Hi Ed,
As I realise you have thru' hole component before epoxy application. As
for our process, we insert the thru' hole after the SMT process. That's the
difference between your process and ours.
I am not too sure about the print life. However, I have been printing since ]
year 92..
The reason why I started off with this method is due to insufficient output
from dispensing machine. I have to feed 2 SMT lines for the same models.
The volume during is pretty high.. I have problem at the beginning with the
epoxy thickness. The SOIC package has a pretty high stand-off. Later,
I have mounted 4 pieces of small 5 mil thick plate at bottom corners of the
stencil. I work OK but inconsistent. Later, I re-design the stencil using the
plate thickness of 12 mil, play around with print speed and squeegee
pressure. It works well.
I only using Camalot for pilot run or Screen printer down for maintenance.
We presently run a model, about 300 points at the solder side, that
require epoxy to hold the component, Epoxy used is Loctite 3607 and
the line has continue running this product for 6 days without changing
the epoxy. So far the printing quality is pretty OK.
I have try Loctite 3612, it works pretty well too. Except for the smell.
To remove the epoxy or clean the stencil that with epoxy, I guess you
have to check with Loctite. They have a good epoxy remover. So far I
have evaluated it, but have not use it, I still have some old ex-stoxk chemical
that blend by one of our local companies.
I am not sure that I have answered correctly. Please do Email me if you need
any info' that I able to provide.
--------------------------------------------------------------------
At , you wrote:
>Poh Kong Hui
>
>You stated that you are stencil printing your smd adhesive. I am aware of
>the process and read about it. We presently build mixed technology boards
>so this process is not necessary for us, we dispense adhesive because the
>thru-hole parts are already in the PCB. I would like to know why you chose
>this process, how you are using it in production and the problems and
>successes that you have with the process, especially in the print life and
>cleaning.
>
>Anyone else is welcome to answer also.
>
>Thanks
>
>Ed Holton
>[log in to unmask]
Poh Kong Hui
Nera Electronics
Fax: (65) 7765492
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