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VIA Covering

Thursday, 20 April 2023
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VIA Covering

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

*Via Plugging (partially filled)

*Via Tenting (simple covering)

*Via Filling (completely filled)

Via Plugging (partially filled)

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

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

GWT 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

1.Protection of solder floating up to the component side

2.Enables vacuum-adaption for production

Designation

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

Via Tenting

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: 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

1.Protection of solder floating up to the component side

2.Enables vacuum-adaption for production

3.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.

Designation

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

Via-Filling

IPC 4761 Type V: Filled Via

The via is filled completely with non-conductive paste.

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 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.