My first surface mount (SMD) design.
Bean
Posts: 8,129
Here is my first design using surface mount componets.
The layout is more challenging, but the assembly is much faster.
I soldered everything except the SX28 (I had someone at work do it), she soldered it by hand with a soldering iron, so it CAN be done folks. But not by me...
If you've never tried a SMD layout it not that hard, go for it.
In case your wondering about the board, it was made with an LPKF milling machine. This machine works like a milling machine and mechanically removes everything that is not copper. Then I tinned the board using a liquid called "Liquid Tin". It's pretty amazing stuff too.
Comments ? Suggestions ?
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/8/2005 9:11:10 PM GMT
The layout is more challenging, but the assembly is much faster.
I soldered everything except the SX28 (I had someone at work do it), she soldered it by hand with a soldering iron, so it CAN be done folks. But not by me...
If you've never tried a SMD layout it not that hard, go for it.
In case your wondering about the board, it was made with an LPKF milling machine. This machine works like a milling machine and mechanically removes everything that is not copper. Then I tinned the board using a liquid called "Liquid Tin". It's pretty amazing stuff too.
Comments ? Suggestions ?
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/8/2005 9:11:10 PM GMT
113K
Comments
ExpressPCB now has surface mount options and I have been working with that. Just worried the same as you about getting it all soldered.
·· Nice work...I haven't soldered surface mount yet to date either.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
If you get the larger size resistors and caps (I used 0805 0.08" x 0.05") they are not that bad. You can get upto 1206 (0.120" x 0.060").
I can solder SOIC chips, but I can't get the dang SSOP. So I was concerned when Ubicom stopped making the SOIC.
You can also buy "blank" chip (these are either bad chips or chip packages with no die inside). You can use them to practice.
And most surface mount resistors are about $0.01 each.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
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Sid Weaver
Need a bezel for your LCD?
Newzed@aol.com
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Bean,
I used to be scared of all this surface mount stuff, but one on our techs showed me a neat trick. Depending on your eye balls you may need to purchase a microscope, a 10x should be sufficient. When soldering a high density part, liquid flux the area liberally and then with solder in one hand and iron in the other, apply solder and heat to all the pins. I'm right handed so I so I do it left to right, iron in my right hand (Metcal SP-200 w/big chisel·tip). At first thought you would think that you'll solder bridge everything, but with a little practice and a little solder wick braid, you'll get a good joint on all the pins every time. Kinda like learning how fast to feed a piece of wood on a table saw to get a smooth cut.
Mike
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"OEM NMEA GPS Module" Now available on ebay for only $19.99
Product web site: http://www.allsurplus.net/Axiom/
Post Edited (Mike Cook) : 6/9/2005 12:22:30 AM GMT
I buy a reel of 5000 from digi-key. It's alot of money, but I figure it's basically a "lifetime" supply. If it's an odd value, then I buy cut-tape.
Mike, I'll have to try that sometime. Thanks for the tip.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/9/2005 1:00:26 AM GMT
As it turns out, Digi-Key is why i found parallax. i was looking through it one day and saw microProcessors. I knew i wanted to buy one seom day.
I did a search on eBay and found some Parallax on there and thta's how I got my BOE and a few processors.
Anyway. That's cool with the surface mount. I bought some IC's a few months back and I goofed and got surface mount on accident . It looked pretty scary to solder so they just sit here with my pile of parts
You said "she" soldered it. You got a girl at work with a steady hand and good eyes or something?
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http://www.paysonarizona.net/
Paul posted a good link to a video that shows just how easy.....
http://www.howardelectronics.com/xytronic/Images/Drag%20Soldering%20107.wmv
My bosses said they had some men, but they can't seem to handle sitting in a chair for 8 hours a day.
I know I could never do what they do. I would go crazy in about a week.
Yeah sure they complain about doing the fine pitch stuff, but they are damn good at it.
Any time we have a small quantity of units they assemble them by hand.
Sometimes they apply solder paste by hand. Then place the parts by hand. But most of the time they just solder them with an iron.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
·
http://www.pulsar.gs/
See Robotroom.com for techniques to use Expresspcb's free software for home circuitboard construction.
The Pulsar system uses a lazer printer sheet to transfer the circuit board traces to a special sheet. This is ironed onto the board, much like the similar press-n-peel system. The special sheet desolves in water, no peeling required
I'm trying a Duck Electric Laminator from Walmart that cost $24 for the iron-on process.
The Pulsar system has a second green sheet that seals the toner on the board. This permits rapid etching with ferric chloride applied with a sponge.
Their website describes the process in more detail, in glowing terms.
Through hole components require drilling the board. This becomes a major workload for home constructed boards. The classic Dremel drill press base is not available until October. Drilling with resharpened carbide drill bits requires high speeds, not available on low cost table top drill presses. I built a Dremel holder for my metal lathe so I may be forced to use that technique.
Instead of complaining about the small soldering space required of smt construction we should consider the benefits of eliminating the drilling required by old through hole devices. ONWARD TO SMT, FOLKS.
Nice looking board! Tracks look realy thick. I've heard of these milling machines, An associate tells me that someone in Durban (thats somewhere in Africa) uses a small Roland machine. Cuts his PCB development time down to about a day! (From circuit design to PCB made, drilled and ready to solder).
