Soldering Surface Mount Components 6

[roydm]

I know most boards are now put together by robot but is there an elegant way to solder surface mount components by hand?
Special solder or flux?

I'm just referring to chips with a low connection count, typical 3 maximum of 8

Thanks
Roy

 

[btrueblood]

Putting a servo in the hot air stream of the opened door seems wrong to me.

 

[itsmoked]

I believe that's correct Dan. On the other hand I don't see any point to different profiles. If you get one that works that's the only one you'll use. So unless you're doing completely different processes like actually drying parts or sintering some strange design you probably do not need multiple programs.

btrue; good point but there is really so little thermal mass in a toaster oven that the servo is 'toasted' for only about 2 minutes.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MacGyverS2000]

I would imagine most of that hot air passes by the servo with minimal transference of heat... now if the servo was placed IN the oven, that might be a horse of another color...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[borisdavenport]

I [highlight #EF2929]use a soldering gun[/highlight] for soldering SMBs. soldering SMb really require skill to do it. We can't just do it by having soldering experience with discrete components

 

[mudandsnow]

I gave ohararp a try with my latest stencil order. Pololu is much better. They are faster, similar price when shipping to Canada, have better shipping options and better time/price options.

 

[itsmoked]

Sorry to hear that. How long did they take?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mudandsnow]

Feb 14: placed order
Feb 16: received email from ohararp saying it "was" shipped on Feb 17
Feb 20: shipper's tracking info did not say it had been picked up. I emailed ohararp asking for update.
Feb 21: tracking info still doesn't say it's been picked up and still no reply from ohararp.

 

[itsmoked]

Crap. After years of faithful service (as stated) he did the same thing to me the exact same times as a you.

After writing him saying essentially, 'you normally take a few hours to ship, here it is 15 days.. It appears you did the postage but never actually shipped it!'.

His response was abject apology, refunded all charges, did it again (or for the first time), shipped it priority USPS, and I got it two days later - 5 days after I got the boards..

Apparently he does this as moonlighting and he said his day job sent him off elsewhere for a week, (I gathered this was a first).

Sorry for your and (my) bad experiences.
I told him, "This is a big problem not knowing what the delivery is really going to be. Some jobs don't matter but some are critical, and if we could just know what the turnaround was going to be then we could go elsewhere when pressed for time."
I got no response.

I'll give Pololu a try next time.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[mudandsnow]

Sounds like he should hire someone. Or put a warning on the website. I like that Pololu lets you decide how many days it'll take. My boards usually take less than a week so I usually want fast stencils but it's nice to have the option of waiting a bit to save some money.

 

[zappedagain]

I had access to solder paste at my previous employer. That makes surface mount hand soldering much easier. Unfortunately I haven't found a vendor yet for purchasing small quantities (a tube or two) of solder paste yet.

Z

 

[itsmoked]

????


All you need, No lead, water washable.


Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

Wow, lots of replies.
I can see where I would need a toaster oven to assemble a board with many components but my boards are single sided probably have about 10 on a board 1-1/2 square.
I have been soldering the surface mount components with just a regular fine tipped iron, typically LEDs or components with no more than 8 legs.
I tin the circuit board first with just a dab of high quality solder then hold the component in contact and just heat each pad with my iron to melt the solder, sometimes melt a dab of solder close to the component leg for good measure.

Crude I know!

 

[mudandsnow]

Zappedagain: There are small syringes of solder paste on digikey.

Roydm: It's best if you just tin 1 pad per component before placing the component. If you only tin one pad then the component can be pushed down to contact the PCB while heating that 1 pad. That was required in avionic communications equipment for a few reasons:

Less chance of losing electrical conductivity when there is a bad solder joint, ex; cracked or cold.

Less chance of contaminant buildup causing short circuit, ex; dust buildup under floating capacitor.

It can reduce the stress on the component and the solder since the component is supported by the PCB instead of by solder.

 

[zappedagain]

Thanks Keith! It's been under my nose the whole time. My previous employer buys it in bulk and has to have it cold-transported and then stored at -40C. They end up throwing about 90% of it away at the expiration date.

Z

 

[itsmoked]

Ah zapped.. I once thought that too. I have since come to a different conclusion.

If you buy the paste I linked you to DKY will automatically ship it next day with an ice pack in an insulated bag. $$$$$$ painful!!!! After using more than ten of those syringes of paste over a couple of years we've found that if we leave the syringes capped and in the insulated bag with the ice pack when not actively using it. It is completely usable for about 3 months. We see no difference at all. After about three months of summer we start to see separation and it doesn't stencil as cleanly.

We simply try to keep its daily temp cycling to a minimum. If we aren't going to use it for a while we toss the bag into the bottom of a loaded (thermal mass) cabinet to keep it as cool as the office can provide in a place with the lowest likely thermal cycles.

We've actually used it out to probably 6 months.

That said I always, in the "checkout instructions", direct DKY to NOT elevate the shipping for the solder paste. The one time they did anyway a call got them to wipe all shipping charges.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[roydm]

Mudandsnow,
Thanks, I will try the one pad method.

The solder paste sounds like a royal pain!

 

[Machors]

Seeedstudio prototype pcb assembly service makes soldering easy, there's no need to soder by yourself.

 

[itsmoked]

We were just thinking of that. How's it work there in particular?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[gaber26111]

Hi
I soldered smt components before,and alot,they made for prototypes,if you planning to do that for a product you sell at the market,then use robot or furnace for production

And yes it needs very skilled technician, even through hole solder may can't solder smd components

It needs heat gun if you solder blga ic's,and heater with very thin tip " the heater equipped with the heat gun is perfect use" if you sold a chip pins on the board surface the solder to be very thin and good quality,

I hope i helped,regards