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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”
10/26/2020 | Pete Starkey, I-Connect007
Designers attending the AltiumLive Europe 2020 Virtual Summit had the opportunity to see at first-hand how circuit boards were made to help them make informed design-for-manufacturing decisions. Pete Starkey details how Würth Electronik welcomed AltiumLive to its Niedernhall factory to take a virtual tour.
10/19/2020 | Pete Starkey, I-Connect007
Although current circumstances have forced the postponement of its live conferences, seminars, and workshops, EIPC continues to provide a platform for the exchange and dissemination of the latest knowledge and technical information to the European interconnection and packaging industry. Pete Starkey details how its current series of technical snapshots, delivered in a webinar format, address technology challenges facing the automotive, telecom, and high-speed sectors of the industry.
10/13/2020 | Dan Feinberg, Technology Editor, I-Connect007
Since AltiumLive this year is a virtual event, coverage is limited to watching some of the presentations virtually. Dan Feinberg describes how he was pleasantly surprised with the quality and excellence of the Würth virtual factory tour.