Fiber optics printed circuit board assembly surface cleaning and roughening

The present disclosure generally relates to printed circuit boards or printed circuit board assemblies for fiber optic communications. In one example, a method may include coupling at least one optoelectronic component to a surface of a printed circuit board. The method may include lasering the surface of the printed circuit board to form a laser-roughened area on the surface of the printed circuit board. The method may include coupling an optical component to the printed circuit board at the laser-roughened area on the surface of the printed circuit board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 201810575121.7, filed Jun. 6, 2018, titled FIBER OPTICS PRINTED CIRCUIT BOARD ASSEMBLY SURFACE CLEANING AND ROUGHENING, and which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure generally relates to printed circuit boards or printed circuit board assemblies for fiber optic communications. In particular, the present disclosure relates to modifications to a surface of printed circuit boards to facilitate manufacture of optoelectronic assemblies, which may result in improved optoelectronic assemblies that incorporate aspects described herein.

Printed circuit boards (PCBs) mechanically support and electrically connect electrical components using conductive couplings such as traces, tracks, pads and/or other features etched from one or more layers of electrically conductive material, such as copper, attached to one or more layers of a non-conductive substrate. Components are generally soldered onto the PCB to both electrically connect and mechanically fasten them to it. PCBs may be used in optoelectronic assemblies that convert electrical signals to optical signals, optical signals to electrical signals, or both. Optoelectronic assemblies may be used, for example, in fiber optic communication to exchange data at increased rates.

In optoelectronic assemblies that implement PCBs, both electrical and optical components may be coupled to the PCB. However, PCB assemblies with both electrical and optical components may pose various manufacturing challenges that may need to be addressed to effectively produce optoelectronic assemblies.

The claimed subject matter is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. This background is only provided to illustrate examples of where the present disclosure may be utilized.

SUMMARY

The present disclosure generally relates to modifications to a surface of a printed circuit board (PCB) to facilitate manufacture of optoelectronic assemblies, which may result in improved optoelectronic assemblies that incorporate aspects described herein.

In one non-limiting example, a method may include coupling at least one optoelectronic component to a surface of a PCB. The method may include lasering the surface of the PCB to form a laser-roughened area on the surface of the PCB. The method may include coupling an optical component to the PCB at the laser-roughened area on the surface of the PCB.

The optical component may be attached at a coupling area on the surface of the PCB, and the laser-roughened area may be positioned at least partially or fully inside of the coupling area. The optical component may be coupled to the PCB using an adhesive, such as epoxy or another suitable adhesive. The optical component may be optically coupled or optically aligned with the optoelectronic component.

The lasering may remove at least a portion of a layer of the PCB. The lasering may increase the roughness of the surface of the PCB. In some aspects, the lasering may increase the arithmetical mean deviation of the assessed profile of the surface of the PCB by at least 0.1. The lasering may remove or decompose contaminants on the surface of the PCB. The lasering may improve the coupling of the optical component to the PCB by increasing the roughness of the roughness of the surface of the printed circuit board and/or removing contaminants from the surface of the printed circuit board.

In some aspects, the method may include applying a solder mask to the surface of the printed circuit board before the laser is applied. The lasering may remove at least a portion of a layer of the PCB and/or at least a portion of the solder mask on the PCB.

The optical component may be a lens optically coupled or optically aligned to the optoelectronic component. The laser-roughened area may at least partially surround the optoelectronic component in a plane defined by the PCB. The optical component may at least partially enclose the optoelectronic component after the optical component is coupled to the PCB. The optoelectronic component may be hermetically sealed between the PCB and the optical component after the optical component is coupled to the PCB.

The method may include attaching at least one electrical component to the surface of the printed circuit board. The laser may be applied for a sufficient time and duration to decompose a surface of the PCB such that the laser-roughened area is visually perceptible. The method may include visually inspecting the surface of the printed circuit board to determine whether a portion of the printed circuit board has been lasered.

In another non-limiting example, an optoelectronic assembly may include a printed circuit board, at least one optoelectronic component coupled to a surface of the printed circuit board, and an optical component attached to a laser-roughened area of the surface of the printed circuit board. The optical component may be attached to a laser-roughened area with an adhesive. The optical component may be optically coupled or optically aligned with the optoelectronic component. The optical component may be a lens or another optical component that at least partially encloses the optoelectronic component.

The laser-roughened area of the surface of the printed circuit board may be rougher than a remaining area of the surface of the printed circuit board. The laser-roughened area of the surface of the printed circuit board may have a larger arithmetical mean deviation of the assessed profile than the remaining area of the surface of the printed circuit board. The difference between the laser-roughened area and the remaining area of the surface of the printed circuit board may be visually perceptible.

The optoelectronic assembly may include a solder mask on the surface of the printed circuit board. The solder mask may be absent at the laser-roughened area of the surface of the printed circuit board. The laser-roughened area may surround the optoelectronic component in a plane defined by the printed circuit board. The optical component may be a lens that at least partially encloses the optoelectronic component. The lens may be optically aligned with the optoelectronic component. The lens may hermetically seal the optoelectronic component.

