SMTA International Conference Proceedings


Author: Kevin Chung
Company: AI Technology
Date Published: 9/12/1999   Conference: SMTA International

Abstract: Traditionally, there are three basic classes of electronic products that use cavity packaging: military based hermetic packages using solder or glass sealing, frequency sensitive communication devices, and optical devices use glass cavity to ensure proper transmission. This type of electronic packages represents less than 1% of electronic packages. Most of the other electronic packages will typically use epoxy molding compound, glob-top encapsulant, and other liquid encapsulation for mechanical and environmental protection.

The primarily reasons for the lack of usage of cavity packaging stems from cost considerations rather than performance considerations. In most applications, package reliability will be improved with non-hermetic cavity packaging rather than hard glob-top encapsulant protection. The technology and process of glob-top encapsulant while reasonably cost effective for large volume manufacturing, the product may post reliability concern for some devices with wide temperature excursion. Currently, a simple lid with adhesive pre-applied or dispensed and assembled in batch processing will normally cost as much as $0.20 to $0.40 each and thus be more costly than glob-top encapsulation which may be in the range of $0.05-0.20 per device, including material and overhead. A new process has been developed that allows in-line lid attaching much similar to that of surface mounting a component with a low cost technology of pre-applying a lid-sealing adhesive. Combining the lower cost of $0.03-0.10 for pre-application of adhesive preforms and the efficiency of in-line rather than batch processing, this new approach to cavity packaging may provide cost effectiveness to be competitive with that of glob-top and in some cases, even molding compound encapsulation if thermal performance is needed. System costs of implementing a lid attach cavity packaging may be as low as $0.10 per device for high volume. This new approach to lower cost cavity packaging may afford the wider use in more expensive devices.

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