JP2001111203A - Method and apparatus for forming surface protection layer of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for forming a surface protection layer of a circuit board whereby the surface protection layer can be formed surely at a low cost, even for a double-side circuit board such as flexible circuit boards. SOLUTION: Two blade coaters 1, 2 are disposed V-shaped to hold a required gap between their coating ends 1A, 2A, a liquid surface protective material 3 having an adequate viscosity resides between the blade coaters 1, 2. A circuit board 4 having mask layers 6 formed on wiring patterns 5 for forming cover openings as connection terminals is prepared and inserted into the gap between the coating ends 1A, 2A of the blade coaters 1, 2 through the liquid surface protection material 3, thereby forming surface protection layers 7 which are uniform in thickness on both sides of the circuit board 4 at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface of a circuit board on which a surface protective layer can be formed reliably and at low cost even if the circuit board has a double-sided structure such as a rigid circuit board or a flexible circuit board. The present invention relates to a method and an apparatus for forming a protective layer.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become higher in density and smaller in size, higher density and smaller size have been required for entire circuit boards mounted thereon. At present, the number of connectors and contacts, etc., in addition to the number of electronic components such as LSIs and chips to be mounted on the devices are increasing.

[0003] Among circuit boards, a flexible circuit board has a thinner material thickness as compared with other circuit boards, and has a good heat dissipation property. I have.

Further, since the flexible circuit board is made of a film material, it can be used in a bent state. Therefore, the flexible circuit board is folded and incorporated in a housing of an electronic device to reduce the size. In addition to the form of a high-density mounting circuit board, it can be developed as a circuit board integrated with a cable, so that the number of cover openings serving as connection terminals increases, while the cover opening is increased. In addition, miniaturization of the size and positional accuracy are also required.

[0005] In general, as a method of forming a cover opening serving as a connection terminal portion for a flexible circuit board or the like, a cover film method, a cover coat method by printing, and a photosensitive cover development method are generally used. In the cover film method, a required hole is formed by means such as a mold or a drill on an insulating film provided with an adhesive layer commonly referred to as a cover film, and the wiring pattern is formed while positioning. The surface protective layer is formed together with the cover opening by bonding to the layer.

In the cover coating method by printing, an insulating varnish or the like is printed on the surface of a circuit board using a screen printing machine or the like, so that a cover opening as a connection terminal portion is formed together with a surface protective layer. It is a method of forming.

On the other hand, in the photosensitive cover developing method, a photosensitive cover material is coated or formed into a film form, then adhered to a circuit board surface and adhered. Forming a surface protective layer together with the openings;

[0008]

For a flexible circuit board or the like, the number of cover openings as connection terminals is increased, and the number of covers is increased.
Although smaller opening size and higher position accuracy are required,
When the surface protective layer is formed by the cover film method, there is a limit to the close distance of the hole in addition to the size of the die,
In addition, there is a problem that the cost is increased due to the higher precision of the mold. In addition, displacement and adhesion of the adhesive at the time of bonding also occur, so that the productivity and the yield are reduced when forming with the required positional accuracy, which poses a problem.

In addition, the cover coating method by printing involves a change in shape due to bleeding of the insulating varnish into the cover opening, a decrease in positional accuracy due to misalignment of the printing plate, and a blur or bubbles during printing. Insulation failure occurs due to the incorporation of foreign matter or foreign matter, so that this method has many problems.

Further, in the photosensitive cover developing method, in addition to the deformation of the cover opening due to the undeveloped residue, the deterioration of the environmental dependence of the electric characteristics due to the remaining impurities such as the photosensitive agent and the developing solution and the long-term use. It is a problem because there is deterioration over time.

Accordingly, the present invention provides a method for forming a surface protective layer having a cover opening serving as a connection terminal portion in a flexible circuit board or the like by using a cover film method or printing as described above. The present invention provides a method for forming a surface protective layer on a circuit board and an apparatus therefor, which can suitably solve various problems associated with a photolithography method or a photosensitive cover developing method.

[0012]

Therefore, according to the method and the apparatus for forming a surface protective layer of a circuit board according to the present invention, two blades are held so as to keep a coating end in a required gap. The docomer is arranged in a V-shape, and the above two blade coaters are arranged.
A liquid surface protective material having an appropriate viscosity, such as a liquid insulating varnish or a liquid photosensitive resist, is stored between them. The circuit board formed with the above is passed through the gap between the application ends of the two blade coaters through the liquid surface protection material, so that both surfaces of the circuit board have a uniform thickness at the same time. It is characterized by forming a protective layer.

