Epec's Blog | Electronics Manufacturing Solutions

The flex PCB stack-up documentation is an important component of the data set of a flexible printed circuit board design. It consists of a description of a flex or rigid-flex circuit board that defines in detail the specific material requirements and construction of the design.

Many electronics assemblies that utilize flexible printed circuit boards are sensitive to either absorbing or emitting electromagnetic interference (EMI). If EMI is left uncontrolled it can negatively impact the performance of the design and in extreme cases completely prevent it from functioning.

With the uncertainty the global economy has brought over the last decade, it has been challenging for many companies to balance the fine line of just-in-time (JIT) inventory management, being line down, and being over budget on inventory numbers. We live in a world where next day delivery of virtually anything has become a guarantee, or at least an expectation.

Pre-baking polyimide-based flex PCBs immediately prior to assembly is required to prevent moisture-driven delamination during reflow. Polyimide materials naturally absorb moisture, which expands into steam under high temperatures and separates layers. Removing this moisture just before assembly is the only reliable way to avoid failures.

When ordering flex circuit boards online, quick turn order delivery timelines can incur setbacks if the data set is either incomplete or if the design has technical issues. Technical issues can be related to either manufacturability or the end use of the parts. These issues then often require multiple communications to resolve and in some worst-case scenarios, extensive design revision. Any of these issues will of course delay the delivery of the finished parts.

The reason printed circuit boards (PCBs) require a surface finish rather than being left as simply bare copper is because while copper is an excellent conductor, leaving it exposed will cause it to oxidize and deteriorate over time. The increased exposure will cause the PCB to fail much sooner than expected.

EMI (electromagnetic interference) and RFI (radio-frequency interference) are disturbances generated by external sources that impact a cable assembly by degrading the assembly's performance or completely preventing it from functioning. These disturbances can cause problems ranging from an increase in error rates of the signal being transmitted through the assembly to total loss of any electronically readable signal.

A printed circuit board (PCB) is an inexpensive and compact way to create many of the necessary interconnects between RF components in a subsystem. The interconnects are most often created with stripline and microstrip transmission lines, as well as vertical coaxial transmission lines created with plated through hole patterns.

A pure notch or band stop filter (also called band reject filter) works by creating a Voltage Standing Wave Ratio (VSWR) resonance over a narrow bandwidth. This creates near total reflection over that bandwidth, while having very little reflection in the surrounding pass bands. By the nature of their creation, these notch filters are typically narrow band. Bandwidth comes linearly with added resonators, increasing size and loss.

When you’re in the process of designing a new product, the last thing you are thinking about is the how the product is going to be packaged for transit. However, failure to prepare for and understand electronics packaging regarding how both your components and your finished unit are going to ship is a costly oversight.