New reflow solder material - Page 1
Forum section: electronics / general

author: romantronixlab
author_rank: Regular Contributor
timestamp: January 09, 2014, 02:11:20 pm
content: As the title reads new soldering materials are rising as the old SnPb solder was phase out from mainstream production. First we had SnAgCu or SAC 305 and now there is the possibility that a new type of solder goes to the reflow market/production, SnCuNi. While the latter contains silver the other does not making it more economical. But according to an article there are fears of the use of it.“SnCuNi melts at 227°C. SAC 305 begins to melt at 217°C, reaching its fully liquid state at approximately 220.6°C. Recommended reflow temperatures are typically at least 13°C higher than melting temperatures, hence the SAC 305 peak temperature window of 233° to 255°C. Applying the 13°C guideline to the SnCuNi alloy results in a minimum peak temperature recommendation of 240°C. It's that 7°C difference in minimum reflow temperatures that generates the fear - of cold joints, incomplete wetting, inconsistent IMC formation or other reliability issues- if the peak temperature of a solder joint falls into that questionable space between 233° and 240°C.” -PRINTED CIRCUIT DESIGN & FAB MAGAt least for me in that matter is that all reflow tables change and also according to temperature changes one must be careful on the components behavior on temperature.

author: ConKbot
author_rank: Super Contributor
timestamp: January 09, 2014, 05:44:29 pm
content: Great, so pure tin melts at 232C, and they've managed to make another solder which is even closer to that...If we could bring the margin between reflow point of solder and the point at which the package chars and the board delaminates even smaller, so its even more miserable when I have to rework COTS items at work, that'd be greatNormal boards I can generally handle, but ROHS RF boards are the bane of my existence. I had to use a hot-air preheater to get out a 6-pin header the other day because the board was lead free and had enough planes to sink away the heat to keep the 63/37 from even alloying with the lead free.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 09, 2014, 06:40:21 pm
content: Once tried to desolder a bunch of output ground wires from a power supply so I could get at the secondary more easily. 16ga copper wire feeding into 12ga aluminum plugs soldered with ROHS solder into a 2oz copper board with large ground planes? Vs. your every day Weller?Nope.jpgI did get about half of them off... But it took an hour and I had to use quite a bit of solder, and I melted the insulation off the wires.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 09, 2014, 06:43:27 pm
content: Quote from: Phaedrus on January 09, 2014, 06:40:21 pmThat would be a doddle with a Metcal or JBC

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 09, 2014, 09:42:41 pm
content: Quote from: mikeselectricstuff on January 09, 2014, 06:43:27 pmWish we had the budget for one, and that I did stuff like that often enough to justify the cost.

author: Fsck
author_rank: Super Contributor
timestamp: January 09, 2014, 09:44:48 pm
content: Quote from: Phaedrus on January 09, 2014, 09:42:41 pmit's like ~100$ for an stss with an old school handle. more than enough.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 09, 2014, 09:48:50 pm
content: When I say we have no budget, I mean we have no budget. We have a shitty power meter that just failed while under 40% load. Higher ups won't approve budget for a competing product I've used in the past that has double the current rating, comparable accuracy, is far more reliable, and costs 1/3rd as much. So I'm buying it on my own dime, to use at home as well.