Optoelectronic modules including an optical emitter and optical receiver
An apparatus includes an optoelectronic module including a light emitting die and a light receiver die mounted on a PCB substrate. The optoelectronic module further includes an optical element on the light emitting die and an optical element on the light receiver die, the optical elements being composed of a first epoxy. A second epoxy laterally surrounds and is in contact with respective side surfaces of the light emitting die, the light receiver die and the optical elements, wherein the second epoxy provides an optical barrier between the light emitting die and the light receiver die. A method of manufacturing such modules is described as well.
1. A method comprising:
replicating optical elements onto respective surfaces of a plurality of light emitting dies operable to emit light having a wavelength and onto respective surfaces of a plurality of light receiver dies operable to detect light having the wavelength, wherein the optical elements are composed of a first epoxy, and wherein the plurality of light emitting dies and the plurality of light receiver dies are mounted on a PCB wafer attached by a double-sided adhesive tape to a support glass;
injecting a second epoxy using a vacuum injection molding technique, wherein the second epoxy is substantially opaque to light having the wavelength, and wherein the second epoxy is injected such that it laterally surrounds and is in contact with respective side surfaces of each of the plurality of light emitting dies, each of the plurality of light receiver dies and each of the optical elements;
forming respective trenches in the second epoxy in regions separating duplex pairs of the light emitting dies and the light receiver dies from one another, wherein each duplex pair includes one of the light emitting dies and one of the light receiver dies, and wherein the trenches partially extend into the PCB wafer, and forming additional trenches that extend through the second epoxy and through the PCB wafer, wherein the additional trenches are formed prior to detaching the double-sided adhesive tape and the support glass from the PCB wafer;
detaching the double-sided adhesive tape and the support glass from the PCB wafer;
separating the PCB wafer at locations of the trenches to form singulated modules each of which includes at least one of the light emitting dies and at least one of the light receiver dies; and
applying an IR coating over at least an exposed surface of one or more of the singulated modules, wherein the IR coating serves as an optical filter to allow only radiation in the IR part of the electromagnetic spectrum to pass.
2. The method of claim 1 wherein prior to replicating the optical elements and injecting the second epoxy material, a first side of the PCB wafer is attached to a first tape, the first side being opposite that of a second side of the PCB wafer on which the light emitting dies and the light receiver dies are mounted, the method including:
using a vacuum chuck to hold the PCB wafer, wherein the vacuum chuck is in contact with the second side of the PCB wafer;
subsequently removing the first tape from the PCB wafer;
subsequently bringing the first side of the PCB wafer into contact with the double-sided adhesive tape that is attached to the support glass; and
subsequently releasing the PCB wafer from the vacuum chuck.
3. The method of claim 1 wherein replicating the optical elements includes: dispensing the first epoxy selectively onto structured regions of an elastomeric layer; and subsequently pressing the first epoxy onto the light emitting dies and the light receiver dies.
4. The method of claim 1 wherein the optical elements are grid array optical elements.
5. The method of claim 1 wherein the second epoxy is a black epoxy.
6. The method of claim 1 wherein the double-sided adhesive tape is a heat-releasable double-sided adhesive tape.
7. The method of claim 6 further including:
attaching a carrier at an outer surface of the second epoxy after forming the trenches in the second epoxy; and
applying heat to remove the double-sided adhesive tape and the support glass from the PCB wafer.
8. The method of claim 1 including:
attaching the singulated modules to a heat resistant tape;
subsequently applying the IR coating to exposed surfaces of the singulated modules; and
removing the singulated modules from the heat resistance tape.
9. The method of claim 1 wherein applying the IR coating includes spraying the IR coating.
10. The method of claim 1 wherein the IR coating is applied to top and side surfaces of the singulated modules.
11. The method of claim 1 wherein the IR coating serves as an optical filter to allow only radiation in an IR part of the electromagnetic spectrum to pass.