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BGA rework station before the operation will need to know
BGA rework station before the operation will need to know
1. lead-free preheating temperature heating rate control in general 1.2~5 DEG C / S (s), the preheating
temperature is generally not more than 160 DEG C, heat preservation zone temperature control in the
160~190 DEG C, reflow peak temperature control in general 235~245 DEG C and the temperature
maintain time in 10 to 45 seconds, from heating up to the time of the peak temperature should be
maintained at about a minute and a half to two minutes.
2.Lead solder melting point is 183 degrees, and lead-free is 217 degrees. That is to say when the
temperature reaches 183 degrees, lead paste begins to melt, the melting point of the solder ball,
owing to their chemical properties will be higher than the solder paste.
3.Machine knowledge:
1, the application is broad: the upper part of the hot air lower dark infrared.Three,
2, temperature area models: the lower part of the upper air of the lower hot air dark infrared.
3, and red appearance: infrared upper lower infrared dark, key points: different types of products
the heating mode of the utility model, using temperature program exist different settings.
4.Introduction of hot air:
Hot air heating is the use of air heat transfer principle, the use of high precision controllable high
quality heating control, adjustment of air volume, wind speed to achieve the purpose of uniform
controllable heating, welding, bga chip ontology for the reason of the heat transfer, the temperature
of the part to the bga chip beads is better than the hot air outlet by a certain temperature, when setting
temperature heating (due to different manufacturers of the machine temperature control of the definition
of temperature is different, the requirement of temperature have certain difference), will take the above
factors into consideration, we also want to know about the performance of solder ball, to distinguish
between temperature period set (specific setting methods please refer to the manufacturer's technical
guidance), the key is the highest temperature adjustment period, first of all, first set a value to test run the
bga rework stations heating, heating to note that in for a new board, don't know under the condition of
the temperature tolerance, to monitor the whole process of heating process, the temperature rises to above
200 degrees, when viewed from the side the degree of melting process of solder ball (can also be from the
bga patch beside a touch gently with forceps, if can patch a displacement, prove that the temperature has
been achieved requirements), in the bga chip solder ball all melt will be obviously observed bga chip to cave
in, this time we want to put the machine the temperature of the instrument or touch screen display and
record the machine running time, the melt temperature at this time plus 10 to 20 seconds, when you can get
an ideal temperature!
Conclusion: BGA, solder ball in achieving the highest temperature go n seconds of time to start to separate,
only need to the temperature curve of the highest temperature is set to the highest temperature constant
temperature 20 seconds. Other procedures please refer to manufacturer to provide the temperature curve
parameters. Under the general condition with welding lead the whole process control in 210 seconds,
lead-free control in 2.8 seconds. Time shoulds not be too long, too long to PCB and BGA are likely to
cause unnecessary damage.