Optoelectronic module with optical transmitter and optical receiver

Abstract

A device includes an optoelectronic module comprising a light emitting die and a light receiver die mounted on a PCB substrate. The optoelectronic module also 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 resin. A second epoxy resin laterally surrounds and contacts respective side surfaces of the light emitting die, the light receiver die, and the optical elements, wherein the second epoxy resin provides an optical barrier between the light emitting die and the light receiver die. Methods for manufacturing these modules are also described.

Description

Technical Field

[0001] The present invention relates to an optoelectronic module comprising a light transmitter and a light receiver. Background Art

[0002] Various consumer electronics and other host devices include compact optoelectronic modules with integrated light-sensing or light-emitting devices. In some cases, space is at a premium within the host device. Therefore, it is desirable to make the modules as small and compact as possible. Furthermore, for modules that include both light-emitting and light-detecting components, providing optical isolation between these components can be important. Summary of the Invention

[0003] The present invention describes optoelectronic modules comprising optical transmitters and optical receivers and methods of manufacturing these modules.

[0004] In one aspect, for example, the present invention describes a method comprising replicating optical components 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 same wavelength. The optical components are composed of a first epoxy, and the light emitting dies and light receiver dies are mounted on a PCB wafer attached to a supporting glass substrate with double-sided tape. The method further comprises injecting a second epoxy using a vacuum injection molding technique. The second epoxy is substantially opaque to light having the wavelength and is injected so that it laterally surrounds and contacts respective side surfaces of each of the plurality of light emitting dies, each of the plurality of light receiver dies, and each of the plurality of optical components. The method comprises forming respective trenches in the second epoxy in areas separating duplex pairs of light emitting and light receiver dies, wherein each duplex pair includes one light emitting die and one light receiver die, and wherein the trenches partially extend into the PCB wafer. The method further includes: removing the double-sided tape and the support glass from the PCB wafer; separating the PCB wafer at the locations of the trenches to form singulated modules; and applying an IR coating over at least the exposed surfaces of one or more of the singulated modules. Each of the singulated modules includes at least one of the light emitting dies and at least one of the light receiver dies.

[0005] Some embodiments include one or more of the following features. For example, in some instances, prior to replicating the optical elements and injecting the second epoxy material, a first side of a PCB wafer is attached to a first tape, the first side being opposite a second side of the PCB wafer on which the optical transmitter die and the optical receiver die are mounted. The method may include: holding the PCB wafer using a vacuum chuck, wherein the vacuum chuck is in contact with the second side of the PCB wafer; then removing the first tape from the PCB wafer; then contacting the first side of the PCB wafer with a double-sided tape attached to a support glass; and then releasing the PCB wafer from the vacuum chuck.

[0006] In some embodiments, replicating the optical element includes selectively dispensing a first epoxy onto the structured region of the elastomeric layer and subsequently pressing the first epoxy onto the light emitting die and the light receiver die. In some cases, the optical element is a grid array optical element.

[0007] The method may further include forming additional trenches extending through the second epoxy and through the PCB wafer, wherein the additional trenches are formed before the double-sided tape and support glass are removed from the PCB wafer. In some cases, the second epoxy is a black epoxy. In some cases, the double-sided tape is a heat-releasable double-sided tape. The method may further include attaching a carrier to an outer surface of the second epoxy after forming the trenches in the second epoxy; and applying heat to remove the double-sided tape and support glass from the PCB wafer.

[0008] In some cases, the method includes attaching the singulated module to heat-resistant tape; then applying an IR coating to the exposed surface of the singulated module; and removing the singulated module from the heat-resistant tape. Applying the IR coating can include, for example, spraying the IR coating. In some cases, the IR coating is applied to the top and side surfaces of the singulated module. The IR coating can act as a filter to allow only radiation in the IR portion of the electromagnetic spectrum to pass through.

[0009] The present invention also describes a device comprising 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 formed from a first epoxy resin. A second epoxy resin laterally surrounds and contacts the light emitting die, the light receiver die, and respective side surfaces of the optical elements, wherein the second epoxy resin provides an optical barrier between the light emitting die and the light receiver die.

[0010] In some examples, the second epoxy substantially fills the space between the light emitting die and the light receiver die.The second epoxy can be, for example, a black epoxy.

[0011] In some embodiments, the optical elements are grid array optical elements.

