Patent Application
20240369633
The following relates to the electronic equipment inspection arts, electronic equipment failure detection arts, and related arts.
Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.
The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
A semiconductor fabrication facility contains a large amount of electrical equipment, including semiconductor processing tools and power delivery electrical equipment such as low-voltage switchgear (LV SWG) panels. A well-maintained routine of scheduled inspection of the large inventory of electrical equipment advantageously can detect incipient issues and enable timely equipment maintenance or replacement to reduce likelihood of unexpected interruption of the semiconductor processing workflow due to electrical equipment malfunction.
There are a number of failure modes by which electrical equipment can fail. In the case of electrical equipment carrying high voltages and/or high electrical current levels, some failure modes relate to fatigue or degradation of the electrical conductors or electrical connections. Such failure modes may be detectable as thermal hot spots generated by elevated electrical resistance at the fatigued or degraded electrical conductor, or elevated galvanic resistance of a degraded electrical connection.
Another possible failure mode is the formation of a tin whisker or whiskers. This failure mode can occur in the case of tin-coated copper or copper alloy bars of LV SWG panels or similar electrical equipment having tin-coated copper or copper alloy conductors. The tin coating serves as a protective coating. The mechanism of tin whisker formation is not fully understood, but is believed to be due to crystalline metallurgical tin migration growth driven by electric fields on the copper or copper alloy conductor. More generally, metal whisker formation (of which tin whisker formation is one example) has been observed in the case of various metal coatings such as tin, zinc, and lead. Tin whiskers can grow to lengths in excess of a one centimeter or longer. In the close confines of tightly packed electrical components and closely spaced electrical conductors common in commercial electrical equipment such as LV SWG panels, tin whiskers can easily produce electrical shunting or shorting and consequent degradation of failure of the subject electrical equipment. While metal whiskers can be relatively long, on the order of a centimeter or more, they are typically very thin, being metallic hairs or whiskers. Tin whiskers, for example, can be on the order of 1-5 microns in diameter, and zinc whiskers are also on the order of a few microns in diameter. The metal whiskers are also usually made of the same metal as the coating (e.g., tin whiskers forming on a tin-coated copper or copper alloy conductor), so that they can blend into the background on visual inspection. Hence, in spite of their substantial length, metal whiskers can easily escape detection during visual inspection of electrical equipment.
The tight confines within the housings of typical commercial electrical equipment further increase the difficulty in detecting hot spots, metal whiskers, or other manifestations of incipient equipment failure modes.
Disclosed herein are inspection apparatus and corresponding inspection methods which beneficially increase the visibility and likelihood of detection of failure modes such as hot spots and metal whiskers. In some illustrative embodiments, the inspection apparatus includes an endoscope with both infrared and visible light imaging sensors, and a visible light source for providing illumination for the inspection using the visible light imaging sensor. In some embodiments, the visible light source is a green light source, as it is recognized herein that green light is especially effective for detecting metal whiskers. This is due to several factors, including strong scattering of green light by metallic features such as metal whiskers, and high sensitivity of the human eye to green light. In a further aspect, in some embodiments the infrared and visible light imaging sensors (and hence the corresponding acquired infrared and visible light images) have significantly different spatial resolutions, with the visible light imaging sensor being higher resolution than the infrared imaging sensor. Making the infrared imaging sensor of lower resolution advantageously enables the infrared sensor to be a smaller and lower-cost component-yet, as recognized herein performance of the inspection apparatus is not degraded because the infrared imaging sensor is mainly used to detect thermal hot spots which are relatively large (especially compared with the micron-sized diameter of metal whiskers).
With reference now to
With continuing reference to
The illustrative rod 12 is a straight rod, and may for example be made of hollow tubular plastic sections 30, 31, 32, and a plastic section for the probe 16 with the imaging sensors 20 and 22 visible light sources 24 and 26 mounted thereon, and a plastic connector 33. The detachable connections between the sections may be implemented for example as threaded connections, or friction- or resistance-fit connections (e.g., with one section having a narrowed outer diameter at one end that fits into an inner diameter of the mating section to form the frictional fitting), or so forth. In another contemplated embodiment (not shown), the rod could be a hollow semi-flexible gooseneck tube that can be bent to form a curve but has enough rigidity to hold the curve.
