Patent Description:
Instruments and apparatus systems that are used for viewing, recording, and analyzing the results of biological and chemical tests and assays often require instrumentation such as a charge-coupled device (CCD) camera, a complementary metal-oxide-semiconductor (CMOS) imager, or other such image sensor. The older CCD and CMOS package designs as shown in <FIG>, left a lot of room on the back side of the image sensor to attach cold fingers for heat dissipation. For instance, <FIG> provides a schematic representation of Sony ICX <NUM> CCD image sensor with the box area indicating an area where the cold fingers could contact the image sensor. The documents <CIT> and <CIT> are relevant prior art documents.

However, the more modern CMOS image sensor, such as a Sony IMX <NUM> image sensor shown in <FIG> and <FIG>, or a Sony IMX183 image sensor shown in <FIG>, have an architecture of grid arrays and thus do not have much available areas for the cold fingers to contact for thermal dissipation.

All other things being equal, the heat conduction using a conventional cold finger is proportional to the area of the image sensor and can be determined by the following equation: <MAT> where:.

Therefore, the heat conducted out of the older image sensor Sony ICX695 (with an area of <NUM><NUM>) of <FIG> is <NUM> times faster than the heat conducted out of the more modern image sensor Sony IMX178 (with an area of <NUM><NUM>) of <FIG>; and the heat conducted out of the older image sensor Sony ICX695 (with an area of <NUM><NUM>) of <FIG> is <NUM> times faster than the heat conducted out of the more modern image sensor Sony IMX183 (with an area of <NUM><NUM>) of <FIG>.

Nevertheless, some existing image sensors comprise pads located at corners of the image sensor as shown in <FIG>. Even if the corner pads are not directly connected with each other by vias inside body of the image sensor, the bulk heat conduction inside the body of the image sensor will pull heat away when the corner pads are cooler than the bulk silicon of the pixel plane of the image sensor.

There continues to be a need in the art for improved designs and techniques for an image sensor assembly with thermally conductive structures for dissipating heat from the image sensor to maintain a controlled temperature for operations of the image sensor.

Embodiments of the subject invention pertain to an electronic component assembly having thermal pads with thermal vias for transferring heat from the image sensor, and an image sensor assembly with active cooling by a thermoelectric cooling element (TEC) for heat dissipation from the image sensor. The invention is solely and uniquely as recited in claims <NUM> and <NUM> with further advantageous embodiments recited in the dependent claims.

According to an embodiment of the invention, an electronic component assembly can comprise a circuit board comprising at least one thermal pad disposed on a top surface of the circuit board; and an image sensor disposed on the top surface of the circuit board, comprising at least one conductive pad disposed at at least one corner of the image sensor; wherein the at least one thermal pad is coupled to the at least one conductive pad of the image sensor; and wherein the at least one thermal pad is formed with a plurality of first thermal vias penetrating the thermal pad and the circuit board for transfer of heat of the image sensor. The electronic component assembly can further comprise a thermally conductive layer disposed on a bottom surface of the circuit board, wherein the thermally conductive layer is made of metal, has a circular or annular shape, and has a plurality of second thermal vias penetrating the thermally conductive layer and being spaced in the thermally conductive layer to transfer heat. Moreover, the electronic component assembly can further comprise a thermal compound material applied between corner areas of the image sensor and corner areas of the thermal pad comprising the thermal vias and extending along lengths of the first thermal pad. The electronic component assembly can further comprise a cooling structuring coupled to the circuit board for transferring heat, wherein the cooling structuring comprises at least one cold finger structure protruding through a through-hole of the circuit board and contacting a surface of the image sensor for transferring heat. Furthermore, the electronic component assembly can comprise a lens mount for mounting the lens, wherein the lens mount and the image sensor are horizontally disposed on a same surface of the top surface of the circuit board.