[0012] The apparatus may further include a host device including a processor and a display screen. The optoelectronic module may be integrated as a component of the host device, wherein the processor is operable to control the component of the host device based at least in part on the signal from the optical receiver die.

[0013] In some instances, the present technology can simplify the overall manufacturing process and can also result in smaller modules.

[0014] Other advantages present in some embodiments include one or more of the following: Various steps that may be required in other techniques are unnecessary and can be omitted. Furthermore, in some cases, the present technique can help increase wafer density, produce smaller module sizes, reduce surface leakage caused by uneven wafer flatness, improve yield due to trench cutting, and avoid optical crosstalk and / or enhanced light leakage.

[0015] Other aspects, features, and advantages will be readily apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 An example of a photovoltaic module is shown.

[0017] Figures 2 to 8 The various steps in a wafer-level process for manufacturing a plurality of photovoltaic modules are shown.

[0018] Figure 9 Further details of various aspects of the wafer level process are shown.

[0019] Figures 10 to 16 Additional steps in the wafer level process are shown. DETAILED DESCRIPTION

[0020] The present invention describes optoelectronic modules that are operable to emit light of a specific wavelength (e.g., in the infrared (IR) portion of the spectrum) and detect light of the same wavelength. The present invention also describes a wafer-level process for simultaneously manufacturing multiple modules in parallel.

[0021] like Figure 1 As shown in FIG, optoelectronic module 20 includes a light source (sometimes referred to as a light emitter) 22 and a light receiver 24 mounted on a support, such as a printed circuit board (PCB) substrate 26. Light source 22 can be implemented, for example, as a VCSEL or LED die (i.e., a semiconductor chip). Similarly, light receiver 24 can be implemented, for example, in an integrated circuit die (i.e., a semiconductor chip) that includes a photodiode for detecting light and associated processing circuitry.

[0022] The electrical contacts on the bottom of each die 22, 24 can be electrically coupled to the PCB substrate 26 via respective surface mount technology (SMT) contact pads 21, 23. Similarly, the electrical contacts on the top of each die 22, 24 can be electrically coupled to the PCB substrate 26 via respective bond wires 28 connected to pads 30. SMT or other electrical contact pads 32 are provided on the bottom surface of the PCB substrate 26. Respective solder masks 34, 36 are provided over the top and bottom surfaces of the PCB substrate 26. For example, the solder masks may be present on an outer, inactive area of ​​the top surface of the PCB substrate.

[0023] Black epoxy 40 laterally surrounds individual semiconductor device dies (e.g., light source 22 and light receiver 24). In the example shown, epoxy 40 also contacts the lateral side surfaces of dies 22, 24. Epoxy 40 is preferably substantially opaque to the wavelengths of light emitted by light source 22 and sensed by light receiver 24. In the example shown, an upper portion of epoxy 40 also defines a baffle, portions of which laterally surround respective optical elements 42, 44 (such as grid optics arrays) arranged on the light emitting and light detecting portions of dies 22, 24. Black epoxy 40 also contacts the lateral side surfaces of optical elements 42, 44. Black epoxy 40 also serves as an optical barrier that provides optical isolation between light source 22 and light receiver 24.

[0024] The optical elements 42, 44 may be composed of, for example, a transparent epoxy resin. In the example shown, an IR spray coating 46 is provided over the upper surface and along the sides of the module 20. The coating 46 acts as a filter, allowing only wavelengths of light in the IR region of the spectrum to pass.

[0025] Figures 2 to 16 The steps in a wafer-level process for manufacturing multiple modules 20 in parallel are shown. The wafer-level process can be useful for manufacturing multiple (e.g., tens, hundreds, or even thousands) of modules simultaneously. This procedure allows the use of reflowable materials (i.e., materials that maintain their mechanical stability and optical performance even when subjected to high temperatures (such as 270°C or higher)). The process can also provide improved adhesion between different layers.

[0026] like Figure 2 As shown in FIG, a printed circuit board (PCB) wafer 100 (including electrical contact pads on its upper and lower surfaces) is attached to and supported by tape 102. A plurality of light sources 22 and light receivers 24 are mounted on the PCB wafer 100. In some cases, a wafer frame 104 is present on the tape 102 adjacent to the perimeter of the PCB wafer 100. Alignment marks 108 may be provided on the PCB wafer 100 to facilitate alignment in subsequent steps.

