PCB News - The evolution of SMT heterogeneous elements

The old adage, "Time is money", is even more fulfilled in today's smt technologically advanced society. Especially in the electronics industry, the product-to-market cycle of computers, disk drives and portable computer products has been shortened from a few years to 12 months or less. The emergence of faster, better, and cheaper products is evolving at a rapid pace. Original equipment manufacturers (OEMs, original equipment manufacturers) and contract electronics manufacturers (CEMs, contract electronics manufacturers) who want to remain competitive in the global market must automate as much as possible to increase output, quality, and production efficiency. The manual processes on the production line must be carefully reviewed to determine how to automate or optimize these processes.

The reality of special-shaped components and their continued existence

Odd-form assembly is a manual process with low efficiency, which can also be found on production lines around the world. It is the placement of components that may have unusual shapes; requires special processing; the number on the board is small; or there are other problems that do not allow it to be automated through a sophisticated placement system. Usually, these special-shaped components are assembled by hand. Due to diversified characteristics and no adjustable stabilization methods, special-shaped assembly is usually considered as a post-automation problem. However, profiled automation is becoming a growing reality for industry leaders, who recognize that this is an unnecessary roadblock to the optimization of complete production lines.

Odd form by default

Contrary to the original idea, the through-hole technology has not completely disappeared. In fact, the advancement of surface mount component technology has permeated the use of more and more through-hole components and special-shaped components. As yesterday's standard components are replaced by smaller and more advanced packages such as flip chip and ball grid array (BGA), the remaining standard components have become special-shaped components. For example, both DIP (dual inline package) components and DIP equipment were once standard in PCB assembly. However, due to the limitations of its use on PCBs, DIP is a common type of component, so it is impossible to purchase equipment that only contains this type of component.

Other form factors that were previously considered standard components have been replaced by smaller and faster component packaging. Examples include connectors, resistors, and capacitors. Although reduced, the use of such components will not disappear because of its reliability, integrity, cost and practicality, and will not require small or advanced packaging components. In addition, many through-hole components are easier to purchase and have shorter lead times than surface mount components. For all these reasons, the industry seems to realize that it makes good business sense to use through-hole components as much as possible, and to treat the profile as an integral part of the future assembly process.

Odd form by design

Other factors that continue to exist in the assembly of special-shaped components are the special-shaped components considered in the design. These components are usually regarded as special-shaped because they are equivalent to other surface mount or through-hole components on the PCB, their size and special processing requirements. Examples of these design-specific shaped components include transformers, LEDs, displays, relays, headers, SIMMs, DIMMs, and power connectors. The value that this type of component provides for the product is that more advanced and higher packaging prices cannot be satisfied, and higher durability can be achieved. For example, in the cost-intensive automotive industry, electronic engine control modules are required to withstand an environment that is difficult to tolerate. Frequent exposure to extremely high temperatures and vibrations requires stable and reliable assembly technology at a reasonable price. Some similar examples can be found in telecommunications, computer electronics, and consumer electronics. In these applications, cost and reliability are the difference between success and failure.

Today's heterogeneous automation

Until now, the existing special-shaped components have made it more difficult to adopt automation equipment because of the small amount of placement/plug-in. In addition, the problem with odd form by design is that there is not enough flexible equipment to handle these highly mixed odd-shaped components. Nevertheless, with the existing special-shaped electronic assembly technology, automation is both reasonable and available. In most cases, equipment manufacturers provide sufficient flexibility to handle highly mixed and high-volume heterogeneous components on a single platform. Using today's technology, special-shaped through-hole and surface mount components can be mounted with a single system, by providing advanced feeding, positioning, grasping and clamping technology .

The current feeding technology includes reliable tape, tube, coil and bulk material feeding methods. This mixing of different products has made it possible to automate almost all special-shaped components. Each feeding method has its advantages and disadvantages, depending on its application, but all provide a more reliable, flexible and faster method for manual substitution. Also, as the industry standardizes component packaging and feeding methods, feeding technology will improve.

Current locating technology includes three-dimensional (3-D) compliance and vision. 3-D compliance technology allows components to be reliably positioned on the feeder, eliminating unnecessary visual requirements. The vision solution is suitable for special-shaped and surface mount applications. The more precise spacing of the pins and the changing packaging design require reliable positioning and placement.

The current grapping technology allows almost all special-shaped through holes and surface mount components to be processed in any mix and sequence without the need to change tools. The existing technology can be grasped through the component body or pins, which is effective when processing DIP. Today's gripping technology ranges from precision tools, which handle only a few component types, to flexible 3-D compliant tools, which can handle multiple component types. Cycle time and mixing/volume requirements usually determine which technology is suitable for a certain application. More sophisticated tools provide better benefits for lower-mix, higher-volume applications, while more flexible 3-D compliant tools produce better benefits for medium and high-mix, medium-volume applications.

The current clinching technology is flexible. High-speed, programmable, single-thimble clamping technology allows any number of pins to be clamped in any direction (0~360°) and angle. Large pins (steel pins up to 0.062") can now be clamped, and the special clamping program used to determine the manual process can now be handled more reliably and faster with today's clamping technology.

The result of these special-shaped technological advances is that the work previously done manually offline (off-line) can be completed more effectively in-line through a fully automatic or semi-automatic special-shaped placement system.

From manual to automation: ideal heterogeneous situation

There are some applications that exist in the automated special-shaped assembly process that will provide more beneficial and productive results on the production line than the manual assembly process. Some of these applications include:

Components requiring pin-in-paste process
Components that are difficult to handle manually due to their size and shape, such as LEDs, triacs, small axial components, and pin headers
Components that require users to cut and shape, such as TO-220
Non-standard surface mount components with dense feet
Components with polarity issues
Components that require clamping (that is, bent feet after the plug-in), such as components with heavier heads
Manual assembly of high-volume components that cannot maintain the rhythm and speed of the production line
Large pin components requiring clamping
Components that require specialized clamping programs
Once the automatic special-shaped equipment has been purchased, the production line balancing is the next step. Usually, the special-shaped placement system is installed near the end of the production line-after the top surface mount component system or special radial or axial plug-in machine, before the wave soldering process. Because most through-hole components can only be processed in a wave soldering furnace rather than a reflow soldering furnace, this layout helps to mix the components with the appropriate soldering process. Until all through-hole components can withstand the reflow soldering environment and wave soldering is not necessary, the layout of this production line will continue to partly depend on the supply of the required soldering process.

Is it economically cost-effective for profiled automation?

The return on investment (ROI, return on investment) of the fully automated assembly system can be realized within 12 to 18 months, and the standard for similar, high reuse fixed equipment is 3 to 5 years. Semi-automatic methods, with relatively little fixed asset costs, may provide even faster returns.

In addition, if you consider the loss of income due to poor quality output usually produced by manual special-shaped assembly, then automation may be more reasonable. If you calculate the additional costs of scrap, waste, rework, repair, re-inspection of returned goods, shipping and repackaging, claim settlement, replacement, and reputation, then manual special-shaped assembly may be too costly.

in conclusion

Special-shaped assembly is not necessarily a manual process. For those factories that have begun to automate the manual processes that have been retained on their production lines, the result shows that the investment is more reasonable. Some industry leaders get a lot of annual savings in rework alone, and single-line defects are reduced by 75%. With such benefits and the existence of automatic and semi-automatic assembly systems, automating the existing manual special-shaped processes on the production line is of good business significance.

The above is an introduction to the evolution of SMT special-shaped components. Ipcb also provides PCB manufacturers and PCB manufacturing technology.