In another embodiment, an image sensor assembly can comprise a cooling structure comprising at least one thermoelectric cooling element (TEC); a circuit board disposed on the cooling structure; an image sensor; and a lens. The image sensor assembly can further comprise an image sensor cover disposed on the image sensor, the lens and the image sensor cover directly contacting or indirectly contacting through a sil pad or graphoil, a lens outer barrel in contact with the image sensor cover, a heat sink structure coupled to the cooling structure, a plurality of fasteners coupling the lens outer barrel to the heat sink structure, wherein the image sensor assembly comprises a structure with a chamber or a structure without a chamber. Moreover, the heat can be transferred from the lens outer barrel to the sil pad or graphoil, from the sil pad or graphoil to the image sensor cover, from the image sensor cover to the image sensor, from the image sensor to the circuit board, from the circuit board to the cooling structure, from the cooling structure to the heat sink. The image sensor cover can be configured to be a solid block of minimal thermal conductivity bonded to the image sensor or a pocket bonded to some or all portions of the image sensor to provide heat to the top surface to avoid condensation when the image sensor is cooled. Heat can be additionally piped through the circuit board with corner pads, central finger, or both. The image sensor assembly can additionally comprise a plurality of gaskets disposed between the lens outer barrel and the circuit board to reduce heat transfer from the lens outer barrel, a plurality of, for example three, reduced areas where the gaskets contact the circuit board and the gaskets make up the intervening space to block light from getting to the image sensor. The image sensor assembly can further comprise a plurality of washers preferably in a form of Belleville washers, respectively disposed between the plurality of gaskets and the circuit board for tilt adjustment. The image sensor assembly can further comprise a lens mount for mounting the lens, and the image sensor and the lens mount can be horizontally disposed on a same plane of the top surface of the circuit board or the image sensor and the lens mount can be disposed to vertically overlap on the top surface of the circuit board.

Embodiments of the subject invention pertain to an electronic component assembly having thermal pads with thermal vias for transferring heat from the image sensor, and an image sensor assembly with active cooling by a thermoelectric cooling element (TEC) for heat dissipation from the image sensor.

Referring to <FIG>, an electronic component assembly such as an image sensor assembly <NUM> can comprise an image sensor <NUM> comprising an image sensor pixel array <NUM> and at least one conductive pad <NUM>; and a camera board fab <NUM> disposed beneath the image sensor <NUM> and coupled to the corner or other non-electrically-functional pads of the image sensor <NUM> and comprising at least one thermal pad <NUM> disposed on a top surface of the camera board fab <NUM>. The at least one thermal pad <NUM> extends under the image sensor <NUM> and is attached directly to the at least one conductive pad <NUM> as shown in <FIG> and in <FIG>.

The image sensor pixel array <NUM> is disposed on a top surface of the image sensor <NUM> and can be a CCD, a CMOS, an organic image sensor, or other such image sensor. The at least one conductive pad <NUM> is disposed on at least one corner area of the top surface of the image sensor <NUM> and is coupled to the at least one thermal pad <NUM> which can thereby cool the image sensor pixel array <NUM> to maintain the image sensor pixel array <NUM> within an operating temperature range.

In certain embodiments, the thermal pad <NUM> can be arranged to be placed on a top surface of the camera board fab <NUM> and extended along the edges of the lateral surfaces or the other surfaces of the corner areas of the image sensor <NUM> to draw thermal energy from the image sensor pixel array <NUM> toward a heat sink (not shown) that disperses the thermal energy or re-route the thermal energy to another element of the image sensor assembly <NUM>. One advantage provided by such arrangement is that the thermal pad <NUM> extends the heat removal path beyond the image sensor <NUM>.

In one embodiment, the thermal pad <NUM> can be formed with a plurality of first thermal vias <NUM> penetrating through the thermal pad <NUM> and through the camera board fab <NUM> to the bottom surface of the camera board fab <NUM> for transferring heat. A thermal via is a thermally conductive conduit through which heat is conducted. At least one of the plurality of first thermal vias <NUM> preferably has a shape of a cylinder and is preferably made of metal such as copper (Cu) or copper alloy. Moreover, the at least one of the plurality of first thermal vias <NUM> can be hollow or be filled with a thermally conductive material.

Moreover, instead of having a finger of Cu going up through a through-hole in the camera board fab <NUM> and touching the bottom surface of the image sensor <NUM>, the plurality of first thermal vias <NUM> can be disposed directly under the conductive pad <NUM> of the image sensor <NUM> with or without solder paste on the top surface of the camera board fab <NUM> via stencil, according to an embodiment of the subject invention. The plurality of first thermal vias <NUM> can be filled with a thermal conductive material, sanded flat and plated. The solder paste if present can be put on a top surface of the plurality of first thermal vias <NUM> such that when the solder paste melts, the solder paste makes direct contact with the bottom surface of the image sensor <NUM>.

The dark current can be reduced with such arrangement on an order of half in comparison with a conventional image sensor assembly.

