An overview of electronic assembly technology development
Electronic assembly technology is constantly advancing along with the development of electronic SMT component packaging technology. What kind of device packaging is there, what kind of assembly technology will be produced. That is, the packaging form of electronic components determines the production assembly process.
Electronic assembly technology is divided into two categories according to the packaging form of components in the assembly process, namely, through-hole technology THT (Through Hole Technology) and SMT (Surface Mount Technology).
1. Origin of development
The advent of electronic tubes announced the birth of a new industry, which led mankind into a new stage of development. The rapid development of electronic assembly technology has thus begun, and the world has since entered the electronic age.
At the beginning, the electron tube was installed on the electron tube holder in the application, and the electron tube holder was installed on the metal base plate. During assembly, discrete leads were used to connect the device and the electron tube holder. By binding and wiring each connection line, ensure that the overall wiring is neat.
Among them, the high-voltage working requirements of the electronic tube make us pay more attention and consideration to the wiring of strong electricity and signals, as well as personal safety during production.
In 1947, Bell Laboratories in the United States invented the semiconductor point-contact transistor, thus creating the era of silicon civilization for mankind. The emergence of semiconductor devices and the application of low-voltage transistor devices have not only brought changes in people’s lifestyles, but also enabled humans to enter the fast track of high-tech development. Transistors with leads and metal shell packages, and miniaturized passive devices with leads have created the basis for us to integrate several related circuits onto a single board.
Therefore, single sided PCB and plane wiring technology came into being. The assembly process emphasizes the manual soldering of a single printed board, thus greatly reducing the volume of electronic products. With the continuous development of technology, in the later period, semi-automatic insertion technology and dip soldering assembly process appeared. Compared with the previous period, the production efficiency has improved a lot.
2. Development process
In the 1970s, with the small-scale plastic packaging of transistors, the application of integrated circuits and thick-film hybrid circuits, electronic devices appeared in dual-in-line metal, ceramic, plastic packages, DIP, and SOIC plastic packages, which made the volume of passive components further increase. Double layer PCB and multilayer PCB formed. The assembly technology has also been developed to fully automatic plug-in and wave soldering technology, and the lead connection of the circuit is simpler.
Since the 1980s, with the continuous development of microelectronics technology and the emergence of large-scale and ultra-large-scale integrated circuits, the integration of integrated circuits has become higher and higher, and computer-aided analysis design techniques have been used in circuit design. At this time, the packaging form of the device also follows the development of electronic assembly technology. In different periods, different packaging forms occupy the mainstream position.
For example, due to the advent of large-scale IC devices for microprocessors and memories in the 1980s, plastic surface-mount packages with peripheral leads and short pins that meet high-speed and high-density requirements occupy a dominant position.
In the 1990s, due to the development of ultra-large-scale and system-on-chip ICs, the development of peripheral pins to area array pins and ball grid array dense packaging was promoted, and it became mainstream. Passive devices have developed to surface mount components (SMC), and continue to develop towards miniaturization, and the packaging of IC devices has surface mount devices (SMD).
During this period, SMD has developed greatly, resulting in ball grid array(BGA) package, chip size package( CSP), high performance and low-cost FlipChip, Multi-ChipModel( MCM) and other packaging forms. The assembly technology is SMT and reflow soldering, wave soldering, and continues to develop towards the narrow pitch and ultra-narrow pitch SMT.
All of these lead to more advanced packaging technology, the ratio of chip area to package area is getting closer to 1, the frequency of use is higher, the temperature resistance is better, the number of pins is increased, the pin spacing is reduced, and the reliability is improved. It is currently in the popularization and application period of this technology.
With the continuous development of microelectronics technology, the performance of devices such as speed and delay time has put forward higher requirements for the interconnection between devices. Due to the increasing influence of interconnection signal delay, crosstalk noise, inductance-capacitance coupling, and electromagnetic radiation, functional circuits composed of high-density packaged ICs and other circuit components can no longer meet the requirements of high performance.
At present, electronic components are increasingly developing in the direction of chipping, miniaturization, compounding, modularization and built-in substrates. The packaging of ICs has changed from single-chip QFP and BGA to CSP, wafer-level (WLP) and system-in-package(SIP).
Passive components have evolved from the mounting of a single component on the surface to the integration of the same number of passive components (IPD), realizing the leap from 2D planar design to 3D three-dimensional space design, thus making the device package volume smaller. Product PCB design is simpler to meet the requirements of higher speed, higher density and lower cost.
3. Significance of development
With the continuous development of device packaging technology, our electronic assembly technology is also updated with each passing day. This kind of continuous change and development not only improves the performance and function of electronic products, realizes thin and light products, but also reduces the soldering in the application. The number of components greatly improves the reliability of electronic products and reduces the assembly cost in production.
Of course, new technologies require a series of new materials, new technologies, new processes and new equipment, such as new assembly processes and corresponding production equipment, testing processes and equipment, rework processes and equipment, wiring CAD/simulation programs, and so on. A new generation of assembly technology is coming to us, are you ready?