SMT soldering

Agent Cobalt

So I was looking for a IC that met the needs of one of my projects and found it and was able to get samples. The only problem is that I didn't take note of the packaging until the samples came and then checked online only to find out that the package type I received is the only one it's offered in. Now the problem comes into play, I've never soldered any SMT parts but some of the ones I have lying around look like they'd be easy to do. This chip on the other hand gives me a headache when I try to look at the pins. The chip packaging is a thin QFN and it's only 16 pins. I was wondering if it's possible (with a miracle maybe?) to solder that by hand or should I just keep looking to see if I can find a chip that does the same thing but in a more "hobbyist-friendly" package?

Edit: More specifically the package size is 5mmx5mmx0.8mm (I think the .8mm is the pin spacing?)

Timmoore

Its doable though practice helps. The first thing is to check the datasheek and look at exactly the form factor, then look for a breakout board for it. e.g. http://www.sparkfun.com/commerce/product_info.php?products_id=495 may do depending on the particular form factor. While .8mm is a valid pin spacing, it doesn't add up to 8 pins for 5mm - unless you have pins on 4 sides?

T Chap

You can solder it, just get some really fine wire. Tin the wire and the pins slightly first. It may help to glue the IC to something, then solder to it. Using very fine wire will help against putting a load on the pins. A very fine solder tip will help also. If the pins are .5mm spacing that will be tougher, but possible.

Agent Cobalt

After looking at the datasheet again the spacing is 0.8 mm (there's pins on 4 sides). Other than sparkfun, where else could I possibly find breakout boards? I highly doubt I'll find one for this package style though. Looks like SMT soldering is going to be my excuse for a new soldering iron.

Phil Pilgrim (PhiPi)

e-PBoard Design's QFN-16 to DIP-16 IC Adapter (#E16-0099 ) is what you need. The also offer a soldering service, if you don't want to do it yourself.

-Phil

Post Edited (Phil Pilgrim (PhiPi)) : 10/2/2008 12:00:28 AM GMT

Agent Cobalt

Thanks Phil, that's exactly what I've spent a couple days looking for online. Guess I just wasn't searching good enough.

Phil Pilgrim (PhiPi)

Having tried soldering QFNs myself, with little success, I'd be tempted to have them do it, if it doesn't cost too much. It's only $8.25. There's nothing to think about. If you do it yourself, you can count on ruining at least one chip and one adapter, especially if you've never soldered any surface-mount devices before.

-Phil

Post Edited (Phil Pilgrim (PhiPi)) : 10/2/2008 12:09:00 AM GMT

CounterRotatingProps

Can I jump in here without hyjacking Agent Cobalt's thread?

I've been having a related headache. Kind of an odd story... I dropped out of electronics work 20 years ago, now picking it back up. The entire SMT stuff, and non-lead solders, are of course, new to me - and making me cRaZy!

After having looked through the confusing types of irons, tips, preheaters, etc. I'm left feeling like a soldering idiot - and I used to do NASA-spec level work ... aaarrrggg!

***Figuring that this is related to Agent Cobalt's original post: What tip / iron should I get? ***
(I'll try a keyword search here too - can't imagine this hasn't been asked before!)

thanks,
Howard in Florida

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Buzz Whirr Click Repeat

Post Edited (CounterRotatingProps) : 10/2/2008 12:52:04 AM GMT

Timmoore

One of the best tutorials on SMT soldering I have seen is here http://www.sparkfun.com/commerce/tutorials.php

rjo_

Agent Cobalt, Howard, et al.

I think magnification is a real issue for... one of the guys uses a stereo microscope, which makes perfect sense... using a microscope naturally steadies your hands.

You can get them for as little as $80 on EBAY http://cgi.ebay.com/FIELD-NATURE-20-50x-STEREO-BINOCULAR-BATTERY-MICROSCOPE_W0QQitemZ110295177135QQcmdZViewItem?hash=item110295177135&_trkparms=39:1|66:2|65:15|240:1318&_trksid=p3286.c0.m14

Then you need an adjustable chair, with arm supports and a small table on wheels that fits between your feet... or a good chiropractor... your choice[noparse]:)[/noparse]

What I'm pushing for is an "easy bake" solution... from partsman73...I met him at the PROPEXPO. He is a great guy, always looking for new product ideas and with a little prodding from the rest of us, I think he might offer a starter kit, with the various extras that you need to get started.



Rich

Brian218

CounterRotatingProps said...
Can I jump in here without hyjacking Agent Cobalt's thread?


I've been having a related headache. Kind of an odd story... I dropped out of electronics work 20 years ago, now picking it back up. The entire SMT stuff, and non-lead solders, are of course, new to me - and making me cRaZy!

After having looked through the confusing types of irons, tips, preheaters, etc. I'm left feeling like a soldering idiot - and I used to do NASA-spec level work ... aaarrrggg!


***Figuring that this is related to Agent Cobalt's original post: What tip / iron should I get? ***
(I'll try a keyword search here too - can't imagine this hasn't been asked before!)

thanks,
Howard in Florida

I use a Weller, adjustable power, soldering station, and find it performs much better than most stand alone irons. I think it was $40-$50. For hobby use you can still use solder with lead, unless it's been outlawed in your local.

