Really frustrating for us to hear that some of you are having a tightness issue (as well as obviously for you as well!!). With the help of Foxconn we have done a full investigation as to why this has happened and how it managed to slip past our current testing procedures. Here is what our investigations found:
Due to the very small size of some of the parts involved in the MiniDrive assembly, the plastic can be quite delicate before and during the ultrasonic weld process.
The way an ultrasonic welder works is by bringing two metal plates together, either side of the two components that you want to be fused, and then vibrates at a very high frequency. This causes the plastic to melt at the point in which the two components touch. It is a very reliable way of joining two surfaces, but when a thin part is heated it can cause a small amount of dimensional instability.
Each time a new model is put onto the production line for assembly the ultrasonic weld heads must be swapped and re-calibrated. Unfortunately, this meant that if a new head is a fraction of a mm out of calibration it could cause a small amount of wall collapse at the front of the MiniDrive, leading to the tightness issues some of you are seeing.
During our pre-production run testing no dimensional instability was detected, and the parts were all fully functional without issue. In addition, it was never a QA point of inspection as it was not something we expected. The problem occurred once we moved across to mass production.
On the assembly line full testing is conducted at three points:
- 100% testing of the bare circuit
- 100% testing of the circuit once assembled (tester pictured below)
- sample testing using a SD card reader and microSD card
As you can see, the 100% MiniDrive circuit tester essentially mimics a microSD card (it tests for opens, shorts and faulty connections), with one critical difference - there is a lot more to hang on to than on a normal microSD card, which gets to the root of why the stiffness issue was not picked up on the assembly line despite 100% testing.
Fortunately (or unfortunately, depending on your perspective) these issues were picked up early by you guys - as it was (and is) our number 1 priority to make sure you all have a fully functional MiniDrive, we shipped out to you guys first, even before we had started assembling the next part of the first batch. As soon as we heard preliminary reports we investigated, identified the cause of the issue and added supports within the ultrasonic welder to prevent any part of the weld from melting more than it should and causing the tightness issues.
Further to this, we are bringing in house our remaining stock for a 100% "real life conditions" inspection. We expect to have this concluded in the next week. If you have a problem with your MiniDrive, please email us on firstname.lastname@example.org and we will send you an in-house verified MiniDrive - we currently have quite a high volume of incoming mail, so response time is about 1+ week long at the moment
As far as improving our assembly process goes, aside from updating the ultrasonic welding machine, we are adding a maximum removal force QA condition to the microSD card portion of the MiniDrive, as well as supplying a model of MacBook for each model of MiniDrive so that "real life" use case conditions can be tested directly on the assembly line.
Please keep us up to date with any further issues you encounter as it is massively helpful for us to iterate and update the MiniDrive. You guys are helping us pioneer this, and we can't do it without you.
As always, we are 100% committed to getting the perfect MiniDrive to you.
All the best,
Piers & The Nifty Team