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Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
Nicko -
Very nice looking boards.
I assume that you are using a stereoscope during soldering?
In another thread, there is an ongoing discussion on PCB fabrication, on-line fab houses, etc. What design tool did you use, and who fabbed the boards?
Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
Herr Zapp wrote ...
Nicko -
Very nice looking boards.
I assume that you are using a stereoscope during soldering?
In another thread, there is an ongoing discussion on PCB fabrication, on-line fab houses, etc. What design tool did you use, and who fabbed the boards?
Thanks for the feedback - still putting the boards together - last bits should arrive this weekend. I use a good USB microscope for fine detail work - its a b*gger but as I get older, I've had to start using varifocal glasses, and SMD gets harder to do. However, a good binocular uscope is on the list (recommendations welcome). The boards above normally use nothing smaller than 0603 (mostly 0805) and chips no smaller than SOT-23.
Everything is done in Eagle (Pro version) - boards fabbed by Olimex. They did charge me a bit extra for the bridge board as I deliberately left some of the polygons exposed (no silk screen) as I want to silver-solder-load the high current traces. All that gold does look nice though Synthesis is mostly in LTspice, physical modelling in SolidEdge.
Not sure if I will build it this w/e as feeling rough - half my staff are either down or going down with H1N1. Rats.
Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
Herr Zapp wrote ...
Very nice looking boards. I assume that you are using a stereoscope during soldering? In another thread, there is an ongoing discussion on PCB fabrication, on-line fab houses, etc. What design tool did you use, and who fabbed the boards?
Hmmm... there has been a delay in making up these boards as my eyesight was not fully up to it, and even though I use nice Metcal MX500 soldering equipment, that wasn't either.
So I've invested in a decent solder paste applicator, an infrared pre-heater & SMD infrared oven.
Hopefully, over the next week or so, I should get the boards built (after some experimentation with some lesser boards)...
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Nicko wrote ...
Sigh. Why is nothing simple...
You brought it on yourself by using SMTs! Should have gone for the Duplo sized through-hole stuff
At work, we have to deal with 0603 and smaller, but we all hate it and would make everything out of DIPs and 1/4 watt resistors if we could still get them. I recently blew up a chip in a 2x2mm QFN with exposed thermal pad, and had to get it off the board and solder on a replacement.
Registered Member #1334
Joined: Tue Feb 19 2008, 04:37PM
Location: Nr. London, UK
Posts: 615
Steve McConner wrote ...
Nicko wrote ...
Sigh. Why is nothing simple...
You brought it on yourself by using SMTs! Should have gone for the Duplo sized through-hole stuff
True - though I've been pretty much all SMT for years. These boards are almost entirely 0805 / SOT-23 or larger and I never used to have problems with them. Main problem has been paste application - just using a syringe has proved... shall we say, problematic... certainly for a dense board like this...
There's lots of folk doing BIG/HUMUNGOUS but not many going in the other direction. I'm a big fan of what Derek and others have done... anyway., BIG scares me...
Initially bought a cheap pneumatic dispenser - bad move bought about by breaking one of my own long standing/cardinal rules - i.e. get the best tools you can afford. Cheap, in this case, meant waste of time and rubbish quality. Time is not something I have a whole lot of, so sent that one back and purchased a much better one. Got some fresh paste with the correct viscosity and profile from Farnell this week - costs three times what it does in the USA... I'm not sure yet about the infrared oven - its a T-962 (pretty much only type available) - lots of 'em on eBay - mixed reviews on the web from users though, mostly complaining about hot-spots on larger boards... Unit construction looks good, so I'm hopeful for smaller boards like these at least. Will test this weekend...
Basic rule of tools: Cheap, long-lasting, good. Choose any two... (you won't get all three)
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uDR/SSTC design - updated with full bridge testing and current monitoring..
Rats.
