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The core board process characteristics of multi-layer circuit boards
2021-08-28
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Author:Aure

The core board process characteristics of multi-layer circuit boards

  1 Overview
 
   is currently designed by a complex circuit, and the design of this complex circuit into a thin and light core board is inseparable from the multilayer circuit board (MLB) manufacturing technology.
 
Multilayer circuit board (MLB) manufacturing technology has developed rapidly, especially in the late 1980s. With the increase in the number of high-density I/O (input/output) leads, the emergence and development of VLSI, ULSI integrated circuits, and SMD devices, SMT The adoption of the multi-layer board has promoted the manufacturing technology of the multilayer board to reach a very high level of craftsmanship. As the "light, thin, short, small" components are widely used, the rapid development of SMD and the popularization of SMT, interconnection technology becomes more complicated, and the manufacturing technology of multi-layer board is promoted to fine line width and narrow. Pitch, thinner and taller, and the development of micro-aperture. The transformation of multilayer printed circuit board technology, that is, multilayer printed circuit board manufacturing technology, has been widely used in civil electrical appliances.
 
The development of MLB is usually divided into two categories according to the scope of application: one is used as the basic components of electronic complete machines, used to install electronic components and interconnected substrates; the other is used for various types of chips and The carrier board of the integrated circuit chip. The MLB conductive pattern used as the carrier board is more refined, the performance requirements of the substrate are more stringent, and the manufacturing technology is more complicated.


The core board process characteristics of multi-layer circuit boards

 
  2. The process characteristics of the multilayer printed circuit board are as follows:
 
  ①、High density

   The high density of multi-layer circuit boards means that the use of high-precision wire technology, micro-aperture technology, and narrow ring width or no ring width technology has greatly improved the assembly density of the printed board. The basic status of multi-layer circuit board high-density interconnection technology is shown in the following table (Table 2-1):
 
  ②, high-precision wire technology
 
  High-density interconnect structure of multi-layer circuit boards, the circuit pattern used requires high-precision wires with a line width and spacing between 0.05-0.15 mm. The corresponding manufacturing process and equipment must have the technology and processing ability to form high-precision, high-density thin lines.
 
  ③、Micro-aperture technology
 
   With the shrinking of the aperture of the multilayer circuit board, higher technical requirements are put forward for the drilling process and equipment. At the same time, it is necessary to adopt full chemical plating and direct plating technology to solve the problems of small hole plating adhesion and ductility.
 
  ④, the ring width of the reduced hole of the core board
 
  The reduction of the ring width around the empty space can increase the wiring space, thus further improving the circuit pattern density of the multilayer circuit board.
 
  ⑤, multi-layer circuit board structure diversification
 
   With the high stability and high reliability requirements of precision devices, the density requirements of multilayer circuit board manufacturing and the increase in the number and complexity of interconnections, the diversification of their structures is inevitable.
 
  ⑥、Thin and multilayer technology
 
  Thin and multilayer technology is fully adapted to the technical requirements of "light, thin, short, small" and high-density components. The current development trend of manufacturing process technology of multilayer circuit boards is divided into: high-level thin boards and general thin boards. The thickness of the high-rise thin multilayer circuit board will be 0.6-5.0MM, and the number of layers will be 12-50 layers or higher; the thickness of the thin multilayer circuit board will be 0.3-1.2MM, and the number of layers will be 4-10 layers or higher.
 
  ⑦, buried, blind and through-hole combined multilayer board manufacturing technology
 
  This type of multilayer printed circuit board has a complex structure and will be solved by a large number of electrical interconnection technologies, which can increase the wiring density by 50% and greatly reduce the pressure on the production of fine wires and ring widths with small apertures.
 
  ⑧, multilayer wiring multilayer circuit board
 
The structure of the multilayer wiring multilayer circuit board is coated with adhesive on the surface of the copper-free substrate, and then use the data provided by the computer to control the wiring machine, and the 0.06-0.1MM square enameled wires are perpendicular to each other in the X and Y directions. Wiring, and then wiring diagonally at 45°, is laid on both sides of the substrate. After wiring is completed, it is covered with a film to play a fixed and protective role. It is curing and CNC drilling and other processes.
 
  ⑨, direct writing technology
 
  Using direct writing technology can completely and quickly produce prototypes (that is, freely formed three-dimensional manufacturing, laser sintering, metal printing technology, etc.) to produce prototypes with three-dimensional structures and characteristics.
 
The advantage of    direct writing is that it has a relatively wide range and can have an impact on the manufacture of electronic systems.

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