Everyone in the BGA repair industry knows that when using the repair table to weld BGA, the temperature is a curve. Whether the curve is set correctly directly affects the repair yield of BGA chip.
Shenzhen Da Tai Feng Xiaobian here to give you a suggestion, in the setting of BGA repair platform temperature curve first through 190 degrees of preheating, and then to 250 degrees, and then to 300 degrees, solder paste can be fully welded, and then decrease the temperature, and then to cooling heat dissipation. In this way, sequential heating or temperature reduction can reduce the deformation of PCBA substrate caused by temperature abrupt change.
Setting method of PCBA substrate repair temperature curve:
For different sizes of chips, different solder paste, different types of boards with different thickness, the temperature and duration of each stage of the temperature curve are not the same. In addition, under normal circumstances, our PCBA is exposed to air, and heating a single part will lead to serious loss of temperature. Therefore, when setting the temperature curve, we should not simply use the way of heating to compensate the temperature, which will cause excessive temperature damage to the entire device itself, resulting in BGA bending and deformation. Therefore, we need to set an appropriate temperature curve when using the BGA repair table so as to achieve the best repair effect.
Here, Shenzhen Da Tai Feng Xiaobian recommended small board chip can consider the use of heat gun repair, if it is a large computer motherboard you need to use a professional BGA repair table.
BGA repair table temperature curve setting:
About the repair platform temperature curve Settings need to pay attention to some problems, Shenzhen Da Tai Feng Xiaobian then talk about the repair operation steps.
1. Choose the right air nozzle, align the air nozzle with the BGA chip to be removed, plug the end of the temperature measuring wire into the temperature measuring interface of the BGA repair table, and plug the other end of the temperature measuring head into the bottom of the BGA chip. Follow the table below to set the temperature curve and save it for next use.
2. Start the BGA repair table. After a period of time, start to use tweezers to gently touch the chip continuously. When the tweezers touch the chip and can move slightly, then the chip's melting point is reached, at this time you can measure the temperature, and then modify the temperature curve and save.
3. When we know the melting point of the chip, we can set this temperature as the highest temperature for welding, and the time can be about 20 seconds for the general equipment. This is the temperature detection method without knowing whether your chip has lead or no lead. Generally, when the actual temperature with lead reaches 183 degrees, the BGA surface temperature will be set as the highest temperature, and when the actual temperature without lead reaches 217 degrees, the BGA surface temperature will be set as the highest temperature.
Temperature curve display of BGA repair table:
Next, we analyze the areas needing attention according to the equipment steps of the repair temperature curve: preheating -- warming -- constant temperature.
Step 1: Preheat
The main function of the preheating and heating section of the temperature is to remove the moisture on the PCB board, prevent bubbling, and play a preheating role on the whole PCB to prevent thermal damage. So in the preheating stage need to pay attention to is that the temperature should be set between 60℃-100℃, the time control in about 45s can achieve the role of preheating. Of course, this step you can extend or shorten the preheating time according to the actual situation, because the temperature rise is related to your environment.
Step 2 Keep the temperature constant
At the end of the second constant temperature time, the temperature of BGA should be kept between (lead-free: 150-190 ℃, with lead: 150-183℃). If it is too high, it means that the temperature of the heating section we set is too high. We can set the temperature of this section lower or shorten the time. If it is too low, the temperature of the preheating section and the heating section can be increased or longer. (Lead-free 150-190℃, time 60-90s; Lead 150-183℃, time is 60-120s).
We generally set the temperature in this temperature section to be slightly lower than that in the heating section. The purpose is to equalize the temperature inside the tin ball, make the overall temperature of the BGA average, and make those temperatures slightly lower rise slowly. And the section can activate the flux, remove the oxide and surface film on the surface of the metal to be welded and the volatiles of the flux itself, enhance the wetting effect and reduce the effect of temperature difference. Generally, the actual test temperature of the tin ball in the constant temperature section is required to be controlled between (lead free: 170~185℃, lead with 145~160℃), and the time can be 30-50s.
Through the above steps you can as a reference to set BGA repair temperature curve a standard, the most important is that the temperature curve will change with your environment and your repaired devices, you need to adjust according to the actual situation, if you are not clear for the division of the chip temperature grade can directly contact Shenzhen Da Tai Feng website customer service for more information.
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