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LGa soldering issues......

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LGa soldering issues...... | 5 August, 2009

Help! We are havin issues installing the new Linear Tech LGA118's. We are installing 17 of these beast per assembly, the problem shorting? Any ideas? Linear Tech is usless, they blame heat, not a big enough reflow oven, moisture, part disty's...etc. Looks like too me they have a part design issue, the part has a 27 page rework doc! Anyone working with the new Lin Tech LGA's? Thanks for your help.

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LGa soldering issues...... | 6 August, 2009

Yeah, those gosh darn disty parts...get you every time. lol

Can we get just a little more info? Let's start with the basics...

Stencil Thickness? Aperture Reduction? Leaded or Lead-Free? No-Clean or Water Soluble?

How's your reflow? Have you profiled your oven to this specific PCB?

We've done a shi...errr...buttload of LGAs. We haven't really had any problems. But then again, I'm not sure if we've placed this specific one.

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LGa soldering issues...... | 10 August, 2009

We don't know dip about your Linear Tech LGA118, but we agree with published reports that say you should have between 4800 and 7000 thou^3 of paste on the pad for a LGA. These volumes were analyzed based on volumes found successful for CGA and then evaluated for LGA.

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LGa soldering issues...... | 11 August, 2009

you gotta ask WHY? thankfully dont place these but I wud imagine you have referenced the datasheet for solder thickness etc.

How is your placement?

You say ypu place 17 of these? are you seeing shorts on all of them or a select few?


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LGa soldering issues...... | 26 August, 2009

Good Morning,

I have been struggling with this part for some time now. I have to agree that whoever designed this part, did not have to manufacture with it. We have advanced to a point where they have a acceptable yield but I believe that will be highly dependent on the application. This is what we found: Manufacturer recommends 1:1 stencil with a .005" foil. We tried 1:1 with excessive bridging. Knee jerk reaction, we cut a new stencil with a 30% reduction. No voids but the solder would columnize between the PCB and part. We cut a new stencil to a 15% reduction and we saw a decrease in bridging and full wetting of the pads. We found that this part was prone to voiding. We also found that after the reduction, any bridge found was associated to a pad with a large void (displacement of the solder)

Rework: We purchased a component print frame stencil. We stencil the part, reflow the solder on the part, and then place it like a BGA. So far we have a 100% success rate

So reduce your stencil slightly, adjust your profile to minimize voids For rework, pre-bump your parts with a component print frame then replace.

Is this a high volume application? If not, I would reduce the paste volume deposited on the PCB and bump the parts from the begining.

Anyway, my $.02

Good Luck


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