Via Covering

Filled & Capped Vias Microsection

Filled & Capped Vias Microsection

Several technical or production-related demands require the covering / sealing of vias. These types of Via covering are possible:

  • Via Tenting (simple covering)
  • Via Plugging (partially filled)
  • Via Filling (completely filled)

In the following, you will find a comparsion of the technical capabilities.

The reference is the IPC 4761, which can be purchased here: https://portal.ipc.org/Association/Index.htm.

Abstract

TypeDescriptionCovering-Material
TypeI-a / -bDescriptionTented one-sided / double-sidedCovering-MaterialDryfilm solder-stop
TypeII-a / -bDescriptionTented & Covered one-sided / double-sidedCovering-MaterialDryfilm solder-stop + LPI solder-stop
TypeIII-a / -bDescriptionPlugged one-sided / double-sidedCovering-MaterialPlugging Epoxy (non-conducting paste)
TypeIV-a / -bDescriptionPlugged & Covered one-sided / double-sidedCovering-MaterialPlugging Epoxy + LPI solder-stop
TypeVDescriptionFilledCovering-MaterialPlugging Epoxy (non-conducting paste)
TypeVI-a / -bDescriptionFilled & Covered one-sided / double-sidedCovering-MaterialPlugging Epoxy + LPI solder-stop
TypeVIIDescriptionFilled & CappedCovering-MaterialSpecial Plugging Epoxy + plating

Via Tenting

Via Tenting - IPC 4761 Type I-a
Via Tenting - IPC 4761 Type I-b

IPC 4761 Type I: Tented Via

The via is completely covered with  dryfilm solder-stop.

One-sided: Type I-a
Double-sided:Type I-b


IPC 4761 Type II-a: Tented & Covered Via one-sided
IPC 4761 Type II-b: Tented & Covered Via doublesided

IPC 4761 Type II: Tented & Covered Via

The via is completely covered with  dryfilm solder-stop and overprinted with normal solder-stop, afterwards.

One-sided: Type II-a
Double-sided:Type II-b


Application

  • Protection of solder floating up to the component side
  • Enables vacuum-adaption for production
  • Covering of critical vias, e.g. beneath BGA

Alternatives

You can apply Via Filling, alternatively.

Through cutting the solder-stop clearance, you can ensure a sufficient solder-stop bridge for BGAs. Using this method, the via annular rings will be partly covered with solder-stop.


Parameters

Covering Max. Drill-Ø
CoveringVia Tenting Max. Drill-Ø 300µm

Designation

It is sufficient to cover the vias within the solder-stop layer.

Via Plugging

Via Plugging - IPC 4761 Type III-a
Via Plugging - IPC 4761 Type III-b

IPC 4761 Type III: Plugged Via

The via is partially filled with non-conductive paste.

One-sided: Type III-a
Double-sided: Type III-b


Plugged & Covered Via - IPC 4761 Type IV-a
Plugged & Covered Via - IPC 4761 Type IV-b

IPC 4761 Type IV: Plugged & Covered Via

The via is partially filled with non-conductive paste and overprinted with normal solder-stop, afterwards.

One-sided: Type IV-a
Double-sided: Type IV-b

Multi-CB recommends one-sided plugging (Type III-a / Type IV-a) as there is a chance of cracks through encapsulated gas while soldering double-sided plugged vias.


Application

  • Protection of solder floating up to the component side
  • Enables vacuum-adaption for production

Parameters

Covering Min. Drill-Ø Max. Drill-Ø
CoveringVia Filling Min. Drill-Ø 250µm Max. Drill-Ø 500µm

Designation

Copy the vias to be filled into an additional layer and define that layer with your order.

Via Filling

IPC 4761 Type V: Filled Via

IPC 4761 Type V: Filled Via

The via is filled completely with non-conductive paste.


IPC 4761 Type VI-a: Filled & Covered Via
IPC 4761 Type VI-b: Filled & Covered Via

IPC 4761 Type VI: Filled & Covered Via

The via is filled completely with non-conductive paste and overprinted with normal solder-stop, afterwards.

One-sided: Type VI-a
Double-sided: Type VI-b


IPC 4761 Type VII: Filled & Capped

IPC 4761 Type VII: Filled & Capped Via

The via is plated-through and cleaned - afterwards a non-conductive paste is forced in and hardened - the ends are planarized, metallized and plated-over. Hence, the surface is planar and solderable.

This technology is mostly used for Via-in-Pad solutions and is also applied for stacked und staggered (Micro-)vias. Via Plugging faciliates routing of additional conductor traces between BGA vias amongst other things.

Filled & Capped Vias are also possible for Blind Vias.


filled via

Filled Via

filled capped via

Filled & Capped Via


Application

  • Space saving
  • Protection of solder floating up to the component side
  • Faciliates stacked und staggered Microvias for sequential build up multilayers (SBU)
  • Facilates Via-in-Pad Technology, e.g. for BGAs

Parameters

Covering Min. Drill-Ø >> Pad-Ø   Max. Drill-Ø >> Pad-ØAspect ratio
CoveringFilled & Capped
IPC 4761 Type VII
Min. Drill-Ø 150µm >> Pad-Ø 350µm   Max. Drill-Ø 400µm >> Pad-Ø600µmAspect ratio1:12
CoveringFilled & Capped
electroplated
Min. Drill-Ø 100µm >> Pad-Ø 300µm   Max. Drill-Ø - >> Pad-Ø-Aspect ratio1:10

*Filled & Capped Vias blind vias have an aspect ratio of 1:1


Designation

Copy the vias to be plugged into an additional layer and define that layer with your order.