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eHam Forums => HomeBrew => Topic started by: KI0BK on January 20, 2013, 09:05:39 AM



Title: Surface mount anyone?
Post by: KI0BK 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


Title: RE: Surface mount anyone?
Post by: KE3WD 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


Title: RE: Surface mount anyone?
Post by: M0HCN 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.


Title: RE: Surface mount anyone?
Post by: WB6BYU 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...



Title: RE: Surface mount anyone?
Post by: KC9KEP 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


Title: RE: Surface mount anyone?
Post by: K5LXP 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


Title: RE: Surface mount anyone?
Post by: KE3WD 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


Title: RE: Surface mount anyone?
Post by: KB1GMX 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


Title: RE: Surface mount anyone?
Post by: ZENKI 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


Title: RE: Surface mount anyone?
Post by: G3RZP 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....


Title: RE: Surface mount anyone?
Post by: WB6BYU 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.


Title: RE: Surface mount anyone?
Post by: KB1GMX 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


Title: RE: Surface mount anyone?
Post by: KE3WD 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


Title: RE: Surface mount anyone?
Post by: W1JKA 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.     


Title: RE: Surface mount anyone?
Post by: KE3WD 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


Title: RE: Surface mount anyone?
Post by: WB6DGN on January 26, 2013, 10:49:59 AM
Quote
Get yourself a flux pen and flux up the pads before soldering on the parts.

I've been doing that a lot lately when I solder and it doesn't have to be surface mount, either!  Been doing that a lot in the kitchen, too!  I think age is finally starting to catch up with me!  BUT, I refuse to quit trying; just cuss a lot more.
Tom


Title: RE: Surface mount anyone?
Post by: KH2BR on January 30, 2013, 06:12:55 PM
I have a simple Juma receiver that covers 40 meters and down. It is all surface mounted parts.
I am modifying it so I can use it on 30 and 20 meters. I will use a dds vfo from N3ZI.
Since the radio is all surface mounted parts I want to use surface mounted parts to design a band pass filter for 30 to 20 meters. I did not want to spend all day looking for some sort of proto board to design the filter on so I took a piece of copper clad board and carved out the solder pads I needed to to make my connections. I used a ruler straight edge and a exacto knife to do the cutting.


Title: RE: Surface mount anyone?
Post by: KE3WD on January 31, 2013, 08:03:14 AM
There are pcb products that can be had that are pre-etched for prototyping, one brand name is SURF BOARD. 

Very handy for the SMT prototyper, experimenter and even work well in "one-off" prototyping and production problem solving. 

http://www.popsci.com/diy/article/2009-04/surfs-up (http://www.popsci.com/diy/article/2009-04/surfs-up)

I keep a few examples of these in the parts drawers, treat 'em just like my stash of other often-needed components. 


73


Title: RE: Surface mount anyone?
Post by: N4OGW on January 31, 2013, 10:54:35 AM
I recently built a SDR-Widget kit here (see http://www.yoyodyneconsulting.ca/pages/SDR-Widget.html). Soldering the LQFP144_20 CPU was a challenge! With this kind of part it is basically impossible to solder to individual pins. But it can be done using just a good soldering iron, solder, and solder wick. Basically:

1) tack the chip down on two sides. Getting the pin alignment perfect is what matters, don't worry about bridging pins.
2) run solder down each rows of pins- get plenty on, again don't worry about solder bridges. it will look terrible after this step.
3) suck off all the excess solder with solder wick. Just the right amount of solder will remain on each pin!

There are some videos at Sparkfun explaining this technique. It is great if you just have a few parts and don't want to build/buy stuff for reflow soldering.

Tor
N4OGW
 



Title: RE: Surface mount anyone?
Post by: WB6DGN on February 13, 2013, 08:18:17 PM
Quote
Basically:
1) tack the chip down on two sides. Getting the pin alignment perfect is what matters, don't worry about bridging pins.
2) run solder down each rows of pins- get plenty on, again don't worry about solder bridges. it will look terrible after this step.
3) suck off all the excess solder with solder wick. Just the right amount of solder will remain on each pin!

Some solder tool manufacturers make a tip specifically for this type of work.  It is commonly referred to as a "hoof" tip as it resembles a horse's hoof.  Basically a bevel tip with the flat concave to hold more solder.  It is slowly drawn over the row of pins as described above but very little or no additional solder needs to be added during the process.  With a little practice, all the pins are neatly soldered and no additional cleanup of excess solder is necessary.  I know that Pace and Metcal make a wide variety of those tips but not sure about Weller and others.  Another handy trick if you're doing much surface mount soldering.
Tom


Title: RE: Surface mount anyone?
Post by: VE3GZB on March 08, 2013, 06:31:32 AM
I used to work regularly in the RFID industry, manually building and repairing SMD 0805 components and on occasion as small as 0201 size. Did that work for 5 years.

73s VE3GZB


Title: RE: Surface mount anyone?
Post by: AK4OL on March 22, 2013, 01:09:49 AM
Those who haven't tried it: do not be intimidated by surface mount soldering.  It is a skill that requires a little practice and a modest amount of equipment is desirable but it is not that difficult a skill to acquire if you can already solder through hole components.  And a lot of better components are simply not available in through hole these days.   Kit designers are being held back by potential customers who are intimidated by surface mount. 

