Journal of SMT Article


Authors: Hiro Suganuma and Alvin Tamanaha
Company: Seika Machinery, Inc.
Date Published: 10/1/2003   Volume: 16-4

Seika Machinery, Inc.

Abstract: Moisture sensitive devices (MSDs) have become widely used with the increased sophistication of electronic products. However, MSDs present a number of challenges when used in surface mount assembly, as they may suffer internal damage during the manufacturing process if they are not handled and stored according to industry standards.

In surface mount assembly, solder paste is printed on to a PCB, components are mounted, and the entire board is sent through a reflow oven. In the reflow process the entire PCB and component packages are heated along with the solder and component leads. The high reflow temperatures can cause a package containing moisture to swell and crack affecting the performance and reliability of the component. These problems are normally the result of poor handling and storage of MSDs.

While many of the damaged components may be detected prior to shipment of the final product, many make it to the market place only to fail out in the field. Although a component with external cracking may pass pre-shipment functional tests, subsequent high temperature and moisture exposure can induce the transport of ionic contaminants through these openings to the die surface, increasing the potential for failure due to corrosion. Furthermore, internal cracking/delamination can be present even if there is no evidence of external cracks. Ball grid array (BGAs) and chip scale packages (CSPs) are especially sensitive to moisture, and damage to these components can be very difficult to detect.

Manufacturers must pay close attention to their handling and storage of MSDs to maximize yields and ensure the quality of their finished products.

Key words: Moisture sensitive devices, MSDs, moisture barrier bags, dry box.

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