Printed Circuit Design & Fab Online Magazine - Features

Features

Not enough solder? Blame the via design!

Vias in pads can be “solder thirsty” and suck up solder from pads at terminals during reflow, creating what may appear to be solder insufficiency at the joints. This problem is typical of a via-in-pad design. It’s unpredictable as well; solder will randomly tend to fill those vias during the reflow process and some locations may appear worse than others, for example.

Exhibitors hope new products will keep the order books filled in 2023.

The good times of 2022 carried over into January as the industry turned out for one of the larger IPC Apex Expo trade shows in some time. The San Diego Convention Center show floor was humming for the better part of the first two days of the three-day event, and most of the more than 300 exhibitors seemed pleased with the attendance.

Some areas of physics have considerable impact on PCB designs.

PCB designers have had exposure to electronics (some more than others). And most of what we do falls under the field of electronics. But designers often have little or no exposure to physics. And some areas of physics have considerable impact on our designs. Here we look at two physical properties of the dielectrics we work with, and why they are important to understand (Note 1).

Understanding reflections caused by transmission line characteristic impedance and termination impedance mismatch.

Analysis of “digital interconnects” is the analog problem in frequency domain where interconnects are simulated as transmission lines defined by characteristic impedance and propagation constant. Digital signals in interconnects are sequences of amplitude-modulated pulses that transmit bits between components. The “digital interconnect” analysis problem is technically an analog problem of pulse propagation modeling in time-domain.

Not leaving enough clearance is a design oversight that can have costly consequences.

As PCB designers, fabricators and assemblers, we wear a lot of hats at Rush PCB. We're always working to design and build PCBAs that are the best they can be. But sometimes we are consigned product to assemble that wasn't designed by our team, and every so often we get boards that tempt us to say, "The designer clearly wasn't thinking about how we are going to build this!"

Taking the confusion out of determining appropriate data collection parameters.

In 1924, Dr. Walter Shewhart was working at Bell Telephone Laboratories. On May 16 of that year, Dr. Shewhart wrote a memorandum in which he presented and proposed the process control chart to his superiors. Bell Telephone Laboratories believed this memorandum gave it a competitive advantage and held this paper internally. In 1931, Dr. Shewhart published his book Economic Control of Quality of Manufactured Product. In this book, Dr. Shewhart explained in detail the fundamental concepts and benefits of statistical process control. This seminal work laid the foundation for the modern quality control discipline, and the process control chart became the bedrock of quality control systems.