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solder paste for 200 degs c continuous operation?

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#66032

solder paste for 200 degs c continuous operation? | 21 March, 2012

we are currently developing a 180 degs downhole tool and are right at the limits of our current solder paste, the tool has mostly surface mount parts and some fine pitch ic's. i was wondering if anyone had any recomendations for a suitable solder paste ?

also are there any other pitfalls to be aware of ?

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#66035

solder paste for 200 degs c continuous operation? | 21 March, 2012

Downhole solder suggestions, in order of preference are: * Kester Sn96.3Ag3.7. Most vendors do not stock straight tin-silver alloys, whose wallet is that fat? * SAC305 can usually be used in place of one of the copper-free tin-silver alloys in downhole applications. * Sn100C [Kester clone K100] is a cheaper alternative to SAC for wave soldering. For hand soldering, Sn100C / K100 is reported to perform a little worse than the silver based lead-free alternatives. * Sn95Sb05 is a more economical lead free solder, but has complaints of "cold" joint problems in downhole applications. * Kester SAF-A-LLOY (Sn97Cu.2Ag.8Sb2), but reports say it does not flow as well as other high tin solders.

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#66036

solder paste for 200 degs c continuous operation? | 21 March, 2012

thanks for the info :)

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#66038

solder paste for 200 degs c continuous operation? | 21 March, 2012

What solder alloy are you using at the moment which is coming to the end of its limits ? Normally in general for safe operation of an alloy we don't like to recommend any operation temp that is higher then two thirds of the solders melt point, but this is only a rule of thumb. In your case this would suggest an alloy with a melt point of 300C, but that would be no good for normal SMT with normal SMT devices. Most SAC alloys will have very little strength if they are heated to 200 C, because it is so close to their melt point @ 220 C. We offer high rel SAC based alloys but I need to check if they can operate at 200 C....but I'd be interested to know what your normal alloy is...thanks

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JAX

#66039

solder paste for 200 degs c continuous operation? | 21 March, 2012

To have an Operating Temp (Tool Classification) within your range, you might want to try.

PB85 (Pb85/Sb10/Sn5)

SMT is normally processed using Vapor Phase but can also be achieved with Nitrogen assisted Convection Reflow depending on size and complexity... with a little luck.

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