This Summary introduces a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary does not identify key features or essential characteristics of the claimed subject matter, and should not be used as an aid in determining the scope of the claimed subject matter.

DETAILED DESCRIPTION

The present disclosure generally relates to printed circuit boards or printed circuit board assemblies for fiber optic communications. Assemblies that incorporate printed circuit boards (PCBs) may be referred to as printed circuit board assemblies (PCBAs). In particular, the present disclosure relates to modifications to the surface of PCB to facilitate manufacture of optoelectronic assemblies, which may result in improved optoelectronic assemblies that incorporate aspects described herein.

PCBs may be implemented in optoelectronic assemblies configured for fiber optic communication. Optoelectronic assemblies that implement PCBs may include both electrical and optical components that are coupled to the PCB. However, PCB assemblies with the electrical and optical components may pose various manufacturing challenges that interfere with effective and efficient production of optoelectronic assemblies.

For example, certain optical components such as lenses, may be optically aligned with other optical components. Therefore the optical components may need to be more precisely positioned and attached to the PCB than electrical components. Furthermore, it may not be practicable to attach optical components to the PCB with solder. Therefore, optical components may be attached to the PCB in other manners. However, additional challenges arise in coupling optical components to the PCBs in a cost-effective and robust manner.

In some circumstances, it may desirable to mechanically couple optical components to the surface of a PCB, for example, using an adhesive or other suitable attachment process. For instance, in some conventional processes to mechanically couple the optical components to the surface, the PCB may be untreated. The untreated PCB includes a substantially smooth surface that is not cleaned. If the surface of the PCB is contaminated, the optical component may not sufficiently bond to the PCB. Furthermore, if the surface of the PCB is contaminated when the optical component is bonded to the PCB, the resulting bond between the PCB and the optical component may be relatively weak. In such circumstances, the bond may break over time, for example, during subsequent processing of the PCB to form the optoelectronic assembly. Additionally, the weak bond may break after the optoelectronic assembly is manufactured, for example, during operation of the optoelectronic assembly. Furthermore, in such circumstances the optoelectronic assembly may fail prematurely because of a weak bond caused by the substantially smooth surface of the PCB or the contaminants on the surface of the PCB left during manufacturing.

Some PCBAs implement through-hole technology (THT). THT refers to a mounting process for attaching electrical components using leads that extend from the electrical components. The leads are inserted into holes formed in the PCB and soldered to pads on the opposite side of the PCB. Other PCBAs implement surface-mount technology (SMT). SMT is a mounting process in which components are mounted or placed directly onto the surface of the PCBs. SMT components are usually smaller than THT components because they have either smaller leads or no leads at all. Generally, SMT speeds up the manufacturing process when compared to THT. However, use of SMT in some circumstances increase the risk of defects due to component miniaturization and denser packing of components on the PCB. In such circumstances, detecting defects (e.g., contaminants or defective bonds) may also be more difficult. Although both SMT and THT may be implemented in various circumstances, SMT has largely replaced THT in manufacture of PCBAs.

The surface of the PCB may be contaminated during the normal course of manufacturing, for example, during SMT or THT processes. Contaminants such as flux, oil, dust, adhesive, or other contaminants may be deposited on the surface of the PCBs as the PCBs are being formed. Such contaminants may be difficult to detect, during and after manufacturing, and may lead to the weak bonds that are also difficult to detect. For instance, the contaminants may be invisible to the human eye, using a microscope, or using other detection methods. Thus, it may be difficult to determine whether a surface of a PCB is contaminated before bonding. Furthermore, it may be difficult to remove contaminants that are not visible or detectable, and to determine whether or not the contaminants were successfully removed.

Even if the surface of the PCBs does not include contaminants, in some circumstances the PCB may not be well-suited for attaching components to its surface. For example, the surface of the PCB may be relatively smooth. Adhesives may not bond as well to smooth surfaces as to rough surfaces. Some PCBs may include a solder mask, which is a thin lacquer-like layer of polymer that is applied to the surface of the PCB. The solder mask may be used to protect electrically conductive traces on the PCB from oxidation and to prevent or reduce undesired electrical connections between adjacent conductive traces that are positioned relatively close to one another. The solder mask may also be relatively smooth, and adhesives may form relatively poor bonds with the solder mask, for example, when coupling optical components to the PCB.

Accordingly, the present disclosure includes configurations to modify the surface of PCBs to remove contaminants (e.g., clean the surface) and/or increase the roughness of the surface. In particular, a laser may be used to remove contaminants on the surface of the PCB. Furthermore, the laser may be used to remove a portion of the PCB (e.g., a portion of a layer of the PCB, an entire layer of the PCB, or more than one layer of the PCB). Additionally, the laser may be used to increase the roughness of the surface of the PCB.

