The key factor for the success of BGA welding chip is the temperature of BGA welding chip, the quick setting of temperature curve of BGA repair table, and the quick setting of the most appropriate temperature curve during the repair operation of BGA chip components. Compared with the quick setting of reflow welding temperature curve in common production, BGA repair operation requires higher temperature control. Under normal circumstances, the temperature curve of BGA repair can be divided into six parts: pre-heating, heating, constant temperature, fusion welding, back welding and cooling. Let the science and technology Xiaobian to introduce the specific method of BGA repair table temperature curve setting.
Notes for quick setting of temperature curve of BGA repair table
1. There are mainly two kinds of tin commonly used in SMT, one with lead and none without lead: lead, Pb, tin, SN, silver, AG, copper, CU. The melting point of the solder paste with lead is 183℃/, and the melting point of the solder paste without lead is 217℃/. That is, when the temperature reaches 183℃, the solder paste with lead gradually begins to melt. Now there is a wide range of lead-free chip pre-heating zone temperature rise speed time control in 1.2~5℃/s(second), insulation zone temperature control in 160~190℃, reflow zone maximum temperature set to 235~245℃, heating duration of 10~45 seconds, Keep the time from heating to the maximum temperature to about a minute and a half to two minutes.
BGA repair table temperature curve peak setting
2. During welding, taking into account the different definitions of temperature control by various manufacturers and the main reason of heat transfer of BGA chip itself, the temperature transmitted to the tin bead of BGA core is a certain temperature difference than that of the hot air outlet. Therefore, when adjusting humidity detection, we inserted the temperature measuring wire into the middle of BGA and PCB, and ensured that the most exposed part of the temperature measuring wire was inserted. Then adjust the air volume and wind speed according to the need to achieve uniform and controllable heating purpose. In this way, the heating precision temperature of the BGA repair table is the most accurate. This method must be paid attention to in the operation process.
BGA repair table welding chip temperature setting
Next, I will introduce the setting method of temperature curve when using BGA repair table to weld chips. Heating: Its function in the early heating and heating section is to remove the water vapor on the PCB board, prevent foaming, and achieve heating effect on a whole PCB to prevent thermal damage. Usually the temperature requirement is: in the heating stage, the temperature can be set in the middle of 60℃-100℃, usually set 70-80℃, 45s can be used for heating. If it is higher, it means that the temperature of the heating section we set is higher, and we can also lower the temperature of the heating section or shorten the time. If it is slightly lower, the temperature of the heating section and the heating section can be raised or the time can be extended.
Although the BGA repair table temperature curve setting process is a little troublesome, but we only need to measure once, after saving the temperature curve can be used repeatedly, is a matter of once and for all, we must be careful and patient in the process of setting the operation step by step. Only in this way can we ensure that the temperature curve is set correctly when BGA repair table is welding chips, and ensure the repair yield.
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