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What are primary and secondary sides of PCB?

I am designing a 2 layer PCB with components on both side of it. SMT components are one one side of PCB, but TH (through hole) components are on both sides. I need to understanding something mentioned by the supplier called primary and secondary sides.

The primary side is the side that has most of the components, especially the ICs. The most common soldering technique these days is reflow soldering. It is simply easier to get precision temperature profiles on one side of the board only.

The secondary side can also support components, but

  1. it’s harder to control the temperature precisely, and
  2. gravity works against you as the solder paste begins to melt and the components on the underside of the board want to fall off.

Read More: Multilayer PCB

#PCB Assembly

Picture of Oliver Smith

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.
Picture of Oliver Smith

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

What Others Are Asking

What will be the role of a copper layer in a metal core PCB in thermal dissipation?

In the design of a power electronic PCB, I want to use a metal PCB for heat dissipation of a TO-220 package MOSFET. To do that I want to mount metal PCB on the MOSFET with the use of thermal paste and screw exactly like we do when we use heatsink for the same package. Should I leave the copper of PCB between MOSFET surface and dielectric of PCB or remove the copper surface and leave only the dielectric opening?

Can I design SMD elements on the back of THT?

I’m designing a PCB right now and found out I can save a lot of space using the back of THT elements. Is it legit to design like that? Are there any problems that might occur? 

Read Detailed Advice From Blog Articles