Fingerprints on new Spark Core

Hi, this post has been sitting in the back of my mind ever since I got my new Spark Core.

When I received the package in the mail, and opened the small cardboard box, I found quite visible (oxidized) fingerprints on the metal housing of the Wifi chip.

How did they get there, and why? Is this a common thing?

Maybe the people who make the spark core have fingers. :smiley:


I believe it was during the placement of the core on to the breadboard.

@will, good point to note for this manufacturing run? :wink:

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This run seems overall sloppier. I had the same fingerprints on both of mine plus some black stuff on the solder points for some of the headers.
Functionally perfect so far but still not what you would expect from electronics manufacturing. Even if the workers have fingers. :slight_smile:

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Hey guys. Will, Supply Chain/Production Manager from the Spark team here.

@akrusen @kareem613 thanks for the feedback. As far as the fingerprints go, it’s something that we’ve raised with the production team at our contract manufacturer a couple of times. We certainly have a cleaning step included in the manufacturing process–it takes place before testing so that flux and other contaminants that might interfere with the testing process can be cleaned away in advance.

However, if Cores need to be retested because they tested out as defective, or need to endure additional handling before being sent to packaging, there are increased opportunities for fingerprints, smudges, etc. The CC3000 is also a fingerprint magnet. :smile:

I’ll raise it again with our factory and check out the line during this upcoming run to see if there are ways we can improve. Functionally perfect is always our first priority, but I definitely hear your feedback–it’s been on my mind recently as well.


I could easily see the Core being pressed into the breadboard by the thumb or index finger right in the middle of the CC3000. If I had to do it all day I wouldn’t want to dig my fingers into the edges of the header pins either. Could get creative with a tool to hold and press the Core in with, but sometimes human hands are just more efficient in doing precision tasks like this. Maybe gloves could be effective, or just those little rubber fingertip covers.

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@BDub you’re right–the best way to press a Core into the breadboard is with the CC3000, but we’ll confirm that those operators are wearing finger gloves. The issue is when units get recirculated for re-testing, that the test operators aren’t all necessarily wearing gloves.

We’ll try to make an improvement on this next run (beginning next week), and hopefully the difference will be visible. The mechanical interface of the test fixtures have been modified to remove physical contact with the top of the Core, so hopefully those help as well. A secondary polishing step and finger gloves at final packaging should do the trick.


So, that makes it a Collector’s Edition, signed by a Spark employee, right? :wink:


Isopropyl alcohol should remove this shouldn’t it?

@Blacksheep unfortunately, if the fingerprint is placed on the Core before reflow, then the imprint of the fingerprint can basically be baked onto the tin can of the CC3000 module, and alcohol doesn’t clean it off.

However, I’m happy to say that we’ve finally gained the bandwidth through new hires to tackle this issue. In the production run that’s occurring right now, we’ve made the following changes:

  1. Added cleaning steps after testing and before final packaging, and after SMT but before wave solder, in addition to the existing cleaning step after wave solder and before testing

  2. Updated our testing fixtures to eliminate the need for direct contact with the top of the Core

  3. Asked our packaging operators to wear thumb gloves when inserting the Core into the breadboard

A small headache, but a headache nonetheless. Hopefully the steps above mean that all future Cores come out of their boxes shiny and smiling.

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