http://www.led-professional.com/products/led-thermal-management/insulated-metal-substrate-denka-hittplate
Very good etching agent for etching a Mcpcb / ims with aluminium core / substrate ,is Sodium Persulfate .
http://en.wikipedia.org/wiki/Sodium_persulfate
I use for every
~500 ml of water ,a
soup spoonful....
It dillutes in cold water ,with a bit of stirring ..
In warm water ,even easier ...
Use the Pyrex glass bowl ,to etch the pcb ...
Let it sink ,inside etching solution ...
Occasionally ,check the progress and stir a bit ...
(...with the
wooden chopsticks ! Or use something made of plastic .
Do not use metallic objects to stir an etching solution ! )
....
When etching is done ,remove the pcb ,and wash it with water ,thoroughly ,
so there will be no etching solution
traces left on pcb ...
Notes :
-In cold etching solution ,procedure lasts long ,but results are really well etched pads/traces ...
-In warm
(low heat ! ~40-50 °C) etching solution ,procedure really speeds up ,but marker cover ups may go off and
tracing is quite " rough "....
( ..Excess copper is removed under the toner print ...At the copper ~70-100um "profile " ...
Giving a "over-etched " apperance to traces/pads ...)
-Fresh Etching solution (transparent ) might cause deposition of copper on exposed aluminium of pcb .
(at sidecuts...
Back of pcb ,still has the protective plastic film on ..) ..
Afterwards ,when etching is done,those copper deposits ,go -off easily by water ...
But under them ,aluminium is ..etched ..Tiny black holes ,where copper was ..Not deep ..
But if pcb is cut exactly in final size and there's no "head room " for some file work ....
Then ...It's pretty bad ....
So better to use some
used ( bluish ) etching solution ,in that case ..
Etching solution ,that already contains some diluted copper (bluish color ) ,does not
affect aluminium ..
Then ,that phenomenon ,completely disappears ...
-Etching solution lasts long ...You do not throw it away ,after it's first use ..
You just add water and etching agent -when needed -,in same first solution..
It can be used for many etchings ...
(kept in a plastic bottle ..I.e of water ... ) .
When colour
has become really blue ,then you'll have to find a way ,to properly , "throw it away " / dispose it ...
It's a toxic for the environment chemical ...
It contains really high amounts of metallic copper!
Meaning it kills almost every aquatic organism..
...You do not flush it in the sink !
-Stirring accelerates the process ...
...
