Instantaneous Measurement of Printed Circuit Boards (PCBs)

The term PCB is used to refer to printed circuit boards that have components mounted. Boards without mounted components are called PWBs (Printed Wiring Boards).

A layer of copper foil is attached on one side of the board.
This type has non-through holes that are made by drilling or punching and aren’t plated. They are mainly used for mass produced electronic appliances for consumer use to reduce production costs.

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  Non-through hole
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  Copper foil
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  Base

Copper foils are attached on both sides of the board.
The cost is slightly higher than a single-sided board, but the space for wiring and mounting is doubled, so the size of the board can be smaller. This benefit is why they are widely used for electronic devices.

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  Through hole
• 2
  Copper foil
• 3
  Base

Multi-layered PCBs include copper foils and insulating layers called prepreg. There are 4-layer, 6-layer, and 8-layer boards. The more layers a board has, the more complicated the structure and the higher the manufacturing cost. Power supply and typical signal lines can be placed inside of the board, which increases the space on the surface and mounting density.

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  Through hole
• 2
  Copper foil
• 3
  Base
• 4
  Prepreg

Flexible boards are commonly used to fit inside moving parts or cases that fold. Film materials, including polyimide, are used for these boards. The boards are thin and have a flexible structure.

Leads are inserted into through holes on the PCB and soldered. As more components are placed on the board, the board size must be increased. Electronic parts that have leads wired downward from the packages for IMT are called DIP (Dual In-line Package) components.

The current mainstream PCB mounting method is Surface Mount Technology (SMT). Electrodes are soldered to pads on PCB surfaces without using through holes. Unlike IMT, the electrodes don’t penetrate, so many components can be mounted on both sides of the PCB, allowing for smaller PCBs. Components mounted without lead are referred to as SMDs (Surface Mount Devices).

The holes that connect different circuitry layers are called vias. Lands are the surrounding areas of through holes to solder the leads of electronic components.

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  Land (Pad)
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  Insulator layer (Prepreg)
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  Through hole
• 4
  Track (Pattern)
• 5
  Plane layer or Wire layer
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  Via

Measuring the average of multiple lines helps reduce the effects of roughness and scratches.

Commonly used for soldering electronic components using a soldering iron. Thread solder has a tube shape with flux in the center.

Used for SMT, in which solder is printed on the lands of PCBs.

Used for IMT, in which the terminals of parts and lands of PCBs are soldered in a soldering pot.

A tool used to heat solder and bonding points. Many irons are electric heaters that use nichrome wire or ceramic heaters. Using soldering irons with temperature control at the tip allows for more stable soldering.

The bottom of the PCB is soaked in a soldering pot filled with melted solder. This is mainly used to mount lead-type DIP parts. There are 2 types of soldering pots: static soldering pots in which the melted solder surface is still, and wave soldering pots in which the surface is moving.

Solder paste is printed on the PCB, and then heated to solder components. Reflow soldering is used to mount SMD components.

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  Heat