Advances in Monitoring of Stencil Printing

Dick Johnson
DEK International
Weymouth, UK

The electronics assembly industry has long wished for and made great advancements toward developing a true, closed-loop automatic print verification and process monitoring technology. While significant progress has been made, many hurdles remain to be overcome. Recent developments in on-board inspection technology, however, have pushed the "lights-out" printing concept even closer to becoming reality.

This paper will present data on a novel print verification technology that uses a series of sensors to capture the full board image, analyze the data and accept or reject the print - all in real time. The system compares the actual print to that of the PCB‟s Gerber data to assess accuracy and paste presence/absence, among other print components, and can be integrated with additional machine performance tools to make the printing platform even more intuitive. By enabling the print and inspection processes to run concurrently and deliver 100% verification at full line speed, production rates can be maintained and throughput is exponentially improved. The technology can have a profound impact on cost reduction, as faulty boards are isolated and removed from the line at the printing phase instead of traveling fully downstream to final assembly. Additionally, integrating such high-speed and powerful inspection technology onto the printing system eliminates the requirement for a dedicated, in-line SPI machine, and saves even more resource including training and floor space.

The inspection component of this next-generation technology can also be combined with verification and traceability tools to confirm all print inputs and outputs and trace materials, boards and processes to origination. This is a requirement for many high-value applications such as medical, defense and aerospace and has tremendous benefit for traditional EMS and OEM assembly operations as well.

Operators and developers of capital equipment such as stencil printing platforms have identified increased automation and closed-loop automatic print verification and process monitoring technology as the optimum path to realize ever-greater process performance, quality, repeatability and productivity. A number of innovative features have successfully eliminated many potential sources of error at setup and during the print process runtime.

But many of these features still work in isolation, and astute equipment specifiers and purchasers increasingly recognize the danger in systems that offer too many disparate tools being unmanageable by operators, negating their potential benefit to productivity. Now is the time to unify these systems by taking advantage of advances in user-interface design and enhanced inspection capabilities. The technologies now exist to create a concurrent and seamless environment that safeguards productivity all the way from product setup to high-speed, high-volume production of verified, known-good boards.