Homebrew PCBs

Does anybody actually know what the required (or recommended) adhesion 
temperature for typical negative acting dry film is?

I for some reason thought it was around 70 to 80 degrees, but I've been 
experimenting with much lower temperatures (maybe 55 degrees C at the 
most) with very good results (I'm using a clothes iron to laminate it 
and the temperature is measured on the hot plate as best my thermocouple 
will).

So I'm wondering what the actual necessary temperature is and how cold 
can we go before adhesion is compromised, for the clothes iron method 
the colder temperature we can use, the better, because of the danger of 
blistering the polymer with irons that are too hot.

On 23/12/13 23:39, James wrote:
> Does anybody actually know what the required (or recommended) adhesion
> temperature for typical negative acting dry film is?
>
> I for some reason thought it was around 70 to 80 degrees, but I've been
> experimenting with much lower temperatures (maybe 55 degrees C at the
> most) with very good results (I'm using a clothes iron to laminate it
> and the temperature is measured on the hot plate as best my thermocouple
> will).
>
> So I'm wondering what the actual necessary temperature is and how cold
> can we go before adhesion is compromised, for the clothes iron method
> the colder temperature we can use, the better, because of the danger of
> blistering the polymer with irons that are too hot.

It is commonly 100 or 110degC.

If 100degC stuff is done at 110degC it wrinkles, or blisters if there's humidity 
trapped.

Russell Shaw wrote:
>  
>
> It is commonly 100 or 110degC.
>

Interesting, I guess that's for a laminator, which will mean the film 
and board itself must be a lot cooler without prolonged contact with the 
heating device.

As mentioned, I'm using a clothes iron, if I took it to 100 degrees the 
film would be useless.  The iron is at best hitting 60 degrees when it 
is heating.  I can quite comfortably hold my hand to the hotplate.

The dry film is the usual no-name blue stuff.

On 24/12/13 09:19, James Sleeman wrote:
> Russell Shaw wrote:
>>
>> It is commonly 100 or 110degC.
>
> Interesting, I guess that's for a laminator, which will mean the film
> and board itself must be a lot cooler without prolonged contact with the
> heating device.
>
> As mentioned, I'm using a clothes iron, if I took it to 100 degrees the
> film would be useless.  The iron is at best hitting 60 degrees when it
> is heating.  I can quite comfortably hold my hand to the hotplate.
>
> The dry film is the usual no-name blue stuff.

<http://www2.dupont.com/Imaging_Materials/en_US/products/dryfilmPhotoresist/etchmaster.html>


This one says the laminator temperature should be 110 +/- 5degC:

<http://www2.dupont.com/Imaging_Materials/en_US/assets/downloads/datasheets/em213.pdf>

If you iron the pcb a few times, there will be more heat-soak and hence 
temperature build up in the pcb compared to a single pass through a laminator.

I typically use just under the boiling point of water (200F/93C) in case
there's any trapped water on the board.  If I know it's dry, I'll use a
little hotter, 240F/115C I think, which is closer to the recommended
temp for Riston films.