With reference to
The electrical conductors 36 are connected to transmit infrared imaging data acquired by the infrared imaging sensor 20 to the proximal portion 14 of the rod 12 and to transmit visible light imaging data acquired by the visible light imaging sensor 22 to the proximal portion 14 of the rod 12.
As previously noted, the infrared image or video 50 is generated from infrared imaging data acquired by the infrared imaging sensor 20, and the visible light image or video 52 is generated from visible light imaging data acquired by the visible light imaging sensor 22. The infrared imaging sensor 20 comprises a two-dimensional array of pixels in which each pixel is sensitive to, and capable of measuring an intensity of, infrared light impinging on the pixel. For example, the infrared imaging sensor 20 may comprise a CMOS imaging array, a CCD imaging array, or so forth. Likewise, the visible light imaging sensor 22 comprises a two-dimensional array of pixels in which each pixel is sensitive to, and capable of measuring an intensity of, visible light impinging on the pixel. For example, the visible light imaging sensor 22 may comprise a CMOS imaging array, a CCD imaging array, or so forth. The spatial resolution of the infrared imaging sensor 20 and of the acquired infrared image or video 50 may be measured in terms of the number of pixels in the two-dimensional array of pixels of the infrared imaging sensor 20. Likewise, the spatial resolution of the visible light imaging sensor 22 and of the acquired visible light image or video 52 may be measured in terms of a number of pixels in the two-dimensional array of pixels of the visible light imaging sensor 22.
In general, higher spatial resolution (corresponding to a higher number of pixels in the array of the imaging sensor) improves likelihood of detecting small features in the image or video, but also correlates with higher cost of the imaging sensor and also to a larger overall size of the imaging sensor in order to accommodate the higher number of pixels. As recognized herein, the optimal spatial resolution for the infrared imaging sensor 20 and corresponding infrared image or video 50 is different from the optimal spatial resolution for the visible light imaging sensor 22 and corresponding visible light image or video 52. The infrared image or video 50 is typically used to identify thermal hot spots in conductors, connections, or components of the electrical equipment undergoing inspection. Such thermal hot spots can indicate degradation and/or incipient failure of the electrical equipment. The thermal hot spots tend to appear as bright regions of the thermal image or video 52, since a hot spot emits a higher amount of infrared light (e.g., according to the Stefan-Boltzmann law, the total emitted radiant heat energy from a hot surface scales with the fourth power of its absolute temperature). Thermal hot spots tend to be relatively large, e.g. comparable with the size of the connection, conductor, or component that is running at an unacceptably high temperature. Hence, the spatial resolution of the infrared sensor 20 and of the corresponding infrared image or video 50 can be relatively low. For example, in some embodiments, the infrared imaging sensor 20 has a spatial resolution of one million pixels or lower. As one nonlimiting specific example, the infrared imaging sensor 20 may comprise a two-dimensional array of 120×160 pixels, so that the number of pixels is 120×160=19,200 pixels. Using a relatively small number of pixels in the infrared imaging sensor 20 (e.g., one million pixels or less in some embodiments) advantageously reduces the cost and complexity of the infrared imaging sensor 20 and can enable a reduced overall size for the infrared imaging sensor 20, without concomitant loss of functionality in detecting thermal hot spots while inspecting electrical equipment. While a smaller number of pixels in the infrared imaging sensor 20 can have such advantages, it is also contemplated for the infrared imaging sensor to have a higher number of pixels, e.g. greater than one million pixels.
Different considerations govern optimization of the visible light imaging sensor 22. The visible light image or video 52 is typically used to identify tin (or other metal) whiskers, dust particle accumulations, or the like. Such features can lead to electrical shunting or even electrical shorting, and consequent degradation or failure of the subject electrical equipment. For example, a tin whisker may originate on the tin-coated surface of one copper conductor or electrical connection; however, as it grows it extends further and further away from that source copper conductor or electrical connection, and by such growth can reach toward another copper conductor or electrical connection, eventually resulting in an electrical arc or short conducting through the tin whisker. Similarly, dust particle accumulation on surfaces of electrical equipment can provide shunting paths, and/or can constitute thermal insulation that adversely affects functionality. Metal whiskers, dust, and so forth are fine features: for example, while a tin whisker can have a length in excess of one centimeter, its diameter is typically on the order of a few microns. Hence, the spatial resolution of the visible light sensor 22 and of the corresponding visible light image or video 52 should be relatively high to provide sufficient resolution to detect these fine features. For example, in some embodiments, the visible light imaging sensor 22 has a spatial resolution of at least five million pixels. As one nonlimiting specific example, the visible light imaging sensor 22 may comprise 12 million pixels. These are merely nonlimiting illustrative examples.
