We make our own laser cutters + direct print software + control electronics:
www.fullspectrumengineering.com/co2laserv2-40w.html
Our 40w has 1000dpi and I can easily do stencils for my .5mm pitch devices
for around $2000. Shameless plug: we have better vector cut quality than
even a $20,000 Epilog laser due to a superior spline trajectory algorithm
(verified side by side).
We also have pulsed fiber lasers that can do stainless steel stencils but
these are $35k+.
Laser transperency is the best material. It is heat resistant and cheap.
Others use kapton but this is an inferior CO2 laser material.
Again take it from me if I don't make the stencil when I make the laser and
can modify the software anyway I want (I just hit File\Print from Altium and
the stencil would pop out) that the syringe is easier for one offs.
You should keep your paste up to room temperature otherwise it will get
stuck in the 25gauge tip.
Henry
On Tue, May 10, 2011 at 12:36 AM, Boman33 <boman33@...> wrote:
>
>
> Thanks everyone for the feedback.
> I am ordering the Zeph paste and the Chipquick one and some thick flux
> paste
> too.
> Both companies have good videos and info.
> My goal is to develop a foolproof procedure since we have to rework over
> 100
> 12 layer PCBs each with six 208 pin 0.5mm spacing ICs for a customer.
> Stencils are not practical on a populated board so that is why I am looking
> for a controlled amount of solder paste dispensing.
>
> Henry: What are you using for the laser cut stencil material?
> Bertho
>
> -----Original Message-----
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Henry Liu
> Sent: Monday, May 09, 2011 23:04
>
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: Controlled solder paste dispensing
>
>
> Using Zeph paste and a 25 gauge plastic syringe + hot air gun , I can
> solder
> a 128 pin .5mm pitch QFP in under 10 seconds (including the pasting time)
> with no bridging.
>
> I cannot usually solder .4mm pitch devices without some bridging. However,
> I just use kester flux in a syringe and a wide soldering iron and drag it
> across the pins and this moves 99% of bridges as long as I made my pcb pads
> big enough.
> Syringes have no cleanup.
>
> I have a laser cutter and it's pretty effortless for me to make a stencil
> but I don't use it unless I need to make more than 2 boards because the
> cleanup time is more than my syringe time.
>
>
>
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