Jet singulation
Techniques for singulating a substrate into a plurality of component parts is disclosed. The singulation techniques include generating a jet stream in order to cut through large components so as to produce smaller components. The techniques are particularly suitable for singulating surface mount devices such as chip scale packages, ball grid arrays (BGA), flip chips, lead less packages (QFN) and the like. The techniques are also suitable for singulating photonic devices.
1. An optical concentration sensor for measuring a moving abrasive slurry associated with a singulation engine capable of cutting semiconductor substrates, the optical concentration sensor comprising:
an inlet coupling configured to receive a moving slurry delivered from a slurry source;
an outlet coupling configured to let out the moving slurry;
a housing that defines a slurry passage therein, the slurry passage being configured to distribute the moving slurry from the inlet coupling to the outlet coupling, the housing including one or more windows that provide optical access to the slurry passage, the windows being formed from a light passing material that substantially withstands the moving abrasive slurry and does not contribute to contamination of the moving abrasive slurry;
a light source configured to direct light into the slurry passage through the window, the light being configured to intersect the abrasive slurry moving through the slurry passage; and
one or more light detectors configured to detect light traveling out of the slurry passage through one or more windows, the light detectors producing signals in accordance with the light intensity of the light traveling out of the slurry passage through the one or more windows, the light intensity varying in accordance with the concentration of the moving abrasive slurry.
2. The optical concentration sensor as recited in claim 1 wherein the inner surface of the slurry passage is formed from a ceramic, carbide or stainless steel, and wherein the inner surface of the window is formed quartz.
3. The optical concentration sensor as recited in claim 1 wherein at least one of the detectors is configured to detect transmitted light emanating out of the moving abrasive slurry.
4. The optical concentration sensor as recited in claim 1 wherein at least one of the detectors is configured to detect scattered light emanating out of the moving abrasive slurry.
5. The optical concentration sensor as recited in claim 1 wherein one of the detectors is configured to detect transmitted light emanating out of the moving slurry and another detector is configured to detect scattered light emanating out of the moving slurry.
6. The optical concentration sensor as recited in claim 1 wherein the slurry passage is substantially cylindrical in shape with substantially straight walls.
7. The optical concentration sensor as recited in claim 1 wherein the light source and detectors are positioned in the same plane and are disposed at various points about the periphery of the housing.
8. The optical concentration sensor as recited in claim 7 wherein the light source and detectors are disposed radially about a longitudinal axis of the housing with each of these components being axially oriented such that their working centerlines point toward the longitudinal axis of the slurry passage.
9. The optical concentration sensor as recited in claim 1 wherein the optical concentration sensor includes a single light source and first and second light detectors, the single light source shining light at the moving abrasive slurry through the window, the first detector collecting transmitted light that passes through the moving abrasive slurry and the window, and the second light detector collecting scattered light that reflects off the particles in the moving abrasive slurry and through the window, the first light detector being placed directly across from the light source and the second light detector being angled such that the centerline traverses the centerline of the light source.
10. The optical concentration sensor as recited in claim 9 wherein the first light detector is placed at 180 degrees relative to the light source and the second light detector is placed 90 or 270 degrees relative to the light source.
11. The optical concentration sensor as recited in claim 9 wherein the first light detector produces voltages in accordance with the light intensity of the transmitted light and the second light detector produces voltages that vary in accordance with the intensity of the scattered light, and wherein the voltages for both detectors are monitored and subsequently translated into concentration.
12. The optical concentration sensor as recited in claim 1 wherein the light source is a light emitting diode and wherein the light detectors are photocells or photodiodes.
13. The optical concentration sensor as recited in claim 1 further comprising:
a control circuit, wherein the signals produced by the one of more light detectors control, via the control circuit, a ratio of abrasive and fluid in the moving slurry such that the moving slurry has a desirable abrasive-fluid ratio to cut semiconductor substrates.