Aspects described herein may improve bonding between the PCB and components attached to the PCB (e.g., optical components or others) using, for example, adhesives or other suitable attachment processes. Specifically, bonding between the PCB and a component may be improved because the laser removes contaminants from the surface of the PCB and/or increases its roughness. This may improve the strength of the bonds between the PCB and optical components, which in turn may decrease the likelihood that the bonds will break during and after manufacturing. Furthermore, assemblies implementing the concepts described herein may be less likely to fail prematurely as result of broken bonds between the PCB and attached components.

In addition, the laser may visibly modify the surface of the PCB, making it easier to determine whether contaminants have been removed from a certain area on the PCB and/or whether the area has been roughened. For example, the laser may change a color and/or a texture of the surface of the PCB where the laser is applied. In particular, the color and/or the texture of the surface may be different in an area because all or a portion of a layer of the PCB may be removed by the laser. Such configurations may also facilitate positioning of components to be coupled to the PCB, because the visibly modified surface may indicate where the component should be attached to the PCB.

Using a laser to modify the surface of the PCB may avoid damaging components coupled to the PCB. In particular, some components (e.g., electrical components or others) may be attached to the PCB before the laser is applied to the surface of the PCB. The laser may be accurately controlled to apply the laser in specific areas on the surface of the PCB. Accurate control of the laser may avoid the components that are already coupled to the PCB so these components are not damaged. Use of the laser may provide some advantages relative to other contamination-removal processes. For instance, other processes for removing contaminants from the PCB such as solvent cleaning, plasma cleaning, etc. may risk damaging components on the PCB.

Reference will be made to the drawings and specific language will be used to describe various aspects of the disclosure. Using the drawings and description in this manner should not be construed as limiting its scope. Additional aspects may be apparent in light of the disclosure, including the claims, or may be learned by practice.

FIG. 1Ais a top schematic view of an example of a PCBA100. The PCBA100may include a PCB that includes an insulating substrate102and a surface118. Various components, such as electrical components104a-e, may be positioned on and mechanically coupled to the substrate102. The electrical components104a-emay be electrically coupled by conductive couplings106a-e. The conductive couplings106a-emay be traces, tracks, pads and/or other features etched from one or more layers of electrically conductive material, such as copper. The electrical components104a-emay be soldered to electrically and mechanically couple them to the PCBA100.

The PCBA100may include a single layer or multilayer configuration. If the PCBA100is a single layer PCB, then it may include one layer of the insulating substrate with conductive couplings positioned on one or both sides. If the PCBA100is a multilayer PCB, then it may include multiple layers of insulating substrate, and conductive couplings may be positioned on and/or in between the multiple layers.

In some configurations, the PCBA100may include a solder mask, which is a layer applied to the surface118of the PCBA100. The solder mask may be a layer on the surface118or proximate the surface118of the PCBA100. The solder mask may protect portions of the PCBA100, such as the conductive couplings106a-e. For example, the solder mask may protect the conductive couplings106a-efrom oxidation and to prevent undesired electrical connections between adjacent conductive couplings (e.g.,106aand106d) that are positioned relatively close to one another. The solder mask may be relatively smooth, and adhesives may form relatively poor bonds with the solder mask, for example, when components are attached to the PCBA100.

In some circumstances, the solder mask may be applied to the PCBA100using a mask or silk screening technique. The solder mask may be applied as an epoxy liquid through a silkscreen pattern onto the PCBA100. Additionally or alternatively, the solder mask may be applied using any suitable technique, such as liquid photoimageable solder mask (LPSM) or dry film photoimageable solder mask (DFSM). Once applied, the solder mask may be cured, for example, using a thermal or ultra violet curing process. Openings may be formed in the solder mask using any suitable process, such as photolithography.

The PCBA100may include optoelectronic components108. In such configurations, the PCBA100may be included in an optoelectronic assembly used for fiber optic communication, although the concepts described herein may be implemented in any suitable PCBA. The optoelectronic components108may include components related to the conversion of electrical signals to optical signals, optical signals to electrical signals, or both. For example, the optoelectronic components108may include a receiver or receiver array configured to receive optical signals and to generate corresponding electrical signals. In another example, the optoelectronic components108may include a transmitter or transmitter array configured to receive electrical signals and to generate corresponding optical signals.

The optoelectronic components108may include or may be coupled to components related to optical transmitters and receivers. Some examples of the components may include amplifiers (e.g., transimpedance amplifiers, limiting amplifiers, or others), clock and data recovery (CDR) circuits, digital signal processing circuits, drivers, digital-to-analog converter (DAC) circuits, modulators, or other suitable components. In some configurations, such components may be included in the electrical components104a-e.

As explained above, the optoelectronic assembly may include electrical components104a-eand/or optoelectronic components108coupled to the PCBA100. The optoelectronic assembly may also include optical components optically coupled or optically aligned to the optoelectronic components108. The optical components may include lenses, filters, collimators, mirrors, polarizers, or any other suitable component used in optoelectronics. The optical components may be configured to perform an optical function such as direct, focus, collimate, modulate, multiplex, or demultiplex optical signals travelling to or from the optoelectronic components108.

