I would appreciate some advise with regard to Leadfree settings for a 5 zone reflow oven.
I have a 35mm square BGA 672 pin on board. I am struggling to get the Delta T down to 2 degrees C . I have 5 Thermocuples drilled up from the bottom and glued into position ( impossible to solder ). One at each corner and 1 in the center.
The 2 leading TC reach Liquidus Temp roughly 3-5 seconds before the trailing TCs.
Peak Temp is within 2-3 degrees C.
Coming out of the Liquidus Zone the Trailig TCs are still in reflow for again approx: 5 secs after the leading TCs.
Settings - Speed 18 inches Per min. 160175215225270
how many layer board is it? what kinda temperatures is your oven currently hitting. In our reflow oven I have been using a profile that is the same for the top and bottom at zone 1 111C zone 2 at 164C zone 3 at 161C zone 4 at 208C and zone 5 at 253C. and 15 inches/minute. This is looking on our boards with NC254 (no-clean) paste. The 3rd zone being lower is because of the bleed over from the next zone, I needed to put it lower to maintain a good soak time. This profile I descrbed was used on a board containing 5 BGA's and it is a six layer board with lots of copper. Good luck!