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press fit on Ni/Au board finish

Romain

#19562

press fit on Ni/Au board finish | 18 April, 2002

Is anyone has experience on problems with press-fit on Ni/Au board finish. Connectors pins are SnPb finished. I am particulary interested by experiences or documentation in very agressive environmental conditions (avionics or space buisness) Thanks regards Romain

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#19567

press fit on Ni/Au board finish | 18 April, 2002

General comments are: * First place I would look is the supplier of the pins that you are trying to install. Most suppliers that sell press fit components have done a good deal of work to qualify the component and will have all the specifications you require to design for and install the component. * We do not press into ENIG barrels. [The lack of SnPb on the board does increase insertion forces to some degree. Ni is not as ductile as the copper, and some barrel cracking may occur, depending upon pin design and forces. Bla bla bla.] But on the other hand, we know people that press into ENIG and they�re happy, happy. * Bible for press fit is Bellcore/Telecordia TR-NWT-000078 (esp. chapters 4, 6, 7). * We would like to never press dissimilar materials. * Bellcore does not address this issue of galvanic intermetal compatibility with regard to press fit. [Potential difference between gold and solder according to MIL-F-14072 is 0.65 volt. According to MIL-F-14072, the magnitude of the potential difference should not exceed 250 mV in order to minimize possible electrochemical corrosion.] * Can you use organic solderability preservative [OSP] instead of the ENIG? Press fit with OSP [organic coating over copper] works rite fine. However, some fabrication process changes may be required depending upon the press fit pin style and plating. The lack of SnPb on the board does increase insertion forces depending on the pin shape. [But you will not know the difference, since you have not pushed SnPb anywho.]

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Bob Willis

#19712

press fit on Ni/Au board finish | 29 April, 2002

I have only seem problems so I would suggest you don't do it.

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ianchan

#19716

press fit on Ni/Au board finish | 29 April, 2002

Hi,

we do Sn plated I/O pinning insertion into Ni/Au thru' holes. no problems here so far, as we cater for the "interference" (fit-allowances) of the I/O pin into the thru' diameter, via improved PCB thru' hole designs. before this cater/consideration, we had S**T crack PCB press-fit holes. Beware!

this current I/O pins product is for optics fibre use. Your's seems much more aggressive in end-applications, as all aerospace thing-a-bob's do. Dun think 63/37 eutectic solder works for what you have in mind. you should try the higher temperature solders like Sn96/Ag4 to provide that mechanical attachment bond between the connector and Ni/Au pads.

Can't you use a SMD level connector? unless its some Mega-huge power supply connectors for some UFO flying saucer? or is it for the Mega-Zoid Plasma Cannons?

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