At least some of the optical components may be mechanically coupled to the PCBA100. As illustrated, an optical component may be mechanically coupled to the PCBA100at coupling area110. The coupling area110may correspond to the size and/or shape of an optical component to be coupled with the PCBA100. In the illustrated configuration, the coupling area110is rectangular and annular (e.g., a rectangular annulus) with rounded corners. The coupling area110may correspond to a rectangular optical component that is to be mechanically coupled to the PCBA100and optically coupled to the optoelectronic components108. In other configurations, the coupling area110may be any suitable shape or size, and the configuration of the coupling area110may depend on the shape and size of the optical component. In the illustrated example, the optical component may include a lens, although any suitable component may be coupled to the PCBA100according to the concepts described in this disclosure.

The PCBA100may include a laser-roughened area112. The laser-roughened area112may correspond to the size and/or shape of the coupling area110or the optical component to be coupled with the PCBA100. In the illustrated configuration, the laser-roughened area112is rectangular and annular (e.g., a rectangular annulus) with rounded corners, corresponding to the coupling area110. The laser-roughened area112may be positioned entirely within the coupling area110as shown, although other configurations may be implemented. In other configurations, the laser-roughened area112may be any suitable shape or size, and the configuration of the laser-roughened area112may depend on the shape and size of the coupling area110, the optical component, or both.

The laser-roughened area112may be formed by a laser applied to the surface118of the PCBA100(e.g., lasering the surface118of the PCBA100), as described in further detail below. The laser may be used to remove a portion of the PCBA100to form the laser-roughened area112. In particular, the laser may be used to remove a portion of a layer of the PCBA100, an entire layer of the PCBA100, or more than one layer of the PCBA100. For example, the laser may be used to remove between about 1 and 30 micrometers (μm) of the PCBA100(e.g., depth or height of the removed portion). In some configurations, the power, intensity and/or wavelength of the laser may be selected to remove a desired amount of the PCBA100. Additionally or alternatively, the laser may be applied repeatedly a given area to remove additional layers or portions of the PCBA100. Accordingly, additional portions may be removed each time the laser is applied to an area on the PCBA100. (e.g., the laser-roughened area112).

The power, intensity and/or wavelength of the laser used to form the laser-roughened area112may be selected to be sufficiently high to increase the roughness of the surface. Additionally or alternatively, the power, intensity and/or wavelength of the laser used to form the laser-roughened area112may be selected to be sufficiently high to remove or decompose contaminants without damaging the PCBA100and/or the components coupled to the PCBA100, such as the electrical components104a-eand the optoelectronic components108. The desired power, intensity and/or wavelength of the laser may depend on materials included in the PCB (e.g., layers of the PCB), materials of the contaminants, materials of components coupled to the PCB, or any suitable combination thereof. In one example, the laser may be an ultraviolet laser, for example, a laser emitting electromagnetic radiation within a range of ultraviolet wavelengths. In some circumstances, ultraviolet wavelengths may include wavelengths between 100 nanometers (nm) and 400 nm. In some configurations, the laser may be a 355 nm wavelength laser, although other suitable configurations may be implemented. Additionally or alternatively, in some configurations the laser may include a laser power of 3 Watts (W).

The laser-roughened area112of the surface118of the PCBA100may be rougher than a remaining area of the surface118of the PCB. The laser-roughened area112of the surface118of the PCB may have a larger arithmetical mean deviation of the assessed profile than the remaining area of the surface118of the PCB. The difference between the laser-roughened area112and the remaining area of the surface118of the PCB may be visually perceptible. Accordingly, it may be possible to visually determine whether or not portions of the surface118has been roughened and/or whether contaminants have been removed in certain areas on the surface118.

FIG. 1Bis a top schematic view of a portion of the PCBA100ofFIG. 1A. In particular,FIG. 1Billustrates a portion of the PCBA100, denoted by circle1B inFIG. 1A. InFIG. 1B, the optoelectronic components108, the coupling area110, and the laser-roughened area112are shown in further detail. As introduced above, the laser-roughened area112may be positioned entirely within the coupling area110. In the illustrated configuration, the laser-roughened area112is concentrically positioned within the coupling area110, although other configurations may be implemented. The optoelectronic components108may be electrically coupled to other components of the PCBA100with conductive couplings106a-d.

As mentioned, the optical component may include a lens. In some configurations, the optical component may partially or wholly enclose the components positioned in an area114inside of the coupling area110. For example, the optical component may define a cavity to enclose the optoelectronic components108between the optical component and the PCB of the PCBA100. In such configurations, the optical component may hermetically seal the optoelectronic components108or other components positioned in the area114. The laser-roughened area112and/or the coupling area110may surround the optoelectronic components108in a plane defined by the PCB of the PCBA100. In addition, the optical component may be optically aligned with the optoelectronic component.

