Types of methods for protecting PCB vias
IPC-4761 (Design Guide for Protection of Printed Board Via Structures) defines several types of methods for protecting PCB vias. These are:
Type I: Tented
Type I: Tented
I(a) single sided
I(b) double sided
Dry film solder mask is stretched over the hole. No other materials are added.
Type III: Plugged
Type III: Plugged
III(a) single sided
III(b) double sided
A non-conductive material (resin) penetrates partially into the hole, but does not go all the way through.
Type V:Filled
Type V: Filled
Fully plugged. A conductive (silver or copper, plugging materials with metal particles) or non-conductive material (resin) penetrates completely into the hole, filling the hole all the way through.
Type II: Tented and covered
Type II: Tented and covered
II(a) single sided
II(b) double sided
An additional dry film or liquid solder mask layer covers the tenting of a Type I tented via.
Type IV: Plugged and covered
Type IV: Plugged and covered
IV(a) single sided
IV(b) double sided
An additional dry film or liquid solder mask layer covers the plugging of a Type III plugged via.
Type VI:Filled and covered
Type VI: Filled and covered
Fully plugged.An additional dry film or liquid solder mask layer covers the filled material of a Type V filled via.
Type VII:Filled and capped
Type VII: Filled and capped
A metalized coating covers the filled material of a Type V filled via. The metallization is on both sides
The capped vias technology requires the hole to be filled with resin or copper and then plated. Via-In-Pad and Ball-on-Via pad in used.