Industrieel printen in de PCB-industrie, een uitdaging voor mechatronicaontwerpers
Richard van Lieshout, mechatronica-architect, Mutracx
Henk Jan Zwiers, directeur, Mutracx
Mutracx is a young company with the ambitious goal of delivering the first inkjet etch resist printer for the production of inner layers for the printed circuit board (PCB) industry. We’ve called this solution Lunaris. It is a fully automated etch resist printer. More a total process than a machine, Mutracx is standing on the threshold of the world’s first viable industrialized inkjet solution for the production of PCB inner layers. Lunaris replaces 11 of the 15 process steps in current lithographic processes. The advantages are evident: a 30 percent reduction in running costs, fully digital flexibility and fast turnaround time. There is also an enormous environmental advantage: less chemical waste, less landfill and lower power consumption.
Our fully digital process prints 100 μm tracks on a substrate using approximately 50 to 100 million drops per core of which not one can be misfired or misplaced. Even using the most reliable heads in the world with a failure rate of one in a billion drops cannot prevent errors every twenty to forty seconds. This challenge is solved with a unique patented technology embedded in the print head, namely Predict, a co-development with Océ. The print head driver piezos used to actuate the channel are also used as a sensor to constantly monitor the acoustics of the channels, detecting possible failure before they can cause any errors. We can detect problems ten thousand droplets in advance, and switch channels a thousand droplets in advance. By switching to redundant available nozzles we prevent errors on the substrate. The resist image is created using a print strategy with a unique gelling resist enabling a controlled flow of drops to form the needed features.
The PCB market is challenging and competitive and therefore demands on engine pricing and running costs are severe, demanding a radically different design approach. In the print engine overall positioning tolerance is very high (within microns). In combination with the introduced thermal load due to printing, this creates another unique challenge. The overall design approach has been to create designs with intelligent calibration strategies. The ‘standard industry approach’ in choosing high-tolerance machined parts is changed to creating a stable well-defined platform without disturbing reaction forces and uncontrolled thermal expansion. Within this platform, control mechanisms with ‘play-free’ actuation (through elastic hinges) and closed-loop measurement gives the required drive accuracy. The final control loop is provided by a line scan on the substrate that is also used to fully validate the print guaranteeing 100 percent yield going to the next process step - the etch line.
The architecture in such a complex system determines 80 percent of the price and performance. Working together with multidisciplinary teams, reviews with lead customers, and involving industrialization expertise in an early stage of the design, underpinned by a strong emphasis on price during the design, will lead to a very competitive, robust machine on a global scale. This phase is the only chance to achieve a breakthrough in costprice. Mechatronics is part of the magic in this approach, we will show you why.
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