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This post is a work of art. Variations in spelling and grammar are intentional, artistic endeavors that add value to all of mankind.

Leon

CounterRotatingProps said...
Can I jump in here without hyjacking Agent Cobalt's thread?


I've been having a related headache. Kind of an odd story... I dropped out of electronics work 20 years ago, now picking it back up. The entire SMT stuff, and non-lead solders, are of course, new to me - and making me cRaZy!

After having looked through the confusing types of irons, tips, preheaters, etc. I'm left feeling like a soldering idiot - and I used to do NASA-spec level work ... aaarrrggg!


***Figuring that this is related to Agent Cobalt's original post: What tip / iron should I get? ***
(I'll try a keyword search here too - can't imagine this hasn't been asked before!)

thanks,
Howard in Florida

I use a second-hand Metcal STSS power unit with an MX-500 handpiece and MX-500 cartridges. It cost me about the same as a new Weller unit and is *much* better. They use RF heating; the tip heats up in seconds and the temp. control is very accurate.

STSS units often come up on Ebay - I bought a second one for £70 as a spare.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Leon

Soldering QFNs isn't too difficult. Position it and tack down two opposite corners. Apply plenty of gel flux and drag solder the connections. The centre pad (if it has one) can be a problem. I design the PCB with a large via in the middle of the pad on the PCB and feed solder in with the soldering iron tip. I use a Metcal soldering station and a stereo microscope, which helps with tricky soldering jobs.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Paul Baker

Leon's advice is what I've found works best. Relying on a mechanical connection of the hidden pad when it is used for a ground and/or heat dissapation is a recipe for disaster. That ground slug needs to be soldered onto a corresponding pad on the PCB, you can either do some sort of reflow (requires lots of practice), or providing access window(s) so you can feed the solder in through the back is the best way for hand soldering them.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Agent Cobalt

Yea after reading what he said about the exposed pad underneath I just went back and checked the data sheet for the IC and it says I can leave it unconnected, so that makes it a little easier on me since the breakout board Phil linked doesn't seem to have a way to ground the exposed pad or make a low thermal resistance path.

Paul Baker

Glad to hear that, it should be much easier then. All thats really involved then is making sure you get two corners tacked so the chip is properly aligned, the remainder of the pins are much easier to solder when it's aligned.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Timmoore

Just make sure you check the alignment carefully before soldering the rest of the pins. Correctly alignment after soldering the rest of the pins needs more than just a soldering iron

Leon

ChipQuik should work with them, the same as with QFP chips. It makes removal very easy.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Phil Pilgrim (PhiPi)

Leon,

I had never heard of ChipQuik before. That's pretty slick stuff! It must be some kind of bismuth alloy to have such a low melting point.

-Phil

Leon

Yes, it's basically Wood's metal. They'll send you a free sample if you request it. It's enough for a couple of chips.

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

jpyle

·Hi Guys. I have been using the 158 degree bismuth alloy for a couple of years now. Removed 100+ chips, no damage and have used less than 2 oz. so far. Does the same as Chip-Qiuck as far as I can tell. I have been able to re-claim some of it as I go along. These guys have it in 1 pound bars for $18.00 ( plus $10,00 shipping from Cal to Oklahoma). Still, it goes a LOOOOONG way for what you pay. Just my 2cents----John



http://rotometals.3dcartstores.com/Low-Melting-Point-Alloys_c_16.html

CounterRotatingProps

Another question to those who've got the SMT skills:

which shape of tip do you use, pencil, chisel, chisel at a 45 degree angle?

and do those "tweezer" style irons work? (I assume they're for the little boxy shaped resistors, etc?)


thanks much for the replies,
Howard in Florida - squinting at these little gizmo's even through the magnifier!

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Buzz Whirr Click Repeat

Paul Baker

This is my favorite tip

·

It makes it easy to do the solderball drag technique for SMT work. (this is a Xytronic tip #44-415443 from HowardElectronics.com)

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

CounterRotatingProps

Wow Paul --- talk about a precision, pictorial reply!

isn't 3 mm a tad wide for those dinky little leads?

thanks for the prompt response, btw.

- H

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Buzz Whirr Click Repeat

Post Edited (CounterRotatingProps) : 10/22/2008 12:12:56 AM GMT

Paul Baker

The drag method involves placing a ball of solder on the end, using a liberal amount of flux on the pins and slowly (and lightly) dragging the tip along the pins. The flux heats up the pins very quickly (and makes thier surface tension low) and the solder on the tip wicks onto the pins as you drag it along. Here is a video demonstrating the technique: http://www.howardelectronics.com/navigate/videoclips.html·(Video Described as: How to drag solder a surface mount IC with the JBC AD2950Soldering Station, 2245 50 watt hand piece and the 2245-031 drag solder tip.)

Because you are dragging it, it's ok for the tip to touch more than one pin simultaneously.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Timothy D. Swieter

For soldering SMT parts I use the tip that came with my iron. I also use the solder ball drag trick. Every now and again I use the "add as much solder and bridge everything trick" too. Then I go back and clean it up with a solder wick and double check all connections with a loupe or magnifying glass before I power the board on.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
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