This is the latest Cu wire recipe that includes the recipe for 1 mil Cu wires.

1. Recipe for Copper Decapsulation Using RKD Elite Etch
Acid Type: Temperature Volume Heat-up Etch time Rinse time
(Celsius): (ml/min): time (sec): (sec):
(sec):
Mixed 3:1 Varies with
35° 5 120 0
Pulse Mode package size
90% Fuming Nitric
See Cookbook
20% Fuming Sulfuric
Post Etch Rinse: Spray with Acetone.
Post Cleaning varies with device.
UltraSonic with Acetone. or D.I. or IPA.
NMP seems to attack the wires. ( Again this is device specific. )
Dry with N2
Note: This works excellent for Cu wire of 2 mil or larger on the Elite Etch.
Acid Type: Temperature Volume Heat-up Etch time Rinse time
(Celsius): (ml/min): time (sec): (sec):
(sec):
Mixed 3:1 Varies with
25° 5 120 0
Pulse Mode package size
90% Fuming Nitric
See Cookbook
20% Fuming Sulfuric
Note: This recipe works with wires ≥ 1 mil. ( These recipes only work with the RKD Elite Etch.
( The Nisene systems are unable to achieve the desired results due to pump technologies, mixture control, and
temperature characteristics. )
Ambient room temperature is also a factor.
The ambient room temperature must be at least 3 degrees colder than the etch temperature for this process to
work.
Post Etch Rinse: Spray with Acetone.
Post Cleaning varies with device.
UltraSonic with Acetone. or D.I. or IPA.
NMP seems to attack the wires. ( Again this is device specific. )