Advanced Materials for Electronics

AlPAD Etch 639

AlPAD Etch 639 is an oxide etchant designed to minimize attack on aluminum pads or other aluminum structures and on silicon surfaces. These oxides are commonly grown in vapox silox or other LPCVD devices. The deposited oxide is often used as a passivation layer over a metallized silicon substrate.  The formulation of AlPAD Etch 639 includes a surfactant to ensure wetout over high surface energy substrates.

Deposited Oxide (Vapox/Silox) Etch Rate: 5000 A / minute @ 22oC

This product contains:

  • Ammonium Fluoride
  • Glacial Acetic Acid
  • Glycol
  • Surfactant
  • Deionized Water


How do I increase the etch rate? 1. The rate will approximately double with every 10°C increase in temperature.
2. Increase the rate of stirring or agitation.
How do I reduce the etch rate? Adding 1 part deionized water to 2 parts etchant will reduce the etch rate approximately 50%.
Do I need to dilute the etchant? No, it is ready to use.
How do I reduce undercutting? Increase the rate of stirring or agitation.
Appearance Water-white
pH Mild acidic
Etch Rate at 22°C
5,000 Å/min.
10,000 Å/min.
Etch Capacity 0 g/gallon
Shelf Life 1 year
Storage Conditions Ambient
Filtration 0.2 um
Recommended Operating Temperatures 20-80oC (30-40oC most common)
Rinse Deionized water; may be followed by alcohol rinse if desired.
Photoresist Recommendations KLT6000 Series, KLT 5300 Series, HARE SQ (SU-8 type), TRANSIST, or PKP Type II
Select Compatible Materials Aluminum, ceramic, gold, nickel, copper

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Select Incompatible Materials Silica, alumina, silicon nitride
Compatible Plastics HDPE, PP, Teflon, PFA, PVC
Country of Origin USA
Availability 1-2 Business Days
Available Sizes Quart, Gallon, 5 Gallon, 55 Gallon
Packaging HDPE
Packing 4 gallons/case
Isotropy Isotropic
Incompatible Chemicals
Additional Information