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

Printed Circuit Board Assembly & PCB Design Forum

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SMD land patterns design for wave soldering



SMD land patterns design for wave soldering | 3 July, 2002

I' designing a PCB with SMD components to optimize the land patterns for wave soldering. I find that the IPC-SM-782 land patterns are not robust enough for wave soldering, yielding ramdom skips and bridges. This PCB will also give me insight on shadowing effects and what distances should be maintained between parts to avoid it. I'm just wondering if someone has done this before and I'm just going to rediscover the wheel, has anyone done this kind of study before? Where could I find such info, if it exists? Thanks for your help. Have a great holliday, regards, Gabriel

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SMD land patterns design for wave soldering | 3 July, 2002

Your thinking is correct. Wave soldering pads that were designed for reflow can create problems: * Large pads used for reflow [too much solder] can create reliability problems. * Bridging [too much solder] creates rework. * Skipping & shadowing from improper location or orientation.

This is well documented. For example, follow the links in the SMTnet thread on robber / thief pads [ ].

We have talked [Well, I've ranted] about this on SMTnet previously. Search the fine SMTnet Archives. The issue seems to come down to board layout people like to use the library that comes with their CAD software. [Yes, using an incorrect pad design that's at hand IS simplier than developing the correct pad design.] The better discussions on this are: * "Manufacturing Techniques For Surface Mounted Assemblies" Wassink & Verguld * "Guidelines For Footprint Design" Philips Electronic Manufacturing Technology

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