JPH0860385A - Etching method and etching device - Google Patents

Abstract

PURPOSE: To make it possible to execute etching while maintaining a specified conveyor speed even if the thickness of the copper foil to be etched changes. CONSTITUTION: This etching device consists of an etching vessel 7, spray nozzles 6, spray pipings 5 for supplying an etching liquid 4 to these spray nozzles 6, conveyor rolls 9 for transporting the plate 8 to be etched, a spray pump 3 for feeding the etching liquid 4 to the spray pipings 5 and an inverter 1 for controlling the discharge pressure of this spray pump 3. The speed at which the plate 8 to be etched passes the inside of the etching vessel 7 is kept constant by the etching device described above and the etching depth is controlled by changing the pressure of the etching liquid to be sprayed to the plate 8 to be etched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method and an etching apparatus. The present invention is particularly useful for manufacturing printed wiring boards.

[0002]

2. Description of the Related Art In the production of printed wiring boards, an etching resist is formed on a printed wiring board substrate in which a copper clad laminate is perforated and plated, and after exposure, development,
Etching and resist stripping are performed continuously.

In the etching process, the plate to be etched is horizontally moved by a conveyor roll and passed through an etching tank. In the etching tank, the etching liquid is sprayed on the upper and lower surfaces of the plate to be etched which normally moves horizontally. Further, the etching baths are connected to each other. The spray pressure of the etching liquid is controlled to be substantially constant, and when the thickness of the copper foil on the plate to be etched changes, the conveyor speed is changed to adjust the spray time for etching.

[0004]

According to the conventional method,
When the copper foil is thick, it is necessary to slow down the conveyor speed to lengthen the spray time, and when it is thin, to increase the conveyor speed and shorten the spray time. For example, when the developing conveyor speed is 4 m / min and the minimum required spray time is set, the conveyor speed when etching a copper foil having a thickness of 35 μm is 4 m / min, when the copper foil having a thickness of 70 μm is etched The conveyor speed must be 2 m / min.

However, in the interlocking development process, the etching resist is dissolved and removed by the developing solution, and the spraying time of the developing solution for that purpose is a time determined by the kind of the etching resist, and the thickness of 35 μm copper is It is often designed to be synchronized with the conveyor speed when etching the strip. Then, when etching a 70 μm thick copper foil, the developing conveyor speed is 4 m.
In this case, the etching conveyor speed is set to 2 m / minute, and the plate to be etched is braked at the entrance of the etching conveyor, so that the etching resist is damaged and becomes defective. Furthermore, with this method, the working speed of the 70 μm copper foil is 2 m / min, and the working efficiency is reduced.

It is an object of the present invention to provide an etching method and an etching apparatus which can perform etching with a constant conveyor speed even if the thickness of copper foil to be etched changes.

[0007]

According to the present invention, the speed at which the plate 8 to be etched passes through the inside of the etching tank 7 is kept constant.
The etching method is characterized in that the etching depth is controlled by changing the pressure of the etching liquid sprayed on the plate to be etched 8.

The etching apparatus of the present invention comprises an etching tank 7, a spray nozzle 6, a spray pipe 5 for supplying the etching liquid 4 to the spray nozzle 6, a conveyor roll 9 for carrying a plate 8 to be etched, and an etching liquid 4. Is composed of a spray pump 3 that feeds into the spray pipe 5, and an inverter 1 that controls the discharge pressure of the spray pump 3.

In the present invention, the pump pressure for spraying the etching liquid 4 is controlled by the inverter 1. However, the set value of the inverter 1 is input in advance to the switchable switch 2, and the switch 2 is switched to perform one-touch operation. By changing the pressure of the spray pump 3 and changing the thickness of the copper foil, the etching liquid 4 can be sprayed onto the plate 8 to be etched at an etching conveyor speed equivalent to the developing conveyor speed.

FIG. 1 is a schematic sectional view of an etching apparatus of the present invention.
Shown in The spray pump 3 for pressure-feeding the etching solution raises or lowers the spray pressure in the spray pipe 5 by changing the rotation speed by a signal from the inverter 1. Here, since it takes time to reconfigure the inverter program for changing the setting value of the inverter 1 for changing the rotation speed of the spray pump 3, several kinds of setting values of the inverter 1 are programmed in advance, and this is changed over. 2 and the pressure of the spray pump 3 is changed by switching the changeover switch 2.

[0011]

[Example] When etching a product having a copper foil thickness of 70 μm on the plate to be etched 8 under the manufacturing condition that the developing conveyor has a speed of 3 m / min, the changeover switch is selected to 1
The pressure of the spray pump in the tank was 215 kPa. Then, when etching a product having a copper foil thickness of 35 μm on the plate to be etched 8, the changeover switch was selected to be 2, and the spray pump pressure of 3 tanks was set to 157 kPa. At this time, the number of working sheets was 138 sheets / hour. Copper foil thickness is 70
No etching defects were observed in any of the products having a thickness of 35 μm and the products having a thickness of 35 μm.

COMPARATIVE EXAMPLE 1 Under the manufacturing condition that the developing conveyor has a speed of 3 m / min, the etching spray pressure was kept constant at 215 kPa, and two etching spray tanks were used to etch a product having a copper foil thickness of 35 μm. It was passed at 2.7 m / min. At this time, the number of working sheets was 125 sheets / hour. Further, there was 2.3% of peeling or scratch defect of the etching resist. This is because the plate to be etched is braked by the etching conveyor roll, and the peeling of the etching resist or the defective defect occurred, and the number of working sheets was reduced to 125.

COMPARATIVE EXAMPLE 2 Under the manufacturing conditions of the developing conveyor at a speed of 3 m / min, the etching spray pressure was kept constant at 215 kPa, and three etching spray tanks were used to etch a product having a copper foil thickness of 35 μm. It was passed at 4.5 m / min. At this time, the number of working sheets was 138 sheets / hour. In addition, peeling or scratch defects of the etching resist was 5.1%. This is because the plate to be etched is pulled by the etching conveyer roll, so that the etching resist is rubbed to cause peeling of the etching resist or defective scratches.

[0014]

According to the present invention, by changing the etching spray pressure, it is not necessary to change the conveyor speed even if the thickness of the copper foil to be etched changes.
Moreover, since the inverter is used, the discharge pressure of the pump can be easily and reliably controlled, and the etching work efficiency is not reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an etching apparatus of the present invention.

[Explanation of symbols]

 1 Inverter 2 Changeover switch 3 Spray pump 4 Etching liquid 5 Spray pipe 6 Spray nozzle 7 Etching tank 8 Etching plate 9 Conveyor roll

Claims (2)

[Claims] 1. An etching method characterized in that the etching depth is controlled by changing the pressure of the etching solution sprayed on the plate to be etched while keeping the speed at which the plate to be etched passes through the etching tank. 2. A spray comprising an etching tank, a spray nozzle, a spray pipe for supplying an etching liquid to the spray nozzle, a conveyor roll for carrying a plate to be etched, and a spray pump for feeding the etching liquid into the spray pipe. An etching device that controls the discharge pressure of the pump with an inverter.