Soldering the LQFP144_20 CPU was a challenge! With this kind of part it is basically impossible to solder to individual pins. But it can be done using just a good soldering iron, solder, and solder wick. Basically:

You really shouldn't dismiss soldering individual QFP pins as impossible.   It isn't impossible.  It isn't even that hard.   If you can see it, you can probably solder it unless you have a really bad physical or visual impairment.   And if you aren't actually legally blind, missing at least one limb, or completely quadrapelgic, and possibly even if you are, you shouldn't dismiss the possibility out of hand without trying some tests first.   Even if you are under-equipped and under-funded.

I have soldered QFP packages (62.5 pitch instead of 50pitch so slightly bigger pins) pin by pin, and it was not hard.    In fact, the first surface mount board I ever soldered (I also designed it) had a 112 pin 62.5 pitch QFP as well as all surface mount parts (except connectors and one voltage regulator) including TSSOPs, SOICS, transistors, electrolytic caps, tantalum caps, crystals, 0805 resistors/ceramic caps.  I have also tried the brute force method you describe and found it was easier (and less likely to damage the board) just to do it right the first time.   You might accidentally bridge a few pins and need to wick them but it is better than intentionally bridging them all.    But I do have a 10X/15X stereo boom microscope.   I also have a magnifying light and visor magnifier (sometimes the latter two were even used together) and I have a 230X USB microscope for inspection.   For that type of package you will probably need to use at least one of these means of magnification.    Depending on your vision, you may be able to do it with the magnifier and not need the microscope.    Sometimes I think it is easier to use the magnifier lamp, possibly even on QFP/TSSOP packages and it is certainly possible.  The microscope lets you see better but is slower to use in some other ways.  I would prefer to have the stereo microscope available on QFP/TSSOP packages but it isn't absolutely necessary.

Again, my rule is "if you can see it, you can probably solder it".   So make sure you have adequate light and at least some form of hands free magnification.   If you don't have magnification good enough to solder by, you probably can not see well enough to properly inspect solder joints done by the brute force method, either.   

Before going out and buying stuff, or throwing in the towel because you think you need to buy stuff, do a little test with what you already have available.    Clean your magnifier and your glasses (if any).   Take junk circuit boards (or even one which isn't junk - "take it apart") with surface mount components on it, put it under your existing magnification.   Add a bright light source if not built into your magnifier.  Take two very small jeweler's screwdrivers.  Pretend one is a soldering iron and one is solder and practice touching each lead in turn under the magnifier.   No animals or circuit boards are hurt in this experiment if you use proper ESD handling procedures.     Just practice your eye hand coordination working under magnification.   At first, you will feel like a bit of klutz because you are 1) making smaller movements than you are used to using and 2) the magnifier changes the loop gain between your hands and your eyes and this confuses your brain.   Give yourself an hour to practice and you will likely find you CAN do it.

Now that you have an idea what YOU can do, try using your finest soldering iron and smallest soldering iron tip (cold).  You might need a finer tip and/or finer solder.   

For those unwilling to spend money on a kit until they know they can handle the soldering, or those who are anxious to get started before you even finish reading this message, you might consider taking some junk surface mount boards and unsoldering some parts with a heat gun, hot plate, or even a blow torch (used carefully, outside, likely to cause damage) and resoldering them.   .  While you want the board and part undamaged enough to use for practice, it is no big deal if you accidentally destroy them.   Maybe even use a proper hot air rework solder/desolder gun as some of these can be had very cheap without hoods and you will eventually want one   You can get old computer boards or cable or DSL modems for a few bucks at the local thrift store or hamfest (or just get on the local repeater and hollar) if you don't already have your own junk boards.   Some of this old junk may be worth more for parts or soldering practice than whole.   Or even some cheap new surface mount boards off of ebay.   Buy something like a new  USB RS-232, USB-TTL serial, USB Jtag, USB sound card, DC to DC converter, etc. and take it apart and put it back together.   After a little practice, you might even be able to use it after you are done playing Dr Frankenstein - if you can keep track of what part goes where.


If you do find that you need a stereo microscope, some are available really cheap these days if you don't need a boom stand (good for working on larger boards) or trinocular port (for cameras).   Entry level ones are about twice the price of a swing arm magnifying lamp.   Just bear in mind that you will want to stick to boards that are less than the throat depth in either dimension unless you want to practice soldering leads from front, back, left, and right and twice the throat depth even if you do.

No-clean flux paste has been recommended.   I agree.  Having a syringe of flux helps.   Tweezers are important. If you are desoldering components to practice on, you might also want a Xylotronic 490 IC popper ($5) or equivalent, though if you are just practicing or scavanging parts, instead of repairing, a sharp rap on the top edge of an empty open cardboard box will indiscrimently remove parts and blobs of molten solder into the box.

When soldering IC packages, tack solder the corner leads first to hold the package in place.

