MMM, today is NOT our day x2... - RC-Monster Forums

suicideneil · 07.30.2009, 08:39 PM

Mount the escs upside down, so the chips arent subjected to the weight of the esc pressing down upon landing a big jump- same principle as having rear facing seats on a bus or train etc...

Granted it will look stupid though, but it might just work... :P

J57ltr · 07.30.2009, 09:20 PM

A vibratory table will sustain forces for a much longer time. A single shock load may be higher but a shaker table will tell you. Since implementing this test we have yet to have a single failure for “lost” components in the field. A ferrite inductor isn't really that heavy (I’ll weigh some in the morning), it may be heavier than the Cap that's sitting next to it but because of the way they broke you can clearly see that the solder joint was not a good one. It happens; they are fixing it under warranty. Excellent customer service as I have seen in the past. I am not saying anything bad about them or their process, hell we are a small company and we screw up all the time. When we find it we fix it and put in place measures so that it doesn't happen again. I am not even saying they made a mistake, a solder joint can get past the best of us, even with a 10X Loupe. And with some of the new solder and components out there it is a problem until you get used to it. I have soldered HPM solder for tools used in the oil field industry. I can freehand any component you put in front of me surface mount a PLCC chip not a problem, SC70 transistor, you betcha, leadless packages all day long. I have done solder inspection till I am blue in the face, it’s a bad solder joint. No big deal. You guys are always blaming the user I don’t understand it.

Jeff

Pdelcast · 10:13 PM

J57:

Wave solder? Is this the 80s?

We use 100% reflow soldering -- there is no wave soldering done. You couldn't wave solder these parts anyway, they are much too small and placed too densely for wave.

The joints look a little grainy because there is a silicone conformal coating over the whole board. Those are beautiful solder joints -- not a cold joint in the bunch.

(Remember, we are 100% lead free, so the solder joints are not as shiny nor as strong as leaded solder joints... but we have no voiding, and 100% of the solder joints are inspected by AOI prior to conformal coating. -- We are lead free because we sell worldwide, and we cannot sell items containing lead in Europe...)

The joints in the picture failed, not because of poor joints, but because of shock. I imagine (even though we didn't see the parts) that the end caps on the inductor failed, the part rotated, and tore the solder joints cleanly. It's pretty obviously a torn joint. A cold joint would have shown voids, not a cleanly torn surface.

Shock can be enormous in these cars -- I've seen 10ga wires ripped in half just from their own weight (think about how many Gs that is!!), 96 mil thick FR-4 circuit boards bent 90 degrees, circuit boards where EVERY pad on one side of the board is torn off the FR-4... you name it, we've seen it. (And 8Gs is nothing... We routinely see forces over 70Gs in RC cars.)

So soldering is very important to us. We use a Heller 7 zone full convection oven (accurate to +- 1 degree in every zone, and specifically designed for lead-free operation), and we profile every batch. We use a very sophisticated AOI system that literally inspects every single solder joint on every single board we produce.

We use a VERY expensive tin/copper/silver solder formulation for our solder paste (printed,) bar solder and wire solder. This is a much stronger (physically) formulation than SN100 (100% tin) which is used in most lead-free industries today. It's still not as strong as 60/40 -- but it's close.

We take quality very seriously -- we aren't perfect (see MMM V1...), but we utilize tools that make the quality easy to maintain, and we check our quality continuously.

Castle isn't a basement operation - - we have some of the most sophisticated equipment in the world in our surface mount line (including the fastest and most accurate chipshooter available today), and we produce around 30,000 controllers a month.

Pdelcast · 07.30.2009, 10:06 PM

Quote:

Originally Posted by suicideneil

Mount the escs upside down, so the chips arent subjected to the weight of the esc pressing down upon landing a big jump- same principle as having rear facing seats on a bus or train etc...

Granted it will look stupid though, but it might just work... :P

But there are parts on both sides of the boards....