In the case of acquisition of the infrared image or video 50 by the infrared imaging sensor 20, the image or video is capturing infrared light emitted by the electrical conductors, connections, and/or components of the electrical equipment due to heating of such conductors, connections, and/or components during operation of the electrical equipment. For example, a poor electrical connection undergoes resistive heating due to electrical conduction through the resistive connection, and this causes emission of heat in the form of infrared light that appears as a hot spot in the infrared image or video 50. As such, no applied illumination is required for the infrared imaging sensor 20 to acquire the infrared image or video 50. Hence, the illustrative endoscope 10 does not include an infrared LED or other infrared light source. Also, if the infrared imaging sensor 20 includes a suitable visible light blocking filter, then the infrared imaging sensor 20 is insensitive (or mostly insensitive) to visible light illumination.
On the other hand, acquisition of the visible light image or video 52 by the visible light imaging sensor 22 generally employs illumination applied by the at least one visible light source 24 and/or 26. For example, the endoscope 10 is often used to inspect electrical equipment that is housed within a housing or other enclosure that substantially blocks out any ambient visible light. The characteristics of the visible light image or video 52 thus depend not only on the characteristics (e.g. number of pixels) of the visible light imaging sensor 22, but also on the characteristics of the applied illumination. In this regard, it is recognized herein that green light is especially effective for detecting metal whiskers, dust, and other fine features. Green light exhibits strong scattering by metallic features such as metal whiskers, the human eye has highest sensitivity to green light when compared with other colors of visible light. Hence, in the illustrative embodiment of
An advantage of using a green LED as the green light source 26 is a green LED produces relatively monochromatic green illumination light. For example, a typical commercially available green LED has a main peak in the green spectral range (that is, a light spectrum with a maximum intensity peak at a wavelength equal to or greater than 495 nanometers and less than or equal to 570 nanometers), with a full-width-at-half-maximum (FWHM) of 50 nm or less. Some commercial green LEDs designed for narrow spectrum have a FWHM of 10 nm or less. Using a green LED as the green light source 26 thus provides relatively monochromatic green light illumination which can promote detection of small features such as metal whiskers with narrow diameter on the order 1-5 microns by way of light scattering, reflection, and potentially also constructive and destructive optical interference of the narrowband green light. The user interface 54 of
While green light is disclosed herein as especially useful for detecting metal whiskers and other fine features during electrical equipment inspection for reasons stated above, it is alternatively contemplated to use illumination of a different color (e.g. orange light, red light, or so forth) or to use white light illumination for acquiring the visible light image or video 52. Furthermore, the illustrative embodiment of
With continuing reference to
In the embodiment of
With reference now to
With reference now to
With the rod 12 (as-is if the rod is of fixed length, or after assembly according to operation 70 if the rod is modular), the user manually positions the endoscope 10 so that the imaging sensors 20 and 22 view the electrical equipment undergoing inspection.