In some configurations, the PCBA100ofFIGS. 1A-1Bway be implemented in optoelectronic assemblies that implement PCBAs. For example, the PCBA100may be implemented in optoelectronic modules for use in transceivers, transmitter optical subassemblies (TOSAs), receiver optical subassemblies (ROSAs), active optical cables, and others. In some configurations, the optoelectronic modules may comply with the Gen4 QSFP or Gen4 QSFP+ form factor.

FIG. 1Cis a top schematic view of a portion of the PCBA100. In particular,FIG. 1Cillustrates a portion of the PCBA100, denoted by rectangle1C inFIG. 1B. InFIG. 1B, the coupling area110and the laser-roughened area112are shown in further detail. As shown, the laser-roughened area112may overlap or be positioned over the coupling area110. In the configuration shown, the laser-roughened area112may be smaller than the coupling area110. In some configurations, the laser-roughened area112may be between about 50% and about 75% of the size of the coupling area110, although other configurations may be implemented. In other configurations, the laser-roughened area112may be substantially the same size or larger than the coupling area110. Furthermore, the laser-roughened area112may not be positioned fully within the coupling area110. In such configurations, the laser-roughened area112may partially overlap the coupling area110.

FIG. 2Ais a cross-sectional schematic view of a portion of the PCB of the PCBA100. InFIG. 2A, the laser-roughened area112is shown in further detail. As mentioned above, a laser may be used to increase the roughness of the surface118of the PCBA100and/or remove a portion of the PCBA100. As shown inFIG. 2A, the PCBA100may include a layer116positioned over the substrate102and defining the surface118of the PCBA100. The laser may be applied to the surface118to remove a portion of the layer116to form the laser-roughened area112. In the illustrated configuration, only a portion of the layer116is removed to form the laser-roughened area112. However, in other configurations the entire layer116may be removed to form the laser-roughened area112, or additional layers (not shown) may be removed from the PCBA100. In some configurations, the layer116may be a solder mask layer, or a portion of the solder mask. Accordingly, the solder mask may be the portion of the PCBA100that is cleaned and/or roughened. The solder mask may be absent at the laser-roughened area112of the PCB or the PCBA100.

FIG. 2Bis a cross-sectional schematic view of a portion of the PCBA100. In particular,FIG. 2Billustrates the surface118of the PCBA100before the laser is applied, denoted at118a, and after the laser is applied, denoted at118b. As shown, the surface118abefore the laser is applied is relatively smooth. In such circumstances, adhesives used to bond, for example, optical components to the surface118amay not bond well, which may result in relatively weak bonds that may prematurely fail. In contrast, the surface118bafter the laser is applied is rougher, as shown. In such circumstances, adhesives used to bond optical components (as described with reference toFIGS. 1A-1C) to the surface118bmay form stronger bonds between the optical components and the PCBs relative to the smooth surface118A. Although any suitable adhesive may be used for bonding, in some configurations an epoxy may be implemented.

One measure of surface roughness is the arithmetical mean deviation of the assessed profile or the mean roughness of the profile of the surface, denoted as Ra. In one example, the Raroughness of surface118amay be less than 0.2 μm and the Raroughness of surface118bmay be greater than 0.3 μm. Accordingly, the laser may increase the roughness of the surface118by at least an Raof 0.1 μm. However, in other circumstances, the surfaces118a,118bmay have other roughness values. For example, the surface118of the PCBA100may have any suitable roughness values. Furthermore, the laser may be used to increase the roughness of the surface118less than or greater than the example values described above.

FIG. 3is flow chart of an example method300of forming a PCBA and/or modifying a surface of a PCB. The method300may be implement in construction of an assembly that includes a PCB such as the PCBA100ofFIGS. 1A-1B. Although illustrated as discrete blocks, various steps inFIG. 3may be divided into additional steps, combined into fewer steps, or eliminated, depending on the desired implementation.

The method300may begin at step302, in which a substrate may be provided. For example, the substrate102ofFIGS. 1A-1Bmay be provided. At step304, conductive couplings may be formed on a surface of the substrate. For instance, referring toFIGS. 1A-1B, the conductive couplings106a-emay be formed on a surface of the substrate102. Any suitable configuration may be used for forming the conductive couplings. For example, a layer of conductive material, such as copper, may be positioned over the substrate, which may be non-conductive. The conductive material may be etched or otherwise processed to remove a portion of the conductive material, and the remaining conductive material may form the conductive couplings on the surface of the substrate.

At step306, one or more components may be coupled to the surface of the substrate. In some configurations, the components may be electrical components and/or optoelectronic components. For example, referring toFIGS. 1A-1B, the electrical components104a-eand/or the optoelectronic components108may be coupled to the surface118of the substrate102. Accordingly, at least one optoelectronic component may be coupled to a surface of the PCB. In some configurations, the components may be soldered to the conductive couplings of the PCB, thereby mechanically coupling the components to the PCB and electrically coupling the electrical components to the conductive traces.

