In recent years, digital home electronics and mobile devices have rapidly become smaller and more sophisticated. This trend is expected to continue to accelerate in future, so that the printed wiring boards that are mounted with electronic components are required to have higher density and more layers.
Fujikura has developed a build-up multilayer FPC suitable for next generation high density printed wiring boards. This FPC is a 6-layer build-up wiring board with circuits formed on the surface layer of a 4-layer core substrate with a through hole (TH) structure that uses the additive process. Build-up circuits with fine line/space (L/S) of 25/25 µm that are difficult to achieve with the conventional subtractive process are formed using the additive process. This kind of substrate can be expected to find applications as a multilayer printed wiring board providing circuits for mounting the components of high density electronic equipment. |
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| Cross section of the substrate |
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| Main specifications |
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Line/space
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25/25 µm |
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Land diameter
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300/100 µm |
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Insulating layer thickness
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20 – 50 µm |
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| The additive process is a method in which plating is grown using a resist pattern, and then the resist is removed to form the circuit pattern. The pattern is more precise than that achieved with the subtractive process using etched resist, and the method is effective for forming fine circuit patterns. |
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