Homebrew PCBs

I think he might mean stencils. The answer is still the same: few of us and 
it doesn't make much difference. The stencil's job is to mask the paste into 
an even thickness only where it's needed. Typically, the stencil is 3 to 5 
mil thick. Adding the solder mask thickness, it leaves about 8 mil of paste 
on the pads after troweling off.

Why might you not need a stencil? Conversely, why are they used if you can 
do without? Very briefly: surface tension, and manual application versus 
automated production line. Apply the paste where it's needed, not too much 
and not too little. Bridging isn't a concern. Experiment a little. Prove it 
to yourself.


----- Original Message ----- 
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, January 31, 2006 12:21 PM
Subject: Re: [Homebrew_PCBs] Re: Question: using surface mount 
resistors/caps ?


> On Tue, 31 Jan 2006 17:20:01 +0100, derekhawkins <eldata@...> wrote:
>
>>> You could also use paste and reflow if appearance is an issue, it
>>
>>> self-centers exactly due to surface tension and looks perfect.
>>
>>
>> No kidding! How many of us are reflowing on boards without solder
>>
>> masks?
>
>
> Most of us, actually, i guess ;-)
>
> Of those that using smd paste that is.
>
> Why would you think you need soldermask?