What is Via in Pad Callout (VIPPO)?

Via in Pad Callout, or VIPPO, is a PCB design technique that involves placing vias directly inside the surface mount pads of components. This technique is becoming increasingly popular in high-density PCB designs as it allows for more efficient use of board space and improved signal integrity.

Benefits of VIPPO

1. Space Savings: By placing vias within the pads, designers can reduce the overall footprint of components and free up valuable board space for other components or routing.

2. Improved Signal Integrity: VIPPO can help minimize the length of signal traces, reducing the risk of signal degradation, crosstalk, and electromagnetic interference (EMI).

3. Enhanced Thermal Management: Vias placed within pads can provide additional thermal paths, allowing for better heat dissipation from components to the PCB’s internal layers or ground plane.

4. Increased Reliability: VIPPO can improve the mechanical strength of the solder joint by anchoring the component to the board more securely.

Design Considerations for VIPPO

When implementing VIPPO in your PCB design, there are several key factors to consider:

Via Size and Placement

The size and placement of vias within the pad are critical to ensure proper soldering and avoid manufacturing issues. The via diameter should be small enough to fit within the pad without compromising the solder joint’s integrity.

Component Pitch	Recommended Via Diameter
0.5mm	0.2mm – 0.3mm
0.4mm	0.15mm – 0.25mm
0.3mm	0.1mm – 0.2mm

Solder Mask Design

When using VIPPO, it’s essential to ensure that the solder mask is designed correctly to prevent solder from wicking down the via during the reflow process. Two common approaches are:

1. Via tenting: The solder mask covers the via, preventing solder from flowing into it.
2. Via Plugging: The via is filled with a non-conductive material before applying the solder mask.

Pad Size and Shape

The pad size and shape may need to be adjusted to accommodate the via while maintaining adequate solder joint strength. Designers should follow the component manufacturer’s recommendations and consider the specific requirements of their PCB Assembly process.

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Implementing VIPPO in Your PCB Design Software

Most modern PCB design software packages support VIPPO, though the specific implementation may vary. Here are some general steps to follow:

1. Define via size and drill pairs in your design rules.
2. Create a pad stack that includes the via and any necessary solder mask adjustments.
3. Assign the VIPPO pad stack to the relevant components in your library.
4. Place components and route traces as usual, ensuring that the vias are correctly positioned within the pads.

VIPPO in Altium Designer

In Altium Designer, you can create a VIPPO pad stack by following these steps:

1. Open the Pad Stack Manager.
2. Create a new pad stack and define the pad size and shape.
3. Add a via layer to the pad stack and specify the via size and drill pair.
4. Adjust the solder mask settings as needed (via tenting or plugging).
5. Save the pad stack and assign it to the appropriate components in your library.

VIPPO in KiCad

To implement VIPPO in KiCad:

1. Open the Footprint Editor.
2. Create a new footprint or edit an existing one.
3. Place a pad and set its size and shape.
4. Add a via to the pad and define its size and drill pair.
5. Adjust the solder mask settings for the via.
6. Save the footprint and assign it to the relevant components in your schematic.

Real-World Applications of VIPPO

VIPPO is particularly useful in designs where space is at a premium, such as:

1. Wearable electronics
2. Internet of Things (IoT) devices
3. High-density connectors
4. Mobile phones and tablets
5. Medical implants

By reducing the footprint of components and improving signal integrity, VIPPO enables designers to create more compact and reliable devices for these demanding applications.

Conclusion

Via in Pad Callout (VIPPO) is a powerful PCB design technique that can help designers save space, improve signal integrity, and enhance thermal management. By carefully considering factors such as via size and placement, solder mask design, and pad size and shape, designers can successfully implement VIPPO in their high-density PCB layouts. As electronic devices continue to shrink in size and increase in complexity, VIPPO will likely become an increasingly essential tool in the PCB designer’s arsenal.

Frequently Asked Questions (FAQ)

1. Q: Can VIPPO be used with any component package?
   A: VIPPO is most commonly used with surface mount devices (SMDs) such as QFPs, BGAs, and LGAs. However, it can also be applied to certain through-hole components with suitable pad sizes.

2. Q: Are there any disadvantages to using VIPPO?
   A: One potential drawback of VIPPO is that it may require more precise manufacturing processes, as the vias must be accurately placed within the pads. This can increase production costs and may not be suitable for all PCB Fabrication facilities.

3. Q: How does VIPPO affect the solder joint strength?
   A: When properly designed, VIPPO can actually improve the solder joint strength by providing additional mechanical anchoring between the component and the PCB. However, it’s essential to ensure that the via size and placement do not compromise the solder joint’s integrity.

4. Q: Can VIPPO be used in high-voltage applications?
   A: VIPPO can be used in high-voltage applications, but designers must take extra care to ensure adequate insulation and clearance distances. The use of via plugging or tenting can help prevent voltage breakdown and leakage currents.

5. Q: Is VIPPO compatible with automated optical inspection (AOI) systems?
   A: Yes, VIPPO is generally compatible with AOI systems. However, the inspection algorithms may need to be adjusted to account for the presence of vias within the pads. Some AOI systems may require additional programming to detect solder defects accurately in VIPPO designs.