PCB Design


Printed Circuit Board Design Technology

My choice of PCB Design software is Altium Designer, I am part of the Altium Online Community and converse daily with other PCB designers around the world. Although Altium PCB software is very expensive to purchase, I believe it is truly one of the very best design environments for professional PCB design engineers to layout schematics and PCB designs. I have invested in many hours of training in Altium PCB Design Software, I am fully confident in vertically every aspect of Altium Designer Software Version 15 (2015). I design professional PCB’s every day of the week as you can see below, please feel free to click / play the 3D Altium videos below of my recent PCB designs.


These PCB designs have been created and designed by John Heritage (Jan 2015) and use many different types of components and design technollogy, ACTEL FPGA, Micro Processor, RAM, FLASH Memory, Level Shifting, FET Switching & Current Sensing, DC-DC Converters, Video Switching & Amplification, etc.





Prototyping

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Before a PCB can be designed for any given product, the product normally starts life as a prototype design, in the above images you can see my early prototype designs of the microprocessor board and CAN controller for the intelligent swimming pool control system I previously designed. I have spent hours of my life designing prototype PCB’s and then constantly tweaking and modifying circuitry until final perfection, reliability and functionality is achieved. Whilst designing a prototype PCB, nothing can be left to change, as any problems and errors missed at this stage can work out very costly in time and money later on down the line.

Important Design Factors

  • Mixed Signals – ensuring Analog & Digital signal paths and power lines are not mixed
  • Star Grounding – ensuring minimal noise through ground loops
  • Good Shielding– ensuring minimal noise generation and inductance from components
  • Good Regulation– ensuring clean stable power supply lines
  • Good Smoothing – ensuring clean stable power supply lines
  • Capacitor Decoupling – ensuring minimal noise generated by mainly digital circuitry
  • Short Circuit Paths – keeping all connecting tracks as short as possible
  • Static Protection – diode protection ensuring antistatic protection for sensitive parts 

Final PCB Design

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Converting the prototype design of a product to the final PCB layout is an involved process requiring technical skill, knowledge and patience. This process is achieved by using complex CAD Software and there are many design rules to take onboard and understand. There is no room for any design errors when laying out a PCB and once the designs have been sent to the PCB manufacturing company it’ too late!

Important PCB Layout Factors

  • Ground Planes  – ensuring good electrically conducting surface and noise shielding
  • Correct Track Widths – ensuring ample current path for power tracks versus signal tracks
  • Capacitors -place capacitors next to every digital IC between its power input and ground
  • High Frequency – keep high frequency traces as short as possible
  • Avoid – running high frequency signals over a gap in a ground plane
  • Separate – analog and digital circuitry
  • Separate – analog and digital grounds that are tied back to a common point
  • Traces – should never have a 90 degree or greater bend. 45 degree bends should always be used to prevent signal reflections and noise
  • Avoid – using an autorouter as much as possible
  • Do not – leave unconnected copper fills on the PCB. They must be connected to ground or removed
  • Avoid – placing vias under components whenever possible
  • Use through hole – components as vias when possible
  • Always – try to use surface mounted components, thus cheaper tooling & final product
  • Minimize – the number of drill sizes used

As can be seen above, there are many important factors to take onboard when laying out professional PCB’s.
I have many years of experience in this field and have designed many printed circuit board with both discrete and surface mounted components.

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