Micro assembly line for zero-defect manufacturing

The former Plantronics from Emmen, manufacturer of wireless headsets, wanted to develop and market a smaller product to strengthen its competitive position and increase its market share.

The existing, larger product had a production failure rate of 10-15%. This product was assembled entirely by hand at production locations in Southeast Asia. The expectation was that a smaller, more critical product would show a much higher failure rate. Continuing with the current production method was therefore not an option. STT Products was invited to think along in this challenge.

Project approach micro assembly line

A team of product developers and production engineers from Plantronics, together with engineers (from all disciplines) from STT Products faced this challenge. Knowledge of product, production and machine construction came together within this team. In the concepting phase, the team quickly came to the conclusion that the unstable factor of manual assembly had to be removed from the process in order to make the process manageable. Because the new product was so much smaller than the previous one, manual assembly was no longer realistic within the set quality requirements.

We experimented a lot to get a feel with the product, the associated critical factors and thus the size of the project. This challenge was divided into several sub-problems to make it more clear and solvable. And, unlike tradition, engineering was done from the inside out. This means that we looked at what the final mechanisation needed from the product point of view. We started with the most critical part, soldering the loose wiring onto a printed circuit board. The accuracy required for this was too high to be carried out manually on a larger scale.

We enlarged the product in a 3D drawing program, so we were not hindered by the small dimensions. Subsequently, a new production method was sought based on the idea: What should be possible in larger dimensions, should also be possible in small.


The team came to the conclusion that the six loose wires should be fixed in position as quickly as possible in the process. We developed a smart product carrier for this. This product carrier takes the product along ten stations where various operations ultimately ensure that a micro connector, a plug, is made. A plug is easier to pick up and has a fixed shape. As a result, it can be picked up again to simultaneously solder the six wires to the printed circuit board. For the connector, the engineers investigated, among other things, what distance is required between the wires in order to be able to tin them.

The most important part of this process was to fix the wires by sorting them by color, tensioning them, tinning them, orienting them for the correct spacing, melting a plastic housing around them, cutting the wires to length and finally soldered to the printed circuit board.

The ability to place six solder joints next to each other in the micro assembly line makes further miniaturization possible in the future.

Productcarrier with plug

Result: a micro assembly line

Good results have been achieved in the project. Firstly, the ability to assemble (solder) the wiring on the printed circuit board without errors. This significantly reduced the failure rate, as desired by the customer.

In addition, a mechanised process has been created with much less manual labour. All stations are constructed in such a way that they can be integrated into a fully automatic production process, which means that the share of manual labor can be reduced even further.

As a result, the production process has become much less operator dependent. There is no longer any need to produce in a low-wage country and you can opt for production on the continent where the product is also sold.