All About Flex: Imaging Methods for Etch Resist, Part 3: LDI

Reading time ( words)

This column is the third and final part on methods for imaging etch resist. Part 1 discussed screen printing and Part 2  discussed traditional photo exposing. The basic process sequence for LDI is similar to photo exposing:

- The flexible substrate is coated with photosensitive resist

- The resist coated substrate is positioned in the LDI exposing unit

- LDI digitally exposes the desired pattern

- The photoresist is developed and the unwanted resist is washed away

- The copper pattern exposed by removed resist is chemically removed (i.e., etched)

- The resist is stripped off; only the copper pattern remains

Unlike photo exposing, LDI does not use a phototool, but directly exposes a digitally saved artwork pattern onto the resist. Photoresist is selectively exposed as the laser beam increments across the substrate in a rastering fashion. The image formation can be likened to the image formation on a CRT screen, which is formed from thousands of horizontal lines across the screen. Like photo exposing, LDI requires a photoresist, but the resist is normally specially formulated for laser printing; LDI resist is much faster-acting than traditional photoresist. Like photo exposing, resist for LDI comes in liquid or dry film options and the resist application methods are identical to those employed when using an artwork phototool. The post-exposing processing of an LDIprocessed flexible circuit is exactly the same as photo exposing.

Read the full article here.


Editor's Note: This article originally appeared in the June 2016 issue of The PCB Magazine.



Suggested Items

Aurora Circuits on Ultra-Heavy Copper PCBs

08/03/2020 | Dan Beaulieu, D.B. Management Group
It’s always fun to talk with a company that can do something different—in this case, ultra-heavy copper PCBs, meaning over 20-ounce copper. Wanting to know more, Dan Beaulieu talked to Aurora Circuits Director of Business Development Thad Bartosz.

Simulation Technology in Acid Copper Pattern Plating

07/17/2020 | Pete Starkey, I-Connect007
PCB designers and CAM engineers may feel there is little they can do to achieve uniform finished copper thickness of PCB traces and holes. But in an illuminating discussion with Robrecht Belis, manager of surface finishing and e-coating with Elsyca NV in Belgium, Pete Starkey learned that nothing could be further from the truth, provided they act on time and use the right tools.

A Year in Review: Cultivate New Opportunities in Crisis, Start Fresh

07/16/2020 | I-Connect007 China Team
Recently, the China Electronic Circuit Industry Association (CPCA) invited Dr. Shiuh-Kao Chiang from Prismark to present an online video report regarding the current and future impact of the current epidemic on the global electronic circuit industry. The I-Connect007 China Team attended the presentation, and the following report summarizes some of Dr. Chiang’s remarks.

Copyright © 2020 I-Connect007. All rights reserved.