What is PCB Fusion Technology
2018-11-23 17:57Writer: qyadminReading:
Development at a rocketing speed of electronics industry lays increasingly higher demands to PCB (printed circuit board) fabrication industry including constantly rising board layers, increasingly high density of tracing and constantly thinner internal layers, all of which leads to increasing significance of layer stackup and lamination technology.
To stop quality issues from taking place during lamination process such as misplacement, fusion is usually called for before layer stackup during the process of multi-layer PCB manufacturing process. Compared with traditional fusion technology, modern fusion technology features advantages of high efficiency, easy operation and low cost, which leads it to be accessible for multi-layer PCB fabrication. Starting from fundamental technologies of fusion PCB fabrication, this article will discuss parameter factors affecting fusion effect and application level of fusion technology and provide a reliable reference with optimal fusion parameters obtained.
Principles of Fusion Technology
As a traditional technology, rivet technology has been widely applied in PCB board fabrication. Nevertheless, rivet technology features some disadvantages as well such as high cost of PCB board due to high cost of rivets, misplacement due to circuit board deformation, stencil's accessibility to damage, rivet-shape indentation on circuit board etc. As a result, fusion technology has been constantly used to replace rivet technology.
Depending on the melting property of epoxy resin prepreg, fusion technology works through getting prepreg melted under a certain temperature so that B-phase epoxy resin is converted into C-phase epoxy resin with internal layers connected through adhesives. Fusion is one of the most important processes during lamination and its performance directly determines behavior of lamination. Key elements concerning fusion technology include:
• Accuracy of Positioning System
The type of positioning system is directly associated with alignment accuracy between internal layers, which further influences percent of pass rate. Excellent positioning systems should be stable, reliable and well repeatable.
• Fusion Point Design
Fusion point is an essential issue as far as fusion technology is concerned with numerous shapes such as square, circle and oval. Fusion point should be agreeable in terms of area since fusion points with too small area tend to lead fusion welding that is not so solid while fusion points with too large area tend to lead image penetration that will possibly cause white spot, loose connection between internal layers or delamination.
• Flatness of Equipment
Equipment flatness influences PCB board angularity during fusion procedure, force distribution during fusion procedure and moment balance. Unevenness will lead circuit board to become deformed, which will further lead to misplacement between layers.
• Temperature and Time Control
In the process of fusion technology implementation, temperature and time should be carefully mastered and controlled to avoid burning, white spot, desoldering and aging. Furthermore, layer stackup of PCB board also plays a significant role in determining fusion effect