Main Causes of Circuit Board Errors
The working principle of the circuit board: to use the substrate insulating material to separate the conductive layer of copper foil, so that the current flows along predetermined paths in various components working amplification, damping, modulation, demodulation, coding, and other functions. There are now many PCB manufacturers available. One of the highly recommended is PCB Assembly China.
Circuit Board Principle
Structure. circuit board mainly by the pad, through hole, installation hole, wire, component, connector, filling, electric limit, etc. Common plate layers include single layer PCB, double layer PCB, and multilayer board (multi-layer PCB) three types. The main functions of each component are as follows:
- Solder plate: metal hole used for welding pin components.
- Top hole: there is metal over the hole and non-metal over the hole, where metal is used to connect the pin component between each layer.
- Mounting holes: to repair circuit boards.
- Conductor: Electric copper network film used to connect the component pins.
- Connectors: for circuit boards the relationship between components.
- Filling: Copper deposits for ground grids can effectively reduce impedance.
- Electrical limit: used to determine the size of the circuit board, all components on the circuit board cannot exceed the limit.
Factors that make disability welding of PCB Assembly factory analysis has the following some reasons:
Solderability hole circuit board affect the quality of welding. The solderability hole circuit board is not good, will result in virtual welding Defects, affect the parameters of circuit components, resulting in multilayer board components and wire inner-layer conduction instability, which causes the whole circuit failure function. The so-called solderability is the metal surface by the liquid solder wettability properties, i.e. solder on the metal surface to form a relatively uniform layer of smooth continuous adhesion film.
The main factors affect the solderability of printed circuit boards:
- Solder composition and soldering properties. Soldering is an important part of the chemical welding process, composed of flux-containing chemicals, general low melting point-metal eutectic- or Sn-Pb. Impurity content must be controlled to prevent dirt from becoming dissolved by flux. The function of flux is to help the soldiers wet the surface of a soldering plate circuit by passing heat and removing rust. Commonly used white resins and isopropyl alcohol solvents.
- Welding temperature and surface cleanliness of iron plates also affect solderability. When the temperature is too high, the current solder diffusion velocity has very high activity, will make the circuit board and solder melt the surface of oxidation quickly, resulting in welding of defects, contaminated surface circuit board can also affect the weldability and thus make defects, these defects include beads tin-beads, spherical tin, open circuit, gloss, etc.