CONTAX HELPS MRP ELECTRONICS ELIMINATE MICRO-CRACKING

Contax Ltd - UK

10 January 2005

MRP Electronics Plc, one of the UK's leading contract electronics manufacturers specialising in surface mount PCB assembly has just purchased 3 McDry cabinets of varying sizes from production automation specialist, Contax Ltd.

MRP Electronics manufactures a wide range of PCB assemblies, many fitted with BGA and QFP devices, and required an effective storage medium to ensure integrity of the product at varying stages of manufacture. The small cabinet will be used for local storage, whilst the medium one will house SMD devices during production, with the largest unit used for permanent component storage.

Explained John Cardi, Production Engineering Manager at MRP Electronics, "The storage of moisture-sensitive devices is critical. When the BGAs are stored in an open enviroment they absorb moisture which can give unpredictable results during reflow. If they are stored in Moisture Barrier Bags (MBBs), once they are removed they have to be used quickly or rebagged.

"We have experienced some problems with 'popcorning' during reflow, where the soldered heat drives out any remaining moisture so the devices crack. This is obviously a waste of both components and test / rework capacity, so we needed to resolve the issue," he said.

The incidence of micro-cracking is widespread and has been highlighted in the standard for 'Handling, Packing, Shipping and Use of Moisture/Reflow Sensitive Surface Mount Devices', IPC/JEDEC J-STD-033a (July 2002).

It is estimated that virtually 100 percent of IC packages containing moisture experience a problem during the reflow process. This results in the corrosion of printed circuits and can cause wiring breakage and many other problems.

MRP Electronics decided that they needed to store the SMDs in a humidity controlled environment to ensure their integrity and prevent a 'use by' date. The Company looked at two leading manufacturers' offerings, and after full evaluation decided upon the McDry cabinets from Contax.

"Both systems were around the same price range, but the service from Contax was outstanding," said John Cardi. "The quote came back quickly, the sales manager was knowledgeable and helpful. From the initial response and service, we knew that Contax would be attentive to our needs and ensure a smooth installation."

He continued, "The McDry cabinets also met our spec exactly. They are available in a range of sizes - and we needed our dry cabinets to be compact and easy to use. They must maintain an RH level of 5 percent or below, and require minimal maintenance."

McDry cabinets are nitrogen-free, instead relying on a powerful zeolite desiccant which is self regenerating and therefore does not need replacing. This ensures that the units save both maintenance time and the associated costs. Furthermore, the cabinets vary in both size and humidity level, going as low as one percent humidity.

"All these factors ensured that we selected Contax as our supplier," continued John. "And we have definitely made the correct decision. The McDry cabinets are working well, and we have the confidence that we are building good devices. This has been borne out with the testing.

"The use of the cabinets has given even tighter control of our processes. We are currently placing in the region of 10,000 BGA devices per month and this figure is growing fast. We would not have been able to expand at this rate without the certainty that our devices are problem-free," he concluded.