Your solder work also looks good. SMD can be tricky to solder, particularly when you get down to the 0,3 mm IC pins. I worked in SMD PCB assembly for a couple of years and we had specially trained and skilled operators to do the repairs and prototyping solder work. Quite specialised work.
I think I'll stick to leaded components for now (though you're already getting components which are only made in SMD packages)
Hey - well done
Kind regards from Kwa Dukuza (Somewher in Africa)
John Bond
I don't understand the "removes everything that is not copper" statement.
How did you mask the traces?
Comparing the two boards:
I see you replaced jumpers with Dip switches. Very nice.
There seems to be more resistors on the SMT board. No?
What did you replace VR1 with? Is that a variable resistor or a transistor.
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Jack
I meant that the milling machine removes copper to create the traces. It is on a X-Y table.
Since the SX chip is soldered in, I added 220 ohm protection resistors to the 8 outputs.
Yes I'm using a different regulator (that's the 5 pin device in the lower left corner).
The SMD version also uses a new program that runs at 20MHz instead of 50MHz and still has all the features. Plus the new background SOUND command.
Since the clock is lower, so it the current down from 100mA to less than 40mA.
The back side of the board is solid ground with 1 Vdd trace. (That was no easy feat).
One thing to keep in mind if you do a SMD layout, is that although the parts are very small, if you plan to assemble it with an iron you have to keep plenty of distance between the parts to get the iron in there.
You also have to be smart about the order you solder the parts in.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/9/2005 4:56:20 PM GMT
can you borrow me the lady soldering the SX on your new board? She did a pretty nice job - having someone here I would convert my designs to SMT immediately
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Greetings from Germany,
G
I don't know what she gets paid... But it's not enough. We would be lost without her.
My next step is to try some of that "toaster oven" or "skillet" reflow stuff with solder paste.
Here is a larger picture of the unit... You can really see the quality of her work... And the lack thereof in my work...
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/9/2005 5:07:44 PM GMT
yes, she really did an excellent job but your solder points don't look that bad at all.
BTW: I can only see a few plated-through holes, so I assume that most of the signal traces are located on the component side. As far as I can see, there is a ground plane (connected to Vss) on the bottom of the board. It might be an idea to fill the empty space on the component side with copper planes connected to Vdd where possible. This would make a nice capacitor to protect against EMI.
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Greetings from Germany,
G
Good idea to make a top plane and connect it to Vdd. Thanks.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
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Don't forget that resistor in parallel with your resonator.....I see you planned for it.
In the past I used a machine as you described to make PCB's. A nice machine....except when the milling bit breaks !!!!!
I actually have some unpopulated boards left over from that process.....I will take a pic tonight and post it just for the heck of it.
Curious on two points....
1. How do you do the vias (looks like vias)?
2. How is the copper held down on the XY table?
2) Believe it or not....Masking Tape... Worlds cheapest clamp. There are two locating pins too.
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
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I would kill for a circuit milling machine.
What a great tool for prototyping. I think everyone should have one.
I wonder if the SX community as a whole could design a milling kit.
I'd be happy to write the Windows interface.
That and a SX oscilloscope..
Ya, I dream big.
NOTE:
This idea has been moved to this thread.
http://forums.parallax.com/showthread.php?p=539099
Continue praising Bean on his board.
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Jack
Post Edited (PLJack) : 6/11/2005 4:19:39 AM GMT
Let's see where this goes. Maybe start a new thread to see if there is interest.
The basic concept as I understood it is
1. Create the artwork
2. Download to the machine
3. Set the milling depth and longitudal speed (too fast and you break bits)
4. Set the milling machine at a known XY corner
5. Hit a button and let it rip.
6. Once the milling was done, it would then wait for a drill bit to be installed, in a certain order for diff size holes.
If this actually goes anywhere, maybe Bean could take some pics of the machine at his work and add details that I left out.
hmmmmmm?????
It would definiately be a great project. Ken Gracey has also expressed interest in a PCB milling machine.
I'll see if I can get some pictures of our machine. It's a "LPKF C60".
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
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LPKF C60 is a German product - shall I check with the manufacturer for a mass discount
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Greetings from Germany,
G
Beautiful board!
I have been looking for a 2-position SMT switch like you have.· Did you get it at Digikey?· Do you have a part number?
Chris I.
The only thing I don't like about them is they have a bunch of lettering on them. I wish they just had the switch number (1,2).
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"If you keep doing what you always did, you'll keep getting what you always got."
Post Edited (Bean (Hitt Consulting)) : 6/11/2005 2:57:29 AM GMT
Yeah, I could do without the letters too.
Chris I.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=58294&item=7522474317&rd=1&ssPageName=WDVW
We got one of these when I was in school. It produced ugly circuit boards, nothing to do with that fine circuit shown on the Bean post.
These are production boards and I soldered everything (yes even the SX28AC/SS, and yes it was a bee itch).
Bean.
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"SX-Video·Module" Now available from Parallax for only $28.95
http://www.parallax.com/detail.asp?product_id=30012
Product web site: www.sxvm.com
"One experiment is worth a thousand theories"