STRETCH.flex

FAQ

Here you will find the most frequently asked questions about our STRETCH.flex technology.

Comparison of costs between STRETCH.flex vs RIGID.flex technology?

Based on the increased handling effort during production, the STRETCH.flex technology is approx. 15 - 25 % more expensive than a comparable RIGID.flex PCB.

Are textile applications possible (e.g. smart textiles)?

Yes, generally textile applications are possible. The polyurethane that we use is able to be laminated onto textiles, but depending on the application we recommend a encapsulation (e.g. glob-top) to protect the components.

Do we have any experience with any further processing of the technology?

We have a lot positive experience with forming, moulding and lamination from various R&D and customer projects.

Is it possible to solder the material?

It is possible to solder a STRETCH.flex PCB with a low temperature solder paste in a reflow process (more details on this can be found in our technical datasheet). Currently we don´t have experience in using other solder methods with low temperature solder paste, e.g. vapour phase soldering or wave soldering, you have to test it by yourself. We don´t recommend the use of normal SAC-solder pastes or in general solder pastes with a liquidus temperature of 145°C, because they reach the melting point of the TPU.

Is a flip chip assembly feasible?

Flip chip assembly is generally possible, but we have to check the process in more detail. If it is a flip chip process with solder paste, it must be ensured that a low-temperature solder paste is used. For a flip chip process with glue (ICA; ACA or NCA), you have to check the curing temperature of the glue because this must fit to the operating temperature of the thermoplastic polyurethane.

Could we realize the traces only with gold (without copper)?

We are using standard PCB manufacturing processes, gold conductors are not possible due too process reasons. But it is feasible to coat the copper conductors with a gold surface during a wet chemical process.

Could we use ink instead of copper to increase the stretchability?

Currently we are only using copper as conductive material, but our R&D are working on layer stacks with stretchable inks.

Do we have any options to manufacture transparent PCBs?

We only use a clear/milky TPU, but we are working on the implementation of different coloured TPUs.

Are automotive applications possible with this technology?

The manufacturing of the STRETCH.flex technology takes place within our IATF certificated production processes. The utilization in the automotive sector depends on the actual application (e.g. applications near the engine are critical). Please contact us for further advice.

What's the maximum production size?

The max. production size is 420 mm x 570 mm and this is restricted by the manufacturing production panel. It's possible to create a meander or snake shape to realize PCBs with larger dimensions.

Is it possible to create meander designs with the established CAD Programs (e.g. Altium, Cadence, EAGLE,…)?

No, this function is currently not available but you can find different meander layouts available for a free download on our homepage.

Could we realize layer stacks with more than one copper layer?

The feasible STRETCH.flex layer stacks can be found in our Design Guide.

Your question is not listed here? Then please send your question by e-mail to our product specialists.