Type 1-7 Via Protection | IPC-4761

In some PCB designs, some PCB fabrication and assembly techniques require vias protection for getting reliable products. These types of Via covering are possible:

  • Via Tenting (simple covering)

  • Via Plugging (partially filled)

  • Via Filling (fully filled)

In the following, you will find a comparison of the technical capabilities. The reference is the IPC-4761.

Type

Description

Via Protection Material

I-a

I-b

Tented Via (one-sided)

Tented Via (double-sided)

Dry Film soldermask

II-a

II-b

Tented & Covered Vias (one-sided)

Tented & Covered Vias (double-sided)

Dry Film soldermask + LPI soldermask

III-a

III-b

Plugged Via (one-sided)

Plugged Via (double-sided)

Plugging Epoxy (non-conductive resin paste)

IV-a

IV-b

Plugged & Covered Via (one-sided)

Plugged & Covered Via (double-sided)

Plugging Epoxy + LPI soldermask

V

Filled Via

Plugging Epoxy (non-conductive resin paste)

VI-a

VI-b

Filled & Covered Via (one-sided)

Filled & Covered Via (double-sided)

Plugging Epoxy + LPI soldermask

VII

Filled & Capped Via

Special Plugging Epoxy + Copper Plating to planarization.

 In general, PCB production cost increases as you go down the Via Type chart, with Type III being more expensive than Type I, etc.

Via Tenting

IPC-4761 Type I: Tented Via

The vias are completely covered with dry film soldermask.

One-sided: Type I-a

Double-sided: Type I-b

 

IPC-4762 Type II: Tented & Covered Via

The vias are completely covered with dry film soldermask, and overprinted with LPI soldermask afterwards.

One-sided: Type II-a

Double-sided: Type II-b

 

Application

  • Protect of solder paste floating up to the component side

  • Enables vacuum-adaption for PCB assembly production

  • Covering of critical vias, e.g. beneath BGA

Alternatives

You can apply Via Filling, alternatively.

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

Parameters

Covering

Max. Drill Diameter

Via Tenting

0.3mm

Designation

It is sufficient to cover the vias within the soldermask layer.

 

Via Plugging

IPC-4761 Type III: Plugged Via

The vias are partially filled with non-conductive resin paste.

One-sided: Type III-a

Double-sided: Type III-b

 

IPC-4761 Type IV: Plugged & Covered Via

The vias are partially filled with non-conductive resin paste and overprinted with LPI soldermask, afterwards.

One-sided: Type IV-a

Double-sided: Type IV-b

 

MADPCB 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 paste floating up to the component side.

  • Enables vacuum-adaption for PCB assembly production.

Parameters

Covering

Min Drill Diameter

Max Drill Diameter

Via Filling

0.25mm

0.5mm

Designation

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

 

Via Filling

IPC-4761 Type V: Filled Via

The vias are filled completely with non-conductive resin paste.

IPC-4761 Type VI: Filled & Covered Via

The via is filled completely with non-conductive resin paste and overprinted with LPI soldermask, afterwards

One-sided: Type VI-a

Double-sided: Type VI-b

 

IPC-4761 Type VII: Filled & Capped Via

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

Via Filled and Capped Technology is mostly used for Via-in-Pad (VIP) solutions and is also applied for stacked and staggered via & microvia. Via plugging facilitates routing of additional conductor traces between BGA vias amongst other things.

Filled & Capped Vias are also possible for Blind Vias.

1595044982992414.jpg  1595044982291608.jpg


Application

  • Space saving

  • Protection of solder floating up to the component side.

  • Protection of solder floating up to the component side.

  • Facilitates stacked and staggered Microvia for sequential build-up (SBU) multilayers.

  • Facilitates Via-in-Pad Technology, e.g. for BGAs.

Parameters

Covering

Min Drill Dia.

>>Pad Dia.

Max Drill Dia.

>>Pad Dia.

Aspect Ratio

Filled & Capped

IPC-4761 Type VII

0.15mm

0.35mm

0.4mm

0.6mm

1:12

Filled & Capped

eletroplated

0.1mm

0.3mm

-

-

1:10

*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 solder paste.

Via-in-Pad

Drills & Through-plating

Blind & Buried Vias

Design Parameters