awful! Inadvertently, the plasma cleaning products are getting dirty and dirty.
Oct 18, 2018

Vacuum plasma cleaning equipment is widely used in precision electronics, semiconductors, polymer materials, etc., but if the equipment is not properly operated, it may cause secondary pollution of the product and economic losses. The small partners of PLAUX use the following cases to remind everyone, for reference only:

1. Problem: A customer reported that the product was contaminated by oil in the use of vacuum plasma cleaning equipment, and this problem did not occur in the same equipment.

2. Analysis of the cause: According to the information provided by the customer equipment operator and PLAUX equipment inspection on site, it is found that the vacuum indoor product is contaminated because the equipment is alarmed, and the equipment is improperly operated, so that some oil and gas generated by the vacuum pump is sucked in. The vacuum room is here.

3. Specific description: The vacuum plasma cleaning equipment is usually operated in the standby state, mainly through the opening and closing of the high vacuum pneumatic flapper valve (baffle valve) to realize the vacuuming function of the vacuum chamber. During the operation of the equipment, if there is a vacuum pump countdown fault, vacuum pump thermal overload fault, power supply deviation and excessive reflection, the equipment will automatically stop (including the vacuum pump) in order to protect the critical parts of the equipment from damage.

After the equipment alarm is stopped, the high vacuum pneumatic flapper valve is also naturally closed, but the vacuum chamber is still in a high vacuum state. For example, after the equipment has a downtime, the operator does not perform the vacuum breaking or the opening of the vacuum pump according to the usage specifications, but directly clicks the start button on the automatic interface, then the high vacuum pneumatic flapper valve is processed into the vacuum chamber. In a high vacuum state, the high vacuum to the vacuum pump end is at a normal pressure state. At this time, after the high vacuum pneumatic flapper valve is opened, if there is residual oil and gas at the vacuum pump end, the oil and gas will be sucked into the vacuum chamber by the negative pressure in the vacuum chamber, causing pollution of the vacuum chamber product.

4, the solution:

4-1 Specification of the operation of the plasma cleaning equipment user

When the equipment is alarmed, stop the vacuum operation and confirm whether the vacuum pump is stopped due to the alarm; if the vacuum pump is stopped, the vacuum pump should be turned on before continuing to use the equipment.

4-2 Increase the interlock function of the control circuit

In addition to the use of the operator, taking into account the mobility of personnel and the execution of operational specifications, PLAUX also considers simple and effective optimization from the control of the equipment, increasing the start of the vacuum pump and the start of the high vacuum flapper valve. The interlock function ensures that the high vacuum pneumatic flapper valve cannot be started when the vacuum pump is not opened, so as to prevent the vacuum chamber from returning due to misoperation.

4-3 Specific introduction of the program

Under normal conditions, the vacuum pump and the high-vacuum pneumatic flapper valve are independently controlled, as shown in the following figure: The second intermediate relay (K1) from the left realizes the control of the vacuum pump, from the left to the seventh The intermediate relay (K7) realizes the control of the high vacuum pneumatic flapper valve, and both receive the signal and the corresponding intermediate relay pulls in to realize the control of the load.

Intermediate relay

In order to ensure that the vacuum chamber does not inhale the oil and gas due to misoperation, it is necessary to ensure that the K7 high-vacuum pneumatic flapper control lines k7 and L7 are not energized in the non-operating state. In this case, the L7 line in the electronic control is shifted. Connect to the other end of the other normally open contact in K1 and connect a wire from the other end to the wiring of the original L7 line in K7. In this way, the interlocking between the vacuum pump and the high-vacuum pneumatic flapper valve is realized, and the high-vacuum pneumatic flapper valve cannot be opened in a state where the vacuum pump is not working. As shown below:

Intermediate relay-2

The blue line on the graph indicates that the original L7 is turned to the end of the normally open contact of K1, and the red line indicates the newly added line.

The above method is the simplest and most effective way to prevent and modify. The operation is simple, safe and reliable. However, in order to ensure the quality of the product, it is necessary to standardize the operation specifications of the users of the plasma cleaning equipment. When the equipment fails, it should enter the manual interface to break. Vacuum action, if the equipment has a long downtime, and the product has been in the vacuum chamber under high vacuum, it will also affect the product.

What is the inspiration for the analysis of this case? Similar questions and solutions are welcome to share your message and share with us.

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