In one embodiment, the at least one conductive pad <NUM> can be thermally or electrically connected with each other. The at least one conductive pad <NUM> may comprise a signal pad for transmitting or receiving signals for the operations of the image sensor pixel array <NUM>.

<FIG> is a close-up view of one of the thermal pads <NUM> of <FIG> with the plurality of thermal vias <NUM> and coupling the image sensor <NUM> and the camera board fab <NUM>, according to an embodiment of the subject invention.

<FIG> is a schematic view of the image sensor assembly <NUM> of <FIG> according to an embodiment of the subject invention. The at least one thermal pad <NUM> is disposed on a surface of the camera board fab <NUM>, extending under the image sensor <NUM> and attached directly to the at least one conductive pad <NUM>.

<FIG> and <FIG> are views of a back side of a prototype of the image sensor assembly <NUM>, wherein the four corner areas are visible in light green color and red lines outlines the outer and inner boundaries of the copper plane on the back side of the circuit board, according to an embodiment of the subject invention.

As illustrated in <FIG>, the camera board fab <NUM> can comprise a thermally conductive layer <NUM> on a bottom surface or a top surface or both surfaces of the camera board fab <NUM>. The thermally conductive layer <NUM> can be made of metal preferably in a form of copper (Cu) or copper alloy and preferably have a circular or annular shape. The thermally conductive layer <NUM> can be formed with a plurality of second thermal vias <NUM> spaced in the thermally conductive layer <NUM> and penetrating the thermally conductive layer <NUM> to increase transfer heat from the front surface and any connected planes inside the camera board fab <NUM> to the rear surface of the camera board fab <NUM>. The thermally conductive layer <NUM> is indicated by the area between the outer red circle and the inner shape in red of <FIG>. The four corner pads with the plurality of vias may have an adhesive such as epoxy on them.

In one embodiment, the thermally conductive layer <NUM> intersects with both the first thermal vias <NUM> as well as the second thermal vias <NUM> shown in <FIG>, allowing the heat to be laterally dispersed better than it would be with only thermally conductive layers <NUM> on the top and bottom surfaces of the camera board fab <NUM>. The thermally conductive layer <NUM> may have a thickness of, for example, <NUM>.

In one embodiment, the thermally conductive layer <NUM> can be arranged to include a laminated structure having a plurality of thermally conductive layers.

<FIG> is a three-dimensional magnified schematic representation (with the thickness dimension is expanded <NUM> times for viewing) of the image sensor assembly <NUM>, illustrating the thermal pads <NUM> with the thermal vias <NUM> coupling the image sensor <NUM> and the camera board fab <NUM> through the at least one conductive pad <NUM> indicated by the area in the red circles in <FIG>, according to an embodiment of the subject invention.

<FIG> is a perspective view of the image sensor assembly <NUM> having the thermally conductive layer <NUM> on a bottom surface of the camera board fab <NUM>, according to an embodiment of the subject invention.

Referring to <FIG>, combined mode visible light and <NUM>-<NUM> mid-infrared (MIR) microscopy images are taken for the image sensor assembly <NUM> and <FIG> illustrate corresponding temperature profiles of the image sensor assembly <NUM> derived from <FIG>. The horizontal line in <FIG> is where the temperature profile is drawn. It is noted that the image sensor <NUM> is a slightly darker rectangle in the middle of the four corner thermal pads <NUM>. When the thermally conductive layer <NUM> is attached to the back side of the image sensor <NUM> through solder connections between the at least one conductive pad <NUM> and the thermal pad <NUM> to allow passive heat sinking, the at least one corner thermal pads <NUM> is dramatically cooler and the image sensor <NUM> is colder than the camera board fab <NUM>.

As illustrated in <FIG>, the image sensor <NUM> can further comprise a plurality of signal pads that transmits or receives signals and the signal pads can be thermally connected to the camera board fab <NUM> to dissipate heat to maintain a controlled temperature for the operations of the image sensor. If the signal pads are grounded ones, they can connect through electrically conductive material such as vias or planes to the back side of the camera board fab <NUM>. The red circles are ones representing where there is a connection inside the image sensor <NUM> from the pad to the pixel plane. The blue ones go through internal circuitry inside the part.

To additionally improve the thermal dissipation efficiency, the image sensor assembly <NUM> can further comprise a cooling structure coupled to the camera board fab <NUM>. The cooling structure may comprise at least one cold finger or other forms of thermal extension component/s that is dimensioned to protrude through a through-hole of the camera board fab <NUM> so as to contact a surface of the image sensor <NUM> for heat transfer, as shown in <FIG> and <FIG>.

