PCB minimum thickness (rigid)

[showmy]

From a practical (readily available material and manufacturing perspective), what is a reasonable minimum thickness for a rigid 4 layer board?

This is a low speed design that will require blind and buried vias.

Suggested material stackup?

 

[Colin Mitchell]

If you are designing a 4 layer board, you will have already produced a double-layer board and know the standard thickness and this can be achieved by combining two boards to achieve the same thickness.

 

[Arouse1973]

From a practical (readily available material and manufacturing perspective), what is a reasonable minimum thickness for a rigid 4 layer board?

This is a low speed design that will require blind and buried vias.

Suggested material stackup?

You tell them the thickness you want, they will tell you if they can make it. I get manufactured thousands of 8 layer, 6 Layer and 4 Layer PCBs each year at 1.6 mm +/- 10% FR4 with no problems.
Adam

 

[gorgon]

I've made 4-layer FR4 PCBs 0.8mm thick, but I see that some manufacturers has a limit around 0.4mm.
I don't know if that is the thinnest you can get to a normal price.

I suppose you know that PCBs that thin is flimsy, and not very 'rigid'. I would never have made 'large' PCBs in that thickness. You need to balance the amount of copper on each side too, or it may bend when soldering. Since you talk about microvia, I suppose you want to use BGAs or equally dense footprints, that may need the correct flatness to solder properly.

 

[AnalogKid]

The vast majority of 4-layer boards are 0.060"-0.062" thick, with some variability among vandors. Also, most vendors have a favorite stackup for non-critical designs.

A 4-layer, low speed design wit buried vias - ???

ak

 

[showmy]

Thanks everyone. What you said really helps a lot for me.

 

[Straw]

I don't believe that anyone will use blind and burried vias in a 4-layer PCB after considering costs and possible alternatives. Before claiming a specific implementation you should specify your design requirements.

A PCB stackup will be designed from available substrates and prepregs acting as a construction kit. Everything > 0.4-0.5 mm (e.g. 200 µ core + 70 µ prepregs) should be feasible.

 

[showmy]

I don't believe that anyone will use blind and burried vias in a 4-layer PCB after considering costs and possible alternatives. Before claiming a specific implementation you should specify your design requirements.

A PCB stackup will be designed from available substrates and prepregs acting as a construction kit. Everything > 0.4-0.5 mm (e.g. 200 µ core + 70 µ prepregs) should be feasible.

The stated design requirement is 0.4mm, one side of the board has electrodes to the outside world and on the other side of the board opposite the electrodes numerous high density IC's that will require vias. I can probably get away with a combination of blind and through hole vias.