solving tombstone

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Hi, Im having problem on tombstone, The part is LF chip comp... - Jul 31, 2008 by MCR

Pattern design, paste volume,printing misalignment, place mi... - Aug 01, 2008 by fowlerchang

thanks,my pad design is 24 x 23 mils and now I chnged my ste... - Aug 01, 2008 by MCR

Pad design is not only the size of pad but also the distance... - Aug 01, 2008 by fowlerchang

MCR

#55784

solving tombstone | 31 July, 2008

Hi, Im having problem on tombstone, The part is LF chip component 1005, and my solder paste is WS leded. tombstone is not in a deg angle but one side is soldered but the other side is just sitting on the solder. Looks like my solder can not wick up to the terminal.

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fowlerchang

#55786

solving tombstone | 1 August, 2008

Pattern design, paste volume,printing misalignment, place misalignment,reflow process include N2 usage. All the factor above can make tombstome happen. And the most important factor is placement misalignment except design issue. But pls check the solderability of this compoenents also.

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MCR

#55787

solving tombstone | 1 August, 2008

thanks,my pad design is 24 x 23 mils and now I chnged my stencil to 24 x 20 mils ship inwrds to lower down my volume. My placement is and part data are ok. My reflow N2 is using 1000ppm, Actual is 700-800ppm I already prolonged my pre-heat butit only solve the DEG angle of tombstone but now one terminal is just sitting on the pad. This problem is only concentrated to 1 part no. also eventhough this part no have two vendors still two vendors having thesame problem. How to check the solderabilty for this chips?

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fowlerchang

#55788

solving tombstone | 1 August, 2008

Pad design is not only the size of pad but also the distance between two pad. N2 will increase tombstone as we tested. 10 zones reflow oven and slow temperature ramp will reduce this defect. MustII is the equipment which is used to test the solderability of components.

Send me the mail address if you need my presentation about tombstone.

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