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[DPRG] PCB fab & SMD parts

Subject: [DPRG] PCB fab & SMD parts
From: Rick Bickle rbickle at intconsys.com
Date: Mon Jul 26 12:44:27 CDT 2010



I use PCBFABEXPRESS.com for by prototype boards. For large volumes I use
a Chinese fab house. You definitely want the solder mask for SMT parts. 


There are several good ways to manually assemble SMT boards. The best
depends on what pitch of parts you will be using. If you have a decent
microscope of about 5x to 10x, you can use a soldering iron and some
thin .020" wire solder to get pretty good results. It does take time
though. I just assembled a board with a 208 pin 0.5mm pitch QFP ARM9
processor using a microscope and soldering iron. 

For hand soldering of SMT passive components, I recommend using 1206
size parts. SOT23's can be hand soldered, you just have to remember with
all of them to do it quickly. Holding the iron on the leads for more
than 1 second or so is likely to damage the part. It also helps to add a
bit of flux to the board before placing the parts. 


I've been tinkering with using my laser to cut out .003" mylar sheets
for use as solder paste stencils. Haven't got it bulletproof yet, so if
anyone has advice here it would be appreciated.





From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org] On
Behalf Of Ray Xu
Sent: Sunday, July 25, 2010 11:17 AM
To: dprglist at dprg.org
Subject: [DPRG] PCB fab & SMD parts


Hey Guys,

Anyone know cheap and fast PCB Fabrication services?  I'm reconsidering
my decision to fabricate my own boards now (advice from a friend)...

Board size would probably be around 6x6in.   
I only need a specific board design made several times.  I also have
several designs needed to be made.
Solder mask not required; but would be nice...
silkscreen not required
double sided & SMD use
board material doesn't really matter
Electric testing not needed.
MOST IMPORTANTLY: affordable/reasonable cost and fast fabrication time
(1-3 days).  Preferred total cost below $30 per 4 or so boards; $50 at

And also...  Since I'm novice to soldering parts onto circuit boards,
I've never really soldered SMDs before.  I'm considering using SMD
resistors, capacitors, transistors (SOT23 package), and ICs (SOIC14
packages or larger) in my design.  Would the soldermask be very helpful
for my level?  What size resistors/capacitors do you guys recommend?  I
want to use a size that is big enough to be hand soldered and thick
enough so it can be easily grabbed by a small tweezer from the top.  And
what about the SOT23; I have scrap boards and they look awfully small to
solder...How hard is it *actually* to solder?

And lastly....I have this
http://www.vellemanusa.com/us/enu/product/view/?id=522806 soldering
station (and with a couple screw driver-like tips).  Is this suitable
for SMD soldering?


Ray Xu  

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