Baking Components ?

Surface Mount Components like QFP's in Tray usually comes sealed in an anti-static plastic pack. In case the QFP's were removed from the said anti-static bag for more than 2 weeks, do these components needed to be baked for they might produce solder balls ? at what temperature and for how long the baking will be? if u can also provide us info on what type of baking oven is used for baking components, or the pcb baking oven can do the job? suggestions are welcome...

thanks and regards,

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| | Surface Mount Components like QFP's in Tray usually comes sealed in an anti-static plastic pack. In case the QFP's were removed from the said anti-static bag for more than 2 weeks, do these components needed to be baked for they might produce solder balls ? at what temperature and for how long the baking will be? if u can also provide us info on what type of baking oven is used for baking components, or the pcb baking oven can do the job? | suggestions are welcome... | | thanks and regards, | | You have choices:

1 High Temperature Bake. Remove components from tubes and reels. Leave in waffle packs. Bake, only once, as follows:

Package Bake at 125�C (257�F) for hours QFP with 132 or more leads 48 Thicker than 2mm (0.08 inch) 24 Thinner than 2mm (0.08 inch) 6

2 Low Temperature Bake. Components may remain in supplier�s carriers. The low temperature bake is a 192 hour dwell at 40�C (+5� C, -0�C) at less than 5% RH. Shipping carriers will not keep their dimensions when baked above 45�C. Longer bakes are required if the humidity exceeds 5% RH.

Do not store components at the low bake temperature longer than the time required to dry out the units for use in the reflow. Longstorage times at elevated temperatures can cause soldering problems and the antistatic properties of the shipping carriers to deteriorate.

Low temp baking has no limitations on the number of rebakes

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| | Surface Mount Components like QFP's in Tray usually comes sealed in an anti-static plastic pack. In case the QFP's were removed from the said anti-static bag for more than 2 weeks, do these components needed to be baked for they might produce solder balls ? at what temperature and for how long the baking will be? if u can also provide us info on what type of baking oven is used for baking components, or the pcb baking oven can do the job? | suggestions are welcome...

It's not solder balls that you have to worry about. It's the package delaminating or blowing apart. Sometimes you can see it, usually under or around a lead exit, often you can't. Needless to say it doesn't do much good for the IC. Yes, it is likely that you should bake your parts. All sealed bags from the manufacturer or reputable distributor will have an MS or moisture sensitivity label giving a sensitivity level from 1 to 6. A 3, for instance is rated for 168 hours or 7 days out of the bag at less than 30C and 60% RH. Baking depends on the carrier tray. If is low temp tray, bake for 192 hours at 40C. If it is a high temperature tray, you can go for 24 hours at 125C. Out of the bag, or course. There is alot more too it as far as handling, RH detection, repackaging, etc. You should get yourself a copy of IPC-J-STD-033 covering the handling of moisture sensitive components. You'll be doing yourself and customer a favor. PS the bag is a moisture barrier bag and not just an anti-static bag. good luck - John Thorup | | |

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