[linears4]

Originally Posted by Dan Collins

Slight correction to previous post. Cooling time was not clear enough.

The G6150 +09 should be ok at 230 max. I see that the 09 date code has more ground planing thus more heat dissipation. But what I do is follow the IPC-7095B for my profile. For those unfamiliar with the IPC, it is the industry standards set by the top people in the field of soldering and reflow and is followed by every major manufacturer in the world. I suggest everyone get a copy, I think it is $50 on the website IPC - Association Connecting Electronics Industries. It is a wealth of info covering every step of the process and how to correct any problem. The IPC guideline for lead free is as follows. (I added some steps to compensate for the RE7500 heating)

Preheat 1 till temp reaches 50C - LH/PH, UH/R/parked
Preheat 2 for 60-90 seconds to 140C - LH/FR, UH/R/normal
Soak for 90-120 seconds to 217C - LH/FR, UH/FR
Reflow for 60-90 seconds to 225C - LH/R, UH?R
Cooling 30-60 seconds to 20C - LH/off, UH/off, Fan on and park UH when temp drops to 217C

The best way to cool this quick is to park the upper heater, fan on, and put a shield between the board and the lower heater when temp hits 217C on the downward cooling slope. Slow cooling will make the solder grainy.

Preheat 1 stage is important to minimize board burning. Heating too quickly causes the board to burn.

The most important thing on the reflow stage is to keep the solder at a liquid state for 60 to 90 seconds.

A correct profile should take 4 1/2 to 6 minutes from start to finish. Patience is mandatory when reflowing.

Another useful tip is to use the new Jovy upper heater reflectors (JV-URS). They direct the heat only to the BGA and not to the surrounding components. Verify the centering of the laser. It is not real accurate.

For the above example, raise the upper heater to 3-3.5 or 2-2.5 if using the reflectors. Moving the upper heater up or down will adjust your timing. I noticed that not all RE7500's are created equal with the temps so play with the upper heater height to get the timings just right.

See if this doesn't double your yield.

thats my suggestion:

swap new bga to leaded solder first... soldering unleaded type will give a too narrow process window and the chance to burn the chip or the motherboard is too high if the thermal control isn't too much accurate.



the distance between the lower heater and the board is too much, so try to elevate the entire machine with something, about 2,5 cm, or one inch if you prefer...

another important suggestion, and i think, the real key for good resuls :

don't turn on, or put the upper heater in normal mode if the temp of the board si not yet 130/140 degrees... if you turn on the upper heater from the begin, or after a 50 degrees preheat, the upper heater action will heat the thermocouple directly, and when you reach 140 degrees you cannot be shure that the pads are at that temperature, because thermocouple is thiny and exposed and quickly reachs high temp, more that the surface under the bga.