JPH0614583B2 - Method and apparatus for coating a resist for pattern formation on a double-sided through-hole substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention provides a double-sided through-hole substrate in which a metal conductor such as copper is coated on the surface and the inner peripheral surface of the through-hole in producing a double-sided printed wiring board. As a material, a pattern forming resist is formed by coating a resist for pattern formation on the double-sided through-hole substrate to optically form a conductor pattern portion in a subsequent step, and protecting and forming the conductor pattern portion in a subsequent etching step. The present invention relates to a coating method and a coating device.

[Prior Art] As a method for forming a pattern forming resist film on a substrate, a dry film tenting method, a hole filling tenting method, a hole filling photoresist method, and the like are known.

In the tenting method using the dry film described above, the substrate surface is covered with a film type pattern forming resist. The hole filling tenting method is a method in which the through holes are filled with hole filling ink before the dry film is applied to the substrate surface.

In the hole filling photoresist method, a through hole is filled with a hole filling ink to fill the through hole and the substrate surface is flattened, and then a liquid resist made of a photosensitive resin for pattern formation is applied to the surface by a roller or the like for coating. It is a method of forming a film.

In addition to the above-mentioned method, in recent years, a so-called ED in which the substrate is dipped in a solution containing a photosensitive resin to form a film of the photosensitive resin on both surfaces of the substrate and the inner peripheral surface of the through hole by an electroplating method. Method (Electrodeposition method)
Is now available. According to this method, a required coating film is formed at one time without requiring a separate process such as filling a through hole in advance.

[Problems to be Solved by the Invention] However, the tenting method using a dry film described above has an advantage that a film thickness for protecting a metal conductor can be sufficiently obtained, but the film itself is expensive, so that cost increase is avoided. There was a problem that can not be. Further, if the land of the through hole is small, the remaining film portion of the land after pattern formation by exposure is small, so that the portion may fall into the hole. In order to prevent this, there is a hole filling tenting method in which the resist ink is previously filled in the through holes, but as mentioned above, in addition to the film itself being expensive, the hole filling ink is filled in the through holes as a previous step, and then this Since an extra hole-filling step of drying is necessary, there is a problem in terms of work cost and work efficiency due to the increase in the number of steps.

Also, the hole filling photoresist method described above is advantageous in terms of work cost in that an expensive film is not used, but like the hole filling tenting method described above, a hole filling step is additionally required, and the substrate surface is polished after the hole filling. However, various operations such as washing with water and drying, and further drying of the liquid resist applied on the surface of the substrate are required, and the work is more troublesome than the hole filling tenting method described above, and it is difficult to improve the work efficiency. In addition, in this case, since the volatile solvent contained in the filling ink disappears by heating and drying after filling the filling hole, the filled ink surface has a concave depression to protect the peripheral portion of the hole when the through hole has a large diameter. Is insufficient and may cause disconnection of the peripheral edge of the hole during polishing of the next substrate surface, resulting in a problem in accuracy.

Next, in the case of the ED method, the liquid resist for pattern formation made of a photosensitive resin can be formed on both surfaces of the substrate and the inner peripheral surface of the through hole at a time, so that the working process can be shortened. However, the ED method requires a large amount of equipment for electroplating, requires equipment for preventing the pollution problem of the plating solution drainage, and has a very high running cost, and also manufactures one substrate. 15 to 20
There was also a problem in terms of work efficiency, such as taking minutes.

The present invention has been made in view of the problems in the above-mentioned conventional methods, and an object thereof is to improve the work efficiency by greatly shortening the work process, and at the same time, to form a resist for pattern formation at low cost and quickly. To provide a method for coating a double-sided through-hole substrate and a coating apparatus therefor.

[Means for Solving the Problems] In order to achieve the above-mentioned object of the present invention, in the method of coating a resist for pattern formation on a double-sided through-hole substrate according to the present invention, the double-sided through-hole substrate is transferred to a coating position. Then, at the coating position, a liquid resist for pattern formation made of a photosensitive resin is supplied to one surface of the substrate by a roller or the like, and the liquid resist is applied to the one surface of the substrate and injected into the through hole. To the other surface of the substrate, apply the overflowing liquid resist to the other surface of the substrate, and apply both surfaces of the substrate and the inner peripheral surface of the through hole by the liquid resist for pattern formation made of the same photosensitive resin. A coating method of coating is proposed.

