Post by thread:[EE:] Lotta sap (flux on tweezers)

'[EE:] Lotta sap (flux on tweezers)'

If you have seen National Lampoon's Christmas Vacation and remember Clark trying to read a magazine

after doing battle with the Christmas tree, that's me with SMT parts stuck to my tweezers after using

liquid flux on SMT boards.  What am I doing wrong??????????????

If you flux after placing the parts then they stick to the flux brush.

I guess one of those little flux syringe doo hickies might be better but haven't picked one up yet.

If you flux first (which is great to hold the part) then it seems that a little flux always wicks up on to the

end of the tweezers. In the TSSOP soldering thread someone mentioned using paste flux. Thoughts?

thanks

chuckc

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> If you flux first (which is great to hold the part) then it seems that a 

> little flux always wicks up on to the

> end of the tweezers. In the TSSOP soldering thread someone mentioned using 

> paste flux. Thoughts?

You may try using one of those flux bottles with a pointy metal applicator. for big chips you can flux the pads, tack the part, flux the legs again, then just melt solder everywhere, and flux does the hard work for you. just don't put too much on. if you do then solder-wick works great. The problem (if I understood right) is for discretes? you flux the pads, place the component then solder? Then I totally agree, you'll have to clean your tweezes after every component... I personally find that just fluxing the part after tacking it works great. The best of course is to experiment.

Paste flux... that's the paste with solder in it? the one they use to oven-solder chips (like the Seattle Robotics, IIRC)?

Christian

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On Sat, 16 Oct 2004, Charles Craft wrote:

> If you have seen National Lampoon's Christmas Vacation and remember 

> Clark trying to read a magazine after doing battle with the Christmas 

> tree, that's me with SMT parts stuck to my tweezers after using liquid 

> flux on SMT boards.  What am I doing wrong??????????????

>

> If you flux after placing the parts then they stick to the flux brush. I 

> guess one of those little flux syringe doo hickies might be better but 

> haven't picked one up yet.

>

> If you flux first (which is great to hold the part) then it seems that a 

> little flux always wicks up on to the end of the tweezers. In the TSSOP 

> soldering thread someone mentioned using paste flux. Thoughts?

Wipe the tweezer tip in a q-tip soaked in solvent before picking the next 

part up, or whenever you feel like it. The q-tip is held with a file clamp 

to the solvent pot lip (tiny glass baby food container in my case) or 

thumb tacked to the wooden table with a sheet of foil under it.

Peter

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use a water soluble flux maybe?  i've used one that isn't sticky at all,

and i just dipped the boards in it.  of course you must rinse it off in

less than 24 hours, at least the one i used (or it took nickel plating

right off the board!  we were avoiding lead in that application and

nickel was the vendors best alternative on a teflon board).  i've also

just used a syringe to deposit solder paste, avoiding other flux all

together and the solder paste wasn't particularly sticky, in fact it

would have been nice if it was a little more sticky.  i've done this

even when using an iron to solder surface mount parts.

Charles Craft wrote:

> 

> If you have seen National Lampoon's Christmas Vacation and remember Clark trying to read a magazine

> after doing battle with the Christmas tree, that's me with SMT parts stuck to my tweezers after using

> liquid flux on SMT boards.  What am I doing wrong??????????????

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I coughed up a hundred clams for a surface mount soldering kit with a syringe of paste flux and several syringes of solder.  I never had any problem with flux on the tweezers with this arrangement. The stuff seems to last forever since you only use a tiny bit each time.  I am sure it has exceeded its shelf life but I am still using it.  

I used flux and solder for a number of years, and got a syringe of solder/flux mixture and had good results with that by itself with no extra flux.  

But if you are stuck with wire solder, you need lots and lots of flux to make surface mount work.  

-- Lawrence Lile, P.E.

Electrical and Electronic Solutions

Project Solutions Companies

http://www.projsolco.com

> {Original Message removed}
Lawrence, where did you buy the smd soldering kit?

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----- Original Message ----- 

From: "Lawrence Lile" <.....llileKILLspam@spam@projsolco.com>

To: "Microcontroller discussion list - Public." <piclistKILLspammit.edu>

Sent: Monday, October 18, 2004 9:13 AM

Subject: RE: [EE:] Lotta sap (flux on tweezers)

{Quote hidden}>I coughed up a hundred clams for a surface mount soldering kit with a 

>syringe of paste flux and several syringes of solder.  I never had any 

>problem with flux on the tweezers with this arrangement. The stuff seems to 

>last forever since you only use a tiny bit each time.  I am sure it has 

>exceeded its shelf life but I am still using it.

>

> I used flux and solder for a number of years, and got a syringe of 

> solder/flux mixture and had good results with that by itself with no extra 

> flux.

>

> But if you are stuck with wire solder, you need lots and lots of flux to 

> make surface mount work.

>

> -- Lawrence Lile, P.E.

> Electrical and Electronic Solutions

> Project Solutions Companies

> http://www.projsolco.com

>

>> {Original Message removed}
> Lawrence,

> Where did you buy the surface mount soldering kit?

Alas Digikey no longer carries it.  My best recommendation is to go to Digikey or Mouser, and get a syringe and some tubes of solder/flux and another tube of just flux.  You can take your pick of no-clean, water soluble or solvent clean, the old solvent clean is probably the best to work with.  Also get a spray can of flux cleaner while you are at it.  

The kit had some handheld vacuum pickup tools and various syringe tips, none of which seemed to work so don't bother with them.  Tweezers work fine. 

-- Lawrence Lile, P.E.

Electrical and Electronic Solutions

Project Solutions Companies

http://www.projsolco.com

573-443-7100 ext 221

> {Original Message removed}