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Author Topic: Surface mount anyone?  (Read 8300 times)
KI0BK
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Posts: 2




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« on: January 20, 2013, 09:05:39 AM »

Have you tried building with surface mount parts?    I started using SMD parts in projects a couple of years ago and found they are both easy and fun to build with and still find it fun to watch the parts "float" into position when heated with the hot air gun.   What are you building?

Jim KI0BK
maker of the Low Loss PwrGate
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KE3WD
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Posts: 5689




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« Reply #1 on: January 20, 2013, 11:02:44 AM »

Been prototyping SMT for commercial product development since they first appeared. 

I just use a regular fine tip iron and eutectic wire roll solder anymore, it is faster and has always worked just as well for me. 

Of course, once the prototypes are proofed, manufacturing facility is used to assemble final products using all of their automated methods. 

But my hand soldered prototype boards are all still operative. 

I think it is a pity that a lot of hams are somehow reluctant to get into Surface Mount for various reasons, there is far more going for it than against it. 

73
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M0HCN
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Posts: 473




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« Reply #2 on: January 20, 2013, 12:26:12 PM »

Seconded, and the key to good hand soldering with SMT is to get a small bottle of liquid no clean flux, makes it go much easier.

1206 is trivial, 0603 is easy if not too dense, 0402 is possible, and 0201 is forget it without a microscope.

I have a pet loathing for QFN & DFN of the sort with thermal pads, send those out to be done in a reflow oven, but for routine things SOIC is trivial and MSOP is not that hard but really needs a magnifier to check.

Kapton tape is helpful with large parts to hold them in place until you get the corners tacked down.

My current build is a DUC/DDC SDR with far too many DFN and LFCSP packages (which are being sent out to be assembled), and one 700 odd ball BGA (A Large FPGA) which is definitely being sent to an assembly house.
Plan is to fit 4 sample synchronous ADCs and DACs so I can run a four square with electronically steered pattern (Or even play some with synthetic aperture stuff on the higher bands).

Oh, if getting boards made, pay extra for ENIG surface, much better to work on then organic preservatives, especially if doing the work on a board over a few weeks.

73 Dan.
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WB6BYU
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Posts: 13243




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« Reply #3 on: January 20, 2013, 09:58:21 PM »

I recently built a hand-held 80m DF receiver using a mixture of SMD and ugly
construction that worked well.  For example, I'd flip a DIP chip upside down
and solder one lead to the ground plane to hold it in place, then "tombstone"
a SMD cap up against the pins that needed bypassing and solder it in place.
Part of the board was milled out with a Dremel tool to make pads, where I
added SMD components for the RF stage (all discrete componets), while the
remaining stages used DIP ICs.  (There was at least one SMD component
connected between IC leads above the board.)

This has actually held up well even in rough service.  (They get dropped
regularly while DFing in the woods.)  And it certainly saved some space
compared to previous Ugly circuits, allowing me to fit the whole thing
(including battery) into an old battery case that was small enough to fit
well in my wife's hand.

Hmmm...  next step might be trying ugly construction with SMD ICs...

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KC9KEP
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Posts: 208


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« Reply #4 on: January 21, 2013, 05:34:02 AM »

I built the NorCal FCC-1 frequency counter and Signal Generator combo a while back.

Hot air gun, tweezers, magnifying glasses and a little patience, but no problem-o at all :-)

--KC9KEP
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K5LXP
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Posts: 4482


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« Reply #5 on: January 21, 2013, 06:18:35 AM »

I have a pet loathing for QFN & DFN of the sort with thermal pads,

Try it with a hot plate underneath to heat the board to near reflow temp, then hit it with hot air from above with plenty of flux.   I do all my SMD RF PA prototypes that way.  I use a small kitchen hot plate with a piece of thick aluminum on top, along with other smaller aluminum blocks on top of that to localize the heat to whatever parts of the board I need.


Mark K5LXP
Albuquerque, NM
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KE3WD
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Posts: 5689




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« Reply #6 on: January 21, 2013, 03:34:32 PM »

Try the tiny regulated iron tip and eutectic electronics wire solder of the smaller diameter. 

No adhesives, no ovens, no hotplates, with my headband magnifier and tweezers I manage quite well in the standard SMT stuff. 

And, its simply faster. 

zitters, caps and other two connect devices, I simply first melt a tiny dot of solder to one of the two pads, grasp the device in the tweezers, place it over the pads and hit the side with the solder with the tip of the iron until I see the device 'drop' into the melted solder.  Then go ahead and solder the other end. 

ICs with pins, I wet one corner pad and do the same thing, carefully positioning said ic over its pads as that first pin is soldered.  Then I go to the opposite corner and solder that pad, careful not to push all the pins out of alignment.  Then it is quick work to go around the circumference of the IC, soldering the rest. 

There is a tiny little soldering iron design from Antek that is both cost effective, has its own quickchange tip design, and is one of my favorites for assembling SMT boards this way.  Not absolutely a necessity, I've used other soldering stations as well, what's important is a tip that is tiny enough at its business end. 

This method has served me well since somewhere around the mid to late 80s, prototyping for R&D work as well as having fun around the shack. 

Those online PCB manuracturers that also have their own free downloadable software are dynamite as well.  Affordable for the small count typically encountered, available with all the trimmings if you wish to pay for them, solder mask, silkscreen, etc. 

