Common PCB Vias Plugged and Filled Process

IPC 4761 type 3a / Vias Plugged (Only single-sided plugged with special plugging ink)

 Note:
1.This protection method must be done after soldering surfaces because single-sided plugged vias may cause diversion of bath media and can also cause missing pad defect (battery effect by different electrical potentials).
2.Special plugging ink, separated and clean curing oven must be used to avoid cross-contamination of soldering surfaces by chemicals and/or dust during curing phase.

IPC 4761 type 5 / Vias Filled

Vias filled with resin (100% by using vacuum).

Less shrinkage of resin in comparison to filling with solder mask

Only possible for HASL surfaces, via 50% filled with solder mask

Via Protection According To IPC 4761

Process overview type 6 with solder mask

Silkscreen Machine 

Sheet before processing;

holes opened to absorb the ink

Vias 100% by silk-screen process

Silk in use with ink in the holes

Vias filled with solder mask and double-sided covered with

solder mask. Coverage „wet on wet“ on the filled vias

IPC 4761 Type 6b / Vias Filled and Double-sided Covered

Vias completely filled with solder mask, resin or copper paste and covered with solder mask

 Double-sided

Filled with solder mask

Filled with resin

Note:

The selection of Type 6 with resin means more cost because this method requires additional processes like manual handling and filling, drying, cleaning and drilling of not filled PTHs including plating.

IPC 4761 type7 / Vias Filled and Capped

Via filled with resin and plated with copper Process can also be used to fill vias on inner layers