JP2724354B2 - Printed board etching method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for etching a printed board, and more particularly, to etching of a printed board surface by an etching solution spray in air and in an etching bath. The present invention relates to a method for etching a printed board characterized by two-stage etching using an etching liquid jet and an apparatus suitable for carrying out the method.

[Conventional technology]

When a circuit pattern is formed on a printed circuit board in which copper foil is laminated on an insulating substrate, unnecessary portions of copper are usually removed by etching. In the conventional etching method, a method of spraying an etching solution on the surface of a printed board in air to etch copper in a portion of the photoresist that is not coated is mainly used.

In order to industrially perform such an etching method, a printed board is often mounted on a transfer device that passes through the inside of the etching apparatus body, and an etching solution is sprayed on the surface of the transferred printed board in the air.

[Problems to be solved by the invention]

However, when the etching solution is sprayed in the air as described above, the etching solution sprayed on the surface of the printed circuit board collides with the surface, and then flows in all directions along the surface. It has been found that such behavior of the etchant on the surface of the printed circuit board prevents uniform etching of the surface of the printed circuit board, and the amount of etching increases from the center toward the periphery (about 20%).

In addition, circuit patterns formed on a printed board generally have a variation in pattern density. When an etchant is sprayed on the surface of a printed board having such a pattern density in air, the amount of etching in a rough portion tends to be larger than that in a dense portion. Therefore, side etching of a rough part also becomes large.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems in the conventional printed board etching method and to provide a method for performing uniform and highly accurate etching.

Another object of the present invention is to provide an etching apparatus suitable for performing the above method.

[Means for solving the problem]

The inventor of the present invention has made extensive researches to solve the above problems and achieve the object of the present invention. As a result, the first etching with an etchant spray in air is performed halfway through the target amount, and the remainder is performed. It has been found that uniform etching can be obtained by performing the second etching having the opposite etching characteristic to the first etching, and the present invention has been made based on the finding.

The method of etching a printed board according to the present invention comprises spraying an etching solution on the surface of the printed board in air to form
Performing a second etching while applying a jet of an etching solution to the surface in an etching bath, and performing one of the two steps first and performing the other later. Features.

Next, the etching apparatus of the present invention suitable for carrying out such an etching method includes a space 2 and an etching bath 3 provided in the apparatus main body 1, and any one of the space 2 and the etching bath 3. A transport device 5 for transporting the printed board in order from one side to the other, and a first spray means 12 for spraying an etching solution in the air toward the surface of the printed board transported in the space 2. And a second spray means 18 for applying a jet of the etching solution toward the surface of the printed board which is immersed in the etching bath 3 and conveyed by the etching solution.

The method and apparatus of the present invention can be applied to both the case where only one side of a printed board is etched and the case where both sides are simultaneously etched. If only one side is to be etched, spray the etching solution from above or below the transporting device according to the etching surface of the printed board transported by the transporting device, apply a jet, and if both surfaces are etched simultaneously, transport What is necessary is just to spray the etching liquid simultaneously from above and below the apparatus and apply a jet.

[Action]

When the first etching is performed by spraying the etching liquid on the surface of the printed board in the air, the etching amount in the peripheral portion is larger than that in the central portion of the printed board surface as described above, and the dense portion of the pattern is The amount of etching in a rougher portion increases. When a second etching is performed on the printed board etched in such a non-uniform manner while applying a jet of etching to the surface thereof in an etching bath, the second etching property becomes the first etching property. In contrast to the characteristics, that is, the etching amount in the peripheral portion from the central portion and the etching amount in the rough portion from the dense portion of the pattern are both small, so that the etching is uniformly performed by using both etchings in combination. A printed board can be obtained.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front sectional view showing an example of an etching apparatus for carrying out the method for etching a printed board of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

A space 2 and an etching bath 3 are provided in the apparatus body 1, and a transfer device 5 for sequentially transferring the printed board 4 into the space 2 and the etching bath 3 is provided.

The illustrated transporting device 5 is an example of a roller conveyor type, in which lower rollers 6 are provided at appropriate intervals over the entire transporting path that linearly passes through the inside of the device body 1, and the space 2, the etching bath 3, and the like. An upper roller 7 is provided at a position where the jet collides with the lower surface of the printed board.

As shown in FIG. 2, the lower roller 6 and the upper roller 7 are fixed to a lower shaft 8 and an upper shaft 9 which are arranged in a direction perpendicular to the conveying direction, respectively, at a fixed interval. ing. Each roller has a relatively thin disk shape made of rubber and has a large number of flow holes for flowing the etchant in the axial through direction.

