RU1824461C - Device for measuring thickness of layer to be removed and rate of etching during progress of dimensional chemical etching - Google Patents

Abstract

The invention relates to measuring technique and improves the accuracy of measurement by taking into account the amount of water vapor in the gas collecting vessel and reducing the time intervals during which information on the layer being removed is absent. The device contains a gas collecting vessel, an alarm device and a pulse counter connected with an indicator of the thickness of the layer being removed. In addition, a clock pulse generator with a clock duration generator and a counting pulse generator, the input of which is connected to the output of the clock generator, and the output to the pulse counter 3 il

Description

The invention relates to measuring technique and can be used to measure the thickness of a film layer during dimensional chemical etching (PXT) of parts.

The purpose of the invention is to increase the accuracy of measurements by eliminating the influence of temperature fluctuations of the solution, as well as reducing by several times the time interval during which there is no information about the layer being removed.

Figure 1 presents a block diagram of the proposed device; Fig. 2 shows experimentally the dependence of the thickness of the metal layer being removed during the filling of the vessel with gas on the temperature of the solution; in Fig.Z - timing diagrams of the proposed device

The sensor 1 of the device (Fig. 1) is combined with the signaling device 2. The signaling device 2 is connected to the input of the clock generator 3 connected to the clock 4. The output of the clock generator 3 is connected to the input of the pulse generator 5, the output of which is connected to the input of the pulse counter 6. The output of the counter 6 is connected to the indicator of the number of pulses 7.

The sensor 1 of the device is a gas-collecting vessel configured to rotate around the axis of rotation when the vessel is filled with gas to a certain level. The device signaling device 2 contains a magnet located on the moving part of the gas-collecting vessel and a magnetically controlled contact located on the fixed bracket securing the sensor to the workpiece. Their mutual arrangement provides the inclusion of a magnetically controlled contact with a magnet when turning a gas collecting vessel (gas discharge). Clock Generator

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Pulse 3 is a stand-by generator of rectangular pulses, the duration of which is determined by the value of the resistance located in the clock duration generator. The counter pulse generator is also a standby generator, but with a shorter and fixed duration of the generated pulses. A pulse counter and indicator are typical.

The device operates as follows.

The gas released at the etching surface enters the gas collecting vessel and gradually fills it. When the vessel is filled with gas to a certain level, the vessel turns over and releases gas. In this case, the magnet approaches the magnetically controlled contact and closes it for a short time. Since the magnetically controlled contact in this case connects the power source to the input of the clock generator, this is the beginning of the clock cycle. The clock cycle time is determined by the timing circuit included in the clock cycle clock. The value of the duration of the clock pulse depending on the temperature of the solution is set either manually according to the scale printed on the panel of the device, or automatically. In this case, thermal resistance enters during the driver circuit.

As the temperature of the solution increases, the partial pressure of water vapor in the solution increases, which, together with the water supply resulting from the etching reaction, are collected in a gas-collecting vessel. This leads to a decrease in the time of filling the vessel with gas and, accordingly, to a decrease in the thickness of the layer to be removed over a given period of time (see Fig. 2). As the temperature of the solution decreases, more hydrogen and less water vapor are accumulated in the gas collection vessel by the time the sensor is triggered. Consequently, a thicker removable metal layer from the workpiece will correspond to filling the vessel with gas. Thus, at different temperatures of the etching solution, a different metal layer is removed from the workpiece during the filling of the vessel with gas.

The signaling pulse that occurs when the sensor is triggered starts the clock

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The first generator, the pulse of which is fed to the input of the counting pulse generator (see Fig. 3), the counting pulse generator starts generating short pulses with a constant repetition rate. The generation of counting pulses continues until the end of the hack pulse.

Since the number of counting pulses and the cycle time decreases with increasing temperature of the solution and, accordingly, increases with decreasing temperature, an automatic detuning occurs from the influence on the measurement accuracy of temperature changes in the etching solution.

Since counting pulses are counted by a pulse counter during the duration of the clock pulse and each new pulse is displayed on the indicator board, this device allows you to obtain information about the thickness of the layer being removed during the entire time the vessel is filled with gas, and not only at the moment of arrival of the signaling pulse that occurs when the reset gas collecting vessel of gas, as in the prototype.

Thus, the measurement of the number of counting pulses during a clock pulse, the duration of which is inversely proportional to the temperature of the solution, provides a significant reduction in the error, both due to temperature fluctuations of the solution and due to the lack of information beyond the filling of the vessel with gas.

Claims (1)

SUMMARY OF THE INVENTION A device for measuring the thickness of a peeling layer and the etching rate during machining of parts by size chemical etching, comprising a gas collecting vessel, a flexible indicator connected to it, a pulse counter and an associated indicator, in order to increase accuracy of measurements, it is equipped with a clock pulse generator connected to its first input by a clock duration generator and counting pulse generator, the signaling device is connected to the second input row clock generator, the output of the clock generator is coupled to an input of counting pulses, whose output is connected to the pulse counter. 657075iO85to 96 Typeratsra races / pbora About With Ft. 2. Impulse: signaling device That who pulses T r Fuck it. impulses FIG. 1 L