In one embodiment, as illustrated in <FIG>, the image sensor assembly <NUM> can further comprise a thermal compound material that may be disposed between corner areas of the thermal pad <NUM> and the corner areas of the image sensor <NUM> and extending along lengths of the thermal pad <NUM> for thermal conduction.

Moreover, instead of having a finger of Cu going up through a through-hole in the camera board fab <NUM> and touching the bottom surface of the image sensor <NUM>, the image sensor assembly <NUM> can further comprise a third plurality of thermal vias disposed directly under the image sensor <NUM> with or without solder paste on the top surface of the camera board fab <NUM> via stencil, according to an embodiment of the subject invention. The third plurality of thermal vias can be filled with a thermal conductive material, sanded flat and plated. The solder paste if present can be put on a top surface of the third plurality of thermal vias such that when the solder paste melts, the solder paste makes direct contact with the bottom surface of the image sensor <NUM>.

<FIG> and <FIG> are top views of the image sensor assembly showing the copper heat sink plate with the green lines indicating a cold finger in <FIG>, according to an embodiment of the subject invention. In comparison, <FIG> is an isometric view of the image sensor assembly from a top side, showing a plated surface under which the filled thermal vias are disposed, according to an embodiment of the subject invention. The blue perimeter in <FIG> is the plated surface under which the third plurality of thermal vias is disposed.

<FIG> is a schematic view of the image sensor assembly, showing a plurality of plated surfaces inside the camera board fab <NUM>, according to an embodiment of the subject invention. The filled thermal vias can be disposed on the plurality of plated surfaces inside the camera board fab. The thermal vias terminate at the bottom plated surface (lowest in <FIG>) and are covered with plating and the intermediate plated surfaces are disposed inside the camera board fab <NUM>. The third plurality of thermal vias is plated on the back side too, providing a flat surface for a Cu or other metal part to touch to conduct the heat out.

<FIG> is a schematic view of the image sensor assembly <NUM> in which the thermal compound material may be applied along entirety of periphery of the image sensor <NUM> for conducting the heat and for sealing to inhibit moisture from getting underneath the image sensor <NUM>, according to an embodiment of the subject invention.

In one embodiment, after the camera board fab <NUM> is made to have a flat surface without any holes, a plurality of holes is drilled on the flat surface of the camera board fab <NUM> and is cleaned, and then a plurality of via barrels is plated in the plurality of holes, respectively. Next, the via barrels are filled with epoxy and covered with Cu. A sanding operation can be additionally carried out to make the thermal vias all flat. Any thermal vias that are not covered by solder masks are plated.

In one embodiment, the space between the edges of the camera board fab <NUM> and the image sensor <NUM> are sealed along the edges. Such sealing together with the sealing around the edges of image sensor <NUM> on the upper surface of the camera board fab <NUM> described above seal off the bottom surface of the image sensor <NUM> where the contacts of the image sensor <NUM> are disposed, thereby inhibiting shorting.

In another embodiment, instead of sealing all the way around on the edges of upper surface of the camera board fab <NUM> to the edges of the image sensor <NUM> and the bottom surface of the camera board fab <NUM> and the hole to the image sensor <NUM>, an underfill material which flows underneath to inhibit condensation is applied. The underfill material may be, for example, a reworkable underfill encapsulant for a ball grid array (BGA), chip scale packages (CSPs), or wafer-level chip scale packages (WL-CSPs). It is noted that the thermal adhesive may still be applied to the corners of the image sensor <NUM> or all the way around on the edges of upper surface of the camera board fab <NUM> for the thermal conduction purpose.

In one embodiment, a conformal coating can be applied in the masked areas for inhibiting condensation-related shorting of the electronic components. In particular, on the upper surface of the camera board fab <NUM>, the conformal coating is applied around the image sensor <NUM> and extended out to the gasket light seal. More conformal coating may be applied outside the gasket light seal and extended to a location where a thermal testing indicates that the surface temperature of the camera board fab <NUM> goes below the ambient temperature or where no electronic components are exposed. In addition, if there are electronic components exposed on the bottom surface, the conformal coating can be applied on the bottom surface of the camera board fab <NUM>. Furthermore, if the camera board fab <NUM> has a flat backed board in direct contact with the TEC, the conformal coating may be applied around the edges of the Cu part where the camera board fab <NUM> gets cooled. Examples of the conformal coating include but not limited to glob top and dam-and-fill encapsulants.