One end of the lower shaft 8 and the upper shaft 9 is pivotally supported by the apparatus main body 1, and the other end is connected to two drive shafts parallel to the transport direction via bevel gears 10 and 11, respectively. The drive shafts are gear-coupled to rotate synchronously in opposite directions, and are driven by a common drive source (drive sources and the like are well-known and omitted from the drawings).

A first spray means 12 is provided above and below the space 2 so as to sandwich the transport device 5. The illustrated apparatus is an apparatus capable of simultaneously etching both sides of a printed board, and includes first spray means 12 provided above and below.
Is responsible for the etching of the printed board one side at a time. However, either above or below (preferably below)
The valve (not shown) of the first spraying means 12 is closed to stop the spraying, so that it can be used for etching only one side of the printed board.

Respective first spray means provided above and below
12 is a main header 13 parallel to the transport direction,
And a plurality of spray nozzles 15 provided at appropriate intervals in each of the branch headers 14 branched in a direction perpendicular to. These spray nozzles 15 are arranged so as to spray the etching liquid toward the surface of the printed board 4 conveyed in the space 2.

Next, the upper part of the etching bath 3 is opened and
Openings 16 and 17 are provided at two corresponding positions on the respective side walls so that the printed board 4 can pass through.
In the bathtub 3, second spray means 18 are provided above and below the conveying device 5 so as to sandwich the conveying device 5. The above-mentioned first spray means 18 provided on the upper and lower sides of the printed circuit board with respect to the etching is shared by the first spray means.
This is the same as the case of the spraying means 12.

Upper and lower second spray means respectively
18 is a main header 19 parallel to the transport direction,
And a plurality of spray nozzles 21 provided at appropriate intervals in each of the branch headers 20 branched in a direction perpendicular to the vertical direction. The spray direction of each of the spray nozzles 21 is determined so as to apply a jet of the etching solution toward the surface of the printed board 4 which is immersed in the etching bath 3 and conveyed by the etching solution.

A liquid stopper 22 for storing a predetermined amount of etching liquid is provided at a lower portion in the apparatus main body 1. An etching liquid 23 in the liquid stopper 22 includes a heating device 24 such as a heater and a cooling device 25.
Is maintained at a predetermined temperature. As the cooling device 25, for example, a cooling coil through which a coolant such as cooling water passes can be used. In the temperature control, a temperature signal of a temperature sensor (not shown) provided in the liquid holder 22 is compared with a set value in a control circuit 26, and an output of the heating device 24 or a cooling device 25 is output.
By controlling the amount of the refrigerant.

The etching liquid 23 in the liquid reservoir 22 is led out of the pipe 27, is pressurized by a pressurizing pump (not shown), and is introduced into the pipe 28. The second branch pipe 30 supplies the main spray 19 to the main header 19 of the second spray means 18, respectively. In addition, a pipe 31 communicating with the liquid stirring pump is provided at the bottom of the liquid reservoir 22, and a pipe (not shown) for supplying a new etching liquid is further connected.

The upper part of the apparatus main body 1 is provided with a plurality of divided openings 32 for maintenance and inspection and the like, and each opening 32 is closed by a lid 33. The gap 34 in each lid 33 is filled with water for liquid sealing.

Next, the operation of the etching apparatus shown in FIGS. 1 and 2 will be described. First, a new etching solution is supplied from a supply pipe, pressurized by a pressure pump, and introduced into the apparatus main body 1 from the pipe 28. The introduced etchant is sprayed into the space 2 through the route of the first branch pipe 29-main header 13-branch header 14-spray nozzle 15 and the second branch pipe 30-main header 19-branch header. 20
Sprayed into the etching bath 3 via the route of the spray nozzle 21;

The etching solution sprayed into the space 2 falls to the liquid retaining 22 as it is. On the other hand, the etching solution sprayed into the etching bath 3 raises the liquid level in the bath 3 and overflows from the upper opening, and partly flows out from the openings 16 and 17 on the side walls thereof. It falls to the liquid stopper 22.

Then, the temperature of the etching solution 23 is controlled by the heating device 24 or the cooling device 25 to a predetermined temperature. In this state, the preparation for etching is completed by activating the transfer device 5. (Note that the transfer device 5 may be activated before that time.) Next, the printed board 4 to be etched is introduced into the device main body 1 from the left in FIG. The printed board 4 is conveyed by the conveying device 5 and, while passing through the space 2, is sprayed on the surface of the printed board 4 in the air by the first spraying means 12 to perform first etching.

Subsequently, the printed board 4 is introduced into the etching bath 3 by the transfer device 5, and while passing through the etching bath, the second
The second etching is performed while the jet of the etching liquid by the spray means 18 is applied to the surface.

The printed board 4 on which the first etching and the second etching have been completed is directly conveyed by the conveying device 5 and discharged from the apparatus main body 1 as indicated by an arrow to the right in FIG.
The printed board 4 is then conveyed to a cleaning device (not shown) for post-processing.