At step308, a solder mask may be applied over the substrate and/or the conductive couplings. The solder mask may be applied using any suitable technique. For example, in some configurations, the solder mask may be applied using a mask or silk screening technique. The solder mask may be applied as an epoxy liquid through a silkscreen pattern or mask onto the surface of the PCB (e.g., over the substrate and/or the conductive couplings). Additionally or alternatively, the solder mask may be applied using any suitable technique, such as liquid photoimageable solder mask (LPSM) or dry film photoimageable solder mask (DFSM). Once applied, the solder mask may be cured, for example, using a thermal or ultra violet curing process. Openings may be formed in the solder mask using any suitable process, such as photolithography. In some configurations, the solder mask may form the surface of the PCB, although in other configurations a solder mask may not be included in the PCB.

At step310, a laser may be applied to the surface of the substrate or the PCB (e.g., lasering the surface). The laser may be applied to a certain area on the surface of the PCB. For example, the laser may applied on portions of the PCB where it may be desirable to remove or decompose contaminants. In another example, the laser may applied on portions of the PCB where it may be desirable to increase the roughness of the surface. In particular, the laser may be applied to a portion of the PCB where a component is to be coupled to the surface of the PCB. In some configurations, the component is to be coupled to the surface of the PCB may be an optical component. The area where the laser applied may be a laser-roughened area, such as the laser-roughened area112, and the area where the component is coupled to the PCB may be a coupling area, such as the coupling area110. As shown, for example, inFIGS. 1A-1C, the shape of the laser-roughened area may correspond to the shape of the coupling area, and in some configurations the laser-roughened area is smaller than the coupling area.

Application of the laser (e.g., lasering) may remove at least a portion of a layer of the PCB and/or may increase the roughness of the surface of the printed circuit board. In some aspects, the laser may increase the arithmetical mean deviation of the assessed profile of the surface of the printed circuit board by at least 0.1. Further, the laser may decompose or remove contaminants from the surface of the PCB. The laser may improve the coupling of the optical component to the printed circuit board by increasing the roughness of the surface of the printed circuit board and/or removing contaminants from the surface of the printed circuit board. In configurations where a solder mask is applied to the surface of the PCB, the laser may remove at least a portion of a solder mask on the PCB.

A characteristic of the laser such as the power, the intensity, and the wavelength of the laser may be selected to be sufficiently high to increase the roughness of the surface and/or remove contaminants without damaging the PCB and/or components coupled to the PCB. The desired power, intensity and wavelength of the laser may depend on materials included in the PCB (e.g., layers of the PCB), materials of the contaminants, materials of components coupled to the PCB, or any suitable combination thereof. In one example, the laser may be an ultraviolet laser, for example, a laser emitting electromagnetic radiation within a range of ultraviolet wavelengths. In some circumstances, ultraviolet wavelengths may include wavelengths between about 100 nanometers (nm) and about 400 nm. In some configurations, the laser may be about a 355 nm wavelength laser, although other suitable configurations may be implemented. Additionally or alternatively, in some configurations the laser may include a laser power of about 3 Watts (W).

Operation of the laser may be manually or automatically controlled using a controller. The controller may specify where on the substrate or the PCB the laser is applied. For example, the pattern that the laser is applied on the substrate or the PCB may correspond to the laser-roughened area112(seeFIGS. 1A-1C). As such, the pattern may be selected such that the laser forms the laser-roughened area112. In some configurations, it may be possible to accurately control the laser to form the laser-roughened area112in specific areas on the surface of the substrate or the PCB.

At step312, the surface of the substrate or the PCB may be visually inspected. Application of the laser to the surface of the substrate or the PCB may visibly modify the surface in the area that the laser is applied. In particular, the laser may be applied for a sufficient time and duration to decompose a surface of the PCB such that the laser-roughened area (e.g., the laser-roughened area112) is visually perceptible. Accordingly, it may be possible to determine whether a portion of the PCB has been lasered, whether contaminants have been removed from a certain area on the surface and whether the area has been roughened by visually inspecting the surface. For example, the laser may change the color or texture of the surface where the laser is applied. In particular, the color or texture of the surface may be different in the area because all or a portion of a layer may be removed by the laser. Such configurations may also facilitate positioning of components to be coupled to the surface because the visibly modified surface may indicate where the component should be attached to the surface.

Additionally or alternatively, visual inspection of the surface may facilitate in determining whether or not the laser was successfully applied to the surface, whether contaminants were removed in certain areas on the surface, and whether the surface was roughened in certain areas. In such configurations, components may be coupled to the surface in areas where contaminants have been removed and/or have been laser-roughened.

