This factory area covers the
inspection, testing, sorting and binning of LED
die according to their quality and electro-optical
performance values. From each processed wafer
a distribution of die is achieved. UNIROYAL,
as company policy, championed the development
of a unique set of capabilities that it presents
to our customers as: Package Ready Known Good
are current-driven, not voltage-driven, semiconductors.
Drive current and light output are directly related.
UNIROYAL, for its characterization testing of
LED die, conducts these tests at the industries'
standard 20 mA DC drive condition.
UNIROYAL has developed extensive
automated test and characterization tools that
are used to define LED performance from Whole
Patterned Wafers through to specified tested and
binned die on tape.
The levels of product currently offered are:
Whole Undiced Wafers (Thinned
or Unthinned) that are Sample Tested (shipped
in pucks); Diced Wafers of Die that are either
Sample Tested or 100% Tested (with ASCII Data
File provided) (presented and shipped on tape/expander
rings); and die that are 100% Tested and Sorted
according to defined parameters: Known Good Die
LEDProbe™ Wafer Testing: Individual wafers (undiced
and/or diced) are loaded via vacuum tip and positioning
mechanisms onto a vacuum chuck. Once loaded the
LEDProbe positions the probe head to encompass
multiple die at a time. The LEDProbe is also equipped
with an individual die “Capture Mask ”, that automatically
sequences through the captured die, recording
electro-optic values for each die in a computer
Test Data File. “Sample ” testing tests selected
(North, East, South, West and centralized) die
sites scattered throughout the wafer. All values
are recorded, a wafer map stored, and a yield
value is determined by formula based upon the
data obtained and an algorithm determined by the
product description which is preprogrammed.
The LEDProbe can also be used to test 100% of
the die sites on each wafer. Data from this method
is captured and shipped with each individually
tested wafer in the form of an ASCII diskette.
Customers using this test level option use the
ASCII file to program their LED die pick and place
equipment with the supplied test data file and
“sort” at the time of packaging.
UNIROYAL LEDSort™ Die Testing: Bare die are picked
by a specialized collet and “read” platform system
containing an integrated photonic receiver and
electrode probe(s) and/or plate. After the die
is “picked” and in transition to be “placed”,
the LEDSort tests the LED die, and then after
test places it based upon its’ individually read
performance criteria, onto its’ applicable “bin”
blue-film tape. Optical measurements are conducted
by a ulti-wavelength spectrometer that measures
brightness and chromaticity.
Electricals are conducted by a Multimeter. “Transfer”of
the die is completed through preprogrammed recognition
software contained within that directs the placement
of die to a defined classification “rank” adhesive
coated blue-film square. Up to seven (7) film
squares/“ranks” can be accommodated at one time.
Multiple wafers are used to populate each film
square with a die count of from 8 to 10K per tape.
Wafer differentiation is provided in the form
of a die “space” row purposely left blank, before
the next wafer’s die is placed. Output from the
UNIROYAL LEDSort provides customers with fully
binned Known Good Die (KGD).
Visual Inspection: Visual inspection is currently
conducted manually under 20X magnification. Individual
die are inspected for damage, defects and contamination
as defined by the UNIROYAL Product Specification
defect identification appendix. This process removes
all defective die prior to shipment.