In one embodiment, for additional thermal performance improvements, the image sensor assembly <NUM> can further comprise a lens mount <NUM> for mounting a lens and for acting as a heat sink by placing the lens mount <NUM> directly onto a top surface of the camera board fab <NUM>. The lens mount <NUM> and the image sensor <NUM> are horizontally disposed on a same surface of the camera board fab <NUM>, as shown in <FIG>.

In case that exact planarity between the lens <NUM> and the image sensor <NUM> is not achievable, depending on the method by which the lens <NUM> and the image sensor <NUM> are formed or mounted on the camera board fab <NUM>, it is desirable to have sufficient planarity to permit better thermal dissipation.

Dark currents of the image sensor for four different cooling structures are measured and the results of the measurements are summarized in Table <NUM>. It is noted that a significantly lower dark current is achieved when the lens is mounted directly onto the camera board fab <NUM> compared to when it is not mounted directly onto the camera board fab <NUM>.

Moreover, since the lens is directly mounted onto the camera board fab <NUM>, there is no intervening mount and back focus adjustment ring, adding point tolerances, thereby reducing the number of parts between lens <NUM> and the image sensor <NUM> by at least two.

<FIG> is a cross-sectional view of the passively cooled image sensor assembly according to an embodiment of the subject invention.

Referring to <FIG>, four different configurations: (a) the image sensor assembly <NUM> having both the thermal pads with the thermal vias arrangement and the cold finger, (b) the image sensor assembly <NUM> having only the thermal pads with thermal vias arrangement, (c) the image sensor assembly <NUM> having only the cold finger, and (d) having no thermal pads with thermal vias arrangement nor cold finger, respectively, are shown, respectively.

Results of simulations of temperature profiles of these three configurations in comparison with the image sensor assembly <NUM> having no thermal pads with thermal vias arrangement nor cold finger are summarized in Table <NUM>.

It is noted that the image sensor assembly <NUM> having the thermal pads with thermal vias only and the image sensor assembly <NUM> having the cold finger only are less effective than the image sensor assembly <NUM> having both the thermal pads with thermal vias and the cold finger in heat dissipation. The temperature of the image sensor is lowered by about <NUM> when the thermal pads with thermal vias are employed in conjunction with the cold finger. The image sensor assembly having neither thermal pads with thermal vias nor a cold finger is the least effective in heat dissipation among the four configurations by about <NUM> degrees Celsius.

Referring to <FIG>, an image sensor assembly <NUM> with active cooling by a thermoelectric cooling element (TEC) is illustrated according to an embodiment of the subject invention.

Referring to <FIG>, the image sensor assembly <NUM> can comprise a lens outer barrel <NUM>, a contact material <NUM> such as a sil pad, or other thermally conductive, compressible materials such as a graphoil or a direct physical connection, with or without a thermal paste, disposed under the lens outer barrel <NUM> to conduct heat from the lens outer barrel <NUM> to a top surface of an image sensor cover <NUM> that is disposed under the contact material <NUM>, a foam light seal <NUM> disposed around the image sensor <NUM> and the image sensor cover <NUM>, a camera board fab <NUM> on which the image sensor <NUM> is disposed, the camera board fab <NUM> disposed under the foam light seal <NUM>, a heat conductor <NUM> disposed under the camera board fab <NUM>, a single or multi-stage TEC <NUM> disposed under the heat conductor <NUM>, a heat sink <NUM> disposed under the TEC <NUM>, and a plurality of fasteners <NUM> such as screws for coupling the lens outer barrel <NUM> and a heat sink <NUM>. The screws comprise a metal such as copper for maximizing heat conduction.

In one embodiment, the image sensor cover <NUM> arranged to protect elements of the image sensor (not shown) can be hollow, bonded to an image sensor <NUM> and have dry gas inside. A desiccant material can be placed inside the hollow image sensor cover <NUM> and held in place by the image sensor cover <NUM> to absorb any moisture that is present ingresses through diffusion through the hollow image sensor cover <NUM> or the glue joint(s) in the assembly.