[0027] Next, if Figure 3 As shown in FIG, the vacuum chuck 110 is aligned with the PCB wafer 100 and brought into contact with the PCB wafer 100. To this end, one or more cameras 111 in conjunction with the alignment marks 108 can be used to determine and confirm proper alignment. Vacuum is applied to hold the PCB wafer 100. Next, the entire assembly is flipped over, as shown in FIG. Figure 4 , and the tape 102 and wafer frame 104 are removed.

[0028] like Figure 5 , the assembly is flipped over again while the vacuum chuck 110 holds the PCB wafer 100. The vacuum chuck 110 brings the PCB wafer 100 into contact with one side of a heat-releasable double-sided tape 112, the opposite side of which is attached to a bottom injection support glass 114. The support glass 114 helps to keep the PCB wafer 100 substantially flat, which can help control the thickness of the subsequently formed vacuum injection molding (VIM) layer. In some instances, resin spacers 116 are provided on the support glass 114 adjacent to the periphery of the PCB substrate 100 and laterally surround the periphery of the PCB wafer 100. The spacers 116 can help compensate for the thickness of the PCB wafer 100 and the double-sided tape 112 during the VIM process (see below). Figure 8 Once the PCB wafer 100 is attached to the tape 112 , the vacuum is stopped and the vacuum chuck 110 releases the PCB wafer 100 .

[0029] Figure 6 An elastomeric (eg, polydimethylsiloxane (PDMS)) tool 117 is shown for replicating optical elements 42, 44 and for the VIM process during which the black epoxy material 40 is injected. Figure 6 As shown in FIG, PDMS tool 117 includes a structured PDMS layer 118 on a glass lens tool 120. The surface of PDMS layer 118 may have structured regions 121 that define the shape of optical elements 42, 44 (e.g., grid array optical devices). Structured regions 121 may be the same as one another or may be different from one another (e.g., providing one type of optical element for light emitter 22 and a different type of optical element for light receiver 24). The outer periphery 122 of PDMS layer 118 may be slightly thicker than the inner region of the PDMS layer to provide thickness control during the subsequent VIM process.

[0030] Next, if Figure 7, a transparent epoxy material 124 is dispensed (e.g., by spraying) onto the structured areas 121 of the PDMS layer 118. In this case, it is not necessary to dispense the epoxy material 124 over the entire PDMS layer 118. Instead, the epoxy material 124 can be dispensed selectively onto the structured areas 121 corresponding to the locations where the optical elements 42, 44 are to be replicated.

[0031] Figure 8 FIG. 4 shows the replication process of the optical elements 42 and 44. Figure 8 As shown in FIG, PDMS layer 122 of the PDMS tool is brought into contact with the top surface of PCB wafer 100 and spacers 116 (if present). Upper (PDMS) tool 117 presses transparent epoxy material 124 against the top surfaces of light emitters 22 and light receivers 24. Epoxy material 124 is then hardened (e.g., by UV curing). At this stage, an epoxy-free space 125 remains between PDMS layer 118 and PCB wafer 100.

[0032] Figure 9 Further details of the injection support glass 114, double-sided tape 112, spacer 116, PCB substrate 100, and upper injection tool 117 are shown, respectively, according to some embodiments. For example, PCB substrate 100 may have a square shape including active area 101. PCB substrate 100 has holes 202 at opposite corners. Holes 202 serve as the inlet and outlet for epoxy resin flow, respectively, during the VIM process. For some embodiments, some or all of the aforementioned details may vary.

[0033] like Figure 9 As further shown in FIG. , bottom injection glass 114 may have a substantially square surface with chamfered corners 204. In some examples, the presence of chamfered corners 204 may be used to allow bottom injection glass 114 to be assembled into other equipment for subsequent processing (e.g., a saw). Double-sided tape 112 and spacers 116 (if present) may have approximately the same outer dimensions as bottom injection glass 114 and may also have chamfered corners. Bottom injection glass 114 also has holes 206 to provide inlet and outlet for the flow of epoxy during the VIM process, and thus align with corresponding holes 202 in PCB wafer 100. Similarly, double-sided tape 112 includes inlet and outlet holes 208 that align with the aforementioned holes 206 in bottom injection glass 114 and holes 202 in PCB wafer 100. For some embodiments, some or all of the aforementioned details may vary.

