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Trouble selective soldering fine pitch connectors

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#67769

Trouble selective soldering fine pitch connectors | 6 December, 2012

We are having difficulty with bridging on a 2x50 pin 0.050" fine pitch connector using our selective soldering machine. It usually bridges at the end of the row, but sometimes it bridges all the pins together as it drags across (solid bridging).

I am questioning the viability of soldering fine pitch connectors using the selective soldering process and would like to know from those who use or tried to use selective soldering on fine pitch connectors if you have had difficulty and what level of success you can achieve in terms of first pass yield.

I tried numerous programming strategies such as pulling off at different angles, nozzle height, drag speed, amount of flux, different nozzle sizes, stopping the pump at the end of the row, moving the end point, etc. with no consistent success. We are getting about a 50%-75% first pass yield and management is complaining about the low FPY. Management wants to see 90+% FPY, which is what I'm getting on 0.100" pitch assemblies. I read that having too much or too little nitrogen flow around the nozzle can cause bridging so I now have a flow meter on it but I cannot produce the amount of flow that the support people tell me I should be getting.

Specs: Pillarhouse Jade MKII using Kester 985M flux, 6mm standard nozzle, ultrasonic spray fluxer, pin protrusion = 0.015", 290C Sn63Pb37 pot, liquid nitrogen tank supply.

I would be especially interested in responses from those who have a Jade machine and use SnPb, but all responses are welcome. For those who have a Jade, what is the total nitrogen flow inputted to the machine? I am told that it needs 21CFH for the pump motor and 42-63CFH for the nozzle. I am only getting around 40CFH total with the nozzle supply valve full open, which is only about half the nitrogen I should be seeing at the nozzle. Is this normal in your experience? Thank you in advance.

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aj

#67777

Trouble selective soldering fine pitch connectors | 7 December, 2012

no expert but would using a smaller diameter nozzle help in anyway?

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aj

#67778

Trouble selective soldering fine pitch connectors | 7 December, 2012

I am no expert but would using a smaller nozzle help in anyway?

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Ken

#67792

Trouble selective soldering fine pitch connectors | 7 December, 2012

We had a similar issue and it was fixed by trimming the connector so there was barely enough lead protrusion through the board to show a discernible lead. We had to get a special plate and small machine to cut the connectors, but we haven’t had a bridge since.

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#67803

Trouble selective soldering fine pitch connectors | 10 December, 2012

We are using our selective solder machine to solder a backplane with sixteen (16) 4x48 pin 0.080" connectors. Our first pass yield is about 85% meaning that 85% of the connectors come out with no bridges. Not quite as fine pitch as your connector and we are using lead free solder but I'll give you the details just in case it sparks an idea for you.

Specs: RPS Automation Rythmn machine with heated nitrogen, 315C SN100C lead free solder pot, Kester 2235 water soluble flux, 2.5mm nozzle

My gut feel is that the smaller nozzle leaves fewer bridges at the ends of the connector pins. At 2.5mm we have to make a double pass on each connector which increases time on the machine. However, more machine time when a human can walk away to do something else productive is better than less machine time with increased human time fixing the bridges. What is the smallest nozzle size you have tried?

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#67809

Trouble selective soldering fine pitch connectors | 11 December, 2012

The issue is surface tension around the connector. Your tip needs to have more surface tension than the pins of the connector as it forms a cluster when being soldered. When I used to solder superfine connectors with a metcal iron it had a horses hoave tip. This would preferently drag the solder away from the pins. you need a similar setup with yout selective wave solderer. Any other approach is only going to run the risk of solder balling up between the pins of your connector.

regards sarason

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#67811

Trouble selective soldering fine pitch connectors | 11 December, 2012

Thanks for the comments so far. The smallest nozzle I've tried is a 4mm, which is what Pillarhouse used on this board to provide a sample. I tried this but wasn't as good as the 6mm. I've soldered the same connectors on a different board using a 10mm with decent success, but is too big for this small board. Lead length is very short.

Dyoungquist, yes I could try soldering one row at a time as you suggest. The smallest nozzle I have is a 2.5mm. I agree that increased process time is insignificant compared to the cost and hassle of rework, especially for us since all defects/rework must be documented per the J-STD-001. I'll try the next time we run and let the forum know the results.

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#67827

Trouble selective soldering fine pitch connectors | 12 December, 2012

Glad to hear we have more Jade users on the forum!

What kind of flux footprint is your fluxer leaving on the board? You called it a "spray" fluxer.. We use the MIC fluxer that functions like a jet fluxer.

Do you flux each individual lead or do a line flux? If its a line, what's the speed and pulse interval?

What are your line speeds and settings for the end of line soldering? Generally a connector with that type of lead pitch we'd do a pull off with the following settings: End Soldering Depart Height: .2 Withdraw Speed: 1 Pull off Time: 1 End Dwell: Generally 1.5sec depending on ground planes..

This setting will bring you solder pump speeds to "idle" which should be about 20-30rpms below your soldering speed.

We have eight of these machines in house. Hope this helps. If I can help anymore just ask.

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#67828

Trouble selective soldering fine pitch connectors | 12 December, 2012

Nitrogen at nozzle supply is at around 47.5cfh.

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#67855

Trouble selective soldering fine pitch connectors | 19 December, 2012

I had a connector like this and here is my recommendation:

1. Flux type(I like better alchohol based flux than water based) 2. Try higher soldering speed(when I say higher I mean several times higher)

Goodf Luuck!

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#68321

Trouble selective soldering fine pitch connectors | 26 February, 2013

Hi, guys.

Does anyone use a EBSO selective soldering machines? Can you write your parameters for two rows connector?

Thx!

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