In another embodiment, the image sensor cover <NUM> can be in a form of at least one solid block bonded to the image sensor <NUM>. The at least one solid block of the image sensor cover <NUM> can be made of acrylic and glass. It is noted that acrylic has a low thermal conductivity of <NUM> W/mK, which is suitable for isolation, but higher thermal expansion than that of glass, making it difficult to be bonded to glass.

In another embodiment, the at least one solid block of the image sensor cover <NUM> can be made of borosilicate having a thermal conductivity of <NUM> W/mK.

In another embodiment, the image sensor cover <NUM> can be in a form of at least one pocket bonded to the image sensor <NUM>, with or without desiccant contained in the pocket. When the at least one pocket of the image sensor cover <NUM> does not include a desiccant, a dry gas such as Argon may be flowing through the pocket for removal of the moisture generated. The at least one pocket of the image sensor cover <NUM> can be made of acrylic or borosilicate glass.

Temperatures of the image sensor for different cooling structures of the image sensor cover <NUM> are measured and the results of the measurements are summarized in Table <NUM>. The image sensor cover <NUM> may include (<NUM>) a solid block made of acrylic and having a thickness of <NUM>; (<NUM>) a pocket made of acrylic and having a thickness of <NUM>; (<NUM>) a solid block made of acrylic and each having a thickness of <NUM>; (<NUM>) a pocket made of acrylic and each having a thickness of <NUM>; (<NUM>) a solid block made of borosilicate and each having a thickness of <NUM>; (<NUM>) a pocket made of borosilicate and each having a thickness of <NUM>; and (<NUM>) a pocket made of borosilicate and having a thickness of <NUM>. It is noted that a significantly lower image sensor temperature is achieved when the image sensor cover <NUM> includes four solid blocks made of borosilicate and each having a thickness of <NUM>.

<FIG> is an assembled view of a first pocket with an enclosed desiccant of the image sensor cover according to an embodiment of the subject invention.

<FIG> is an explosive view of the first pocket with the enclosed desiccant of the image sensor cover according to an embodiment of the subject invention.

<FIG> is another explosive view of the first pocket with the enclosed desiccant of the image sensor cover, the first pocket having a structure keeping pellets from going in according to an embodiment of the subject invention.

<FIG> is an assembled view of a second pocket with an enclosed desiccant of the image sensor cover according to an embodiment of the subject invention.

<FIG> is an explosive view of the second pocket with the enclosed desiccant of the image sensor cover according to an embodiment of the subject invention.

<FIG> and <FIG> are respectively a top view and a side view of the second pocket with the enclosed desiccant according to an embodiment of the subject invention.

In another embodiment, the second pocket with the enclosed desiccant can be made from three machined, water jet, or laser cut parts, the second pocket having a flat lower part with a hole in it bonded to the image sensor, a four-sided wall part, and a flat top part.

The image sensor <NUM> is disposed on a top surface of the camera board fab <NUM> and can be a CCD, a CMOS, an organic image sensor, or other such imager which is coupled to the TEC <NUM> which can thereby cool the image sensor to maintain an operating temperature range for the image sensor. If components are disposed on the back side of the camera board fab <NUM>, an intermediate highly thermally conductive heat conductor <NUM> can be positioned between the back surface of the camera board fab <NUM> and the TEC <NUM>. The TEC <NUM> can draw thermal energy from the image sensor toward the heat sink <NUM> which can disperse the thermal energy or re-route the thermal energy to another element of the image sensor assembly <NUM>.

In one embodiment, the TEC may be configured to transfer heat away from the image sensor within the apparatus in any suitable manner, for example, by direct coupling to the image sensor or by indirect coupling to the image sensor using thermally conductive material such as cold finger structures where necessary or desirable.

In one embodiment, the image sensor assembly <NUM> can comprise a chamber structure in which a sample region, the image sensor, and the optical path are sealed or a chamberless structure in which the sample region, the image sensor, and the optical path are not sealed by a chamber.

<FIG> illustrates thermal communication and heat flow pathways within the image sensor assembly <NUM>, according to an embodiment of the subject invention. The heat is transferred up through the plurality of fasteners <NUM> to the lens outer barrel <NUM>, from the lens outer barrel <NUM> to the contact material <NUM>, from the contact material <NUM> to the image sensor cover <NUM>, from the image sensor cover <NUM> to the image sensor <NUM>, from the image sensor <NUM> to the camera board fab <NUM>, from the camera board fab <NUM> to the heat conductor <NUM> if the heat conductor <NUM> is present, if not, then to the TEC <NUM>, from the heat conductor <NUM> to the TEC <NUM>, and from the TEC <NUM> to the heat sink <NUM>.

