Product category: Electronics Manufacturing Machinery and Materials
News Release from: DEK | Subject: Mass measurement inspection process
Edited by the Electronicstalk Editorial Team on 25 November 2002

Mass measurement is
front-line inspection process

A novel solder paste inspection system aims to provide paste inspection on 100% of every board with no programming requirements, negligible setup time and no impact on throughput

DEK has introduced a working prototype of a new solder paste inspection system to provide paste inspection on 100% of every board with no programming requirements, negligible setup time and no impact on throughput. Although the concept is still in development, DEK has successfully tested it in both live manufacturing and laboratory environments.

The mass measurement inspection process weighs a board before and after printing to determine if the correct amount of paste has been deposited.

Integrated into a DEK Infinity 2+2 with a high throughput conveyor, the prototype system high readability, laboratory-grade digital scales on both the input and output conveyors.

The data is fed through the Infinity's QC Calc SPC program where it is processed for viewing in conjunction with other real time SPC process data.

"A manufacturer has to have an in-control process to successfully implement this kind of inspection system", says Ricky Bennett, Applied Product Development Manager at DEK.

"Mass measurement inspection systems have been explored before, but earlier attempts failed because the data output didn't mean anything with the wide variances in the process.

With today's process control, the data feedback can provide useful information to the operator".

Mass measurement inspection can catch a wide range of printing defects, because almost every error results in either too much or too little solder paste on the board.

A misalignment error, for example, features a lack of gasketing between the board and stencil and results in excess solder paste bleeding onto the board.

This system is not meant as a replacement for localised inspection but as a monitoring system that can raise a flag if there is a deviation from the norm.

It cannot tell the user exactly what error has occurred and where on the board it is, but instead performs a quick check to see if any errors are present.

"Mass measurement can be an affordable 'traffic cop' for all boards.

If an error turns up, the operator can use conventional inspection techniques to investigate the cause", said Bennett.

As part of the product development, DEK partnered with a customer to use the system on a live production line.

The manufacturer used the mass measurement system and correlated with end of line defects.

The objective was to establish if mass measurement would be feasible in today's manufacturing environments.

"The results were encouraging and demonstrated that mass measurement did correlate with end of line defects", says Bennett.

In continuing laboratory tests, the DEK team used a state of the art 3D measurement system, set to 100% inspection, alongside the mass measurement system.

Process errors were induced onto boards to see how the system would react.

In every case, defects were flagged by the mass measurement system coinciding with the 3D data output.

Bennett says, "It's just not feasible for a manufacturer to use a vision system for 100% of every board, as we did in the test cycle.

The typical solution is to inspect sample areas, but inevitably that will let errors go through.

But the mass measurement system identified the same problem boards with no time loss compared to the eight minutes of full 3D inspection".

Development on the mass measurement inspection system is ongoing.

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