H83297 Datasheet, PDF (281/393 Pages) Renesas Technology Corp – Single-Chip Microcomputer

14.4 Handling of Windowed Packages
(1) Grass Erasing Window: Rubbing the glass erasing window of a windowed package with a
plastic material or touching it with an electrically charged object can create a static charge on the
window surface which may cause the chip to malfunction.
If the erasing window becomes charged, the charge can be neutralized by a short exposure to
ultraviolet light. This returns the chip to its normal condition, but it also reduces the charge stored in
the floating gates of the PROM, so it is recommended that the chip be reprogrammed afterward.
Accumulation of static charge on the window surface can be prevented by the following
precautions:
1. When handling the package, ground yourself. Don't wear gloves. Avoid other possible sources
of static charge.
2. Avoid friction between the glass window and plastic or other materials that tend to accumulate
static charge.
3. Be careful when using cooling sprays, since they may have a slight icon content.
4. Cover the window with an ultraviolet-shield label, preferably a label including a conductive
material. Besides protecting the PROM contents from ultraviolet light, the label protects the
chip by distributing static charge uniformly.
(2) Handling after Programming: Fluorescent light and sunlight contain small amounts of
ultraviolet, so prolonged exposure to these types of light can cause programmed data to invert. In
addition, exposure to any type of intense light can induce photoelectric effects that may lead to chip
malfunction. It is recommended that after programming the chip, you cover the erasing window
with a light-proof label (such as an ultraviolet-shield label).
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