What is PCB?
PCB is brief for Printed Circuit Board
, also known as Printed Wire Board, which is the core thing of an electronic product. It's the primary aid physique for digital components and an issuer of electrical connections for digital components. As the circuits and the relative sample (soldermask and silkscreen) are generated and transferred to the board via the printing way so it is known as a “printed” circuit board.
The position and feature of PCB in a number of digital devices
1. PAD: Providing mechanical aid for fixing and assembling IC and all types of digital components.
2. Track: Realize track route and electrical connection (signal transmission) or electrical isolation between a number of digital factors such as built-in circuits. Providing the required electrical characteristics, such as attribute impedance, etc.
3. Solder-mask and silkscreen: Providing the soldermask images for automated assembly, Providing identification texts and pix for aspect insertion, inspection, and maintenance.
PCB Technology Development Stages Summary
Since 1903, it can be absolutely summarized three tiers through the software and the improvement of the PCB meeting technology
1. Through-hole science (THT) stage:
1-1. The feature of via metalized holes (PTH) :
(1). Electrical connection and Signal transmission
(2). Supporting components-Pin dimension decides the gap dimension smaller and smaller:
a. Rigidity function of the pins
b. Requirements of automated mounting technology.
1-2. The way of enhancing the density
(1). Minimizing the aspects of hole size, however, the gap measurement should be no longer much less than 0.8mm due to the restriction from the stress function of the issue lead pins and the mounting density of the components.
(2). Minimizing the tune width/spacing:0.3mm-0.2mm-0.15mm-0.1mm
(3). Increasing the PCB layer counts: single side-double sides-4L-6L-8L-10L-12L-64L
2. Surface mounting technological know-how (SMT) stage PCB.
2-1: The thru through holes function: solely for electrical interconnection, gap dimension to be as small as possible, by means of holes plugged as well.
2-2: The way of enhancing the circuit interconnection density
(1). The through holes measurement decreased generally smaller and smaller: 0.80mm->0.50mm->0.40mm->0.30mm->0.25mm->0.20mm->0.15mm
(2). Essential exchange going on in the through holes structure.
a. The gain of blind & buried via growing music course and sketch density above 1/3, reduce PCB measurement or decreasing the circuit board layer counts, enhance reliability, impedance controlling improved, minimize sign interference, noise or distortion(because music quick gap small).
b. Via gap in pad eliminates relay holes and wiring
(3). Thinning: 2L PCB:1.6mm-1.0mm-0.8mm-0.5mm
(4). PCB flatness:
a. Concept: The warpage of the PCB base fabric and the coplanarity of the pads floor on the PCB board.
b. PCB warpage is the blended end result of thermally and routinely caused residual stress.
c. PAD floor lined finish: HASL,ENIG,plated(electronic)Ni/Au
3.Chip Scale Package (CSP) Stage PCB
CSP has begun to enter into a drastic trade and development, advertising the non-stop improvement of PCB technology, and the PCB enterprise will pass closer to the laser generator and the nano era.
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