Instabeat PCB at the assembly line

Instabeat Manufacturing Process

This is a long blog post explaining Instabeat’s complex manufacturing process.

Step 1-a: Printed Circuit Board (PCB) manufacturing + assembly [PCBA]

Location: China + USA

This process consists of manufacturing the electronic boards and assembling them with the components. The Instabeat board consists of 2 parts: A rigid one for the heart rate sensor, motion detection sensors, power, etc., and a flexible one that has the LED’s for the real-time display. The LED portion of the product needs to be flexible because it has to adapt to various goggle shapes and head frames.

To make sure the dimensions and tolerances are tight, both the flexible and rigid parts are manufactured in a single board called a ‘rigid-flex’ board. This is the same board used in cellphones, quite a complex process especially for small volumes. As a matter of fact, the first batch of 1,000 boards we got last December was entirely defective due to a manufacturing process gone wrong, and we had to throw them all away.

We went through a lot of tests to make sure that nothing is wrong with the design and the failures were only due to manufacturing, and after multiple design reviews and stress testing, we placed the second order at another board house in the US right next to our engineers’ offices; the boards are manufactured in China then shipped to the US for assembly with the components and testing. The second time around, the process went well and we got fully functional boards ready for the next stage of production!


Step 1-b: Plastic cover manufacturing

Location: China

The PCB is placed in a plastic cover to protect it from temperature and pressure when we inject the plastic on top of it. The plastic covers are manufactured in China since we had originally intended to manufacture and assemble the boards there as well, then shipped to the US to be assembled with the PCB and go through the next step. (I will not get into how counter-intuitive it is to manufacture products in China and the ship them to the US vs. manufacturing everything in one place).


Step 2: Potting

Location: Mexico

The PCB and the plastic are both shipped to Mexico for the third step of the process, potting, which consists of adding a thin layer of resin on top of the heart rate sensor in order to make it waterproof and protect it from scratches, wear, etc. While this seems pretty simple, it is actually quite complex because the surface needs to be absolutely flat to get an accurate signal. The process is done entirely manually, which makes is almost impossible to make it consistent and repeatable. It also means that it takes a lot of time to pot each board.

This process is currently the principal bottle neck of our supply chain. We have gone through many different resins, processes and suppliers to find the best solution. We have been spending a lot of time reworking the surfaces to compensate for whether they are convex or concave at the first pass, and this is the main reason why we have not been able to have a consistent supply.

Once units are potted and tested, they are shipped to China for overmolding.


Step 3: Overmolding

Location: China

Overmolding is an injection-molding process that consists of placing the electronic board inside the mold before shooting the plastic over it.

Overmolding is very tricky because it exposes the PCB and battery to a very high temperature and pressure, which might damage the electronic components. In our case, overmolding is absolutely necessary because it is the only way to get a flexible and waterproof product (The Nike Fuelband and Jawbone Up are also overmolded products).

Our PCBA and the plastic are placed inside the mold, and the blue plastic is shot on top to create the shell that makes the unit waterproof, gives it its flexible shape and allows it to mount on goggles.

We went through hundreds of iterations for the overmolding: we tried several plastics to find one that would not wear out, resist to chlorine and salt,after a few months of usage. We have found the right parameters for our overmolding, however the yield is not as high as we would have hoped and this also makes it difficult to have a constant supply of units to ship.

Once the unit is overmolded, it goes through one final round of testing, and qualified units go to the assembly process.


Step 4: Assembly + Packaging

Location: China

The units are tested one last time, they are then assembled with the package, USB cable and user manual and put in boxes ready for shipping.


Step 5: Shipping

Location: Hong Kong

Shipping LiPo batteries from China is not allowed, so we have to send the packages to Hong Kong by truck and they are shipped out from there!


As you can see, manufacturing Instabeat is quite a challenging process, involving different suppliers in 3 different countries, which can get tricky for a small startup like ours.

We would like to thank you for being so patient while waiting for your Instabeat!


  1. Hello Hind,

    Yes, you weren’t communicating enough, indeed. Being so behind any schedules, month+ updates are way too long. It has been asked months ago that we’d like to know what is our number (by order date, or I can even imagine a personal message to every customer) and it’s the first time you seem to take a notice. And we still don’t know how long is the queue before us.
    The “Latest updates” section of the Instabeat page shows two posts from 2014-03-15 and 2014-07-24.

    Being an MScEE, I know a lot about manufacturing so I don’t blame you for the delay itself. These things just happen, especially in China. And I’d rather wait for a quality item.

    Please fill the “(picture)” placeholders with the appropriate content.

    And please, please go on with the posts.

    1. Hi John: Thank you for your feedback and for understanding the delays. This is a very long blog post so it will be written over a few days thus the incomplete paragraphs and pictures. I am definitely learning a lot from your comments and this experience in general, and working on improving! 🙂

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