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Application: Design guidelines to improve the flexibility and reliability of flexible circuits.
Many of the issues that arise when using a flex circuit come from a lack of knowledge about how to properly design one, especially when the circuit is required to bend. Many novices will design a circuit that calls for bending the flex in too tight of a bend radius, which can cause damage to the circuit and lower the reliability of the end product. This series of articles will focus on the seven key aspects to consider when designing for maximum durability and maximum “flexibility”. It is important to know that because flexibility is a relative term this study will instead use the term reducing bend radius. Below are two of the seven design strategies. Please see Part I and Part III for more tips!
3. Do not allow electroless copper as a seed layer prior to plating vias.
- Also, an area to be concerned about is the type of plating your vendor uses. Some copper plating requires a seed layer of electroless copper. This seed layer becomes an ED copper layer and can lead to conductor cracking. For a tight bend radius direct metallization is the preferred plating method.
4. Use only Polyimide covers in the flexing area.
- There are two options for applying dielectric material over copper:
A. Polyimide cover material: This is the preferred material in areas where parts will be bent. As a general rule, you will want to specify a dielectric thickness and adhesive thickness separately. A rule of thumb is that for every 1 ounce of copper thickness there is 1 mil of adhesive thickness.
B. Flexible Solder Mask: Flexible solder mask has a minimum bend radius of 0.4” and is not recommended for any dynamic flexing application or application where the bend radius will be tighter than 0.4”
07/02/2020 | Pete Starkey, I-Connect007
For Pete Starkey, the highlight of the recent HDP User Group Automotive Technology Webinar was Alun Morgan’s presentation on materials for automotive applications. This forward-looking informational session covered the latest developments in automotive standards and automotive electronic packaging.
06/04/2020 | Pete Starkey, I-Connect007
The emerging trend for “electronics on everything, everything with electronics” was the theme of iNEMI’s webinar presentation of the highlights of its recently published Flexible Hybrid Electronics Roadmap Chapter, delivered by Girish Wable, senior engineering services manager with Jabil. Pete Starkey provides an overview.
05/01/2020 | Pete Starkey, I-Connect007
In an informative and enlightening webinar, iNEMI Project Manager Steve Payne was joined by Isola Group CTO Ed Kelley to explain, review, and discuss the details of the recently published “iNEMI 2019 Roadmap for Organic PCBs.” Pete Starkey provides an overview.