SMD Soldering Question

[tubegeek]

Oddly enough I have been doing that with through hole components for years, except that instead of hitting the board itself on the desk I let my hand hit and the impact through my hand is enough to knock off melted solder. This has been effective for smaller SMD components, but when I tried it on the IC in question (a PT2399) the only thing I succeeded in doing was knocking solder blobs onto adjacent pins

Smack it harder, with a hammer?

Have you guys seen this, from the mind of Fran Blanche?



http://www.frantone.com/designwritings/design_writings5.html#hold

[vigilante397]

Have you guys seen this, from the mind of Fran Blanche?

A rather intriguing idea. I picked up a lovely set of various tweezers on clearance at the local hardware store, so that's what I've been using, and I've only flung 8 or so components across the room never to be seen again

I suppose I should post an update on the original topic: The solder wick didn't seem to work (it could be that I'm just not very experienced with solder wick), and the solder pump (obviously too large) had no effect, so I tried my pound-against-the-desk method again and managed to bridge 4 pins together But with the assistance of a fine conical soldering tip I was able to remove the bridges, and I am now back on track for finishing my first SMD boards ...... whenever my elusive resistors show up Ordered several "grab bags" from the eBay and everything has shown up except my resistors.

[Tony Forestiere]

Are you using solder flux?

BIG difference as I have read.

[thelonious]

+1 to everything Transmogrifox said.

Also, crosslocking tweezers (a.k.a. self-locking, a.k.a negative action, a.k.a. squeeze to open) are quite useful for holding tiny devices while soldering the first leg/pad. They also act as a heat sink.



I usually use a flux pen to flux the pads, place the part with standard tweezers, clamp it with the crosslock tweezers, and solder. If there's too much solder, I clean the tip of the iron and drag it across the pad or leg a second time.

[bloxstompboxes]

Flux pens we use at work that I like: http://www.all-spec.com/products/CW9200.html?gclid=CjwKEAiA9KymBRD6g6iOvv2joU0SJAB0vRQyDi8FYhnVLyCB2dvCdy8OLbk-Xk8uGTFsXEyXZUqJWBoCPv3w_wcB

Tip: Take the flux pen and run it down your solder wick. Makes the wick really "wick" up the solder.

These are very similar to the tweezers we use as well: http://www.newark.com/aven/18032ezf/precision-tweezer-120mm/dp/01N4765?mckv=sjH4yGJ0e|pcrid|53816251821|plid|&CMP=KNC-GPLA

[vigilante397]

Tip: Take the flux pen and run it down your solder wick. Makes the wick really "wick" up the solder.

That is an excellent idea, definitely seems like it would improve the use of solder wick.

Also, crosslocking tweezers (a.k.a. self-locking, a.k.a negative action, a.k.a. squeeze to open) are quite useful for holding tiny devices while soldering the first leg/pad. They also act as a heat sink.

I actually have a pair of these and figured they would be excellent so I tried them out today, but the problem I found was that when holding passive devices it was too easy to rotate them within the tweezers' grasp because the tweezers don't hold as tightly as I like to.

[bloxstompboxes]

I believe some solder wick already has flux integrated in it or whatever. But adding some doesn't hurt.

[thelonious]

but the problem I found was that when holding passive devices it was too easy to rotate them within the tweezers' grasp because the tweezers don't hold as tightly as I like to.

My tweezers hold pretty tightly, but I'm usually doing 3-6 boards at a time, assembly line style, and my flux dries a little on the pads and gets tacky enough to keep the components from rotating.

I've heard you can use paste solder and a toaster oven! That's on my SMD soldering "bucket list"... I've just been afraid of destroying something. 

[amptramp]

but the problem I found was that when holding passive devices it was too easy to rotate them within the tweezers' grasp because the tweezers don't hold as tightly as I like to.

My tweezers hold pretty tightly, but I'm usually doing 3-6 boards at a time, assembly line style, and my flux dries a little on the pads and gets tacky enough to keep the components from rotating.

I've heard you can use paste solder and a toaster oven! That's on my SMD soldering "bucket list"... I've just been afraid of destroying something. 

I would not advise it unless you have some way to get the temperature vs. time profile published with most SMD parts.  Temperatures have to be held to certain limits and a toaster oven is too crude at temperature control and temperature variation within the oven for that.

[thelonious]

I would not advise it unless you have some way to get the temperature vs. time profile published with most SMD parts.  Temperatures have to be held to certain limits and a toaster oven is too crude at temperature control and temperature variation within the oven for that.

Good to know. I'll skip it then. 

[duck_arse]

Oddly enough I have been doing that with through hole components for years, except that instead of hitting the board itself on the desk I let my hand hit and the impact through my hand is enough to knock off melted solder. This has been effective for smaller SMD components, but when I tried it on the IC in question (a PT2399) the only thing I succeeded in doing was knocking solder blobs onto adjacent pins

Smack it harder, with a hammer?

