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Printed s.r.o.: Českolipská 1449, Mělník, Tel.: +420 315 670 137, Fax: +420 315 671 495, E-mail: printed@printed.cz
Technology > Multilayer PCBs > Preparing the material

Příprava materiálu
When cutting the laminated layers it is necessary to pay attention to the composition of the laminate of the PCB. The warp and the weft orientation of the prepreg must match with the w.& w. orientation of the core.
There is no effect in using various rests of the prepreg as their warp-weft orientation can be wrong.
We use universal dimensions for the inner layers. The core is allways divided without rests into exact parts on which the inner motif is etched. The prepreg is oriented and cut the same way, put on the core, so that no interchange can happen. Only this guaratees absolutely flat PCBs after the pressing.

Before pressing the FR4 boards must be tempered. Not pre-heated boards would slightly change their size during the pressing. Our drilling machines measure these deviations of all layers inside the ML-PCB and count the optimal coordinates for the holes.
The tempered boards cause less difficulties when being drilled. But this problem can not be avoided when
the TOP and BOT layers are lightened. There is no such optimum - the films are lightened independently.
We make sure that all ML-laminates are tempered before processing.