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Reflow Profile ENIG Vs. Immersion Ag

KT

#33237

Reflow Profile ENIG Vs. Immersion Ag | 16 March, 2005

We are moving from ENIG to Immersion Ag. We notice PCB's with Ag finish getting more heat(increase in peak temp) than the ENIG. Any reasoning behind this phenomenon ?

KT

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#33238

Reflow Profile ENIG Vs. Immersion Ag | 16 March, 2005

Are you using a standard convection reflow oven ?

This does not make any sense. I have never heard of anything like this.

If you are using a standard oven, then I would say that it is time to get your profiler calibrated.

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#33243

Reflow Profile ENIG Vs. Immersion Ag | 16 March, 2005

KT, What sort of delta T are you getting?

This does sound a bit odd. TCs are in EXACTLY the same position on each board?

Something I only recently found out - according to Mark Cannon from ERSA re profiling, that you may wish to consider. 1.TCs should be stripped and reformed after each solder joint is formed or varying results may occur. I.E. if you desolder the TC from one pcb and solder it straight onto another pcb without making it "new", strange things may happen. 2. TCs should only be twisted at the point of contact with the joint - this is where the temp reading comes from. eg if you made a 1mm twist and stuck the pointy end in the joint for 1/2mm then the actual reading will be 1/2mm away from the joint in the open air. The temp is read where the twist starts from the hoop, not the end of the twist.

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KEN

#33245

Reflow Profile ENIG Vs. Immersion Ag | 16 March, 2005

Where does this notion that thermal profiling is absolute come from?

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Rob

#33248

Reflow Profile ENIG Vs. Immersion Ag | 17 March, 2005

The people who charge lots of money for their thermal profiling products.

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Grant

#33250

Reflow Profile ENIG Vs. Immersion Ag | 17 March, 2005

Hi,

Thermal profiling is not absolute? It seems to work great for us.

Regards,

Grant

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Slow Ride

#33264

Reflow Profile ENIG Vs. Immersion Ag | 17 March, 2005

How much more? A couple degrees? That would be normal from one board to another, depending if the t-coupls are in the exact same spot etc.

What type oven? IR ovens can be affected by colors.

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Kt

#33358

Reflow Profile ENIG Vs. Immersion Ag | 22 March, 2005

Its not IR oven. Its consitent variation of around 3 - 5 degrees.

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jdumont

#33366

Reflow Profile ENIG Vs. Immersion Ag | 23 March, 2005

Any reason why you would switch to Immersion Ag from ENIG? I am also considering the use of Immersion Ag (switching from good ol 63/37). Are there any papers on the benifits/problems of ENIG vs Immersion Ag?? Thanks in advance JD

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#33373

Reflow Profile ENIG Vs. Immersion Ag | 24 March, 2005

There's a lot of comparison tables on the web. Here's one:

Properties - Summary [A Winlow Circatex] Attribute||Hasl||Immersion Silver||Immersion Tin||Electroless Pd||OSP||Eless Ni / Imm Au Shelf Life (months)||12||12||12||12||12||6 Multiple Reflows||4||5||5||5||4+||4 Cost||Medium||Medium||Medium||High||Low||High Process Effort||High||Medium||Medium||High||Low||High Process Temp.||240oC||50oC||70oC||70oC||40oC||80oC Thickness (microns)||1 - 25||0.05 -0.20||0.8 - 1.2||0.15 -0.40||0.20 -0.50||0.05 -0.20 Au 5 Ni Flux compatability||Good||Good||Good||Medium||Medium||Good Holding time constraints||Growth of Intermetallic||n/a||Growth of intermetallic||?||7 days||Oxidation of Ni

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URL

#33383

Reflow Profile ENIG Vs. Immersion Ag | 24 March, 2005

3-5 degrees between two different boards is not that great a deal. It could simply be a combinations of the t-couple and where/how it's mounted on each board. It could be related to the metal or it's thickness, depending on your layout. Over all, if it's not causing a problem I wouldn't worry about it. If you need to know, you should t-couple up about 30 boards of each and run em' through to get some good statistical data.

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#33384

Reflow Profile ENIG Vs. Immersion Ag | 24 March, 2005

other than the fact that silver is a better conductor of heat, I can't think of anything.

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