To maintain continuous improvement of its manufacturing processes, SB Electronics (sbelectronics.com), a designer and manufacturer of film capacitor technology, reports that it has specified Pressurex, a tactile surface pressure-indicating film from Sensor Products Inc. (www.sensorprod.com).
According to Sensor, the Pressurex film has a range of uses in multi-layer printed circuit board assembly, including analyzing contact uniformity and verifying flatness (planarity) between semiconductor wafers and bonding heads. Further, the company says the film can reveal such problems as overloading of connector contacts, standoffs, and component solder joints. Industrial applications also include assessing surface contact inconsistencies in clamps, connectors, heat sinks and heat-sealing elements.
The film is available in seven different ranges that measure pressure from 2 to 43,000 PSI, and allows for rapid determination of compression magnitude and distribution. According to Sensor, when placed between two contacting or mating surfaces, the film instantly and permanently changes to different shades of red, with the color change proportional to the actual pressure applied. Precise pressure magnitude is determined by comparing the resultant color intensity to a color correlation chart (conceptually similar to interpreting Litmus paper, notes the company).
SB Electronics says that many of its radial lead products are designed to take up the minimum amount of space on printed circuit boards; this is achieved by flattening the round capacitor profile in a pressing operation between aluminum plates.
“After histograms indicated that some of our tighter tolerance parts (±1% capacitance) were going out of spec, and making some initial dimensional measurements, I needed to visually determine the tactile surface pressure,” explains David Bryan, manufacturing engineering manager for SB Electronics.
Bryan reports that he inserted Sensor’s Pressurex film in “super low” pressure range of 70 to 350 PSI between the press plates during a product run. The film let him observe the uneven distribution of pressure between the capacitors; as a result, Bryan says he was able to prove that the press plates weren’t flat, and were causing uneven pressure distribution.
Bryan notes that while he continues to use such standard tools as gauges and calipers, he’s asking that Pressurex be included as an ongoing ISO quality control protocol. He’s also used the film to evaluate bolted flange designs for custom fittings in vacuum systems.
