Known good die

Previous microreactor packing schemes developed at both MIT and DuPont could not be used since the electrical and fluidic interfaces required significant effort to implement. The microreactor packaging problem was eventually solved by using the DieMate Known Good Die (KGD) socket manufactured by Texas Instruments (Texas Instruments Incorporated, 34 Forest Street, P.O. Box 2964, Attleboro, MA). 

Figure 12.1 shows photographs of the Texas Instruments DieMate Known Good Die socket used for the final microreactor packaging scheme. The particular DieMate socket chosen for the microreactor scale-up system was the 110-pin version (Texas Instruments, Dallas, TX, P/N GBGllO 004 K) since this could accommodate the required sensors. 

Fig. 12.1 Texas Instruments DieMate Known Good Die socket used for microreactor packaging in the scale-up system.

In general, there are four levels of bare die test and burn-in, referred to as four levels of known good die (KGD). In Table 8.10, these test levels are summarized, along with their impact. The lowest KGD level is to just use the same tests normally done at wafer level, referred to as the wafer sort tests. Here the chips are normally subject to a low-speed functional test combined with some parametric measurements (e.g., measurement of transistor curves). With this KGD level, test costs for bare die are limited to wafer test costs only. There is some risk, however, that the chip will not work when tested as part of the MCM. This risk is measured as the test escape rate. With conventional packaging, the chips are tested again, perhaps at full speed, once they are packaged, making the test escape rate zero. 

Some applications require even higher levels of known good die. Aerospace applications usually demand burn-in of the die, particularly for memories, so as to reduce the chance of infant mortality There are two levels of burned-in KGD. In the lowest level, the die are stressed at high temperatures for a period of time and then tested. In the higher level, the die are continuously tested while in the oven. 

TABLE 8.10 Levels of Known Good Die and Their Impact... 

Known Good Die Level Test Cost Impact Test Escape Impact... 

Known good die (KGD) Bare silicon chips (die) tested to some known level. 

When mounting unpackaged chips on these interconnecting substrates, it is not always possible to ascertain that only properly operating chips have been assembled. By now, there are a number of methods proposed to solve this known good die (KGD) problem. 

One of the issues in the application of MCP technology is the availability of known good die. Clearly considering that, for most dies, the package die test yield after wafer test runs... 

Ingestion of commercial preparations that contain digestion-resistant starches and bacteria (e.g. homolactic lactobacilli) increases volatile fatty acid formation in the colon. This provides more fuel for colonocytes it is claimed regular intake of these preparations improves intestinal function and hence mood, known sometimes as die feel good factor. 

Certain thiazoles, isothiazoles and benzisothiazoles have been directly oxidized to sulfoxides and sulfones. 4,5-Diphenyl-1,2,3-thiadiazole is converted by peracid into die trioxide (190). Although 1,2,5-thiadiazole 1,1-dioxides are known, they cannot be prepared in good yield by direct oxidation,... 

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