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In this column, I will be revisiting topics covered in some of my older columns and fleshing them out with new, updated information. In this job, I truly learn something every day, and I’m happy to share a few notable nuggets with you.
The Quote Process
Ultimately, whether it’s a quick-turn or standard lead-time job, customers would like to see all quotes back within a couple of hours, not a couple of days. Additionally, they want to see accurate quotes that take into account all additional processes. It’s never good when, once quoted, the fabricator comes back with additional costs for unforeseen processes. Again, this is why it is important to get a manufacturing review done if anything outside the norm is required on the drawing or quote. This includes a proper review of impedances to ensure that materials are available and the impedances work without requiring large variances in dielectric or line sizes, buy-offs for any deviations of material type or copper weights, etc.
Beyond the quote process, be sure that your fabricator is capable of all the processes necessary to ensure the board is built as expected. You want your board shop to be IPC-6012 Class 3 capable and ISO certified, and perhaps ITAR as well. Even if you can’t visit the shop for a physical qualification, send them a job to quote and see how they respond. A good fabricator will be diligent and get back to you within a few hours after completing a preliminary examination of the files, impedance calculations and proposed stackup if the board is impedance/dielectrically controlled. They should also be able to let you know right away if the job does not meet their process minimums and can’t be built. If deviations are allowed, a good fabricator will also have an alternative for many situations, such as a deviation for material type, starting copper weight, dielectrics or line sizes to be able to produce the job.
Read the full column here.
Editor's Note: This column originally appeared in the July 2013 issue of The PCB Design Magazine.
Nolan Johnson, I-Connect007
Nolan Johnson checks in with Polar’s Martyn Gaudion on the evolving needs of global PCB manufacturing markets in a post-pandemic world, where generating accurate PCB specification documentation is essential to successfully navigating today's rampant supply chain constraints. Polar has positioned itself to meet these needs through agile software product developments that allow OEMs and fabricators to simulate material interactions and end-product specifications, including in-demand features like a comprehensive "structure view" that allows users to visualize all the transmission lines on a given a PCB. Though keeping pace with the demands of a rapidly growing industry has been challenging, Polar's commitment to innovation has kept its software suite ahead of the curve.
Douglas Brooks, Consultant, and Johannes Adam, ADAM Research
Most of are aware that when we pass an electrical current through a trace (conductor), the trace will heat up. This temperature increase is caused by the I2R power loss dissipated in the resistance of the trace. The resistance of a copper trace is mostly determined by its geometry (cross-sectional area), and there are lots of studies trying to look at the relationship between the current down a trace (of known size) and the resulting temperature of the trace. But the situation is much more complicated than this. There are physical properties that exist that result in helping to cool the trace. These properties are usually a combination of conduction of the heat away from the trace through the material, convection of the heat away from the trace through the air, and radiation of the heat away from the trace.
Happy Holden, I-Connect007
I was first introduced to James Maxwell in 1967 as a college student. I had to decide whether I would take the Maxwell fields course or the switching and coding course. Being a chemical engineering major with a co-major in control theory, I had heard about the trials and tribulations of the infamous Maxwell fields course.