Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Micro BGA baking

Vijay

#17164

Micro BGA baking | 10 August, 2001

Hello Friends, Please advise how critical is the Micro BGA baking? The BGA size is around 7x7mm and we need to program it before mounting. The Micro BGA's are supplied in Trays and are put in to tape and reel after programming.We need to put these BGA's in to tape and reel due to Pick and place machine limitation. The Micro BGA's are 32 mils pitch and 10mils dia.

Thanks, Praveen

reply »

#17177

Micro BGA baking | 10 August, 2001

Probably, but the fabricator of these components can best respond to this question.

The need to bake depends on the component design. J-STD-020 and J-STD-033 [as I recall] relate to moisture sensitive components and define 6 classes of moisture sensitivity. [The fine SMTnet Archives give sources where you can download these docs.]

Usually the moisture sensitive device [uBGA in your case] fabricator labels their packaging to inform you of the moisture sentivity handling requirements. Since you have these parts repackaged, it wouldn't surprise anyone if this handling information is on the cutting room floor someplace.

You may need to bake these components before use. Be carefull before starting on such an adventure, because some carrier tapes do not take to baking well. [The fine SMTnet Archives has more on this.]

reply »

#17183

Micro BGA baking | 13 August, 2001

Praveen,

Once you find out the MS level of your components, you will need to track the exposure time from when the parts are initially removed from their dry bags, through test, programming, taping, and during subsequent dry storage and use of these parts.

As you will understand from reading J-STD-033, whenever parts have been exposed outside of their original dry bag for more than one hour, the clock of exposure time has started and will never stop, even when the parts are put back into dry bags.

The standard does take into account the drying effect of returning previously exposed components back in dry bags or dry cabinets. This is called the short duration rule and it is equivalent to a room temperature bakeout. The parts can be treated as completely dry if they have been exposed less than 8 hours and then put back in dry storage for 5X the prior exposure time.

If your overall test/programming/taping process takes more than 8 hours then the clock of exposure time will keep on ticking until all parts are placed and reflowed or until they are completely baked.

Since the bake cycle is much longer at lower temperature (68 days at 40C for parts in reels vs 48 hours at 125C for parts in high temperature trays), it may be advantadgeous to bake just prior to re-taping.

I hope this information is helpful.

reply »

PCB Soldering Tools

SMT in-printer dispensing