JPH0649957B2 - Jet etching method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet etching method for forming a circuit on a printed circuit board.

(Prior Art) For example, in a manufacturing process of a printed circuit board, a copper foil of a copper clad laminate, which is usually formed by adhering a copper foil to an insulating substrate, is partially removed, and an etching process is performed to form a complicated conductor pattern. Is applied. There are various methods of etching, and there is a method of spraying an etching liquid onto the object to be etched. The outline of this kind of etching method will be described with reference to FIG. In FIG. 2, reference numeral 1 denotes an object to be etched, which has an etching resist attached according to a conductor pattern to be formed on a copper foil of a copper clad laminate, and a cross section is shown in the drawing. It is moving in the direction perpendicular to the paper surface. An etching solution 3 is contained in the etching tank 2, and the etching solution 3 is, for example,
It is composed of an aqueous solution of ammonium persulfate or cupric chloride, and is sprayed onto the object to be etched 1 from the nozzle 5 of the spraying unit 4 through the circulation path 6 made of a pipe by the operation of the circulation pump 11, and then into the etching tank 2. It falls and circulates in the above path. The copper foil of the object to be etched 1 is etched by the etching liquid 3 sprayed from the nozzle 5, and the chemical concentration between the copper and the etching liquid causes the copper concentration in the etching liquid 3 in the etching tank 2 to increase. Is consumed and deteriorates, so the concentration changes over time. By the way, in order to perform stable etching, the etching liquid 3 sprayed from the nozzle 5 along with the moving speed of the object to be etched 1
It is necessary to control so that the concentration and temperature of are kept constant. Therefore, in order to maintain the concentration and temperature of the etching liquid ejected from the nozzle 5 at a predetermined constant value, the etching liquid 3 in the etching tank 2 is constantly stirred by a stirrer (not shown) while the chemical liquid management sensor is used. The concentration and temperature are measured at 13, and the electromagnetic valves 22 and 23 are operated by the concentration control measuring device 15 to inject the liquid medicine from the liquid medicine inlet 24 and water from the water inlet 25, and to adjust the temperature. The heater 26 and water injection from the water injection port 25 adjust the concentration and temperature of the etching solution 3 in the etching tank 2 to be maintained at predetermined values. At this time, needless to say, the moving speed of the object to be etched 1 is always kept constant.

(Problems to be Solved by the Invention) In a conventional method for controlling the concentration and temperature of an etching solution, the etching solution is circulated and moved, and the concentration and temperature are adjusted in a state of time-dependent adjustment. ± 1 ° C
The change in temperature before and after is unavoidable, and it is 5 to 10% when converted to the etching rate. Also, if the etching solution is not stirred rapidly, non-uniformity will occur in the etching tank.
When converted to etching rate, variations of up to around 20% occur. When the concentration and the temperature vary as described above, the etching rate varies, but on the other hand, since the moving speed of the object to be etched is kept constant, the etching excess or deficiency occurs. In particular, when the width of the conductor pattern is narrow, an undercut or the like may be caused by overetching to break the wire, and in the case of underetching, insulation failure between the conductor patterns may occur, which makes it difficult to manufacture a fine circuit.

Further, in the above-mentioned jetting type etching method, the conductor pattern is in the same direction, at a right angle direction, at an angle, or at a corner with respect to the direction of introducing the object to be etched into the etching apparatus. The amount of etching changes depending on how the conductor pattern is routed. Therefore, in general, correction is performed, for example, by correcting the mask film so that the etching resist becomes finer at the corners, depending on how the conductor pattern is drawn around the mask film used when forming the etching resist. However, it is difficult to grasp the correction value in the etching method based on the conventional etching liquid management method as described above because the etching rate changes with time.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and the etching solution in the etching tank is circulated through a circulation path to be jetted onto the object to be etched. In the spray-type etching method performed as described above, two relay tanks equipped with a thermostatic device are installed in parallel in the circulation path between the etching tank and the spray part of the etching solution, and the concentration in one relay tank is increased. And the temperature-adjusted etching liquid is guided to the spraying unit and sprayed, while the etching liquid in the etching tank is guided to the other relay tank and stored in a predetermined amount, and then a predetermined concentration and When the temperature is adjusted and the etching liquid in the former relay tank becomes less than a predetermined amount, the former relay tank and the latter relay tank are switched by a switching valve, and similarly, the latter At the same time that the etching solution whose concentration and temperature have been adjusted is sent from the relay tank to the spraying section, the etching solution in the etching tank is introduced into the former relay tank, and the concentration and temperature are adjusted to the predetermined values. As described above, the present invention provides an etching method in which two relay tanks are alternately switched by a switching valve and the etching solution whose concentration and temperature are adjusted is continuously jetted in the relay tank.