Further, in the above proposed method, when a roller is used to supply the liquid resist for pattern formation, after the step of supplying the liquid resist from one surface of the substrate by this roller, the other surface of the substrate is coated at the coating position. The same resist as the liquid resist is supplied by different rollers, and the resist is applied to the other surface of the substrate by the relative movement of the roller and the substrate, and the resist is spilled onto one surface of the substrate through the through holes. A method is proposed.

Further, a method is proposed in which, of the liquid resist injected into the through hole, the surplus portion is dropped from the through hole by air blow.

Further, in the apparatus for coating the pattern forming register on the vehicle through-hole substrate according to the present invention, means for conveying the double-sided through-hole substrate to the coating position,
Corresponding to one surface of the substrate at the coating position, a liquid resist for pattern formation made of a photosensitive resin is supplied from a supply source to the one surface of the substrate, and is moved to the one surface by relative movement with the substrate. Liquid resist supply means such as a roller for applying and injecting the liquid resist into the through hole to overflow the liquid resist to the other surface of the substrate through the through hole, and the liquid resist overflowing to the other surface of the substrate for the other surface It is proposed to coat the both surfaces of the substrate and the inner peripheral surface of the through hole with the liquid resist for pattern formation made of the same photosensitive resin.

Further, in the above proposed coating apparatus, there is also proposed a configuration in which an air blow means for dropping the surplus portion of the liquid resist injected into the through hole from the through hole is arranged at the coating position.

Further, it is proposed that the viscosity of the pattern forming resist made of a photosensitive resin suitable for use in the coating method and apparatus according to the present invention is in the range of 1 to 150 poise.

[Operation] In the method of the present invention and the apparatus therefor, a liquid resist for pattern formation made of a photosensitive resin is applied to one surface of the substrate by means of a roller or the like, and the liquid resist is injected into the through hole. And the liquid resist is applied to the other surface of the substrate, so that both surfaces of the substrate carried into the coating position and the inner peripheral surface of the through hole are made of the same photosensitive resin. It is coated with a liquid resist for formation, and the substrate is continuously conveyed at the coating position without the need for complicated pre-work such as filling and drying with a filling ink different from that for pattern formation and polishing the substrate surface. The required coating work is completed in the meantime.

Further, by applying the liquid resist for pattern formation made of a photosensitive resin from the other surface of the substrate as described above, more reliable coating is performed.

In addition, the surplus amount of the resist injected into the through hole in the above series of processes is dropped from the through hole by air blow to eliminate the sagging of the resist, and only the amount necessary for coating the inner peripheral surface of the through hole is eliminated. I'm leaving it.

The liquid resist for pattern formation made of a photosensitive resin used in the method of the present invention and the apparatus therefor preferably has a viscosity in the range of 1 to 150 poises.

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment] Referring to FIG. 1, a coating apparatus for carrying out the coating method of the present invention will be described. 10 is a coating apparatus main body, 12 is a substrate loading section, 14 is a substrate unloading section, 16
Is a drying device connected to the carry-out section 14.

The double-sided through-hole substrate P processed in this coating apparatus is a metal conductor such as copper by plating over the entire surface of the substrate body 20 in which the through holes 18 are drilled as shown in FIG. 22 is coated, and this is sent as a raw material to the coating apparatus.

The substrates P are placed one by one on the elevator 24 of the carry-in section 12, and are raised to the conveying height via the elevating device 28 driven by the motor 26, where the vacuum 30 is set.
Is sucked by, is moved along the rail 32 in the transport direction indicated by the arrow, and is lowered onto the transport roller row 34.

As a result, the substrates P are sequentially sent one by one in the transport direction by the roller row 34.

When the substrate P enters the coating position 36 of the apparatus body 10, it is covered by a tape at the tape adhering device 38 so that the resist does not adhere to the side edge portions of the upper and lower surfaces of the substrate P during coating.

In the coating apparatus 36, the substrate P first passes through a supply roller section 40 which constitutes a liquid resist supply means. The supply roller unit 40 includes a collecting roller 44 that rotates counterclockwise in the drawing so as to pick up the liquid resist R from a pan 42 containing the liquid resist R for pattern formation containing a photosensitive resin as a main component. Corresponding to this, there is a supply roller 46 that extends in the width direction (depth direction in the drawing) of the substrate P that has been carried in and that rotates in the clockwise direction in the figure in a state where it is constantly in sliding contact with the lower surface of the substrate P.

