Newbie SMT question: What chip size to spec?

[jdupre]

I am working on my first SMT project, and have run into the issue of what size of chip components use.

For example, a 27pF, 50V, NPO, 5% ceramic capacitor is available in EIA 0402, 0603, 0805 and 1206 packages from at least 4 different manufacturers.

There is plenty of space on this board, so I have no need to select small parts.

Should I just pick the largest size to it is easier for the assembler to deal with?

How do some of you decide what size to go with?

Thanks!

- Joe

[Colorado-PC-Dude]

Joe,

Some of the larger sizes (1005, 1008, 1206, etc..) are getting hard to source. I would use 0603s and 0805s as these are easy to source and are not so small as to cause problems at assembly. We've only specified 3 or 4 chip component parts larger than 0805 and we don't really need to go that small. That's just where the best pricing and selection are at.

Ben

[CAD_Monkey]

Selection is based on power requirements, availability, assembly house capability, and board density. I'd stick to 0805 and 1206.

[randychase]

What Ben said. I would just use 0805s for now.

[Tom]

Joe,

I have to agree with Ben. The 2012 (0805) and the 1608 (0603) are the most popular parts in today's market space. Readily available from multiple sources in every value. The 3216 (1206) is sort of being phased out and is currently in low volume production. And then on the other hand you don't want to use a 1005 (0402) if you have plenty of space on your design. These parts are harder to handle on a rework level.