The respective etching amount ratios of the first etching and the second etching can be changed, for example, by changing the ratio of the length of the first spray unit 12 and the second spray unit 18 in the transport direction. As an example, there is a method in which the length of the first spray means 12 is designed to be longer, and the number of branch headers 14 to be sprayed is adjusted by a start valve (not shown) or the like. The amount ratio between the first etching and the second etching is determined so as to finally obtain a uniform etching characteristic in consideration of the respective etching characteristics as described above. Is preferred. Note that the present invention relates to a case where the etching is switched from spraying an etching solution in air to a jet flow in an etching bath, and a case where the etching is switched from a jet in an etching bath to etching by spraying an etching solution in air. Both conditions are included, but the conditions for both may be the same depending on the type of printed circuit board, or may be required to be different. In such a case, as described above, the optimal etching ratio between the first etching and the second etching is determined by considering the respective etching characteristics and experimentally so as to finally obtain a uniform etching characteristic. Preferably, the value is determined.

Similarly, due to the difference in etching characteristics due to the density of the pattern and the difference in etching characteristics between the central part and the peripheral part, complete uniform etching may not be achieved only by the quantitative ratio of the first etching and the second etching. Although it is conceivable, in that case, an optimum value can be obtained in an experiment within a range that is practically acceptable.

Next, an experimental example using the etching apparatus shown in FIGS. 1 and 2 will be described.

<Apparatus specifications> First spray means 12; five headers 14 at intervals of 21 cm along the transport direction, and eight branch diameters in each branch header 14
mm spray nozzle Second spray means 18; 5 branch headers at 50 cm intervals in etching bath 3 having a length of 100 cm along the transport direction
20, 12 spray nozzles having a diameter of 1.2 mm are used for each header 20. <Etching solution> An alkali etching solution (alkali etchant), trade name A process manufactured by Meltex Co., Ltd. is used.
The composition is as follows: 145 g of copper component, 145 g to 170 g of chlorine, 8.0 to 9.2 g of total ammonium NH ₃ (N), liquid temperature: 50 ° C., pressure: 1 kg / cm ² (at spray nozzle) in liquid 1. A 50 micron thick copper foil is laminated on both sides of a glass fiber reinforced epoxy board of 60cm x 50cm and thickness of 2.0mm.

On both surfaces of the copper foil, a circuit pattern in which a large number of circuits having a width of 80 μm, including a pattern and a coarse / dense pattern, were wired at an interval of 80 μm was applied by a photoresist.

Under the above conditions, the printed board was passed through the apparatus at a speed of 0.5 m / min, and then washed and dried. After that, the main part was cut out, and the cross section was observed with a microscope (100 times magnification). As a result, no difference in the etching amount between the peripheral portion and the central portion was observed.
The same was true for the rough and dense portions of the circuit pattern.

〔The invention's effect〕

Since the method for etching a printed board according to the present invention is configured as described above, there is a uniform difference between the center and the periphery of the printed board and between the rough portion and the dense portion of the circuit pattern. Can be etched.

Further, the etching apparatus of the present invention suitable for carrying out the above method can continuously and efficiently etch a large number of printed boards.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an example of an etching apparatus for carrying out a method of etching a printed board according to the present invention.
The figure is a sectional view taken along the line AA in FIG. DESCRIPTION OF SYMBOLS 1 ... Device main body, 2 ... Space part 3 ... Etching bath, 4 ... Printed board 5 ... Conveying device, 6 ... Lower roller 7 ... Upper roller, 8 ... Lower shaft 9 ... Upper Shaft, 10, 11 Bevel gear 12 First spray means 13, 19 Main header 14, 20 Branch header 15, 21 Spray nozzle 16, 17, 32 Opening 18 ... Second spraying means, 22... Liquid retaining 23... Etching solution, 24... Heating device 25... Cooling device 26... Control circuit 27, 28. … Second branch pipe, 31 pipe 33, lid, 34 gap

Claims (2)

(57) [Claims] A step of spraying an etching solution on a surface of a printed board in air to perform a first etching; and a step of performing a second etching while applying a jet of an etching solution to the surface in an etching bath. A method of etching a printed board, wherein one of the two steps is performed first and the other is performed later. 2. A space (2) and an etching bath (3) provided in an apparatus body (1), and said space (2).
And a transport device (5) for transporting the printed board in order from one of the two to the other in the etching bath (3), and blowing the etching liquid toward the surface of the printed board transported in the space (2). A first spraying means (12) for spraying the inside of the substrate, and a second spraying means for applying a jet of the etching solution toward the surface of the printed board which is immersed in the etching bath (3) and conveyed. And a spray means (18).