A supply roller unit 40 and a guide unit 48 that sandwiches the substrate P and that suppresses upward movement of the substrate P and that ensures a sliding contact between the supply roller 46 and the substrate P are arranged opposite to each other. The guide portion 48 has a pair of guide bars 50a and 50b having a rectangular or rhombic cross section which is spaced from the contact position (supply position) between the substrate P and the supply roller 46 along the transport direction.
Are provided in parallel to the width direction of the substrate P, and the corner portions of the bar are fixed so as to be in sliding contact with the upper surface of the substrate P at the edges.

As shown in FIG. 2, the liquid resist R for pattern formation applied to the peripheral surface of the supply roller 46 through the collecting roller 44 is the liquid at the contact position with the lower surface of the substrate P moving in the transport direction indicated by the arrow. The resist R is applied, and at the position of the through hole 18, it is injected into the through hole 18 and overflows to the upper surface of the substrate P. As described above, not only the liquid resist R is applied to the lower surface of the substrate P but also the relative moving speed of the substrate P and the supply roller 46, the supply amount of the liquid resist R, and the liquid resist R so that the liquid resist R can overflow to the upper surface of the substrate through the through hole 18. The viscosity and the like of the liquid resist R are selected to be optimum.

In particular, the viscosity of the liquid resist R for pattern formation containing a photosensitive resin as a main component used herein is preferably in the range of 1 to 150 poises.

Note that the peripheral speed of the supply roller 46 is set to be slightly higher than the transport speed of the substrate P, so that the liquid resist is positively injected into the through hole.

The liquid resist R that has overflowed to the upper surface is applied to the upper surface of the substrate P in a substantially uniform state by the one guide bar 50a on the front side along the transport direction.

In this manner, the pattern forming liquid resist R is simultaneously applied to the upper and lower surfaces of the substrate P and the through holes 18 at the supply roller section 40.

The substrate P then passes through the second supply roller portion 54 arranged above the substrate transport path 52 indicated by the chain line. The second
Like the supply roller unit 40 described above, the supply roller unit 54 includes a pair of rollers, applies the same pattern forming liquid resist from the upper surface side of the substrate P to apply the same to the upper surface of the substrate P, and through the through hole 18, the liquid liquid. The resist is made to overflow to the lower surface side, and is applied to the lower surface of the substrate by a pair of rollers 56 placed on the lower side so as to face the second supply roller portion 54.

In the first supply roller unit 40, the second supply roller unit 54 complements the first supply roller unit 40 when liquid resist should be injected into the through holes and overflowed to the upper surface of the substrate insufficiently. Although it is desirable to install it for the coating process, usually, the first supply roller unit 40 alone can provide sufficient coating.

It should be noted that, in this example, a configuration using a roller as the liquid resist supply means is shown, but instead of the roller,
It is also possible to use a spray coater and supply the resist so that the resist is sprayed onto one surface of the substrate and at the same time inject the resist into the through holes, or use a flow coater that supplies the resist on the substrate. is there.

The substrate P to which the liquid resist R for pattern formation is applied as described above is sent to the scraping member 58 and the air blow 60, which are called smoother or squeegee, along the substrate transport path 52. Excessive resist of the liquid resist applied to both surfaces of the substrate P is scraped off by the scraping member 58 corresponding to both surfaces, and the surplus amount of the liquid resist in the through hole 18 is arranged above the substrate P by air. By the blow 60, it is made to fall from each through hole downward by the pressurized air as shown by the arrow, and the resist film is left on the inner peripheral surface of the through hole.

The substrate P is further moved along the substrate transfer path 52 by the roller coater 62.
And the resist film thickness on the substrate surface is made uniform there.

In this way, in the coating device 36, the pattern forming liquid resist R made of the same photosensitive resin is used to coat the resist film not only on both surfaces of the substrate P but also on the inner peripheral surface of the through hole as shown in FIG. It Then, the processed substrate P is sent out to the drying device 16 in the next step via the substrate unloading unit 14, and the resist film dried in the device 16 is fixed on the substrate P.

Next, the substrate P is moved to a pattern forming step, and a circuit pattern is formed by exposure, development and etching by a known photographic method. In this case, the photographic film used for the circuit pattern has a negative type or a positive type, but the liquid resist for pattern formation of the photosensitive resin used in the present invention corresponds to both the negative type and the positive type. It can be appropriately adopted.

