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76 PCB007 MAGAZINE I MAY 2023 In wet processing, the transport of thin materials and substrates (<1 mil in thickness) can be a rather tricky process. ese materials are vital in manufacturing flexible circuits, but oen this flexibility adds new challenges. Most of these materials are easily damaged, and in some cases require well-trained personnel to handle them. You would think that this could be easily remedied with conveyorized equip- ment, but that is not entirely the case. Trans- porting thin materials through a conveyor aids the process to a degree, but once you get to the wet-processing stages—cleaning, devel- oping, etching, and stripping—there are risks for error if you do not have the right tools or equipment. in material transport in wet processing is challenging because, for it to perform, the con- The Challenges of Thin Material Transport veyor needs to have open spaces. In PCB fab- rication, the goal of all wet processes is to have a liquid interact with the surface of your prod- uct. Most oen, this is done with spraying. If you want interaction from both top and bot- tom sides of the PCB, there must be gaps for that spray to come through and reach the prod- uct. If the conveyor were a simple, flat conveyor belt that pulled the board through, you could make the product go from one end of the con- veyor to the other, but it would receive no etch- ing on the bottom side. Even if the belt were porous, this would still leave shadow marks behind, because the point of contact between the board and the conveyor would remain the same throughout the process. e conveyor needs enough gaps in the bottom side, and it also needs to change points where it touches The Chemical Connection by Christopher Bonsell, CHEMCUT