How to choose bga rework station

Hot Air is older and traditional, been around for about a decade. IR is relatively new in the reworking market.

Hot Air gives uneven heating. IR provides more even heat due to absorption rather than penetration thus a simple benefit of IR is it can remove plastic components, such as a CPU socket, with IR it penetrates the solder joints and does not burn or melt the plastic. IR is usually silent in operation because it has no air flow, while Hot Air uses a forced air system which is heated.

Technically speaking a Hot Air rework station is more complicated to manufacture than IR in structure and the cost is higher. This is because there are many cables in top hot air heater along with a fan system. Hot Air uses nozzles which is both a pro and a con, the con is you have to purchase different nozzles for different sizes of chips and the pro is that nozzles can be rotated in 360 degree which very easy for alignment.

IR stations tend to use ceramic heating plate, they give even heating without causing shift of other surrounding components due to the lack of air movement, but due to the IR plate being a fixed size, you may need to use high temperature tape to cover the surrounding area of the BGA chip. However when using Hot Air you may come across the same issue if your nozzle is not an exact fit or the air flow is too high.

Many of the expensive machines use Hot Air because well its been around longest and many companies do not want to switch. They have procedures in place and changing them will cost too much. Samsung or Intel with several millions of employees having to retrain and re certify them is too much. Why do you think so many companies still use Win 2K or XP, its all about the transition cost and time.

IR is newer, but it is gaining much more interest, the reason it has a bad name is due to the inferior plates being used. Higher end plates such as those fitted with Elstein heaters will perform much better.

Any person can perform reworking with just about anything. Anything from an open flame to a million dollar rework station. Heat guns, SMT stations, BGA stations, torches, stoves, ovens and more can all be used as heat sources. Understanding the heat source, using it properly and ensuring that its the right heat source for the job, is where many fail. Many rework technicians attribute their setup as being successful. Having success in regards to any amount for example 60% success rate or even 30% gives the user confidence in themselves and their process. 

Reworking is a science, its not just about heating things. Simplistically it can appear to be that is all we do, heat the chip and remove it. There are many variables involved. MSL moisture sensitivity level, package size and type, environmental variables, pcb thickness and quality, copper planes, flux, solderability and more.

Variables that affect User B may not be the same for User A thus having less success but longevity. The success rates can also change if the user does not update processes and monitor variables. The same principles can be applied to a chef, chef A is a veteran and has a dull knife, chef B is a noobie but has a very sharp knife. Chef A or B could have a better cut with their current setup, but if the 2 switched setups chef A would most always have the better cut while chef B would blame their setup for the lack of success.

Package temperature is also very important, non ROHS, PB, or lead packages would tolerate a temperature of around 235c, while ROHS, PB free, or lead free packages tolerate temperatures of around 260c. New processors and chipsets use integrated heat spreaders or IHS. It is a heatsink that is affixed semi permantely to the chip. When reworking an RSX chip with Hot Air the package would be much higher than the solder ball temp and this is due to the penetration technology heating up the RSX since it is closer to the heating source and was absorbing much of the heat, applying heat resistant tape to the IHS reduced the temperatures considerably. When reworking with IR the package temp was very close to the solder ball temp due to the absorbtion technology