Tag Archives: Manufacturability Index

Manufacturability Index in Practice

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My prior blog covered the Screaming Circuits Manufacturability Index. It’s something I’ll be using from time to time when discussing new components I run across. I’ve got a few examples to put the numbers into context.

On the low side of the index, we have:

1: Just about anyone could hand solder the part
Examples: Through-hole parts

The SN7400 quad NAND Gate, shown on the right, is a good example. It’s big, it’s through-hole, and if someone has trouble hand soldering it, they really need a few more classes. 

Closer to the other end, is a new chip I’ve run across. The Silego GPAK4 is a small FPGA-like mixed signal device. It’s got a number of analog peripherals, a bank of programmable logic, and the ability to configure it up the way you want. Take a look at it below:

This little thing is housed in a 2mm x 3mm QFN package. That’s pretty tiny by the standards of my giant fumble-fingers. I’ve given it a rating of 4.b, on the Screaming Circuits manufacturability index. The number ranking “4” means: “Needs advanced automated assembly technique“, and the letter suffix “b” means: “Typical level of challenge within the number rank.” In other words, right up our alley.

Unless you posses super-human abilities, and maybe lasers in your eyes, you won’t be hand soldering these. You’ll have them assembled by us (or someone with the same technical capabilities as us), where it will be a standard process.

If you do want to put one or more of these in your design, you will want to make (or find) a custom library footprint for your CAD software. Due to the variable length pads, a standard one-size-pad footprint might lead to solder joint reliability issues.

Duane Benson
The chips go marching one by one, hurrah, hurrah
The chips go marching one by one,
The little one stops to suck her thumb
Just to see if the solder is lead-free

http://blog.screamingcircuits.com/

Component Manufacturability Index

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Screaming Circuits’ Manufacturability Index Ranks the difficulty of assembling a component. Index is one to five, with one being easiest, and five being the most complex

Sub index: a, b, c

a: Not a challenge within the number rank
b: Typical level of challenge within the number rank
c: Fits in the ranking, but likely needs special process, fixtures or attention

1. Just about anyone could hand-solder the part
Examples: Through-hole parts

2. Surface mount. Should be machine placed, but big enough to hand solder
Examples: 0805 or larger surface mount passives, SOIC packages

3. Pretty much any grade of surface mount equipment can handle this component
Examples: TSSOP or larger, 0.8mm pitch BGAs

4. Needs advanced automated assembly techniques
Examples: 0.4mm pitch BGAs or QFNs, CSP (chip scale package) or WSP (wafer scale package) BGAs, 0201 size passives, Package on Package (POP)

5. More or less R&D at this point. Few companies have or will assemble this part
Examples: 0.3mm pitch micro BGA, 1,700+ ball BGAs, 01005 passives

Just about everything 4b, and below are routinely within Screaming Circuits standard (guaranteed) process. 4c, 5a, 5b, 5c, are becoming more common here. These are special process (falling outside of our guarantee), but we can usually do a good job with them. You’ll need to speak with a manufacturing engineer before placing the order.

Duane Benson
A colossal negative space wedgie of great power coming right at us at warp speed
Readings are off the scale, captain

blog.screamingcircuits.com