[0034] like Figure 9As further shown in FIG, the upper PDMS tool 117 can be square in shape, with outer dimensions identical to corresponding outer dimensions of the bottom injection glass 114. The upper injection tool 117 can have slots 210 that overlap with the locations of the inlet / outlet holes 202 in the PCB wafer 100. For some embodiments, some or all of the foregoing details may be different.

[0035] like Figure 10 As shown in FIG, the VIM process can be performed by injecting a black (or other opaque) epoxy 126 material into the space 125 between the PDMS layer 118 and the PCB wafer 100. The epoxy 126 laterally encapsulates other components, including the light emitter 22 and the light receiver 24. The present technique can avoid the need to, for example, form trenches in a transparent epoxy material and then fill the trenches with an opaque material to serve as an optical barrier between the emitter 22 and the adjacent receiver 24. Therefore, the present technique can simplify the overall process and can also produce smaller modules. Similarly, as Figure 10 As can be seen in FIG, the spacers 116 provide more uniform (ie, flat) support and prevent bowing of the PCB wafer 110 during the VIM process.

[0036] After injecting the black epoxy material 126 into the space 125, the epoxy material 126 can be hardened, for example, by UV and / or thermal curing. In some examples, this can be done while the PDMS tool 117 remains in place. After the epoxy material 126 is hardened, the PDMS tool 117 is removed.

[0037] Next, if Figure 11 As shown in FIG, narrow vertical trenches 130 are formed through the black epoxy 126. The trenches preferably extend partially into the PCB wafer 100 and serve to relieve stress. The trenches 130 can be formed, for example, by dicing. In the example shown, the trenches 130 separate the paired light emitting die 22 and the associated light receiver die 24. Alternatively, larger trenches 132 can be formed closer to the edge of the PCB wafer 100 and can aid in the subsequent release of the PCB wafer 100 from the tape 102.

[0038] Then, if Figure 12 As shown in , the intermediate carrier 134 is attached to the top of the assembly (ie, on the outer surface of the black epoxy 126 and the replicated optical element 124). Figure 13 As shown in FIG, heat is applied to remove the double-sided tape 112 and the bottom injection support glass 114. During the final singulation process (eg, dicing), the partially separated modules (see FIG. Figure 14 ) are completely separated from each other, such as Figure 15 As shown in .

[0039] Next, if Figure 16 As shown in FIG, the module can be attached to heat resistant tape 136. An IR coating 138 is then sprayed on the top and side surfaces of the module, which acts as a filter to allow only radiation in the IR portion of the electromagnetic spectrum to pass. A post-bake process can be applied to cure the IR coating 138 and provide a final heat cure for other parts of the module (such as the black epoxy 126). This process produces a plurality of modules, each of which has the above-mentioned combination of Figure 1 Features of the module 20 discussed. The module can then be removed from the heat-resistant tape 136.

[0040] For embodiments that provide carrier glass to support the PCB wafer 100 , the carrier glass can be easily recycled for reuse because little or no epoxy comes in contact with the glass (except for, for example, inlet and outlet holes for epoxy flow during the VIM process).

[0041] Although the injected epoxy 126 may be referred to as black epoxy, more generally, the epoxy 126 is preferably opaque to light of wavelengths sensed or emitted by the optoelectronic devices 22 , 24 (eg, optical receiver chips or optical transmitter chips) mounted on the PCB wafer 100 .

[0042] The modules 20 described herein can be integrated into a wide range of portable computing devices, such as smartphones, wearable devices, biometric devices, mobile robots, surveillance cameras, camcorders, laptop computers, tablet computers, etc. These modules can be used, for example, as proximity sensor modules or other optical sensing modules, such as for gesture sensing or recognition.

[0043] The designs of smartphones and other portable computing devices referenced in this disclosure may include one or more processors, one or more memories (e.g., RAM), storage (e.g., disk or flash memory), a user interface (which may include, for example, a keypad, a TFT LCD or OLED display screen, a touch or other gesture sensor, a camera or other optical sensor, a compass sensor, a 3D magnetometer, a 3-axis accelerometer, a 3-axis gyroscope, one or more microphones, etc. and software instructions for providing a graphical user interface), interconnections between these components (e.g., buses) and interfaces for communicating with other devices (which may be wireless (such as GSM, 3G, 4G, CDMA, WiFi, WiMax, Zigbee or Bluetooth) and / or wired (such as via an Ethernet local area network, a T-1 Internet connection)). In some instances, one or more processors use signals from a module (e.g., a signal from the receiver die 24) to adjust the brightness of the display screen of the host device.

