COMPARISON OF PLASTIC AND HERMETIC RELIABILITY DATA

Industry data comparing hermetic and plastic microcircuits on standard reliability tests have generally shown PEMs to be equivalent to hermetic parts [15,16]. This is supported with regard to reliability data generated on commercial, non-burned-in devices for the following process technologies: CMOS Metal Gate (CD4000 Series), CMOS Silicon Gate (CD74HC/HCT Series), and Bipolar ICs. These technologies are assembled in 8 to 20 lead Dual-in-Line and Small Outline packages, incorporate mostly single level metal on approximately 60-150 mil2 die, and were chosen as vehicles for reliability comparison because they have a substantial amount of data on many identical device types in both hermetic (CERDIP) and plastic (PDIP and SO) over the same time frame (Jan. 1987 - Jul. 1994). The data by package type for the combined technologies are summarized in Tables 1 and 2 and Figures 1 - 3. It is shown that plastic and hermetic parts are basically comparable on these microcircuit families, relative to the overall FIT (failures in time) rates and DPM (defects per million) values exhibited on the tests shared by both.

Accelerated moisture test results for PEMs on the same product families are shown in Table 3. The DPM values for these types of moisture stresses, especially with regard to aluminum corrosion, do not indicate a basic moisture related issue. For obvious reasons, hermetic parts are not routinely subjected to these tests. However, it has been reported that hermetic CERDIPs can develop serious problems on 85/85 THB due to leaching of lead ions from the sealing glass [17].