Dual Access Flex PCBs

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Dual Access Flex PCBs

Dual Access Flexible Circuits: 


微信截图_20240814220604.pngDual access flexible circuit boards denote the flexible circuits that can be accessed from both the top and bottom sides, yet possess only a single layer of conductor trace. Coverlay openings are present on both sides of the flexible circuit, thus there are solderable pads on both the top and bottom, which is analogous to double-sided FPC.


Nevertheless, as the dual access flexible circuit board has merely one layer of copper trace, there is no requirement for the plating process of plated through holes (PTH) to establish a connection between the top and bottom, and the trace layout is significantly simpler.


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Dual Access Flexible Circuits & Circuitries

Base material is copper only and thickness is always 1OZ because rigidness of thinner copper (such as ½ OZ) will be too low to be useful, and thickness of coverlay always to be at least 1mil (25um Polyimide + 25um Adhesive), so total thickness will be 0.13mm which is the same like the most cheapest option of 1 layer FPC

That stack up is also similar like opposite Flex Flat Cable (FFC) which also has one trace layer but can be connected from both top and bottom, but coverlay opening can be anywhere on dual access FPC, comparing to FFC which can only be on both end edges (gold fingers).  

Here is stack up of dual access flex circuit:

Here is stack up of dual access flex circuit:


Application:

  • Vibration Motor for Mobile Phone
  • LCD Module for Mobile Phone
  • Printer

Dual access circuit advantages:

  1. It can be connected to both side through copper, and do not need to make a through hole. If it is 2 layers FPC, you have to make a through hole to connect both sides.

  2. The flexibility and bendability are better than 2L flexible circuit because of simpler stack up

  3. Soldering PAD can be anywhere on both top and bottom side.

Dual access circuit disadvantages:

  1. Complex production process: The production process is similar to 2 layers flex circuit, but it will be more difficult and complicate compared with 2 layers flex. And the manufacturability of dual access circuit board will be limited due to production technique.

  2. Easy to wrinkle. Because only copper itself, which is too thin and too flexible to be keep flat during manufacturing process, so it will be easy to tear up. When it comes to hot laminating process, wrinkles and blister will be happened more frequently. 

  3. Only few components can be placed on, because the copper trace easy to be broken if there’re too many components.

  4. In most of cases, we will transfer dual access FPC into 2 layers FPC which is simpler to be made and the cost is the same. Please contact us today for more information or any enquiry for dual access flexible circuit.


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