Hello everybody,
Thanks for the answers.
I will try to answer to all the suggestions and make clear some
other
things.
1 Sophie, I want to make LCD's so we cannot change the substrate it
is a soda-lime glass with ITO on it.
2. Joao, I am using SU8-100 dissolving it with GBL if neccesary. SU8
2000 are not possible to use as it uses cyclopentanone as solvent.
3. Bill, The kiln is not an oven it is a kiln with ten sections of
hotplate I can set up temperature for each section and how much time
the
glass is in the kiln It not an oven we use.
4. Nadim, The layer thickness we want to achieve is 15 microns. I
dont actually know what thickness we have (it is close to 15
microns).
Usually I have a two step cooling in the kiln first from 95 to 65
then
to 45 and then to room temp.
Increasing the exposure time spoils the patterns we have to expose.
Another thing I am not coating the SU8 with spin-coater, but we are
trying to coat it with screen printer. At the moment the layer is
not
very even. So I have seen sheets where the SU8 is not developing at
all
where the coating is thinner but is lifting off during development
at
other parts.
I will try to change the cooling of the sheet to slower rate and see
what will happen.
Another question from me. How much the post exposure bake could
influence the adhesion to substrate?
Thanks everyone for the answers,
Janis
On 11.03.2014. 17:05, Bill Moffat wrote:
> Hi Bill
> His problem is most likely underbaking. SU8 process
recommendations are specific. Hot plate is recommended, not kiln. If
what he means by kiln is an oven, he is probably forming a skin and
trapping solvents and not baking enough to get them out.
>
> As far as an adhesion promoter that he probably doesn't need,
APTES or GOPS would do. It's epoxy resist, so either epoxy to meld our
amine to bind....
> Janis input from Ken Sautter our senior Process Engineer.
Additional thoughts, adhesion to ITO has always been difficult. I
quote Grant Wilson a true resist guru, "we have always had problems
with adhesion to ITO". This has been solved partially by treatment
with OCTS and totally with treatment with vapor OCTS. This is
unfortunately with standard positive resist. It may need APTES or GOPS
for adhesion to SU8. Bill Moffat
>
> -----Original Message-----
> From: [email protected]
[mailto:[email protected]] On
Behalf Of Janis Klavins
> Sent: Monday, March 10, 2014 7:51 AM
> To: General MEMS discussion
> Subject: [mems-talk] SU8 adhesion problems
>
> Hello everybody,
>
> I am trying to coat an SU8 material on ITO etched glass. I have a
problem that during development the SU8 lifts off the glass very
easily.
> if the glass sheet is immersed in the developer the SU8 lifts off
and floats away.
>
> I believe that this is a baking problem (too much or not enough)
after coating the SU8. I am using a two step kiln 65 degrees ( 1 min)
and 95 degrees (4 min). The same settings for post exposure bake.
>
> Has anyone seen a problem like this?
>
> --
> Best regards,
> Mr. Janis Klavins
> EuroLCDs
> Phone: +37163600300
> Mobile: +37126141049
>
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