Have you guys seen this, from the mind of Fran Blanche?



http://www.frantone.com/designwritings/design_writings5.html#hold

this looks a lot like something I thought I'd invented, right down to the elastic bands. except I don't have a pick, and the whole didn't work. too much play in the holding arm, not enough push-down. I'm looking for a metal baseplate (pc side cover) to use with a fixed upright, and a toothbrush handle (bendy!) with half a bamboo skewer shoved up it. the tip of bamboo is specially trimmed/cut/butchered to notch on the part in quextion.

it will happen, soon.

[J0K3RX]

I would not advise it unless you have some way to get the temperature vs. time profile published with most SMD parts.  Temperatures have to be held to certain limits and a toaster oven is too crude at temperature control and temperature variation within the oven for that.

Good to know. I'll skip it then. 

There are hundreds of these, here's just one..
http://letsmakerobots.com/node/28793

[Transmogrifox]

I believe some solder wick already has flux integrated in it or whatever. But adding some doesn't hurt.

It's like the idea of flux-core solder not being a complete substitute for using solder flux.  It really improves the wicking action if you add a little more.  I have had some seemingly "dead" wicks do wonders with an extra squirt of flux.

As for the toaster oven, one of the researchers at university where I attended successfully used a toaster oven for his prototypes.  He may have modified it with an advanced temperature control option for all I know ;-?

[amptramp]

I would not advise it unless you have some way to get the temperature vs. time profile published with most SMD parts.  Temperatures have to be held to certain limits and a toaster oven is too crude at temperature control and temperature variation within the oven for that.

Good to know. I'll skip it then. 

There are hundreds of these, here's just one..
http://letsmakerobots.com/node/28793

The typical production infrared soldering machine is a conveyor with correct heating stations along the way that follow the soldering profile established for the most delicate of the parts used.  The thing looks like the conveyor oven for Quizno's submarine sandwiches.  Hmm... now you have me thinking.  Stainless conveyor.  Check.  Controlled IR environment.  Check.  Maybe I could check the business equipment sales for stores going out of business and selling their stuff...

[PRR]

> the conveyor oven for Quizno's ... Maybe I could check the business equipment sales...

Or just ask the dude at Quiznos to toast your PCB instead of your sandwich. (When the boss/owner isn't around.)

[thelonious]

There are hundreds of these, here's just one..
http://letsmakerobots.com/node/28793

THAT is brilliant.

[guitarpedalparts]

I admittedly did not read the entire thread, but at risk of repeating someone...

I hate solder braid in general. Really hate the stuff for just about all purposes.  SMD soldering IC (2-side) chips is fairly easy with a steady hand and some good technique, without solder braid.

The key, as I did see mentioned earlier, is flux. Not solder with flux, but additional flux. Get a liquid flux pen for a few bucks. Use thin solder, about half the diameter of regular solder. 0.032 I think it is? A smaller diameter iron tip also helps.

1. Goop all the pads with the liquid flux and place the IC on the pads.
2. Hold IC chip firmly in place with pliers or tweezers.
3. Run the flux pen one more time over all the pins.
4. Get a small bit of solder on your iron and touch it to one pin to tack it in place.
5. Switch to the un-tacked side. Lay the solder completely across all of the IC pins.
6. Simply touch your iron in between the pins, melting the solder. Press down into the pins and pull outward. Repeat for each pin.
7. Move back to the other side and solder those pins.
8. Check all connections for bridging. A 10x eye loupe helps, also just a few bucks.

[duck_arse]

soon is now!

here's how my smd arm has turned out, it seems to work ok thus far, he says, touching some wood. it is in fact a toothbrush, minus the head, screwed to a longish block of wood, for its weight. a 3.5mm hole was a good tight fit for the downtube, a section of telescopic antenna, the diameter chosen to match the bamboo skewer that does the poking, shown with some thread-seal tape as packing. the top spring is the internal twanger from a video cassette.




the second pic shows the tool pretending to be in use. the skewer will probably need to be sanded smooth w/ some 400p, the tip is shaped to a flat blade wit der exacto, then a notch is cut wide enuff to jamb a 1206 (which is as far as I'm going, sizewise), and just not deep enough that the tips touch the board. the good thing about the bamboo is that you can cut bits to different lengths to accommodate different board heights, or different shapes for clunkier parts, like those feck tants.

the top spring is good cause you can finger lift it (a cam lift system was beyond me), and push the parts about with the toothpick you've loaded into your favourite clutch pencil, then re-press-down them. there is enough pressure to hold them still while soldering, and the plastic arm is rigid enough for jazz, even though it's not square or straight.

so, there's some more junk I've gotten shift.

[pickdropper]

I do it with tweezers, a flux pen (or syringe) and magnification.

For the flux pen, I like the Kester 186 pen.  I'm not a fan of the no-clean version (Kester 951, IIRC).  I don't mind cleaning my boards, so the RMA type is fine.  The Kester 186 is mild enough hat you can probably just leave it on the board, but it's a bit of a sticky mess.

Earlier in the thread somebody mentioned water soluble flux.  That will work, but it must be cleaned or it will eat away at the board.  Some folks avoid it for that reason.

[287m]

dont forget simple tips
http://runawaybrainz.blogspot.com/2014/05/macgyver-smd-soldering-iron-adaptor.html
and drag soldering if you not have needle solder like Mr Pickdropper

Peace Mr Pickdropper