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Technical Paper

Flexibility in SMT Pick and Place Assembly

The meaning of the commonly used term 'flexible production' is open to interpretation.

By Joerg Widmer

Flexible production is key in meeting the challenges of SMT Pick and Place assembly. The full meaning and implications of flexible production, new product introduction (NPI) and its impact on manufacturing must be understood and specifically defined.

The market for big production lots is diminishing, with the remaining market for smaller lots requiring more flexibility in choice and use of pick and place machines. The current state of the industry is lower volumes and higher product mixes. The ability to change over rapidly in product lots is important, but if the process itself is inefficient, it will not be cost-efficient. Efficiency makes the difference in turning a profit, so "flexibility" means more than physical quickness when it comes to small production lots and fast product changeover.

On a production line, solder paste ideally would no longer be put in the printer, and feeders would not be set up for the pick-and-place machines. Additionally, AOI programming would not be necessary. The aim of the electronics assembly industry remains total automation.

Questions to ask include: Is the SMT Pick and Place line running right now, or is it down? If it is down, why? How many people are working on that line? Is the automation level high, or is there room for improvement? Often, the result will be a search for and evaluation of newer, more efficient machinery.

Taking a closer look at a typical SMT pick-and-place machine, most suppliers are offering chipshooters and fine-pitch placers to sell the capability of placing the widest range of components. In terms of flexibility, an even work-balance between those two modules rarely can be achieved because one of the two modules will always finish earlier than the other. The resulting machine downtime will require the requisite balancing efforts by the machine operator.

The next question involves board handling. Is someone carrying the printed circuit boards (PCB) between the printer, the SMT pick-and-place machine, and the reflow oven? These steps can be automated through PCB handling and conveyor systems. Implementation of automation might result in short-term reduction of jobs, but longer term, it probably would create new ones.

If a higher degree of automation already has been achieved, fine-tuning might be considered the next step. Questions include:

Is the line loaded automatically through a bare board loader?
Is the screen printer equipped with an automatic cleaning tool and 2-D inspection?
Is the pick-and-place machine running without downtime? If so, can the feeders be configured for two different jobs? Are smart, inexpensive feeders being used?
Is the reflow oven easy to clean and equipped with exchangeable filters?
Is the line self-unloading, or are the boards unloaded manually?

All of these issues can be resolved relatively easily with "smart" equipment.

Few manufacturing floor managers tend to push automation to a higher level due to the misperception that the necessary investment will be too high. But return on investment (ROI) can be calculated when the decreased cost in personnel is brought into consideration.

The automotive manufacturing industry is well ahead of electronics assembly in the degree of factory automation; yet some facilities are operating with fully automated job preparation, linked to fully automated stock floors where robots get parts and bring them to the manufacturing floor. The entire assembly line is running automatically with automated product change, automated width adjustment and automated feeding of the line through magazine management.

This is truly flexible production, not mass production. Lot size one is an absolute reality and can be achieved within the context of flexible manufacturing.

Increased levels of automation often are difficult to realize in a mid-sized or larger company, when management does not understand the impact of such a move. Only numbers can prove what ROI would be and the benefits of such a step. The calculation must be done by looking at the mid-term benefits, including reduction of salaries, increased quality and enhanced process stability. Other important factors could include tracability and feasibility when looking to new, more efficient solutions for SMT pick and place.

Conclusion
Greater efficiency and a higher level of automation enhance a manufacturer's overall flexibility to deal with changing products and economic and market variations. True flexibility is achieved through greater cost efficiency, higher profitability and increased competitiveness, ultimately adding jobs and growth.

Joerg Widmer is Sales Manager at Mimot, North America and may be contacted at MIMOT, 16 Technology Drive, Suite 133, Irvine, CA 92618; (949) 727-4600, E-mail: jwidmer@mimot.com;

Paper first published in Surface Mount Technology (SMT) December, 2003
Author(s) : Joerg Widmer