[0044] Various modifications will be apparent and may be made to the foregoing examples. Features described in conjunction with different embodiments may in some cases be incorporated into the same embodiment, and various features described in conjunction with the foregoing examples may be omitted from some embodiments. Therefore, other embodiments are within the scope of the claimed invention.

Claims

1. A method for manufacturing a photovoltaic module, the 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 comprised 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 to a support glass by double-sided tape; injecting a second epoxy resin using a vacuum injection molding technique, wherein the second epoxy resin is substantially opaque to light having the wavelength, and wherein the second epoxy resin is injected such that the second epoxy resin laterally surrounds and contacts 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 areas separating duplex pairs of the light emitting die and the light receiver die from one another, wherein each duplex pair includes one of the light emitting die and one of the light receiver die, and wherein the trenches extend partially into the PCB wafer; Remove the double-sided tape and the supporting glass from the PCB wafer; separating the PCB wafer at the locations of the trenches to form singulated modules, each of the singulated modules including at least one of the light transmitting dies and at least one of the light receiving dies; and An IR coating is applied over at least the exposed surface of one or more of the singulated modules; wherein the IR coating acts as a filter to allow only radiation in the IR portion of the electromagnetic spectrum to pass.

2. The method according to claim 1, wherein Prior to replicating the optical element and injecting the second epoxy resin material, a first side of the PCB wafer is attached to a first tape, the first side being opposite to a second side of the PCB wafer on which the light emitting die and the light receiver die are mounted, the method comprising: holding the PCB wafer using a vacuum chuck, wherein the vacuum chuck is in contact with the second side of the PCB wafer; then removing the first tape from the PCB wafer; then contacting the first side of the PCB wafer with the double-sided tape attached to the support glass; and then releasing the PCB wafer from the vacuum chuck.

3. The method according to claim 1 or 2, wherein Replicating the optical element comprises: selectively dispensing a first epoxy resin onto the structured areas of the elastomeric layer; and A first epoxy is then pressed onto the light emitting die and the light receiver die.

4. The method according to claim 1 or 2, wherein The optical element is a grid array optical element.

5. The method according to claim 1 or 2, wherein: The second epoxy is black epoxy.

6. The method of claim 1 or 2, further comprising forming additional trenches extending through the second epoxy and through the PCB wafer, wherein The additional trench is formed before the double-sided tape and the supporting glass are detached from the PCB wafer.

7. The method according to claim 1 or 2, wherein: The double-sided tape is a heat-releasable double-sided tape.

8. The method of claim 7, further comprising: After forming the trench in the second epoxy resin, attaching a carrier at an outer surface of the second epoxy resin; and Heat is applied to remove the double-sided tape and the support glass from the PCB wafer.

9. The method according to claim 1 or 2, comprising: attaching the singulated module to a heat-resistant tape; then applying the IR coating to the exposed surfaces of the singulated modules; and The singulated modules are removed from the heat-resistant tape.

10. The method according to claim 1 or 2, wherein: Applying the IR coating includes spraying the IR coating.

11. The method according to claim 1 or 2, wherein: The IR coating is applied to the top and side surfaces of the singulated module.

12. A device comprising a photovoltaic module, wherein the photovoltaic module is manufactured by the method for manufacturing a photovoltaic module according to any one of claims 1 to 11, the device comprising: The optoelectronic module includes a light emitting die and a light receiving 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 receiving die, wherein the optical element is composed of a first epoxy resin. a second epoxy laterally surrounding and contacting respective side surfaces of the light emitting die, the light receiver die, and the optical element, wherein the second epoxy provides an optical barrier between the light emitting die and the light receiver die; and an IR coating on at least the exposed surface in said photovoltaic module, Therein the IR coating acts as a filter to allow only radiation in the IR part of the electromagnetic spectrum to pass.

13. The device of claim 12, wherein: A second epoxy substantially fills the space between the light emitting die and the light receiver die.

14. The device according to claim 12 or 13, wherein The optical element is a grid array optical element.

15. The device according to claim 12 or 13, wherein The second epoxy is black epoxy.

16. The apparatus according to claim 12 or 13, further comprising a host device, the host device comprising a processor and a display screen, the optoelectronic module being integrated as a component of the host device, wherein: The processor is operable to control components of the host device based at least in part on signals from the optical receiver die.

Images