In the circuit board having such a surface protective layer formed thereon, a required cover opening serving as a connection terminal can be easily formed by removing the mask layer, and the cover opening can be easily formed. In the wiring pattern portion appearing in the above, an appropriate surface treatment such as gold plating can be easily performed as necessary.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in further detail with reference to the illustrated embodiments. FIG. 1 is a conceptual configuration diagram of an apparatus for forming a surface protective layer of a circuit board according to the present invention. In FIG. 1, 1 and 2 are arranged in a V-shape made of, for example, an aluminum plate or the like. A plate-like blade coater is shown, each lower end of which is arranged as a coating end 1A, 2A so as to have a required gap, and each coating end 1A, 2A.
A can be formed in an appropriate blade shape so that the surface protective layer of the circuit board can be uniformly formed to a required thickness.

The gap formed between the coating ends 1A, 2A can be adjusted by, for example, arranging the blade coater 1 in an oblique direction as shown in the figure. However, such a gap adjusting mechanism can also be provided on the blade coater 2 side so that both blade coaters 1 and 2 can move simultaneously.

Then, the two blade coaters 1, 2
A liquid surface protective material 3 having an appropriate viscosity, such as a liquid insulating varnish or a liquid photosensitive resist, is stored between the two. -It can be replenished between the tankers 1 and 2.

In order to form a surface protective layer on a circuit board by using the above-mentioned apparatus, as shown in FIG. The formed circuit board 4 is manufactured, and a suitable mask layer 6 is formed on the surface of the wiring pattern 5 to be the connection terminal.

Therefore, in the apparatus shown in FIG. 1, the circuit board 4 formed in the shape of a strip or a strip is passed through the liquid surface protection material 3 to apply the coating ends 1A, 1A, 2
By inserting the gap between A and pulling out as shown by the arrow F, the projections such as the wiring pattern 5 and the mask layer 6 exist on both sides of the circuit board 4 as shown in FIG. It is possible to easily form the surface protective layer 7 to a uniform thickness even in the state where it is present.

Here, when the gap between the coating ends 1A and 2A of the blade coaters 1 and 2 is appropriately adjusted, the thickness of the surface protection layer 7 is reduced as shown in FIG. Since the mask layer 6 and the mask layer 6 can be formed to have the same total thickness, the mask layer 6 can be removed and a cover opening serving as a connection terminal can be easily formed there.

Also, a dummy pattern is formed on both sides of the circuit board 4 inserted into the gap between the coating ends 1A and 2A of the blade coaters 1 and 2 so that the coating thickness can be regulated, for example. By doing so, it is possible to reduce the coating thickness to a required value and to appropriately prevent the liquid surface protection material 3 from undesirably flowing out of the circuit board.

It is easy to apply a surface treatment such as gold plating to the portion of the wiring pattern 5 appearing in the cover opening serving as the connection terminal portion, if necessary.

[0022]

By using the method and apparatus for forming a surface protective layer on a circuit board according to the present invention, there are various methods involved in a conventional cover film method, a cover coat method by printing or a photosensitive cover development method. A flexible circuit that is required to solve various problems while increasing the number of cover openings serving as connection terminals, reducing the size of the cover openings, and also requiring high positional accuracy of the cover openings. A surface protective layer such as a substrate can be formed with high efficiency.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram of an apparatus for forming a surface protective layer of a circuit board according to the present invention.

FIG. 2 is a process diagram illustrating a method for forming a surface protective layer of a circuit board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Blade coater 1A Coating end part 2 Blade coater 2A Coating end part 3 Liquid surface protection material 4 Circuit board 5 Wiring pattern 6 Mask layer 7 Surface protection layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B05D 7/26 B05D 7/26 F term (Reference) 4D075 AB12 AB32 AB52 AB56 CA47 DA06 DC22 EA05 4F040 AA12 AB06 AC02 BA47 CC01 CC19 4F042 AA02 AA06 ED01 5E314 AA24 BB02 BB12 CC01 EE01 FF01 GG24

Claims (5)

[Claims] 1. Two blade coaters are arranged in a V-shape so as to keep a coating end portion at a required gap, and an appropriate viscosity is provided between the two blade coaters. A circuit board having a mask layer formed on the surface of a wiring pattern where a cover opening serving as a connection terminal portion is to be formed through the liquid surface protection material having Bladeco
A method for forming a surface protection layer on a circuit board, wherein a surface protection layer having a uniform thickness is simultaneously formed on both sides of the circuit board by inserting a gap between coating ends of the circuit board. 2. The method according to claim 1, wherein said liquid surface protective material is a liquid insulating varnish or a liquid photosensitive resist. 3. The method for forming a surface protective layer on a circuit board according to claim 1, wherein said mask layer is removed after forming said surface protective layer to form a cover opening serving as a connection terminal. 4. Two blade coaters are formed so as to hold a coating end in a required gap corresponding to the insertion of the circuit board in order to form a surface protective layer on both sides of the circuit board. An apparatus for forming a surface protection layer on a circuit board, which is arranged in a V-shape and in which a liquid surface protection material having an appropriate viscosity is stored between these two blade coaters. 5. One or both of said blade coaters are:
5. The apparatus for forming a surface protection layer on a circuit board according to claim 4, wherein the gap between the coating ends is variably arranged so as to be adjusted corresponding to the circuit board.