(Operation) In the method of managing the etching solution shown in the conventional example, it is not easy to adjust the concentration and temperature of the etching solution to be constant without fluctuation by adjusting the etching solution constantly circulating and changing with time. According to the method, it is possible to manage the etching liquid in a state in which it is once stored in the relay tank and does not change with time so that the concentration and the temperature are kept constant, so that the etching liquid can be managed extremely accurately. Therefore, the etching solution ejected from the nozzle is stable in both concentration and temperature, the etching rate becomes constant, and stable etching is performed if the concentration and temperature of the etching solution are properly selected together with the moving speed of the object to be etched, and Further, since the etching rate is stable without change over time, the mask film can be corrected appropriately and easily as described above, and it is sufficiently effective for forming a fine circuit.

(Embodiment) FIG. 1 is a schematic view showing an embodiment of the method for etching a printed board according to the present invention. In the figure, reference numeral 1 denotes an object to be etched such as a printed circuit board, which is moving at a constant speed in the direction perpendicular to the paper surface. Reference numeral 2 denotes an etching tank, which contains an etching solution 3 made of, for example, an aqueous solution of ammonium persulfate or cupric chloride. 4 is a jetting part of the etching liquid, and many nozzles 5
Is provided. A circulation path 6 for the etching liquid is provided between the etching tank 2 and the spraying unit 4. Relay tanks 7 and 8 are installed in parallel in the circulation path 6, and each of the relay tanks 7 and 8 is provided with a thermostatic device, a stirrer, a chemical solution inlet, a chemical solution management sensor, etc. Switch valves 9 and 10 for switching the inflow and outflow of the etching solution are provided on both sides of the switch 8 and 8, and a circulation pump 11 is provided between the switch valve 9 and the etching tank 2.
However, a circulation pump 12 is provided between the switching valve 10 and the injection unit 4.

Therefore, the switching valve 9 is opened to the relay tank 8 side, the switching valve 10 is opened to the relay tank 7 side, and the etching solution maintained in the relay tank 7 at a constant temperature and concentration is circulated by the circulation pump 12 to the injection unit 4 And is sprayed onto the object to be etched 1 from the nozzle 5 to etch the object to be etched 1, and the etching liquid drops into the etching tank 2. At the same time, the etching solution 3 in the etching tank 2 is sent to the relay tank 8 by the circulation pump 11, and when the predetermined amount is reached, the circulation pump 11 is stopped and the etching solution in the relay tank 8 is a chemical solution without any change over time. The concentration and temperature are measured by the control sensor 14, and the concentration control measuring instrument 15 operates the electromagnetic valves 18 and 19 to inject the chemical liquid from the additive liquid tank 16 and the like, and the mixture is agitated by the agitator and adjusted to the predetermined temperature and concentration. To be done. When the etching solution in the relay tank 7 is reduced to a predetermined amount or less, the switching valve 9 and
10, the etching liquid in the relay tank 8 is sent to the injection unit 4 by the circulation pump 12, while the etching liquid 3 in the etching tank 2 is sent to the relay tank 7, where the electromagnetic valve 20, 21 to activate the additive liquid tank 17
It is adjusted to a predetermined temperature and concentration by, for example, injecting a chemical solution from. By the switching valves 9 and 10 as described above, the circulation pump 11 is always stopped in the relay tanks 7 and 8, and the etching solution controlled to a predetermined temperature and concentration is alternately applied to the injection unit 4 in a state where there is no change with time. Since it is sent, the etching liquid sprayed on the object to be etched 1 is always maintained at a predetermined temperature and concentration.

(Effects of the Invention) According to the etching method of the present invention, since the concentration and temperature of the etching solution can be controlled in a state where the relay tank is stopped, an etching rate with little variation can be obtained, and therefore, it is jetted onto the object to be etched. The concentration and temperature of the resulting etching solution are stable, etching can be performed with high precision, and the mask film can be easily corrected during formation of the resist to be etched, so that fine circuits can be formed with high precision.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of a jet etching method according to the present invention, and FIG. 2 is a schematic diagram for explaining a conventional jet etching method. 1: Object to be etched, 2: Etching tank, 3: Etching solution, 4: Injection part, 5: Nozzle, 6: Circulation path, 7,
8: relay tank, 9 and 10: switching valve, 11 and 12: circulation pump.

Claims (1)

[Claims] 1. A spray-type etching method in which an etching solution in an etching tank is circulated through a circulation path and sprayed from an injection part onto an object to be etched, and two relay tanks are installed in the middle of the circulation path, The etching solution whose concentration and temperature have been adjusted in one relay tank is guided to the spraying section for spraying, while the etching solution in the etching tank is guided to the other relay tank, in which the predetermined concentration and temperature are set. A spray-type etching method, which comprises adjusting and alternately switching the two relay tanks by a switching valve to continuously spray an etching solution whose concentration and temperature are adjusted in the relay tank.