Direct glass attached on die optical module

The present application is a continuation of de Guzman et al., U.S. patent application Ser. No. 11/177,904, entitled “DIRECT GLASS ATTACHED ON DIE OPTICAL MODULE”, filed Jul. 7, 2005, now U.S. Pat. No. 7,576,401, issued Aug. 18, 2009, which is herein incorporated by reference in its entirety.

1. Field of the Invention

The present invention relates generally to the packaging of electronic components. More particularly, the present invention relates to an optical module and method for fabricating the same.

2. Description of the Related Art

Image sensors are well known to those of skill in the art. An image sensor included an active area, which was responsive to light. The image sensor was used to fabricate an optical module, sometimes called a camera module.

The optical module was incorporated into a device such as a digital camera or camera phone. To allow miniaturization of these devices, the optical module should have a minimum size.

In accordance with one embodiment, an optical module includes an image sensor having an active area and a window mounted directly to the image sensor above the active area. The optical module further includes a mount mounted to the window, the mount supporting a barrel having a lens assembly. By mounting the window directly to the image sensor and the mount directly to the window, the substrate surface area of the optical module is minimized.

These and other features of the present invention will be more readily apparent from the detailed description set forth below taken in conjunction with the accompanying drawings.

FIG. 1 is a cross-sectional view of an optical module in accordance with one embodiment of the present invention;

FIG. 2 is a cross-sectional view of the optical module of FIG. 1 during fabrication in accordance with one embodiment of the present invention;

FIG. 3A is a cross-sectional view of the optical module of FIG. 2 at a further stage during fabrication in accordance with one embodiment of the present invention;

FIG. 3B is a cross-sectional view of an optical module similar to the optical module of FIG. 1 during fabrication in accordance with another embodiment of the present invention;

FIG. 4 is a cross-sectional view of the optical module of FIG. 3A at a further stage during fabrication in accordance with one embodiment of the present invention;

FIG. 5 is a cross-sectional view of the optical module of FIG. 4 at a further stage during fabrication in accordance with one embodiment of the present invention;

FIG. 6 is a cross-sectional view of an optical module in accordance with another embodiment of the present invention;

FIG. 7 is a cross-sectional view of an optical module in accordance with another embodiment of the present invention;

FIG. 8 is a cross-sectional view of the optical module of FIG. 7 during fabrication in accordance with one embodiment of the present invention;

FIG. 9 is a cross-sectional view of the optical module of FIG. 8 at a later stage during fabrication in accordance with one embodiment of the present invention;

FIG. 10 is a cross-sectional view of an optical module in accordance with another embodiment of the present invention; and

FIG. 11 is a cross-sectional view of an optical module in accordance with another embodiment of the present invention.

In the following description, the same or similar elements are labeled with the same or similar reference numbers.

In accordance with one embodiment, referring to FIG. 1 , an optical module 100 includes an image sensor 114 having an active area 118 and a window 124 mounted directly to image sensor 114 above active area 118 . Optical module 100 further includes a mount 132 mounted to window 124 , mount 132 supporting a barrel 140 having a lens assembly 146 A, 146 B, 146 C. By mounting window 124 directly to image sensor 114 and mount 132 directly to window 124 , the surface area of substrate 102 is minimized thus minimizing the size of optical module 100 .

More particularly, FIG. 1 is a cross-sectional view of an optical module 100 , sometimes called a camera module, in accordance with one embodiment of the present invention. Optical module 100 is used in a wide variety of applications, e.g., digital cameras and cellular camera phones.

Optical module 100 includes a substrate 102 , e.g., formed of ceramic, pre-molded plastic or laminate, although substrate 102 is formed of other materials in other embodiments. Substrate 102 includes an upper, e.g., first, surface 102 U and a lower, e.g., second, surface 102 L, opposite upper surface 102 U.

Formed on upper surface 102 U of substrate 102 are a plurality of electrically conductive upper traces 104 , which include a first upper trace 104 A. Formed on lower surface 102 L of substrate 102 are a plurality of electrically conductive lower traces 106 , which include a first lower trace 106 A. Extending through substrate 102 from lower surface 102 L to upper surface 102 U are a plurality of electrically conductive vias 108 , which include a first via 108 A. Lower traces 106 are electrically connected to upper traces 104 by vias 108 . To illustrate, lower trace 106 A is electrically connected to upper trace 104 A by via 108 A.

Formed on lower traces 106 are electrically conductive pads 110 , which include a first pad 110 A. Formed on pads 110 are electrically conductive interconnection balls 112 , e.g., solder. To illustrate, pad 110 A is formed on lower trace 106 A. A first interconnection ball 112 A of the plurality of interconnection balls 112 is formed on pad 110 A. Interconnection balls 112 are used to connect optical module 100 to a larger substrate such as a printed circuit mother board.

Although a particular electrically conductive pathway between upper traces 104 and interconnection balls 112 is described above, other electrically conductive pathways can be formed. For example, contact metallizations can be formed between the various electrical conductors. Alternatively, pads 110 are not formed and interconnection balls 112 are formed directly on lower traces 106 .

Further, instead of straight though vias 108 , in one embodiment, substrate 102 is a multi-layer laminate substrate and a plurality of vias and/or internal traces form the electrical interconnection between traces 104 and 106 .