In the case of a negative type liquid resist, the resist film on the inner peripheral surface of the through hole is hardened by scattered light entering the through hole during exposure and remains, and sufficiently protects the metal conductor 22 during etching. For this reason, it is desirable to drop the excess liquid resist by the air blow 60 in advance so that the light can sufficiently pass through the through holes. Further, in the case of a positive type liquid resist, the through hole portion is left unexposed by the photographic film. In this case, if excess liquid resist remains in the through hole, it will hang down from the through hole and interfere with the transition to the next process. It is desirable to remove sufficiently.

In this way, the double-sided through-hole substrate P is not only applied to both sides of the substrate but also to the through-holes by the pattern forming liquid resist R made of the same photosensitive resin while being fed along the substrate transport path 52 at the coating position 36. The inner peripheral surface can be simultaneously coated with a resist film.

As described above, according to the present invention, the pattern forming liquid resist made of the same photosensitive resin is used to perform coating on both surfaces of the substrate and simultaneously protect the inner peripheral surface of the through hole. Unlike conventional methods such as hole-filling tenting method and hole-filling photoresist method, it does not require additional steps such as hole filling and drying, and unlike ED method, it does not require electroplating, so it can be performed easily and quickly. The film forming work can be performed efficiently and at low cost, and the mass productivity can be dealt with.

[Brief description of drawings]

FIG. 1 is a schematic view of a coating apparatus for carrying out a coating method according to the present invention, and FIG. 2 is an enlarged explanatory view of a main part including a supply roller for applying a liquid resist for pattern formation in the coating apparatus, FIG. FIG. 3 is an enlarged cross-sectional view of a main part of a double-sided through hole substrate coated according to the present invention. P: Double-sided through-hole substrate R: Liquid resist for pattern formation 10: Coating device body, 18: Through hole 20: Substrate body, 40: Supply roller part 54: Second supply roller, 60: Air blow 62: Roller coater

Continuation of the front page (56) References JP-A-50-89872 (JP, A) JP-A-58-132992 (JP, A) Actual development Sho-59-187164 (JP, U)

Claims (9)

[Claims] 1. A method for coating a double-sided through-hole substrate coated with a metal conductor such as copper with a resist for pattern formation, the substrate being conveyed to a coating position, and a pattern formed of a photosensitive resin at the coating position. Supply liquid resist to one surface of the substrate, apply the liquid resist to the one surface of the substrate and inject it into the through hole to overflow to the other surface of the substrate, Coating on the other surface of the substrate and coating both surfaces of the substrate and the inner peripheral surface of the through hole with a liquid resist for pattern formation made of the same photosensitive resin. how to. 2. The method for coating a resist for pattern formation according to claim 1, wherein the liquid resist is supplied to one surface of the substrate by a roller. 3. At the coating position, after the step of supplying the liquid resist from one surface of the substrate by the roller, the same resist as the liquid resist is supplied from a different roller from the other surface of the substrate and The method for coating a resist for pattern formation according to claim 2, wherein the resist is applied to the other surface of the substrate by relative movement with respect to the substrate, and the resist is overflowed onto the one surface of the substrate through a through hole and applied. 4. The pattern forming resist according to claim 1, wherein an excess of the liquid resist injected into the through hole is dropped from the through hole by air blowing. Method. 5. A coating apparatus for coating a resist for pattern formation on a double-sided through-hole substrate coated with a metal conductor such as copper, a means for transporting the substrate to a coating position, and one of the substrates at the coating position. Corresponding to the surface of, a liquid resist for pattern formation made of a photosensitive resin is supplied from a supply source to the one surface of the substrate, applied to the one surface by relative movement with the substrate, and injected into the through hole. And a means for applying the liquid resist overflowing the other surface of the substrate to the other surface of the substrate through the through hole, and a means for applying the liquid resist overflowing the other surface of the substrate to the other surface of the substrate. Both sides and through hole inner peripheral surface,
A coating device for coating with a liquid resist for pattern formation made of the same photosensitive resin. 6. The coating apparatus according to claim 5, wherein the liquid resist supply means includes a roller which is in rolling contact with the one surface of the double-sided through-hole substrate. 7. The coating apparatus according to claim 5, wherein an air blow means for dropping the surplus portion of the liquid resist injected into the through hole from the through hole is arranged at the coating position. 8. The pattern forming liquid resist comprising a photosensitive resin has a viscosity in the range of 1 to 150 poises.
5. A method for coating the pattern forming resist according to any one of 1 to 4. 9. The liquid resist for pattern formation comprising a photosensitive resin has a viscosity in the range of 1 to 150 poise.
7. The coating apparatus according to any one of 1 to 6.