A random sample was conducted by selecting 3 packages of different types, with varying date codes of devices available for testing. The 3 package types were a 28-lead plastic leaded chip carrier (PLCC), a 14-lead thin shrink small-outline package (TSSOP), and an 8-pad very thin small-outline non-leaded package (VSON).

Laser decapsulation was performed on the selected devices to expose the die and examine for defects. No corrosion, cratering, or bond pad cracking was found. Rochester partnered with industry experts for the design, manufacture, and use of printed circuit boards to mount various surface-mount devices of differing package types and date codes. All devices successfully completed reflow at the independent PCB assembler. Rochester verified these results via optical and X-ray inspection of solder joints, cross-sectioning along the length of soldered leads, and SEM imaging of cross-sectioned solder joints.

Fifty-seven plastic surface-mount devices of 12 different outlines, packaged as early as 2006, were mounted on both sides of each PCB. All pads were inspected, and no failures were found, confirming successful PCB assembly.

To gain further insight into otherwise obscured solder fillets, PCB assemblies were imaged by X-ray at an oblique view. Imaging of the VSON package didn’t provide any additional detail, due to the length scale and density of solder coverage.

Additionally, SEM images were captured after cross-sectioning through leads, revealing the precise profile and internal structure of solder fillets. Internal structures of solder fillets were found to be robust, matching external inspections and further validating successful PCB assembly.

The same imaging techniques were also used to validate the integrity of encapsulated materials and inspect internal device features for defects. No defects were observed.

All devices were laser decapsulated and finished with a short acid etch. No damage consistent with environmental stresses or proposed mechanisms of degradation after long-term storage was observed. All devices were found to be free of cracking, delamination, and bond wire defects.

Three products of 2 different date codes were tested to their respective datasheet requirements. The tested devices span nearly 15 years. Twenty 9513APC devices, 25 27S21PC devices, and 50 UC3835N devices of each date code were tested. All devices met their respective datasheet specification limits and exhibited no significant or consistent shifts in data distributions across date codes.

The data presented indicates that devices maintain internal and external integrity, including robust soldering to printed circuit boards, beyond a decade of storage. Devices exhibited no evidence of corrosion, cracks, or delamination. The tested devices passed all applicable functional and timing tests.

Rochester’s diligent research has shown that long-term storage doesn’t necessarily result in product degradation. In fact, components can still be functionally assembled and are electrically viable for many years. Storage presents a viable solution for long-lifecycle applications.

Read these white papers to learn more:

Rochester Electronics Technical White Paper: "Effects of Long-Term Storage on Mechanical Integrity and Electrical Performance”

Rochester Electronics Technical White Paper: “The Effects of Long-Term Storage on Solderability of Semiconductor Components”

Texas Instruments Technical White Paper: “Long Term Storage Evaluation of Semiconductor Devices”

Texas Instruments Technical White Paper: “Component Reliability After Long Term Storage”