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SMT electronics assembly manufacturing forum.


Touch up on 0603 Chips ( Ceramic caps)

Ashok Dhawan

#7656

Touch up on 0603 Chips ( Ceramic caps) | 31 January, 2000

I have got a number of assemblies back from a customer with feedback that the solder fillet is less than 25% of chip height per IPC-Standard-610B Class 2. Most of my joints are having good wetting but fillet height does not meet min ht requirement of 25% .The parts have termination with grayish look , vendor is murata which is saying that part need to be soldered at higher temp or longer dwell time to make a good solder joint. Low residue soldering method is used. I am asked to touch up all those joints and add solder to meet min requirement of 25% fillet height. I am looking for suggestions how such a dauting task can be completed ? What is most recommended method for touching up solder joints ? - flux and reflow -remove and replace -talon tweezers -hot gas tips ? - ????

I will appreciate feedback from you how we can proceed further this ?

I guess Rev C does not require fillet height to be 25%. I do not know why IPC chnaged to

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#7657

Re: Touch up on 0603 Chips ( Ceramic caps) | 1 February, 2000

Ashok: A fine mess you gotten us into now!!! ;-) You have no good options.

BEST OPTION: Get the customer to accept the boards "as is." Rework will only degrade the product. Agree to accept all liability related to this solder condition (which you�re gonna have to do anyhow!!!). Agree to fund a reliability test at an independent lab. NEXT BEST OPTION: Make a template to selectively spray flux the defective terminations and reflow the board. NEXT BEST OPTION: Use a flux pen to selectively flux the defective terminations and reflow the board (similar to above). BAD OPTION: Talon tweezers ... tough to control, operators will comatose fast. WORSE OPTION: Hot gas tips ... tougher to control, operators will comatose faster. TERRIBLE OPTION: Remove and replace ... hand work will eat you up, operators will comatose the fastest.

Good luck

Dave F

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APE South

#7658

Re: Touch up on 0603 Chips ( Ceramic caps) | 2 February, 2000

Ashok,

I don't understand what they're saying about the gray joint. Usually a gray joint has to do with too much heat. Also, the higher the temperature the lower the fillet because of the increased viscosity of the solder. Correct? Wouldn't you want to run the board through with a lower temperature? Around 50 degrees over eutetic flow.

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#7659

Re: Touch up on 0603 Chips ( Ceramic caps) | 2 February, 2000

Dave, Ashok mentioned that the end termination of the component were dull and grey. I have had similar problems with Murata components exibiting the same characteristics on the end terminations. As it turns out, they have some exotic plating material that oxidized quickly and resulted in a slightly less solderable surface. The answer to our problem was to switch this application to an OA flux type that was capable of eating through the oxidation on the terminations. This may not be possible with his process. I agree with Dave F that the best way to approach this is to get the customer to accept the solder joints as is and provide some reliability testing. Refluxing and reflowing may still require a more aggressive flux type to increase the fillet height especially after it has already been through the oven. If solderability was the problem, it will be worse post reflow.

My $.02

Chris

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