Surface Mount Technology (SMT) is a vital catalyst to integrate a large number of electronic components onto the Printed Circuit Board (PCB). The need for high circuit density, reliability, improved performance as well as miniaturization of electronic components has driven the adoption of SMT in assembly lines. This trend will grow further by the increasing demand for higher frequency, highly integrated and smaller foot-print devices in the vertical markets such as Automobile, Consumer electronics, Industrial Automation and Process Control, Telecommunication, Internet of Things (IoT), Computing and Storage, Networking, Medical, and Aerospace & Defense. The technical advancements in SMT will be greatly focusing on precision in the process to reduce defects and optimized utilization of assembly operations to improve productivity. Adoption of faster change over time for flexibility, automation, reduced labor cost and smart factories could be a few areas where development could be expected.
Evolution of Surface Mount Technology
The first usage of surface mounted device is dated back to 1950 when the US military mounted flat packs on the surface of the board. However, cost factor limited the usage. In the subsequent two decades, the industry witnessed parallel developments in chip packaging techniques, usage of shorter leads and design improvements in the end caps across different verticals such as the U.S Military market, European Watch market, and Japan’s Telecommunication market. This progressively resulted in increasing reliability of the assembled device, higher space, and cost savings. These advantages of the SMT gained rapid and widespread adoption in the assembly lines from 1980’s. SMT does not require holes to be drilled on the PCB, unlike through-hole technology, to secure the components on the board. However, it is to be noted that, through-hole technology is not obsolete and is still used to integrate heavy components such as transformers and some classifications of power semiconductors.
Surface Mount Technology Process Flow
Brief Illustration of the process flow involved in the SMT is provided below
Trends in the Process Equipment
The technology is matured in terms of process methodologies. Hence, advancements in Processing Equipment will be a vital area to focus on developments in SMT. In this report, trends in Screen Printing, Placement, Soldering, and Inspection machine are discussed in association with demands from vertical markets.
1. SMT Screen Printing Equipment
The primary objective of screen printing machine is to dispense solder flux over the predefined locations, called solder pads, in the PCB. The Screen Printing technology evolved from Glue Dispense method to overcome production bottleneck. Screen printing technology gained wide adoption due to mass production capability and the control over dot size and profile. As it is unavoidable to use glue dispensing, today’s screen printing machine has additional facility to accommodate glue dispenser for use in two-sided PCBs. The recent introduction of Jet Printing technology based solder pasting process is gaining traction. The solder paste jet printing provides several advantages over screen printing, such as excellent printing accuracy, handling boards with various degrees of complexity, zero change over and control over the dot profile. However, the jet printing speed has to be improved to prove advantages in mass production. The Aerospace industry which has one of the complex requirements is a key driver for jet printing.
2. SMT Pick and Place Equipment
The Pick and Place equipment play a very important role in the SMT. The objective of the process is to mount the electronic components at predefined locations on the board. However, the increasing complexity and high volume of components to be mounted on the PCB pose a huge challenge to complete the operation in best possible time while maintaining placement accuracy. Key improvements observed are in feeder mechanism, software technology, and factory management systems which will aid in productivity improvement and defect reduction. High volume and low mix scenario from Automotive, Consumer electronics, Medical, Aerospace, and Defense sectors is likely to drive the medium speed segment. The trend could even shift to a new segment between medium and high-speed segment.
3. SMT Soldering Equipment:
It is the third step in the SMT, where the solder gets melted and flux will burn off, thereby establishing contact with the PCB. The Reflow soldering equipment are able to accurately solder small components and this segment will be driven by the miniaturization of components across portable and wearable consumer electronics market. Selective Soldering, a relatively new technology, is done on components that will be damaged by the heat of the traditional reflow soldering. The Selective Soldering segment faces a challenge to meet productivity demands. Hence, there is a need for high investments in the nozzle design and multiple nozzle usage techniques to cater for high volume manufacturing. Overall, the SMT soldering equipment market is set to be driven by increase in outsourcing.
4. SMT Inspection Equipment
Inspection equipment are used to find defects in the bare board, screen print, pre and post reflow soldering. The Automated Optical Inspection (AOI) segment is witnessing innovations such as 3D AOI technology which is able to detect the flatness of contacts with the board. However, this technology is still at a nascent stage. The Solder Paste Inspection (SPI) market will witness higher adoption rates due to the increasing miniaturization of components in key vertical markets such as A&D, Medical, and Industrial applications where reliability is a critical factor. The X-ray Inspection Segment (AXI and MXI) will be driven by higher adoption of stringent Quality Assurance standards imposed by the OEMs in key vertical markets such as Automobile and Consumer electronic devices.
Summary
The necessity to meet a high degree of performance in electronic devices, combined with the increasing production demands and higher quality assurance standards from the growing vertical markets such as Automotive, Consumer electronics, Medical, and so forth will drive higher adoption rates and technological enhancements in the SMT.