At step314, another component may be coupled to the surface of the substrate or the PCB. The component may be coupled to the surface at the coupling area and/or the laser-roughened area formed by application of the laser. In some configurations, the component may be an optical component, such as lens, although the concepts described herein may be applied to other types of components as well. The component may be attached at a coupling area on the surface of the PCB, and the laser-roughened area may be positioned at least partially or fully inside of the coupling area. The component may be coupled to the surface in any suitable manner, and in some configurations an adhesive such as an epoxy may be used. In circumstances where the component is an optical component, the optical component may be optically aligned with one or more optoelectronic component coupled to the surface.

In some configurations, the optical component may at least partially enclose the optoelectronic component(s) after the optical component is coupled to the PCB. Additionally or alternatively, the optical component may hermetically seal the optoelectronic component(s) in between the PCB and the optical component. Accordingly, the optoelectronic component(s) may be hermetically sealed between the PCB and the optical component after the optical component is coupled to the PCB.

In some configurations, the method300may include attaching at least one electrical component to the surface of the substrate or the PCB, such as the electrical components104a-eofFIGS. 1A-1B. In some configurations, the electrical component(s) may be coupled before the laser is applied, although in other embodiments the laser may be applied prior to or substantially concurrently with coupling the electrical components. The electrical component(s) may be electrically coupled by conductive couplings such as traces, tracks, pads and/or other features etched from one or more layers of electrically conductive material, such as copper. In some configurations, the electrical component(s) may be soldered to electrically and mechanically couple them to the substrate or the PCB.

FIG. 4is flow chart of an example method400of forming a PCBA and/or modifying a surface of the PCB, such as the PCBA100ofFIGS. 1A-1B. The method400may include any suitable aspects of the method300, or vice versa. Although illustrated as discrete blocks, various steps inFIG. 4may be divided into additional steps, combined into fewer steps, or eliminated, depending on the desired implementation.

The method400may begin at step402, in which one or more optoelectronic components may be coupled to the surface of the PCB. For instance, the optoelectronic components108ofFIGS. 1A-1Bmay be coupled to the surface of the PCB. Accordingly, at least one optoelectronic component may be coupled to a surface of the PCB. In some configurations, the optoelectronic component may be soldered to the conductive couplings of the PCB, thereby mechanically coupling the optoelectronic to the PCB and electrically coupling the electrical components to the conductive traces.

At step404, the surface of the PCB may be lasered to form a laser-roughened area on the surface of the PCB. The laser may be applied to a certain area on the surface of the PCB. For example, the laser may applied on portions of the PCB where it may be desirable to remove contaminants and/or increase the roughness of the surface. In particular, the laser may applied to a portion of the PCB where a component is to be coupled to the surface of the PCB. The area where the laser is applied may be a laser-roughened area, and the area where the component is coupled to the PCB may be a coupling area. The shape of the laser-roughened area may correspond to the shape of the coupling area. In some configurations, the laser-roughened area is smaller than the coupling area. The laser-roughened area may surround the optoelectronic components in a plane defined by the PCB.

The laser may remove at least a portion of a layer of the PCB and/or may increase the roughness of the surface of the PCB. In some aspects, the laser may increase the arithmetical mean deviation of the assessed profile of the surface of the PCB by at least 0.1. Further, the laser may remove contaminants from the surface of the PCB. The laser may improve the coupling of the optical component to the printed circuit board by increasing the roughness of the surface of the printed circuit board and/or removing removes contaminants from the surface of the printed circuit board. In some configurations, a solder mask may be applied over the PCB before the lasering. In such configurations, the laser may remove at least a portion of a solder mask on the PCB.

The power, intensity and/or wavelength of the laser may be selected to be sufficiently high to increase the roughness of the surface and/or remove contaminants without damaging the PCB and/or components coupled to the PCB. The desired power, intensity and/or wavelength of the laser may depend on materials included in the PCB (e.g., layers of the PCB), materials of the contaminants, materials of components coupled to the PCB, or any suitable combination thereof. In one example, the laser may be an ultraviolet laser, for example, a laser emitting electromagnetic radiation within a range of ultraviolet wavelengths. In some circumstances, ultraviolet wavelengths may include wavelengths between 100 nanometers (nm) and 400 nm. In some configurations, the laser may be a 355 nm wavelength laser, although other suitable configurations may be implemented. Additionally or alternatively, inn some configurations the laser may include a laser power of 3 Watts (W).

In some configurations, the surface of the substrate or the PCB may be visually inspected. Applying the laser to the surface of the substrate or the PCB may visibly modify the surface in the area that the laser is applied. In particular, the laser may be applied for a sufficient time and duration to decompose a surface of the PCB such that the laser-roughened area is visually perceptible. Accordingly, it may be possible to determine whether a portion of the printed circuit board has been lasered, whether contaminants have been removed from a certain area on the surface and/or whether the area has been roughened by visually inspecting the surface. For example, the laser may change the color or texture of the surface where the laser is applied. In particular, the color or texture of the surface may be different in an area because all or a portion of a layer may be removed by the laser. Such configurations may also facilitate positioning of components to be coupled to the surface, because the visibly modified surface may indicate where the component should be attached to the surface.

