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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


White Residue

Vinesh Gandhi

#8319

White Residue | 4 December, 1999

Hi All,

I am facing a strange problem. One of my esteemed & valued customers has an unusual requirement of cleaning the board with IPA after soldering is complete. I am using alpha metals UP78 no clean sodler paste during reflow. This IPA cleaning is leading to white residue generation but still the customer is insisting on IPA cleaning.

May I request you all to send some technical papers/documents/your views via e-mail regarding the bad effects of white residue on the board assembly.

Best Regards Vinesh Gandhi

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cklau

#8320

Re: White Residue | 6 December, 1999

Halo;

In your last message you did not mentioned why your customer need to use IPA to clean PCB's as their requirement and what subtances they want to get rid of (is it flux stain PCB's or component?).If so recommend your value customer of flux 910 which is more clean and cost effective.Although IPA is not recommended for use as preffered detergent (because of it's ice cold nature of it's properties- when react with air it become white color stain), I must say that it is a most effective cleanning solution.

You can persuade your customer to use other chemicals like CRC go contact cleaner. RS had a wide range of product's that might help.

Regards;

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#8321

Re: White Residue | 6 December, 1999

Vinesh: The white residue is perfectly expected, when washing a no-clean with water (and some alcohol). In some cases, the white resin that you are seeing can be removed. Your paste supplier should be able to provide details.

Recognize that cleaning no-cleans is far more expensive than cleaning water soluable fluxes. So, you've increased your soldering process cost (as compared with an aqueous flux) for your no-clean and now you've increased your cleaning cost. Bummer!!!

I suggest that your customer is living in a land of washable fluxes and has not kept currect with the vagaries of no-cleans and your mission is to educate them of:

1 Costs of washing a no-clean and then trying to remove the white residue 2 Accetability of leaving the white residue on the boards.

Good luck

Dave F

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C.K.

#8322

Re: White Residue | 6 December, 1999

To Dave's point - I just hate when people in this industry CHOOSE to remain undeducated and uninformed of the latest developments in soldering or any other types of new technology. I am struggling with this problem at my current company where we've got 5 mfgr. facilities, world-wide, and some "experts" at some of our sights don't even know what "VOC" stands for.

Dave F writes:

>I suggest that your customer is living in a land of washable >fluxes and has not kept currect with the vagaries of no-cleans >and your mission is to educate them of:

>1 Costs of washing a no-clean and then trying to remove the >white residue >2 Accetability of leaving the white residue on the boards.

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Vinesh Gandhi

#8323

Re: White Residue | 9 December, 1999

Thanks for your feedback. I definitely agree with your viewpoints. Can you send across any documents/papers through e-mail or post them on the smtnet which clearly describes the HARMFUL EFFECTS OF WHITE RESIDUES.

My customer's only apprehension is bout the leftover flux on the board after no clean soldering.

Best Regards Vinesh Gandhi

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#8324

Re: White Residue | 10 December, 1999

Vinesh: You�ll find no papers that "clearly describes the harmful effects" of your style "of white residues," because no one is crazy enough to brag that they are doing what your customer wants you to do.

The residue of no-clean fluxes are designed to be benign for most applications. They are called no-clean, because these benign residues do not require cleaning. Here�s what I think you should do:

1 Establish measures of cleanliness by:

� Telling your customer that you appreciate their concern about flux residues and that you want to meet their cleanliness standards. � Asking them to quantitatively define their cleanliness standards (rather than telling you how to go about cleaning boards). It�s their job to tell you what they want and it�s your job to give them what they ask for, as long as it�s not too stupid. � Agreeing on and documenting the method the two of you will use to measure the cleanliness of the boards.

2 Educate you customer about no-clean fluxes by:

� Calling you flux supplier, describing the situation, and requesting they give you and your customer a presentation on no-clean fluxes from a technical perspective. � Developing pricing alternatives of no-clean soldering only, no-clean soldering with IPA cleaning and accepting the white resin coated, ugly solder connections, and no-clean soldering with IPA cleaning and further cleaning to remove the white resin coated, ugly solder connections. � Considering the alternative of using OA flux and washing for this customer.

Good luck

Dave F

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