PCB_MF

Fig. It is an example of a conventboard. s- Signal plane, G-Ground

tional six layer through holed plane. & V- Voltage plane.

10.3 Buried Via:A plated through hole colayers of multilayer board, bstructure but not coming tothe board.used when signal trace rorequiring more via sites con

onnecting two or moreburied inside the boardo the external surface ofouting is very densennecting signal.

Layers and more channelsconventional multilayer canCost is more because of th

s for signal traces than an offer.he added process step.

Fig. Buried via multilayer

r board

10.4 Blind via:A plated through hole conto one or more layers of a mdoes not go through the enThese holes can be used omultilayer board and can bevia and component holes w

nnecting the surface layermultilayer board whichntire board thickness on both sides of a e used in conjunction withwhich go through the board.





10.5 CORE LAYER :The multilayer build up prraw two-sided laminate layeeach side surface destined tetched in this form.Surface destined to becomfully copper-plated. These ecores.

rocess starts with a set ofers coated with copper onto become inner layers areme outer layers are leftetched laminates are called





10.6 Board lay upThe layering of a multilayesymmetrical and it is best tocopper layers These requirements will hkeep the finished board flat

p: er board should be kept o have an EVEN number of help the manufacturer to t

10.7 constructionsFor example : 1.6mm, 4 layer boaCopper layer, electrolyticCopper layer base no. 1Base laminateCopper layer base no. .PrepregCopper layer base no. 3Base laminateCopper layer base no. 4Copper layer, electrolytic

sard construction - 25µm - 35 µm - 640 µm - 35 µm - 120 µm - 35 µm - 640 µm - 35 µm - 25 µm

10.8 Multilayer PressTo laminate the multilayerequiredthe pressure needed to mfree intermediate expose lato 500 psi.The pressure is applied tofrom the B-Stage resin towaboard.

:er board a 25 ton press ismake laminates with void-ayers is in the range of 200o drive the air bubbles out ards the edges of the

As some air bubbles get trtime curing starts, a borderside should be left for trimmThe temperature neededtypically 180oc.The press must be capabltemperature over the entire

rapped in the edges by ther of perhaps 25mm on eachming. for laminating of epoxy isle of maintaining an evene laminate area.

10.9 Multilayer laminating p1. The inner layers are for process and tooling hol2. Dielectric thickness for depend upon the numb board thickness specifi3. Inner layers must be tre coating solution.

process:rmed by print and etchle to be drilled.r these inner layers willber of layers and over allication.eated with a black oxide

4. Keep the Prepreg and bottom of pre-etched panels.5. The platens and the press a temperature of 180o6. The multilayer package a the plates, as shown in

copper foil to the top and two sided inner layers plates are pre heated toocassembly is placed betweenn the figure.