Now I'll turn it over to the guy who *always* has to comment about the few chip types around that cannot be hand soldered, so he can have his fun pointing out the absurd warning about those chips that really are likely out of the scope of the majority of projects, right? 


73
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KB1GMX
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Posts: 772




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« Reply #7 on: January 21, 2013, 03:51:49 PM »

Use them at work, use them at home, and I find them to to work better than leaded.

while I do make PC boards, I also use them as deadBug (ugly) construction looks different
but less leads I stand resistors and caps on edge and unless the active device needs heat
sinking (copper pad) I support it on parts. Works well. 805 and 1206 size parts are better
suited to that but I use what I have.


Allison
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ZENKI
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Posts: 934




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« Reply #8 on: January 25, 2013, 05:33:07 AM »

Yup,  resistance against SMT parts are just from hams who are too lazy to build anything. You hear this excuse all the time "them thar  there parts are too small for my eyes" Its just a rubbish excuse really. Why I know this?
When the K2 first came out these same hams at the club were complaining about SMT. I brought in my first K2 showed them the kit and construction. All the super hams chickened out of the club buy of the K2 project.
If you dont want to build ham gear just say you dont want to do it rather than making up BS excuses about the part sizes. SMT is easy

You can also get one of the PC USB microscopes and use  them as your eyes.  In pinch I even use the camera on my smartphone if i cant see something.

I am old and have shaky hands and I find SMT much easier than through hole parts and kits. I can assemble a board much faster than a through hole kit. Once you have the right tools and magnifying headset
you fly through the assembly.

If you do decide to get into SMT get yourself the best possible SMT tweezer set with parts holder. Just avoid the rubbish from China.

I also  have mastered the technique  of removing SMT parts. I just use a bog blob of solder at the end of the iron and move the part around. WHen the part moves I just flick it off with the iron tip. Its lot safer
than the cutting the part technique which can left those fine PCB traces. 60/40 lead solder works best for this. Some of the none lead solder does not "blob" up as well as the 60/40

Another good trick to make SMT assembly fly is this. Get yourself a flux pen and flux up the pads before soldering on the parts. Its amazing how better the solder flows once you have fluxed the pad.

PCB layout for SMT is also much easier for SMT parts than through hole.

Have you tried building with surface mount parts?    I started using SMD parts in projects a couple of years ago and found they are both easy and fun to build with and still find it fun to watch the parts "float" into position when heated with the hot air gun.   What are you building?

Jim KI0BK
maker of the Low Loss PwrGate
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G3RZP
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Posts: 4569




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« Reply #9 on: January 25, 2013, 07:51:37 AM »

Haven't seen any surface mount tube sockets or air spaced variable capacitors yet, though! Although maybe some of the old baseboard mounting tube sockets from the 1920s would count....
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WB6BYU
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Posts: 13243




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« Reply #10 on: January 25, 2013, 01:39:39 PM »

SMD doesn't use sockets - makes mess in the wave soldering machine. 
You just bend the tube pins 90 degrees radially and solder them directly
to the board.
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KB1GMX
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Posts: 772




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« Reply #11 on: January 25, 2013, 03:17:05 PM »

I built a radio using 5899s and a few other leaded subminiature tubs SMT part as well.

Most PC mount sockets would mount SMT style and SMT does use socket and connectors.


Allison
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KE3WD
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Posts: 5689




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« Reply #12 on: January 25, 2013, 04:29:25 PM »

Haven't seen any surface mount tube sockets or air spaced variable capacitors yet, though! Although maybe some of the old baseboard mounting tube sockets from the 1920s would count....

I've done it, just throw the footprint for the thru-hole tube socket or thru-hole cap onto the SMT board when designing it.  This is one of the big advantages to using an online PCB house that includes the software for design - including libraries which already have tube socket footprints in them. 

No big deal.


73
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W1JKA
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Posts: 1664




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« Reply #13 on: January 26, 2013, 04:53:31 AM »

Re: ZENKI reply#8
         Other than your accepted and noted cure for the visually impaired I would be most interested in your cure for your own shaky hands and to those of us due to possible physical impairments or just plain older age who experience the same and are also interested in building with SMT.     
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KE3WD
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Posts: 5689




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« Reply #14 on: January 26, 2013, 08:50:01 AM »

Re: ZENKI reply#8
         Other than your accepted and noted cure for the visually impaired I would be most interested in your cure for your own shaky hands and to those of us due to possible physical impairments or just plain older age who experience the same and are also interested in building with SMT.     

My two cents worth while you await ZENKI's reply: 

I love COFFEE in the morning.  The coffee also seems to increase the shaky hand problem.

So I try not to do SMT assembly after drinking my favorite beverage.

I have also found that building up some HAND RESTS on either side of the project to give my hands or wrists a stable platform works really well on the problem.  This could be as simple as two stacks of books on either side of the slightly elevated board, sized in height to suit. 

The use of digital camera as magnifier works well, but I find it to be something I only resort to for the really close in and problematic work, such as soldering in a large IC that has multiple parallel pins on all four sides.  Most of the time, I like wearing my headworn magnifier.  I also picked up the 10X foldover loupe attachment and screwed it on the side of my favored eye.  Flipping in that extra magnification quickly comes in handy at times. 


73
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