Future problems with using fluxite when soldering?

With the reliability problems of going lead free and the exceptions that allow the use of lead. I would just claim that your product is for a high reliability application and is therefore exempt from being lead free...

Seems to me that with the reliability problems this lead free law is a right pain in the bum...

John.

Unfortunately suppliers do not dictate what the market uses in the way of products and compliance. The customers write up their compliance lists and you have to ensure (and proof) that your products live up to the stated specs.

We have to be lead free as we also have to use UL rated components and parts listed in the Rohs directive. We have to use poison free cable insulators in case our product catches fire and the list goes on, we cannot change that demand.

Leaves me sitting here trying to solder with a great blob of goo on the end of my iron and the question if I am creating a future problem with my fluxite?

We have been using the lead-free stuff for a couple years now and have had no complaints from customers about corrosion. We do wash the boards thoroughly though to remove any flux. The stuff is nasty to work with though. It smells bad, exposure to fumes is bad for you, it hardens to a dull finish that looks like a cold solder joint with regular solder, it spits flux all over the board and it forms cavities or holes when it cools so you wind up soldering the same connection two or three times. It does eat soldering tips like mad, usually a tip lasts at least a month, with the lead free solder we were going through a tip a week.

Hi Stevem,

Many of your problems sound exactly like ours. Unfortunately we cannot wash our solder joints as we solder d-sub computer connectors and motor flyleads. Our products are already placed on a microscope stage and as such a bit fragile and expensive, certainly not very resistant against being washed down.

Have you got any useful tips or hints about making your life easier using the leadfree solder? Did you find wire material and make of solder tips to be of any influence? Just trying to come to grips with this and so help our manufacturing process to go a bit smoother.

Just found out that there is a problem with the acid levels in the flux. It should not be left on the product after soldering so we will stop using it altogether from now on. That leaves me in even more need for a solution to this leadfree soldering?

Please _help?

Afraid I can't help... we design custom instruments and equipment and ignore the lead free rules as most of our instruments need to meet very high reliability medical standards, and we can't have tin whiskers growing and shorting out tracks after a year or so...

The way I reason it is that if the military insist on tin/lead for high reliability, then why shouldn't we all enjoy high reliability?

John.

if you can place a small drop of wash solution, and then suck it off with a vacuum, with two hypodermic needles, and do this several times until the joint is clean. Then dry with air, a little heated, and then with another needle place a drop of conformal varnish over the area. This would remove traces of moisture and protect the joint. You could even apply sealing grease and a shrink spaghetti nub ober the d-sub connectors after this wash process.

I'm shooting from the hip, but it sounds like the fluxite is a acid base flux that should not be used for electronic assemblies. It can, however, be used to tin your soldering iron, providing you clean the tip after it is tinned. Activated rosin flux should be used when soldering electronic components. So, use your fluxite to keep the iron tinned, and rosin for soldering.

Now that sounds like it could go somewhere. I will look that up and if I have ant problems finding it I will call back here later.

Thanks

I just Googled Fluxite. It conains zinc and ammonium chlorides in petrolium grease. Chlorides are definately chemicals you don't want to leave on solder joints for the electronics industry. I suggest you stop using the fluxite for this purpose. Tin-Silver is not difficult to use and flows at a temperature only slightly higher than Tin-Lead. You should be able to use water white, or mildly activated rosin flux. I suggest you contact the flux manufacturers for a recommendation

Try Oleic acid, an organic acid flux. Inert at room temp. mild flux at solder temp

I am with Electro man on this one...

Just provide some on your electronic boards to the medical industry, (even at cost), if need be, then you can legally insist on the leaded tin which has been used for many many years, trouble free..

Hopefully, babies won't be chewing in printed circuit boards...

The other alternative is problems, such as you are having, and eventually this:

http://nepp.nasa.gov/whisker/background/index.htm

the Choice is yours..

Sorry but can't agree with you or electroman.

There is no point at all burying your head in the sand. There does not need to be a problem and the industry is moving away from lead weather you like it or not. Even in medical and military specs they cannot deny the legislation laid down by law such as weee (EC Directive on Waste Electrical and Electronic Equipment). Even if there are some deviations from the already implemented obligation to manufacturers and suppliers of those goods in order to give enough time to find alternatives, there will be a time that even those exceptions will have to stop and everybody has to go lead free.

Tin whiskers are predominantly a problem for zinc galvanised materials and are a problem when pure zinc is laid down on weak semi structural components which may move or deform during their normal life (such as lowered ceiling components and computer cases). Once disturbed these whiskers can become airborn and cause problems in electronics. The whiskers growing from lead free soldering are very easy to prevent simply by a mechanical barrier around the joint wherever possible or a proper coating of varnish all over the board.

I am currently looking at hydrogenated rosin flux, rosin amine flux and carboxylic acid as a flux. Main producers are Alphametals and Kester. Just hoping I can find these products in the UK easily enough to try them out. These fluxes are part of a "no-clean" process in order to save time while retaining a corrosion free product.

It depends on the metals being soldered.

Copper, for example, remains corrosion-free in virtually anything other than nitric acid, and there's none of that in soldering flux.

Old electrical equipment (in the good-old thermionic valve days!) would have been soldered using either 'Fluxite' or 'Bakers' fluid or paste. 50 years is enough time for a corrosion fault to develop and most soldered joints have none.

In model-making, recently-soldered brass surfaces can be cleaned using an acid dip followed by a mild surface etchant prior to thorough drying and aerosol painting. http://www.myreader.co.uk/msg/13511358.aspx gives some experiences on soldering whitemetal. Hubert Carr's soldering potions can be found in good model shops across the UK (other fluxes are available).

If in doubt, flux residues can be removed using an alkaline cleaner and washing ("scouring powder" and an old toothbrush?). The flux manufacturer's information can be used as a guide. Do "exactly what it says on the tin"!

Here are some ideas to look at.

The epoxy flux sounds like a winner to me.

http://www.kester.com/en-us/leadfree/flux.aspx

http://www.kester.com/en-us/Epoxy_Flux.htm

Thanks both of you guys, I have already found KESTER and we are in the process of finding out the ease with which we can get hold of the stuff. We might try the mildly activated rosing flux from kester 185 first but who knows their technical team may recommend something else.

Thanks again,

Case491