BGA welding method

BGA welding method

Desoldering BGA is best with the help of BGA rework station to complete. So how to set up the appropriate

temperature curve? First confirm the board is lead or lead-free (Pb solder balls on the melting point is 183

degrees, lead-free solder melting point is 217 degrees), also confirmed that the chip and the PCB board is

consistent (some PCB is lead-free solder balls is lead; solder is lead-free PCB and lead), but also according

to the size of the BGA and PCB board thickness to set the temperature. Under normal circumstances, the

chip surface to solder ball internal temperature will be 20-30 degrees out of phase, to a BGA ball melts

completely, you must enable solder ball temperature higher than the melting point of 10-20 degrees. There

is generally a lead of the BGA in the degree of melting between 215-235 degrees, lead to the melting of

BGA degrees between 245-265 degrees. It's easier to set the temperature curve after the temperature is set.

Below to a group of lead free temperature for example to explain: (general temperature is divided into four

parts)

A. preheating section (temperature at 100-200 degrees, 2 segments)
LI:170 D1:30 R1:3.00
L2:200 D2:30 R2:3.00
B. heating part (temperature in 245-265 degrees, 2 segments)
L3:220 D3:30 R3:3.00
L4:245 D4:40 R4:3.00
C. return part (10 degrees higher than the heating part of the heating section, 1 Section).
L5:255 D5:20 R5:3.00
D. cooling section (lower 20-30, 1).
L6:230 D6:15 R6:3.00

Note that the BGA does not need to be located in the cooling section, only when the temperature of the

need to set the temperature.
How to determine the temperature curve is appropriate? Of course still need to remove the chip to confirm

the temperature curve in before the demolition, also confirmed that the PCB board is dry (PCB heating

moisture blister easily deformed, baking). Then to remove the chip, the chip with tweezers or other tools

gently test chip in the heating part when there are no loose, and record the chip in the heating part so as

to determine the time required to extend and modify the time (from the beginning to melt completely

melted chip needs 30-40 seconds). If the heating part is not the end of the melting temperature is low,

need high heating part temperature to 255 degrees (or according to the actual situation and higher) then,

time constant, reflux temperature corresponding to 265 degrees, and then start welding. The welding in the

heating part began to observe and record the melting process to confirm whether the solder melting time

enough. The change process of melting solder: first light, and then stretched line, then slowly even collapse.

The final test confirms the success rate of the chip of the temperature curve, and then the temperature curve of OK is preserved.