The workshop is revealed
It is quite possible that you never came across the term ‘SMT’ in your textbook. Don’t get disappointed. Two top executives of American Tec, Avishek Tyagi, regional manager-sales and marketing, and Pradyunma Salaria, deputy manager-SMT, reveal that the basic knowhow of electronics as well as other allied fields like electrical engineering and mechanical engineering is quite important. However, they specifically mention that it is no longer enough to know the fundamentals. The professionals are operating in a very cut-throat environment, so they should know not only how to survive but also compete.
N. Chandramohan, country head-SMT division, Juki India, opines that “proper training along with professional degree would be the turnkey for a fresher. This training should be totally industry-focused.” He feels that an effective collaboration between the industry and academia may be fruitful for both the parties. The existing industry-institute partnership models of some reputed foreign universities are ideal to follow.
From chip to ship
Undoubtedly, this training should be balanced enough to deal with both theoretical and practical aspects of SMT. Tyagi suggests that “a holistic training for the entry-level professionals in the field of SMT should cover the basic theory and application of SMT operation, process flow of SMT, soldering technique and solder pastes, basic principles of machineries used for SMT, software and hardware related to the SMT process, maintenance and quality control procedures and protocols in the SMT process and also storage, shipping and handling of SMT products.”
Besides the basics and applications of SMT, you need to know the basics of electronic circuit designing and also production technology.
Keep in mind that SMT is a whole new package responsible for improved integration of the circuit. That’s why the reliability of both chip-to-chip and chip-to-device interconnections is important. Basically, SMT reduces the package size resulting in greater functionality in the same board area. Mobile and handheld electronic items such as video cameras and cellphones are examples of low weight, high performance and also reduction in noise (primarily due to smaller electrical paths than leaded components) achieved with SMT. SMT is particularly useful for RF and microwave circuits where low noise contribution is mandatory. Moreover, it results in a higher operating speed due to shorter interconnect distances.
At first, today’s device requirements appear to oppose each other. SMT solves this problem in a different way. New types of components, new mounting and testing techniques and a new set of design guidelines are dedicated for this purpose.
SMCs: the building blocks
Proper training along with professional degree would be the turnkey for a fresher. This training should be totally industry focused. I feel an effective collaboration between the industry and academia may be fruitful for both the parties.
—N. Chandramohan, country head-SMT division, Juki India
You need to have a clear picture of surface-mount components (SMCs) as these are the building blocks. Functionally, they are no different from leaded ones.
SMCs are mounted on the surface of the PCB. The solder joints are all the more important as these impart both electrical and mechanical connections unlike the through-hole components where the component leads sit in the plated through holes which provide certain amount of mechanical strength when soldered.
You can identify SMCs with their unique identifiers which are a combination of their dimensions (width and length) expressed in inches; e.g., 1208 component means its dimensions are 0.12 (w)x 0.08 (l) inch2. Ceramic capacitors, tantalum capacitors and thick-film resistors form the core group of passive components.
There are two main categories of chip carriers: ceramic and plastic. The plastic chip carriers are primarily used in commercial applications. The ceramic packages are expensive and provide hermeticity. These are used primarily in military applications. Both the passive and active SMCs are much smaller in size than their through-hole analogues. Not only the size but also the shape of these components is modified according to the need of automated handling and better stability.
SMCs are most commonly available in flat rectangular shape. Another interesting point is the leadless format of passive components, whereas active components may have mountable lead or leadless terminals. To reduce the size of the circuits, these components often have reduced pitches.
The current trend is towards the usage of larger pin-count packages. Packages having more than 84 pins become impractical with 50mil lead centres due to larger package area and difficulties in manufacturing. To overcome the difficulties associated with larger pin-count packages, VLSI manufacturers have adopted 25mil centre. Often, this extreme size reduction reduces the mechanical strength. Thus, it becomes a designer’s challenge also.