MIL 217 reliability

RL-

Design of circuitry that must withstand vibration, would certainly use construction techniques that minimize joint failure. As long as I can recall, solder joints have been known as a weakness. Solder should never be used for physical strength.

It has been at least 40 years since I worked with 217, so I can't answer your question directly. I know that back in the 60s, tests were run on different construction techniques including soldering, crimping, wire wrap, welded modules, et cetera. I found several web sites that appear to have MIL HDBK 217F available for download. Your best bet is to download a copy and see if such data is included.

Fred

Electrical solderability in the military is now covered under standard COTS standards, and that standard is now IPC-610-a rev E.

It even covers intermetallic effects.

You only EVER need to follow that OLD spec if it is specifically called out, and to do so usually means a bigger quote, so you should not be seeing that spec being asked for compliance against, and if you are, you should insure that you need to.

If you do, you should hope that the person that quoted the contract made sure to charge for such compliance costs which get incurred.

"Failures associated with connection of parts into circuit assemblies are not included within the part failure rate models." That's handled separately in, for example, Section 16.1, Interconnection Assemblies with Plated-Through Holes.

Right.... what Rich said.

I still use 217F for space avionics reliability predictions and I have to account for the number of through-hole leads and surface-mount leads that are soldered although I have a program that automatically counts leads and puts the appropriate numbers in the formulas in section 16.1.

Tom P. Albuquerque

Yes, in fact solder joints are treated in different ways if they are thru-hole or smd solder joints. It also takes into account factors such as how was the solder joint made, for example, a board that was wave soldered has a higher reliability than one that was hand- soldered.

Section 16-1 covers thru-hole, section 16-2 is about smd.

Regards, Pedro

Section 16.1 covers plated through holes, 17.1 covers crimped, welded, wrapped, and other methods, including hand and reflow soldering.

MIL-HDBK-217 hasn't had an amendment since 1995. You'll find the failure rates for any technology introduced after the mid 80's to be unrealistic or unaccounted for.

RL

PCB manufacturing, as evidenced by via count increases, has all but solved the problems of interlayer interconnections in plated through holes.

Well, lets at least just say that the days of counting the vias, and striving to keep that count low are gone. And it used to a primary concern.

Boards are pretty good these days. Most hi tech stuff includes post manufacture, pre-delivery failure mode testing and culling. So they are good to go upon receipt in most cases.

Then, some lame group of crybaby idiots over on the other side of the pond shoved ROHS down our throats.

How quaint, in our stifled economy to inject such total horseshit into it.

Another shift of billions from over here to over there.

Metallic form Lead does NOT disturb water tables, you idiots!

Same for Mercury.