Printed Circuit Design & Fab Online Magazine - Current Issue

Current Issue

Exposed copper coupled with silver final finish is causing opens.

Figures 1 and 2 show two images of the same problem: one x-ray, the other optical. In both cases it’s the result of sulphur corrosion on the surface of copper and silver surfaces. Both surfaces remain exposed after a soldering operation, and in the presence of sulphur, it is possible to witness corrosion. In time it can result in an open connection, as the figures show. Figure 1, taken on a Dage x-ray system, shows different degrees of corrosion on the tracking just below the solder joint fillet. In failure investigations it’s important to see and record as much as possible without change or damage to the sample. On one joint there was an open connection on this QFP device.

Read more: Sulphur Corrosion on Solder Joints

John Burkhert, Jr. A structured design review process ensures alignment across teams.

One thing is certain about printed circuit board design: change is inevitable. The vernacular surrounding the art and science of PCB design gives credence to this statement. Upfront, it’s a schematic editor that leads to a layout editor. If you get far enough downstream, you’re working with a Gerber editor. Across the board, the notion of making changes is distilled into the process.

Read more: Reviewing the PCB Design Review Process

John Burkhert, Jr. UCIe 3.0 is where bandwidth meets bravado.

In August, the Universal Chiplet Interconnect Express standard revision 3 was issued. This follows revision 2 by exactly a year. The first selling point of revision 3 is higher data rates, double that of the previous version. If that sounds like another standard, PCIe, then chalk it up to UCIe using PCIe as a template, along with the Compute Express Link (CXL), to build the UCIe ecosystem. It remains adaptable and scalable according to needs.

Read more: Interconnect Technology for Chiplets

John Burkhert, Jr. When passive heat management isn’t enough, fans or blowers are “cool” solutions.

It has been said that good things come in small packages. This is true of electronics up to a point. Chip companies compete for bragging rights over package size. Less is more. Increased density permits faster operation due to reduced lag in shorter traces. This trend extends beyond just chips; shrinking the entire product represents a significant “marketing breakthrough.”

Meanwhile, a compact board will have more wattage to dissipate per unit area. The power supplies are spread around the board with dedicated regulators assigned to each chip even when the voltage requirements are the same from one device to another.

Read more: Concerning Thermal Challenges with Printed Circuit Boards