A 230X USB microscope used on low magnification (around 27X) has a long enough focus distance to use for soldering but note that it is not stereo so you lose depth of field, there is a short time lag, you need to remove the clear bezel (mine was glued but was able to force it off and still put in on/take it off), you want a good focusing stand, and it is plastic so it is vulnerable to melting from the heat of the iron so it should be protected by a small piece of glass..  Better for inspection than soldering.

Tip: If you do not have the artwork for your printed circuit board, scan it on a flatbed scanner or take a good high resolution digital image (macro mode up close but not closer than the camera can focus, camera steady).   This way you will not only have documentation of traces that end up hidden under parts, you will also know which pins are supposed to be shorted together because in many cases these will form solder bridges that will drive you nuts if you don't know they are supposed to be there.

My first surface mount board was a microcontroller board which I designed.  I wrote diagnostics to test almost every pin for opens and short circuits.   You can also use the in-circuit debugger to the same end, manually.  Some chips, including CPLDs, FPGAS, and some microcontrollers, have JTAG which can be used to test connections (though you might need to write your own software).  These methods will not detect a poor connection but will detect shorts and opens.   On the other hand, a processor with external flash and ram memory could require a whole lot of solder joints to be correct before the "brain" functions well enough to be useful in testing the others.

Here are some SMD kits I have seen recently that have some potential as SMD starter kits for people with various levels of ambition:
The Xprotolab kit ($35):  Small, cheap, useful, reasonably challenging.  Low speed oscilloscope/logic analyzer/arbitrary waveform generator/frequency counter that fits on a breadboard.
http://www.gabotronics.com/electronic-kits-modules/kit-to-build-xprotolab.htm
http://www.gabotronics.com/development-boards/xmega-xprotolab.htm
Relatively few pins have to be soldered correctly for the "brain" of the project to function and then it could be used to help you find faults in the other parts.    If you have essential power/decoupling and at least one of the LCD, the USB port, or the in-circuit debugging port working, you should be able to exercise other pins using those.

Those who want to start simpler (no IC packages) could try something like this surface mount power supply kit for $11+ship. 
http://www.ebay.com/itm/SMD-Adjustable-Power-Supply-Kit-2127A-/390564075772?pt=LH_DefaultDomain_0&hash=item5aef6ed8fc

And for a real no-brainer, here is two versions of an SMD dummy load kit:
http://www.wa0itp.com/dummyload.html

Or the QRPme RF Probe kit:
http://www.qrpme.com/?p=product&id=RFP

For $150, there is the Peaberry SDR transceiver kit (which is just about all surface mount except for the connectors, 1 TO-220, and some inductors) with built in USB soundcard.
http://ae9rb.com/index.php?main_page=product_info&cPath=1&products_id=1

Finningly 80M single band SDR receiver kit, £16.50,  surface mount kit similar to early softrock kits, external sound card needed:
http://www.kanga-products.co.uk/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=17&category_id=6&option=com_virtuemart&Itemid=58

AT sprint II is an SMD transceiver but it appears you need to be on the yahoo groups to see when batches become available.

BGA packages are another story, since the solder joints are hidden from view, but homebrewers have even had some success with those.

These days, there is a lot of info out on the net on surface mount soldering.


Title: RE: Surface mount anyone?
Post by: K1CJS on March 22, 2013, 03:45:25 AM
I don't think people are as put off by building with surface mount components as they are by repairing boards made with surface mount components.  I still recall an article written years ago where the author stated something like this: 

"On factory made circuit boards, when replacing individual components, It's neat to be messy."

He advocated chopping the leads to defective components off right at the component, bending the leads over on both the new component and the leads coming off the board, making a good mechanical connection and soldering the connection.  I never saw the advantage in doing so--I always unsoldered the leads to the old component from the board and resoldered the leads to the new one right back at theose solder points.  It's easy--and it looks better--IF (yes there's an if) you use the right tools.

Same thing with SMD technology.  If you have the right tools, you can do the job.


Title: RE: Surface mount anyone?
Post by: KH2BR on March 24, 2013, 03:04:22 PM
My 2 cents worth. If you need to remove a resistor or capacitor, use 2 soldering irons. One on each side and the part just slipps off. I have been using desoldering wick and discovered this by chance.


Title: RE: Surface mount anyone?
Post by: WB6DGN on April 02, 2013, 09:13:51 PM
Quote
My 2 cents worth. If you need to remove a resistor or capacitor, use 2 soldering irons. One on each side and the part just slipps off. I have been using desoldering wick and discovered this by chance.

Works well except for those, like me, that can't seem to get both hands working together like they should.  I see that the price of "heated tweezers" is coming down to the point where there are some nice looking ones for well under $100.  Still pricey, true enough, but if you're someone who does a lot of SMT projects, no doubt worth it.  Check out the usual electronic tool suppliers; you may find something within your price range.
Tom


Title: RE: Surface mount anyone?
Post by: KE3WD on April 03, 2013, 05:41:39 AM
For removal of just about any SMT component where you can SEE the leads: 

CHIPQUIK


This is a very good system, cost effective and, with familiarity of use, I can definitely remove SMT devices faster than anybody using any of the more expensive dedicated soldering removal systems. 

I use it almost every day I'm at the test bench. 


73