Via in pad · VIPPO
Via in Pad PCB: Filled & Capped Vias for Fine-Pitch BGAs
Via-in-pad plated over (VIPPO) puts the via directly in the component pad, then fills and copper-caps it for a flat, solderable surface. It is essential below 0.8 mm BGA pitch.
- BGA pitch
- 0.4–1.0 mm
- Min. pad
- 0.25 mm
- IPC-4761 fill + cap
- Type VII
- Fill verified by microsection
- 100%
What is via in pad
Via in pad, explained.
Via in pad places a plated via directly inside an SMT or BGA pad instead of routing out to a dog-bone via. The via is filled with epoxy, planarized and plated over with copper (VIPPO, IPC-4761 Type VII), so the pad is flat and solder cannot wick into the hole.
It frees routing space under fine-pitch BGAs, shortens the path to inner planes (lower inductance for decoupling and high-speed signals) and improves heat transfer from thermal pads.
When to use
When via in pad is the right choice.
- BGA pitch below 0.8 mm where dog-bones no longer fit
- Decoupling capacitors that need the shortest path to planes
- QFN / LGA thermal pads needing thermal vias without solder voids
- High-speed signals where stub and loop inductance matter
- HDI builds — see HDI PCB
Specifications
Via in pad specifications.
| Parameter | Capability |
|---|---|
| Pad size | Down to about 0.25 mm diameter |
| Via size | Typically 30–50% of pad diameter; 75 µm+ laser or 0.10 mm+ mechanical |
| Fill type | Non-conductive epoxy (Type VII) or conductive fill (Type VI) |
| Cap | Copper plated over, planarized for flat pads |
| Verification | Vacuum-assisted fill; microsection to confirm fill |
| Finishes | ENIG / ENEPIG recommended for fine pitch |
Process
How VIPPO is made.
- 01
Drill & plate
Via drilled and copper-plated.
- 02
Fill
Vacuum-assisted epoxy fill, then cure.
- 03
Planarize
Excess resin removed flush with copper.
- 04
Cap
Copper plated over; pad imaged and finished.
Fabrication + assembly
Via-in-pad is a fabrication and assembly decision together.
Via-in-pad only works when fabrication and assembly agree. The fill must be void-free, the cap planar enough for paste printing, and the finish suited to the package. We confirm the method against the device, finish and assembly process, and review it with the HDI build-up rather than as an isolated feature.
- Identify every BGA / fine-pitch location needing via-in-pad
- State pad-flatness, finish and inspection expectations
- Review with the HDI stack-up — HDI PCB
Fill methods
Via filling methods for a filled via PCB.
| Fill | Conductivity | Cost | Use |
|---|---|---|---|
| Copper fill | Best electrical and thermal | Highest | Power, thermal, stacked microvias |
| Conductive epoxy | Good | Medium | Thermal pads |
| Non-conductive epoxy | Barrel only | Lowest | Signal via-in-pad |
IPC-4761 types
Via protection types and capped vias (IPC-4761).
| Type | Description | Use |
|---|---|---|
| Type I–II | Tented / tented and covered | Covering only; not for pads |
| Type III–IV | Plugged / plugged and covered | Partial fill |
| Type V | Filled | Full fill, no cap |
| Type VI | Filled and covered | Fill plus cover |
| Type VII | Filled and capped (VIPPO) | Via-in-pad standard |
Capped vias are plated vias filled with epoxy or conductive paste and then plated over with copper. They are the reason via in pad can be soldered: the via location becomes electrically and mechanically equivalent to a solid copper pad, so paste prints evenly, the part sits flat and the joint forms without wicking or voids.
Inspection
How filled and capped vias are inspected.
Fill quality is checked by microsection on coupons, looking for voids in the fill, cap thickness, dimple or protrusion at the surface, and the bond between cap and barrel. We use vacuum-assisted filling to reduce voids and inspect fill on every production lot that uses via in pad.
BGA pitch guide
When BGA pitch calls for via-in-pad.
| BGA pitch | Typical approach |
|---|---|
| 1.0 mm | Dog-bone fan-out; via-in-pad rarely needed |
| 0.8 mm | Dog-bone on outer rows; via-in-pad for inner rows or decoupling |
| 0.65 mm | Via-in-pad on inner rows, often with microvias |
| 0.5 mm | Via-in-pad with HDI (1+N+1 or 2+N+2) |
| 0.4 mm and below | Copper-filled via-in-pad, stacked/staggered microvias |
RFQ
What to include in a via-in-pad RFQ.
- Fabrication data and stack-up intent
- Via-in-pad locations and fill type
- Finish and planarity requirements
- Assembly context (BGA pitch, reflow passes)
- Quantities and schedule
Design rules
Via in pad design rules.
- Mark every via-in-pad location in the drill table and fab drawing
- Specify fill type (Type VI or VII) and capping
- Avoid mixing open and capped vias in the same BGA
- Expect one extra plating cycle in cost and lead time
- Pair with laser-drilled microvias and blind & buried vias as needed
FAQ
Common questions.
What is via in pad?
A via placed in a component pad and filled and capped with copper so the pad stays flat and solderable.
Is via in pad the same as VIPPO?
VIPPO (via-in-pad plated over) is the filled-and-capped form of via in pad, the version required for reliable soldering.
Does via in pad increase cost?
Yes, modestly: filling, planarizing and capping add a plating cycle. It often saves layers or HDI steps overall.
Which fill should I specify?
Non-conductive epoxy (IPC-4761 Type VII) is standard. Conductive fill is used where extra thermal or current capacity is needed.
Can open vias be left in pads?
No. Open vias in pads wick solder and cause voids or opens; they must be filled and capped.
Does via-in-pad affect assembly yield?
When properly filled and capped, no. Poorly filled vias cause voids; we use vacuum filling and inspect fill on every lot.
What is a filled via PCB?
A filled via PCB is a board whose vias are filled with epoxy, conductive paste or plated copper instead of being left open. In via in pad the filled via is then copper-capped so a component can be soldered on top.
Capped vs tented vias?
Tented vias are only covered with solder mask; capped vias are filled and copper-plated so you can solder on top of them.
Ready when your files are
Send your design for a capability check.
Upload Gerber, ODB++ or IPC-2581 data. Every quote includes a written engineering DFM review, typically within one business day.