TypeCatDescription figureprocess RemarkII-aTented ViaTented Via (Type I Via):A via with a dry film mask material applied bridging over the via wherein no additional materials are in the hole. It may be applied to one side (Type I-a) or both sides (Type I-b) of the via structure.Process: Vacuum laminated film material that is photo-definable.Single Sided Tented Not RecommendedII-bTented ViaIIII-aTented and Covered ViasA Type I via with a secondary covering of mask material applied over the tented via. The material may be applied to one side (Type II-a) or both sides (Type II-b) of the via structure.Process: Application of mask over Type I.Single Sided Tented and Covered Not RecommendedIIII-bTented and Covered ViasIIIIII-aPlugged ViaA via with material applied allowing partial penetration into the via. The plug material may be applied from either one side (Type III-a) or both sides (Type III-b) of the via structure.Process: Screened and Roller Coated.Single Sided Plugged Not Recommended.IIIIII-bPlugged ViaIVIV-aPlugged and Covered ViaA Type III via with a secondary covering of material applied over the via. The plug and secondary covering material may be applied from either one side (Type IV-a) or bothsides (Type IV-b) of the via structure.Process: Application of mask over Type III.Single Sided Plugged and Covered Not RecommendedIVIV-bPlugged and Covered ViaVVFilled ViaA via with material applied into the via targeting a full penetration and encapsulation of the hole.Process: Screened, roller-coated, or squeegeed.VIVI-aFilled and Covered ViaDry Film CoverA Type V via with a secondary covering of material (liquid or dry film solder mask) applied over the via. The covering material may be applied from either one side (Type VI-a) or both sides (Type VI-b) of the via structure:Process: Application of mask over Type V. Fill material can be electrically and/or thermally conductive depending on end use.VIVI-bFilled and Covered ViaDry Film CoverVIVI-aFilled and Covered ViaLiquid Film CoverVIVI-bFilled and Covered ViaLiquid Film CoverVIIVIIFilled and Capped ViaA Type V via with a secondary metallized coating covering the via. The metallization is on both sides:Process: Metallized coating over Type V. Applicable where high density features are required.Partially Filled ViaThough not identified as a via protection type, this document does recognize manufacturing processes where solder mask flows into the hole during liquid solder mask application, without intending to provide complete coverage or protection, and may result in partial plugging. This is not acceptable with bare copper surface finishes. The illustrations below show typical via configurations when liquid solder mask is used with no specific process for via protection. Inconsistency of coverage can lead to a mix of all configurations on the same board. Process should not be implemented over bare copper. If the final finish is HASL the center of the hole wall will be bare copper.