Multilayer Printed Circuit Boards

PCB Fast has been making multilayer PCBs in Melbourne for over 25 years.  Multilayers are pressed using vacuum lamination which eliminates delamination risk at assembly and drilled using x-ray reference targeting to ensure the holes are aligned to the inner layers.

When making through hole multilayers, we use thin core laminate for the inner copper layers and then sandwich them together with prepreg and foil in the press, at heat and under pressure.

Cores are processed using a double sided print and etch process similar to that used for making single sided pcbs.  The number of cores required is directly linked to the number of layers overall.

  • 4 layer – one core is required to produce layers 2 & 3.
  • 6 layer – two cores are required: one for layers 2 & 3 and one for layers 4 & 5.
  • 8 layer – three cores are required: one for layers 2 & 3, one for layers 4 & 5 and another for layers 6 & 7.

We have standard builds we use if a custom layerstack is not required or necessary.  If a layerstack is not detailed we we will always use our default build of 0.8mm core with 7628 prepregs for a 4 layer multilayer.  This is the build we will use for a 4 layer share panel as well.

We stock the following 140°Tg multilayer materials:

  • 1 oz copper clad FR4 laminate (140°Tg): 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.5mm, 0.8mm, 1.0mm, 1.1mm, 1.2mm
  • Prepreg styles (140°Tg): 1080 & 7628

Material thicknesses are nominal and subject to a tolerance of +/- 10%.  Prepreg thickness can vary with age and temperature, whilst the position in the layup and the number of pieces in a dielectric have an impact on resin flow during the press process.