same height as the slits 9 and 10, and an opening slightly above the substrate passage 13 through which the liquid 3 flows. 4, and a guide portion 15 for preventing the substrate 1 from falling, which passes under the opening 4. The resist film electrodeposition apparatus for a printed wiring board according to claim 2. 5 The main electrodeposition tank B is provided with slits 9 and 10 through which the copper-clad laminate substrate 1 with through holes 2 can pass horizontally, and the pretreatment tank A is provided with substrate passages 13 at the same height as the slits 9 and 10. The liquid inlet 14 is provided at a lower position so that the resist liquid 3 can be supplied by the pump 16, and the liquid 3 is provided below the substrate passage 13.
A guide part 1 for preventing the substrate 1 from floating, which is provided with an opening 4 through which the flow overflows, and which passes over the opening 4.
5. A resist film electrodeposition apparatus for a printed wiring board according to claim 2, comprising: 5. 6 The main electrodeposition tank B is provided with slits 9 and 10 through which the copper-clad laminate substrate 1 with through holes 2 can pass horizontally, and the pretreatment tank A is provided with substrate passages 13 at the same height as the slits 9 and 10. An opening 4 through which the liquid 3 flows is provided slightly above the opening 4, and a chamber 19 above the opening 4 is provided.
A resist film of a printed wiring board according to claim 2, wherein the resist solution 3 can be supplied by a pump 16 at the opening 4, and a guide portion 15 for preventing the substrate 1 from falling down passing under the opening 4 is provided. Electrodeposition equipment. 7 The main electrodeposition tank B is provided with a slit through which the copper-clad laminate substrate 1 with through holes 2 can pass vertically, and the pretreatment tank A is provided with a slit through which the copper-clad laminate substrate 1 with through-holes 2 can pass vertically, and the pretreatment tank A is provided with a substrate passage 13 on the same surface as the slit.
Resist liquid 3 pressurized in one side chamber 17 with
A liquid inlet 14 is provided, and an opening 4 through which the liquid 3 can flow into the other side chamber 18 is provided.
A resist film electrodeposition apparatus for a printed wiring board according to claim 2, further comprising a guide portion 15 for preventing horizontal wobbling of the substrate 1.