In an operation 74, infrared imaging data are acquired, for example using the infrared imaging sensor 20 of the endoscope 10. In an operation 76, the infrared image or video 50 is generated from the infrared imaging data and displayed, e.g. on the display 42 of the electronic controller 40. The generation of the infrared image 50 may entail, for example, receiving the pixel values from the infrared imaging sensor 20 as a sequence of numbers forming the infrared imaging data and rendering the pixel values in a two-dimensional array to form the infrared image or video 50. Although not shown in
In similar fashion, in an operation 80, green light imaging data are acquired. In some embodiments, the operation 80 uses the white light imaging sensor 22 in combination with green light illumination provided by the green light source 26. In an operation 82, the green light image or video 52 is generated from the green light imaging data and displayed, e.g. on the display 42 of the electronic controller 40. The generation of the green light image 52 may entail, for example, receiving the pixel values from the white light imaging sensor 52 as a sequence of numbers forming the green light imaging data and rendering the pixel values in a two-dimensional array to form the green light image or video 52. Although not shown in
In some embodiments, the operations 74, 76, 80, and 82 are performed concurrently to acquire and display the infrared image 50 and the green light image 52 simultaneously. If this is the case, then the infrared imaging sensor 20 should include a white light blocking filter to block the green light illumination from reaching the photosensitive pixels of the infrared imaging sensor 20. Alternatively, the operations 74 and 76 can be performed at a different time than the operations 80 and 82. In this case, the blocking filter can optionally be omitted and the green light source 26 turned off during the operations 74 and 76. (typically, the white light source 24, if provided, will be off at least during the operations 74 and 80).
With continuing reference to
In a variant embodiment, an automated algorithm performed by the electronic controller 40 may automatically detect thermal hot spots in the infrared image or video 50. For example, the automated algorithm may determine a histogram of pixel intensity values for the infrared image (which may be a video frame in the case of video). Each bar of the histogram corresponds to an intensity range bin and each bar has a value corresponding to a count of the number of pixels whose intensity value falls in that intensity range bin. From the histogram, an average or other characteristic intensity value and the range of intensity values over the image may be determined. Using these values, a threshold intensity for detecting thermal hot spots is chosen, and then any region of the image whose intensity is above that threshold is flagged as a thermal hot spot. In other embodiments, a machine learning algorithm such as a convolutional neural network (CNN) can be trained to detect thermal hot spots using a corpus of training infrared images for which depicted thermal hot spots are labeled. The algorithm can automatically annotate any identified thermal hot spots in the displayed infrared image or video 50, e.g. using the crosshairs and “1”, “2” and “3” labels as shown in
With continuing reference to
In a variant embodiment, an automated algorithm performed by the electronic controller 40 may automatically detect tin whiskers in the green light image or video 52. For example, matched filter techniques can be used to detect characteristic long thin features as tin whiskers, optionally after applying an edge enhancement filter to strengthen the image contrast of the tin whiskers. In other embodiments, a machine learning algorithm such as a CNN can be trained to detect tin whiskers using a corpus of training green light images for which depicted tin whiskers are labeled. The algorithm can automatically annotate any identified tin whiskers in the displayed green light image or video 52, e.g. using the annotated circle of
While the operations 80, 82, 90, and 92 are described above as using green light images, more generally these operations could be performed in conjunction with illumination of another color, or in conjunction with white light illumination.
In the following, some further embodiments are described.
In a nonlimiting illustrative embodiment, an inspection apparatus is disclosed for performing electrical equipment inspection. The inspection apparatus includes a rod, a probe attached to a distal end of the rod, an infrared imaging sensor disposed on the probe, at least one visible light source disposed on the probe, and a visible light imaging sensor disposed on the probe. Electrical conductors pass through the rod from the probe at the distal end of the rod to a proximal portion of the rod opposite from the distal end of the rod. The electrical conductors are connected to transmit infrared imaging data acquired by the infrared imaging sensor to the proximal portion of the rod, and to transmit visible light imaging data acquired by the visible light imaging sensor to the proximal portion of the rod.
In a nonlimiting illustrative embodiment, an inspection method for electrical equipment inspection is disclosed. An infrared image or video of electrical equipment is acquired using an infrared imaging sensor. A green light image or video of the electrical equipment is acquired using a visible light imaging sensor and while illuminating the electrical equipment with green light illumination provided by a green light source. The infrared image or video of the electrical equipment is displayed on a display. The green light image or video of the electrical equipment is displayed on the display.
In a nonlimiting illustrative embodiment, an inspection apparatus s disclosed for performing electrical equipment inspection. The inspection apparatus includes a rod, a probe attached to a distal end of the rod, a green light source disposed on the probe and configured to emit green light, and a visible light imaging sensor disposed on the probe. An electronic controller is configured to acquire a green light image or video of the associated electrical equipment using the green light source and the visible light imaging sensor, and display the green light image or video on a display of the electronic controller.
The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.
