The cores are then automatically drilled or punched on a x-ray optimiser.
The cores are then aligned with each other with the specified prepreg seperating the layers
4 layers require no alignment sysytem
Greater than 4 layers we use a welding system, called InDubond
The welded package is then removed and the sequence is repeated for the panel.
Once the batch is completed, they are ready for bonding.

 

Multilayer Bonding click to collapse contents 

Bond Multilayers
The innerlayers and prepreg’s are then laid up as follows, this is done according to the build stated on the job card, such as
The transport plates carrying the multilayer package is automatically transported into the Hot press, the rams close just enough to apply a kiss pressure ( light ), and the heaters then automatically start applying heat to the stack, and 5 mins, the full pressure ( up to 600 KN ), is applied for 70 minutes at 180 degrees C, this causes the epoxy resin from the prepreg to melt and flow into the contours of the tracking, pushing out all the trapped air, and effectively gluing all the layers together.
The transport plates with the hot pressed multilayers is then automatically transeferred into the cold press, which will slowly remove the heat from the package, while applying pressure, this will ensure that the pressed panels will be flat and not warped.
The pressed panels are then automatically transported to the de-stacking area, the pressed multilayers panels are then removed, inspected for surface finish, and the final thickness is measured using a sheet micrometer, the details of the press time, temperature and pressure along with the thickness are recorded inside the job card.
Then once the BGA comes out the press it looks like the folllowing