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PCB washing - 05-/24-07 by jmabie

PCB washing - 05-/24-07 by Pete C

PCB washing - 05-/24-07 by jmabie

PCB washing - 05-/24-07 by Steve Thomas

PCB washing - 05-/24-07 by jmabie

PCB washing - 05-/24-07 by davef

PCB washing - 05-/24-07 by jmabie

PCB washing - 05-/25-07 by Michael

PCB washing - 05-/25-07 by bschreiber

PCB washing - 05-/25-07 by mfgengr

PCB washing - 05-/25-07 by jmabie

PCB washing - 05-/29-07 by Real Chunks

PCB washing - 05-/30-07 by RDR

PCB washing - 05-/30-07 by jmabie

jmabie

#50372

PCB washing | 24 May, 2007

We use a washer soluable solder flux for our solder wave. We then wash the boards in a dishwasher. We have done it this way for years without problems. We just got a new dishwasher and now we get residue on the solder (white marks) Anyone know of what causes this ?

Jerry

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Pete C

#50377

PCB washing | 24 May, 2007

Is wash temp the same in the new washer? I'm thinking that may be a clue. Are you sure nothing else changed, like water supply at all- conditioner? Do you have a supply of DI water?

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jmabie

#50378

PCB washing | 24 May, 2007

Everthing is the same. I did not check water temp or wash cycle time. No DI just straight from water supply. How do I do the DI ?

Jerry

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Steve Thomas

#50383

PCB washing | 24 May, 2007

By purchasing or leasing a DI system and supplying it for your final rinse, at least. You'll avoid some troublesome ionics on your boards that way.

Kind of off topic, but are you filtering or boiling off your washer's waste water or are you sending your waste stream directly into your city's sewer system?

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jmabie

#50384

PCB washing | 24 May, 2007

The waste water is filtered then sent to city sewer. When we first started we had inspections and then they said our volume was so low and did not require continued testing.
We wash 20-40 boards a month. Small 3x4 inch boards. If we hand rinse the boards with DI water with this help to reduce contaminates ?

We use compressed air to dry boards

We used this same methode for years without problems. Do you think its just a cheap dishwaser or could water temp be an issue ?

We dont do enough volume to make the investment in a DI washer.

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davef

#50385

PCB washing | 24 May, 2007

We'd guess that your white residue on the solder is from minerals in the supply water. We expect the levels of these minerals that you see:
* Vary depending on the season. Check with your public water authority for anaylsis. [Recognize that this maybe risky, because they may not be aware of your processes. If they were, they may not happy with you returning lead, flux residues, and other schmutz from your wave process to them.]
* Percipitated differently between washers, depending on the water preheat process.

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jmabie

#50386

PCB washing | 24 May, 2007

Our filter removes all contaminates authou it takes forever to evaporate 20 gallons it work quite well. I will check with local water supply for mineral analysis. Will a water softener remove the minerals that may be causing the problem ?

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Michael

#50387

PCB washing | 25 May, 2007

Never use a water softener for defluxing. They add sodium to the water which is bad for boards. The white residue may be flux. If that's the case, either the dishwasher is not powerful enough or the wash water is not hot enough. Another possibility is that you are not subjecting the board to enough rinse cycles. Dishwashers are for dishes, not circuit assemblies so there is a lack of rinse cycles.

DI water is you best bet. Rent (don't buy) a system from US Filter. Average rental price is between $ 50.00 - $ 100.00 per month (plus exchange fees).

Mike Konrad
Aqueous Technologies
www.aqueoustech.com
konrad@aqueoustech.com

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bschreiber

#50392

PCB washing | 25 May, 2007

You should also check the quality of your compressed air. If the proper filters and desiccants are not in place, you could be recontaminating your washed boards with condensed water and oil residues from the compressed air used for drying.

Bill Schreiber
Smart Sonic Corporation
Bill@SmartSonic.com
www.SmartSonic.com

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mfgengr

#50393

PCB washing | 25 May, 2007

I had a similar problem a long time ago. I eventually traced the problem to undercured solder resist. The flux was reacting with what was left of the uncured resist, leaving a white residue. We could not even hand scrub this off. The solution was to soak the board for ten minutes in the flux, completely submerged, then re-wash.
Undercured solder resist is not unusual. Board shop employees run the resist with the lowest amount of catalyst (sometimes too low) to increase their pot life, and reduce material changeout.

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jmabie

#50394

PCB washing | 25 May, 2007

We have 4 diffrent boards that have the problem. The boards have two diffrent suppliers. I dont think this is the case. I more leaning toward not enough rinse cycles in the washer.

Jerry

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Real Chunks

#50419

PCB washing | 29 May, 2007

Hi Jerry,

Sounds like the white stuff is flux. I doubt if 4 pcb mfgers could be undercuring all at once. Good point though.

Since you changed washers and now have the problem - it's your new washer. Can you bring back the old one to make sure? if not, double check to see if the old one refreshed it's water between cycles. Could be your new one is just recircing your water and not refreshing the water as much as the old one. Times of each cycle are another area to double check. Could be your rinse cycle if very short compared to the old one. Just a thought.

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RDR

#50443

PCB washing | 30 May, 2007

you are sure that noone has brought in any alcohol based no clean flux?

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jmabie

#50445

PCB washing | 30 May, 2007

Yes

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