| Hi everybody. | Somebody know any consideration or special care to make a profile for BGA's. | | any advice is aprecied. | | thanks | Al Carrillo | | Hi Al, A BGA should be looked at just like any other surface mount device. However, just like any surface mount device, the different types of BGAs are going to have different thermal characteristics with relation to reflow. For example, the CBGA and SBGA (EBGA) is going to pull a lot of heat into the component and away from the substrate. These types of devices cause "cool" spots on your board. The best way to develop a profile is to phyisically insert thermocouples into the device. Drill through your substrate at a pad location. Use an .020" drill bit. Insert a thermocouple up into the substrate from underneath the board. Use #5 thermocouple wire. The total diameter is about .020". Paste up the location, populate it and run the board through your process. Record the time vs. Temperature data and adjust your profile accordingly. Watch out for overheating the PBGA packages. Also, make sure the PBGA packages stay "dry". Pay close attention to the moisture sensitivity levels and bake the components if necessary. A good indicator that something is wrong on a PBGA process, is the coplanarity of the device after it is soldered. The component should collapse evenly on the substrate. Don't be too intimidated by the BGA package. To quote the infamous Phil Zarrow, "BGAs, what's the BFD?"
Regards, Justin Medernach
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