In one embodiment, the image sensor assembly <NUM> with active cooling by a thermoelectric cooling element (TEC) can comprise a lens mount for mounting the lens, the lens mount and the image sensor <NUM> being horizontally disposed on a same surface of the camera board fab <NUM> to limit the number of parts between the image sensor <NUM> and the lens to reduce or eliminate the need for lens tilt alignment.

<FIG> is a cross-sectional view of the actively cooled image sensor assembly according to an embodiment of the subject invention.

<FIG> is a cross-sectional view of the conventional image sensor assembly, showing ten parts between the image sensor and the lens. In comparison, there are only three parts between the image sensor and the lens in the actively cooled image sensor assembly of <FIG> according to an embodiment of the subject invention.

In one embodiment, the image sensor assembly <NUM> can further comprise a plurality of gaskets <NUM> disposed between the lens outer barrel <NUM> and the camera board fab <NUM> to reduce heat transfer from the lens outer barrel <NUM> by reducing contact metal area while simultaneously blocking light. The gasket <NUM> may include a foam or like resilient inner member that is compressible, deformable or deflectable. Moreover, the image sensor assembly <NUM> can comprise a plurality of washers <NUM>, preferably Belleville washers, respectively disposed between the plurality of gaskets <NUM> and the camera board fab <NUM> or between components of a multi-piece lens mount for tilt adjustment.

Referring to <FIG> and <FIG>, the image sensor assembly <NUM> with active cooling by a thermoelectric cooling element (TEC) comprising the plurality of gaskets <NUM> and the plurality of washers <NUM> are shown according to an embodiment of the subject invention.

The primary purpose of the gaskets <NUM> is to reduce heat transfer from the warm lens outer barrel which is in contact with the image sensor cover such as a pocket or a solid block. The waste heat is used to keep the front of the pocket or solid block sufficiently warm to inhibit condensation from forming on the surface of the image sensor cover. Moreover, the contact area between lens outer barrel <NUM> and the camera board fab <NUM> is reduced to a few small areas where the gaskets contact the camera board fab <NUM> and the gaskets <NUM> make up the intervening space to block light from getting to the image sensor.

<FIG> is a view of the image sensor assembly <NUM> with active cooling by the thermoelectric cooling element (TEC) and having a plurality of gaskets <NUM> and the plurality of washers <NUM>, illustrating that the lens outer barrel is tilted, according to an embodiment of the subject invention. Since the gasket is there and is flexible and under compression, tilt adjustment can be made when needed, but loosening screws to allow Belleville washers under compression to push the mount outward slightly. It is noted that the lens outer barrel is tilted by <NUM> degree with respect to the blue line. It is noted that the separation of the right outer barrel attach surface, with uncompressed Belleville exposed.

In one embodiment, the image sensor assembly <NUM> may have a two-piece lens mount in which a first piece is mounted flat to the circuit board, a second piece is initially disposed plane-to-plane and can be configured to be tilted with respect to the circuit board, and the lens is mounted to the second piece. The two-piece lens mount allows easy assembly, checking for tilt after the assembly, and if no tilt is found, no adjustment is required to inhibit stress from washers locally compressing the circuit board.

In one embodiment of the uncooled version, a dark current of <NUM> e-/pixel/second is measured at room temperature which is <NUM> times lower than a dark current of <NUM> e-/pixel/second measured at room temperature for the conventional Sony IMX178 image sensor system.

Claim 1:
An electronic component assembly, comprising:
a circuit board comprising at least one thermal pad (<NUM>) disposed on a top surface of the circuit board; and
an image sensor (<NUM>) disposed on the top surface of the circuit board, comprising at least one conductive pad (<NUM>) disposed at at least one corner of the image sensor (<NUM>);
wherein the at least one thermal pad (<NUM>) is coupled to the at least one conductive pad (<NUM>) of the image sensor; and
wherein the at least one thermal pad (<NUM>) is formed with a plurality of first thermal vias (<NUM>) penetrating the thermal pad (<NUM>) and the circuit board;
characterized in that the plurality of first thermal vias (<NUM>) is disposed directly under the conductive pad (<NUM>) of the image sensor on the top surface of the circuit board, and the plurality of first thermal vias (<NUM>) are filled with a thermal conductive material, sanded flat and plated.