TRANSAT CORP.TRANSAT CORP.
| QUARTZ BLANK PRE-ETCHER MODEL QBP-1000 |
"Pre-Etching" of blanks before final -frequency etching offers important advantages in etch processing. Pre-Etching covers the initial non-linear etch phase, during which the blank surface is cleaned of the lapping debris.
The traditional etch-to-frequency sequence has been:
LAP ® SORT ® FINAL-ETCH,
But some manufacturers have changed the sequence
LAP® PRE-ETCH (to linear range) ® SORT® FINAL-ETCH
This approach has the advantage of smaller frequency spread, more accurate air gap measurement, reduced final-etch time, and a more uniform final-etch rate. For etch control with Transat's Crystal Etch Monitor (CEM), it has the added benefit that a single monitor blank can be used for multiple etch runs, since its surface finish need not be the same as that of the load blanks.
The disadvantage of separate pre-etching is high labor cost, unless it can be simplified and automated. Some users have developed their own solution to this, but it appears that until now, no suitable commercial equipment has been available.
The Model QBP-1000 is made from etch-resistant Polypropylene, except for the drive motor. It has a removable (via bayonet snap lock) barrel with meshed walls. For etching, it is filled with completely clean (to prevent sticking together) blanks, and then sealed with a cap. It is then mounted on the drive and the whole unit is put in the etchant such that the top of the barrel is immersed about 6 mm below the etchants surface. The barrel is rotated at variable speeds (4 to 20 rpm), while internal ribs help tumble the blanks.
After etching, the unit can be immersed in neutralizing/cleaning tanks. If desired, the immersed mass of the unit can be reduced by removing the units base stand and providing slots in the tank for holding the unit.
The pre-etching can be controlled by time or by the CEM. The required removal into the linear
range depends on the blank's surface finish. For example, a removal if about 1 "Fsquare" is sufficient
for a 5-micron surface finish. The barrel has a diameter of 63 mm and comes in two lengths, 70 mm and 100 (240m
without base) and 85 mm width.
Product Information
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