Printed Circuit Design & Fab - April 2008 - (Page 33) FIGURE 2. Intuitive graphical user interface. FIGURE 4. Targets printed during exposure alleviate the need for drilled tooling. FIGURE 3. LDI target types. also faster, more sensitive LDI resists available that can be used. The choice is left with the users based on their process requirements and resist cost targets. The beauty of a digital system is that almost any combination of scaling can be implemented. The options run the gamut from fixed scaling (similar to contact exposure, where only one scaling factor is used for the whole batch), through iterative, corrective mechanisms (where the optimum scaling is converged upon, as the batch is being printed), to global scaling systems (where each panel receives the best scaling factor applicable to that particular panel). Both primary imaging and solder mask can be imaged using the LDI system. There are several companies who have introduced faster solder resist inks to the market in the past two years. This choice would be optimal from the point of view of scaling accuracy, but some PCB fabricators may be reluctant to introduce the LDI in the solder mask area, either because it involves another equipment purchase, or because they need their customer’s approval to make a material change. Until LDI is used in the solder mask area, the PCB fabricator can continue to use the LDI for inner and outer layer imaging, even with global scaling. Since you cannot have one http://www.wssi.com/pcdm http://www.wssi.com/pcdm
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