... for copper preparation. | THE PERFORMANCE CHARACTERISTICS | of RF-excited CO2 lasers enable them to create microvias at high speed. In most dielectrics, for | CIRCUIT BOARDS | example, microvias can be formed sequentially at speeds of up to 450 microvias/sec. CO2 lasers are used for resin-direct drilling (a common use in Japan) | CIRCUIT BOARDS | or for conformal mask drilling (common in Europe and the rest of Asia). The drilling process is progressive and usually takes three pulses or shots | CIRCUIT BOARDS | to form the microvia (Figure 6). | FOR MICROVIA FORMATION |. The vast majority of UV DPSS lasers operate at the frequency- tripled wavelength of | CIRCUIT BOARDS | 355 nm for microvia formation. Most materials become more absorptive at the laser wavelength of 355 nm, including copper and glass. Conse- quently, UV DPSS | CIRCUIT BOARDS | lasers can directly form microvias through the copper layers of MLBs. At currently available UV power levels, direct formation speeds range from 50 to 100 | CIRCUIT BOARDS | microvias per second through copper and dielectric together. Through dielectric ...
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... an accumulator for cool down and availability to the imaging operation. Image LPI Mask Dried solder mask is imaged in a manner similar to | CIRCUIT BOARDS | that used for imaging the circuitry. Phototools containing black areas where the solder mask is to be removed are placed in direct contact with both | CIRCUIT BOARDS | sides of the panel. The panel is then exposed to UV light. The amount of light used is controlled by an integrator. Printing is done | CIRCUIT BOARDS | with a semi-automatic dual drawer printer. While one drawer is being loaded with a panel and phototools, the other is inside the machine being exposed. | CIRCUIT BOARDS | This dual drawer printing system runs at the same rate as the screen printer to insure continuous flow. Develop LPI Mask After the panel has | CIRCUIT BOARDS | been exposed, it is placed in a vertical developer. The unexposed solder mask is dissolved in a high pressure spray of developing solution. The solution | CIRCUIT BOARDS | temperature, concentration and conveyor speed control the development process. The developer solution concentration is maintained ...
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... test netlist and fixturing files. All fixturing software must convert lands in order to produce a dependable netlist, that is, one that will test | CIRCUIT BOARDS | all points. If draw to flash is not completed when generating these files, the software will not place a test point for that feature, leaving | CIRCUIT BOARDS | that net untested. Open Road: Output plane layers in a negative format. THIEVING AND COPPER BALANCING Thieving and copper balancing is the process of adding | CIRCUIT BOARDS | a copper pattern to the outer layers of a board. Balanced copper helps to ensure even plating and etching. Bottleneck: PCB designers have started adding | CIRCUIT BOARDS | copper thieving and balancing to the copper layers. Unfortunately, if the design rules are shared, the CAM operator is challenged with a confusing design rule | CIRCUIT BOARDS | check. The computer has problems understanding these features and calls out many errors. Open Road: The designer should give design rules for thieving to the | CIRCUIT BOARDS | manufacturer, and the copper features should be added to the CAM systems. An ...
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