Hot air reflow machine is the key to the entire BGA rework process. There are several issues that are more important:
1. Chip rework reflow machine curve should be close to the original welding curve with the chip, hot air reflow soldering curve can be divided into four zones: preheating zone, heating zone, reflow zone, cooling zone, the four zones of the temperature, time parameters can be set up separately, through the connection with the computer, you can store these programs and call at any time.
2. in the reflow soldering process to correctly select the heating temperature and time of each zone, while attention should be paid to the speed of warming.
Generally in the 100 ℃ before the maximum heating speed of no more than 6 ℃ / s, 100 ℃ after the maximum heating speed of no more than 3 ℃ / s, in the cooling zone, the maximum cooling speed of no more than 6 ℃ / s. Because too high a heating speed and cooling speed may be damage to the PCB and the chip, this damage is sometimes the naked eye can not be observed.
Different chips, different solder paste, should choose a different heating temperature and time. Such as CBGA chip reflow temperature should be higher than the reflow temperature of PBGA, 90Pb/10Sn should be 63Sn/37Pb solder paste selection of higher reflow temperature. For no-clean solder paste, its activity is lower than non-no-clean solder paste, therefore, the soldering temperature should not be too high, the soldering time should not be too long, in order to prevent the oxidation of solder particles.
3. Hot air reflow soldering machine, the bottom of the PCB board must be able to heat.
Heating has two purposes: to avoid warping and deformation due to the PCB board single-sided heat; so that the solder paste to shorten the dissolution time. For large-size board rework BGA, bottom heating is especially important.
The advantage of hot air heating is that the heating is uniform, and it is generally recommended to use this kind of heating in the rework process. The disadvantage of infrared heating is that the PCB is not uniformly heated.
4. To choose a good hot air reflow nozzle. Hot air reflow nozzle belongs to the non-contact heating, heating relies on high-temperature air flow to make the BGA chip on the solder joints of the solder dissolved at the same time.
This nozzle will be sealed BGA components to ensure a stable temperature environment throughout the reflow process, while protecting adjacent components from convection hot air heating damage.
Features of NeoDen IN12C reflow oven
1. NeoDen N12C is a new environmentally friendly, stable performance intelligent automatic orbital reflow soldering. This reflow solder adopts the exclusive patented design of "even temperature heating plate" design, with excellent soldering performance.
2. Built-in welding fume filtration system, effective filtration of harmful gases, beautiful appearance and environmental protection, more in line with the use of high-end environment.
3. Hot air convection, excellent welding performance.
4. The heat insulation protection design, the shell temperature can be effectively controlled.
5. Intelligent control, high-sensitivity temperature sensor, effective temperature stabilization.