Evaluation and control are performed by a transmitter with integrated control contacts, while an attached dosing pump supplies hydrogen peroxide from a reservoir
Jumo Instruments has introduced the Corrotrode for measuring the hydrogen peroxide concentration.
The PCB manufacturing industry employs etching baths based on sulphuric acid for various production processes, such as the manufacture of through-hole plating for multilayer PCBs (blackhole method), the 'microclean' stage and pre-treatment (pre-etching) during track formation.
In most cases, the etching baths consist of an approximately 8.5% sulphuric acid (H2SO4) solution, with a hydrogen peroxide (H2O2) component of about 25g/liter.
The concentration of hydrogen peroxide, in particular, is decisive for the quality of the product, and should be kept as nearly constant as possible.
Depending on the number of boards being processed, the hydrogen peroxide concentration in the etching bath diminishes as a result of dispersal and decomposition. Situation up to now.
Several times a day, depending on the throughput and the operational life of the plant, technical staff perform laboratory tests (titration of a sample with a potassium permanganate solution) to determine the hydrogen peroxide concentration.
Additional manual dosing restores the etching properties of the medium.
Disadvantage.
Isolated manual dosing causes overdosing of hydrogen peroxide at some times, and insufficient dosing at other times.
Solution.
In order to achieve a consistent rate of etching, and with it a consistent PCB quality, the hydrogen peroxide concentration should be kept constant by continuous automatic dosing.
The new, patented Jumo Corrotrode, fulfills the task of measuring the hydrogen peroxide concentration.
Evaluation and control are performed by a transmitter with integrated control contacts, while an attached dosing pump supplies hydrogen peroxide from a reservoir. Advantages of the Jumo Corrotrode measurement system.
Reduced consumption of the dosing agents.
Avoids incorrect dosing. Ongoing check of the media condition can be made through displayed value.
Continuous automatic dosing (controlled). Prevents underdose/overdose.
Reduces man-hours spent on laboratory measurements.
Alarm is generated if measurements drift.
Alarm is generated if there is no dosing agent (dosing time monitoring).
CIP processes alarm monitored.
The Jumo Corrotrode is a potentiometric sensor (CPPS = corrosion potentialbased potentiometric sensor) with an output signal covering a voltage range of several hundred mV.
Other areas of application are conceivable, such as semiconductor manufacture.