Additionally or alternatively, visual inspection of the surface may facilitate in determining whether or not the laser was successfully applied to the surface, whether contaminants were removed in certain areas on the surface, and/or whether the surface was roughened in certain areas. In such configurations, components may be coupled to the surface in areas where contaminants have been removed and/or have been laser-roughened.

At step406, an optical component may be coupled to the surface of the PCB. The optical component may be coupled to the surface at the coupling area and/or the laser-roughened area formed by applying the laser. In some configurations, the optical component may be a lens, although the concepts described herein may be applied to other types of components. The optical component may be attached at a coupling area on the surface of the printed circuit board, and the laser-roughened area may be positioned at least partially or fully inside of the coupling area. The optical component may be coupled to the surface in any suitable manner, and in some configurations an adhesive may be used. In some circumstances, the optical component may be optically aligned with one or more optoelectronic component coupled to the surface.

FIGS. 5A-5Billustrate an optical component550coupled to the surface of the PCBA100. In particular,FIG. 5Ais a top schematic view of the PCBA100with the optical component550andFIG. 5Bis a side schematic view of the PCBA100with the optical component550coupled to surface. In some configurations, the optical component550may be coupled to the surface of the PCBA100at the coupling area110and/or the laser-roughened area112formed by applying the laser (seeFIG. 1A). In some configurations, the optical component550may be a lens, although the concepts described herein may be applied to other types of components. The optical component550may be attached at a coupling area on the surface of the PCBA100, and the laser-roughened area may be positioned at least partially or fully inside of the coupling area. The optical component550may be coupled to the surface in any suitable manner, and in some configurations an adhesive may be used. In some circumstances, the optical component550may be optically aligned with one or more optoelectronic component coupled to the surface.

In some configurations, the optical component550may at least partially enclose optoelectronic components, such as the optoelectronic components108ofFIG. 1A, after the optical component550is coupled to the PCBA100. Additionally or alternatively, the optical component550may hermetically seal optoelectronic components in between the PCBA and the optical component550. Accordingly, the optoelectronic components108ofFIG. 1Amay be hermetically sealed between the PCBA100and the optical component550after the optical component550is coupled to the PCBA100. The optical component550may be a lens optically coupled or optically aligned to the optoelectronic components108.

In some configurations, at least one electrical component may be attached to the surface of the PCB, such as the electrical components104a-eofFIGS. 1A-1B. In some configurations, the electrical component(s) may be coupled before the laser is applied, although any suitable configuration may be implemented. The electrical component(s) may be electrically coupled by conductive couplings such as traces, tracks, pads and/or other features etched from one or more layers of electrically conductive material, such as copper. In some configurations, the electrical component(s) may be soldered to electrically and mechanically couple them to the substrate or the PCB.

In some circumstances, lasering the surface of the substrate or the PCB may be improve the bond between the component and the surface. In particular, the laser may improve the coupling of the optical component to the printed circuit board by increasing the roughness of the surface of the printed circuit board and/or removing contaminants from the surface of the printed circuit board. Such configurations may improve bonds when adhesives are used, buy may also be similarly advantageous in other bonding mechanisms. Furthermore, the configurations described herein may be used to avoid weak bonds, formed, for example, by contaminants and/or smooth surfaces of the substrate or PCB.

When the concepts described are implemented to bond optical components to the PCB, the resulting bond may robustly secure the optical component to the PCB. Furthermore, weak bonds may be avoided by removing any contaminants from the surface of the PCB where the optical component is bonded to the PCB. In such circumstances, the bond formed may be stronger and therefore may not break over time. The stronger bond may be useful during subsequent processing of the PCB to form the optoelectronic assembly, because the bond will not break during handling or subsequent processing. Additionally or alternatively, the stronger bond may not break after the optoelectronic assembly is manufactured, for example, during operation of the optoelectronic assembly. Such configurations may also prevent optoelectronic assemblies from failing prematurely because weak bonds caused by smooth surfaces or contaminants on the surface of the PCB may be avoided.

Although the described configurations may be particularly advantageous to bond optical components to PCBs, in other configurations the concepts described herein may be applied to improve bonding between any component and a PCB, for example, electrical components or any other component that may be bonded to a PCB.

The terms and words used in the description and claims are not limited to the bibliographical meanings, but, are merely used to enable a clear and consistent understanding of the disclosure. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.

As used herein, an “electrical component” refers to a component that involves electricity, an “optical component” refers to a component that involves electromagnetic radiation (e.g., visible light or others), and an “optoelectronic component” refers to a component that involves both electrical signals and optical signals, and/or the conversion of electrical signals to optical signals, or vice versa.

Aspects of the present disclosure may be embodied in other forms without departing from its spirit or essential characteristics. The described aspects are to be considered in all respects illustrative and not restrictive. The claimed subject matter is indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.