The future development trend of SMT surface technology
Since its inception in the mid-1960s, SMT has become the mainstream of today’s electronic manufacturing technology after more than 40 years of development, and it is continuing to develop in depth. Its development trend is mainly manifested in the following aspects:
1. Green production
With the gradual implementation of the “Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment” (RoHS Directive) globally, the SMT process is also rapidly developing in the direction of lead-free. Lead-free solder, anisotropic conductive adhesive film and solder resin conductive materials have all been put into practical use. At the same time, in order to achieve true lead-free, the corresponding process materials, components, production equipment, testing methods and equipment are constantly improving and have entered the practical stage.
2. The development of components
With the advancement of component R&D technology, components are moving in the direction of smaller size and higher integration. The packaging form of components is also moving towards smaller size, lighter weight, and higher operating frequency with the requirements of assembled products. Development in the direction of high, stronger anti-interference and higher reliability. The modularization of SMC is the future development direction of components. As the size of components is increasingly facing the limit, and the accuracy of automatic production equipment is also approaching the limit, the compounding and modularization of chip components will be rapidly developed and widely used. At present, the British system 0603, 0402 and 0201 are widely used on PCB, but 01005 is close to the limit size of equipment and technology, so 01005 is only suitable for module assembly technology and high-performance mobile phones.
The development of integrated circuit packaging technology is also very rapid, from DIP (dual in-line packaging) to SMD, and SMD is rapidly developing to small, thin and fine pitch; the lead pitch has changed from the past 1.27 mm J mm, 0.86 mm , 0.65 mm developed to the current 0.5 mm, 0.4 mm, 0.3 mm; the pin arrangement developed from the peripheral pins to the ball grid array pins at the bottom of the device. In recent years, it has developed to two-dimensional and three-dimensional, with the emergence of MCM (multi-chip component) and POP (package on package); finally, it will develop to SOP (small outline package).
With the maturity of SMT technology, especially the successful development of low thermal expansion coefficient PCBs and special solder and filler materials, the technology of direct mounting of bare chips on PCBs has developed rapidly. At present, bare chip technologies mainly include COB (chip on board) Technology and FC (flip chip) technology, which will become the mainstream of the development of chip applications in the 21st century.
3. Development of production equipment and technology
In order to adapt to the placement of new components, the placement accuracy of production equipment is getting higher and higher, and the technology that can mount ultra-fine pitch components is becoming more and more mature (such as 0201 chip components and pin spacing of 0. 3 mm的Integrated circuit, etc.), manufacturing process technology continues to improve, through-hole reflow soldering process and selective wave soldering process are more and more widely used, and the circuit board is also developing from hybrid PCB to SMB (Surface Mount Printed Board). In short, with the development of miniaturization and high-density packaging, and with the continuous emergence of new components, some new technologies and new processes have also emerged, which greatly promotes the improvement, innovation and development of surface assembly technology, and makes it more Development in an advanced and more reliable direction.