PCB News - Multilayer circuit board application field and structure

Multilayer circuit board application field and structure

In terms of fields, there are many Shenzhencircuit board factories that only do one or two application fields, while some can make circuit boards for multiple application fields. From the structure of the circuit board, it can be used as a single-sided circuit board and a PCB multi-layer circuit board. Today, Shenzhen Circuit Board Factory focuses on introducing you to the application fields and structure of multilayer circuit boards.

1. The cross-sectional geometry of the multilayer circuit board

According to the number of layers of the circuit, the multi-layer circuit board will have: single-sided circuit board, double-sided circuit board, 4-layer, 6-layer, 8-layer and other multilayer circuit board factory structure. As for the high-density HDI circuit boards that are often mentioned recently, because the usual manufacturing method is to build a core hard board in the center, and use this as a basis for the growth and build-up of the upper and lower sides, so there are two common names. One is to use the number of hard board layers in the center as the first number, and the number of additional wire layers on both sides as the other number, so there are so-called descriptions of 4+2, 2+2, 6+4, and so on. But another name may be easier for people to understand the actual situation, because most multi-layer circuit board designs use symmetrical design, so the names 1+4+1, 3+6+3, etc. are used. At this time, if Some people say that a 2+4 structure may be an asymmetric structure, and it must be confirmed.

2. The way of connection between multi-layer circuit boards

The circuit board builds the metal layer on an independent circuit layer, so the vertical connection between the layers is indispensable. In order to achieve the purpose of interlayer connection, it is necessary to use a drilling method to form a via and form a reliable conductor on the hole wall to complete the connection of power or signal. Since through-hole plating was proposed, almost all multilayer circuit boards have been produced using this method.

The increased-density multi-layer circuit board explores the build-up production mode, which is formed by forming small holes in the dielectric material by means of laser or photosensitive, and then conducting it by electroplating. Some manufacturers use conductive glue to fill the connecting holes to achieve conduction. The ALIVH, B2it, etc. developed in Japan fall into this category.

3. Application fields of multilayer circuit boards

PCB multi-layer circuit boards generally use plated through holes as the core, and the number of layers, board thickness, and hole position configuration vary with the line density. Most of the classification of its specifications is based on this. Rigid-flex boards are mostly used in military, aerospace and instrument equipment. Under the precondition that electronic products tend to be multi-functional and complex, the contact distance of integrated circuit components has been reduced, and the speed of signal transmission has been relatively increased. This is followed by an increase in the number of wiring and the length of wiring between points. The performance is shortened, and these require high-density circuit configuration and microvia technology to achieve the goal. Wiring and jumper are basically difficult to achieve for single- and double-sided circuit boards, so multi-layer circuit boards will become multilayered; and due to the continuous increase of signal lines, more power layers and ground layers become The necessary means of design, these have made multilayer printed circuit boards more common.