RF POWER SUPPLY and MATCHINGBOX
6. Matching Adjustment
70
②
At the point where there is even a little discharge, manually operate the TUNE/MATCH variable
capacitors and adjust them in the direction where the discharge grows stronger (the direction
where Pr decreases).
* It depends on the equipment, process conditions, gas pressure, gas type, electrode configuration,
temperature and the presence of an igniter, but generally, if you move the variable capacitors in
the direction where VPP increases, electrical discharge will occur more easily.
③
Because of the tendency for Pr to decrease, see "Pr decrease direction and adjustment methods"
below and increase or decrease the number of coil turns or add a fixed capacitor.
Table 6-1 Pr decrease direction and adjustment methods
Symptom
Cause
Action
MATCH variable capacitor at minimum.
Pr at minimum
Insufficient coil (L) short circuits
* L is too large.
Decrease the coil turns.
Adjust the taps, replace the coil, etc.
MATCH variable capacitor at maximum
Pr at minimum
Excessive coil (L) short circuits
* L is too small.
Increase the coil turns.
* Adjust the taps, replace the coil, etc.
TUNE variable capacitor at minimum
Pr at minimum
The R component of the load impedance
is too large.
Add a capacitor in parallel to load.
TUNE variable capacitor at maximum
Pr at minimum
The R component of the load impedance
is too small.
Add a capacitor in parallel to TUNE
variable capacitor.
The TUNE/MATCH variable capacitors
are both within 0% to 99% and Pr is at
the minimum point, but a little Pr
remains.
The length of the coaxial cable is not
appropriate.
Try changing the length of the coaxial
cable ±1 m from the current length.
Can match at low power but Pr increases
abruptly if Pf is increased.
①
Coaxial connector poor contact
②
Wiring failure between MBX-load
③
Poor withstand voltage between
MBX-load
④
Variable capacitor damage (abnormal
electrical discharge)
Repair the locations with poor contact and
repair the locations with poor withstand
voltage
Pr is entirely reflected in every position
the TUNE / MATCH variable capacitors
are placed.
①
If there is no discharge, RF line
wiring is faulty
②
If discharge is weak, insufficient
matching adjustment
Check the wiring and try greatly changing
the number of coil short circuits.
