2. The through-hole inside the pad is a crucial component in modern PCB design.
3. Firstly, the process involves drilling, followed by electroplating or flash plating.
4. The pad is then filled with epoxy resin or copper epoxy resin and flattened to ensure a smooth surface for assembly.
5. The advantages of this technology include tighter component packaging, enhanced thermal management, and the reduction of parasitic inductance and capacitance, as these through-holes minimize the signal path length.
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As product design wiring density continues to increase, HDI boards (High-Density Interconnects) are becoming more prevalent, and micro blind buried hole technology is being increasingly utilized. Whether first order, second order, third order, or beyond, higher-order vias present greater technical challenges, including those associated with through-hole technology.
A through hole is a micro conductive path drilled into a PCB, used to establish electrical connections between different layers. Essentially, through holes act as vertical wiring within a PCB. The increase in signal speed, circuit board component density, and PCB thickness of solder pads or solder holes has led to the need for internal solder pads. CAD design engineers use VIPPO and traditional through-hole structures to meet distributed linearity and signal integrity requirements.
The process of creating vias can be divided into two stages: the first stage is called “drilling,” and the second stage is referred to as “plugging.” Various methods can be used to handle vias, including through holes, blind holes, buried holes, and back drilling. Among these, through holes are typically used in copper plating and plugging processes, such as full plug, half plug, VIPPO, and SKIPPO.
When drilling holes and placing electronic components on a pad, VIPPO (Via in Pad Plated Over) or SKIPPO (Skip Via in Pad Plated Over) must be used. VIPPO and SKIPPO are commonly employed on BGA pads.
VIPPO vias can be either through holes or blind holes, while SKIPPO specifically refers to blind holes that extend from the top layer to the third layer, and from the bottom layer (n) to the n-2 layer.
The diameter of VIPPO vias should not exceed 0.5mm. If it does, solder paste during SMT may flow into the hole, or during heating, flux may enter the hole, generating gas and resulting in insufficient connection strength. This can lead to virtual soldering issues between the device and the pad.
Electroplated pad through holes (VIPPO) are similar to standard pad through holes, except that VIPPO is integrated within the SMT pad rather than a regular pad, such as a blind hole pad. Additionally, VIPPO can be used for back drilling (depth-controlled drilling) to remove excess metal from below the inner end connections.
In PCB design, electroplating (VIPPO) technology, also known as via electroplating (POFV), is widely used in small PCBs with limited BGA space. The via in pad process allows the via to be electroplated and concealed under the BGA pad. This process requires PCB manufacturers to fill the through-hole with epoxy resin and then perform copper plating to make it nearly invisible.
POFV technology can greatly enhance the efficiency of PCB design engineers by reducing the space occupied by vias during design, which in turn decreases wiring complexity. The incorporation of vias into solder pads provides additional space for wiring, making the PCB layout more compact. The hole-in-tray process makes the PCB layout three-dimensional, effectively saving space and meeting the evolving demands of the electronics industry. Generally, using a vacuum plug-hole machine for plugging and a ceramic grinder for polishing can stabilize the quality of PCB plug holes.
**Advantages of VIPPO Technology:**
1. Enhances routing efficiency by providing holes on the solder pad.
2. Assists in heat dissipation through holes in the pad.
3. Reduces inductance in high-frequency PCBs with holes on the solder pads.
4. Offers a flat surface for components through holes in the pad.
VIPPO differs from regular vias in that it features a copper cap flush with the solder pad. VIPPO is primarily used in high-end products such as communication devices and servers.