In yet another embodiment, interconnection balls 112 are distributed in an array format to form a ball grid array (BGA) type optical module. Alternatively, interconnection balls 112 are not formed, e.g., to form a metal land grid array (LGA) type optical module. In yet another alternative, pads 110 /interconnection balls 112 are not formed, e.g., to form a leadless chip carrier (LCC) type optical module. In another embodiment, optical module 100 is inserted into a socket that is pre-mounted on the larger substrate, e.g., on the printed circuit mother board. BGA, LGA and LCC type modules are well known to those of skill in the art.

In another embodiment, a flex connector, sometimes called an edge connector or flex strip, is electrically connected to lower traces 106 , e.g., for applications where optical module 100 is remote from the larger substrate. Other electrically conductive pathway modifications will be obvious to those of skill in the art.

Mounted, sometimes called die attached, to upper surface 102 U of substrate 102 is an image sensor 114 . More particularly, a lower, e.g., first, surface 114 L of image sensor 114 is mounted to upper surface 102 U, for example, with an adhesive 116 , sometimes called an image sensor adhesive or die attach adhesive.

Image sensor 114 further includes an upper, e.g., second, surface 114 U. An active area 118 and bond pads 120 of image sensor 114 are formed on upper surface 114 U. In this embodiment, upper surface 102 U, lower surface 114 L, and upper surface 114 U are parallel to one another. Although various structures may be described as being parallel or perpendicular, it is understood that the structures may not be exactly parallel or perpendicular but only substantially parallel or perpendicular to within accepted manufacturing tolerances.

Generally, active area 118 of image sensor 114 is responsive to light, e.g., electromagnetic radiation, as is well known to those of skill in the art. For example, active area 118 is responsive to infrared radiation, ultraviolet light, and/or visible light. Illustratively, image sensor 114 is a CMOS image sensor device, a charge coupled device (CCD), a pyroelectric ceramic on CMOS device, or an erasable programmable read-only memory device (EPROM) although other image sensors are used in other embodiments.

Upper traces 104 are electrically connected to bond pads 120 by bond wires 122 . To illustrate, a first bond pad 120 A of the plurality of bond pads 120 is electrically connected to upper trace 104 A by a first bond wire 122 A of the plurality of bond wires 122 .

A window 124 is mounted to image sensor 114 . More particularly, a lower, e.g., first, surface 124 L of window 124 is mounted to upper surface 114 U of image sensor 114 with a window adhesive 126 . In one embodiment, window 124 includes a filter, e.g., an infrared filter. Accordingly, window 124 is sometimes called an IR glass.

In accordance with this embodiment, lower surface 124 L of window 124 corresponds to upper surface 114 U of window 114 . Stated another way, lower surface 124 L of window 124 has the same shape, e.g., a rectangular shape having the same length and width, as upper surface 114 U of image sensor 114 such that the total surface areas of lower surface 124 L and upper surface 114 U are equal. However, in other embodiments, the total area of lower surface 124 L of window 124 is greater than or less than the total area of upper surface 114 U of image sensor 114 .

In accordance with this embodiment, window adhesive 126 mounts the periphery of upper surface 114 U of image sensor 114 to the periphery of lower surface 124 L of window 124 . Window adhesive 126 is applied directly on and covers bond pads 120 and at least a portion of bond wires 122 . Window adhesive 126 is a nonconductive material, sometimes called a dielectric or electrically insulating material. Window adhesive 126 spaces window 124 above the loop height of bond wires 122 , i.e., apart from bond wires 122 .

Window adhesive 126 does not cover active area 118 in accordance with this embodiment. Accordingly, a cavity 128 is formed by upper surface 114 U of image sensor 114 , lower surface 124 L of window 124 , and window adhesive 126 . Active area 118 is located within cavity 128 .

Bond wires 122 are enclosed in an encapsulant 130 . More particularly, encapsulant 130 covers the exposed portion of upper surface 102 U of substrate 102 , sides 114 S of image sensor 114 , window adhesive 126 and bond wires 122 . Encapsulant 130 protects bond wires 122 . Further, in accordance with this embodiment, encapsulant 130 , e.g., a cured liquid encapsulant, mounts a mount 132 above and to window 124 .

In this embodiment, mount 132 , sometimes called a lens holder, includes a mounting surface 134 , which is attached to encapsulant 130 and the periphery of an upper, e.g., second, surface 124 U of window 124 . Window 124 further includes sides 124 S extending between and perpendicular to upper surface 124 U and lower surface 124 L of window 124 .

To increase the contact surface area and thus the bond strength with encapsulant 130 , mounting surface 134 includes a protruding lip 136 which protrudes into encapsulant 130 around window 124 . Protruding lip 136 includes first and second surfaces 137 A, 137 B. First surface 137 A, sometimes called vertical surface 137 A, is parallel to and abuts side 1245 of window 124 . Second surface 137 B, sometimes called slanted surface 137 B, is angled upwards and outwards from first surface 137 A. As discussed in greater detail below with reference to FIG. 5 , slanted surface 137 B serves as a funnel for encapsulant 130 and causes encapsulant 130 to flow away from the direction of window 124 during mounting of mount 132 .

By mounting window 124 directly to image sensor 114 and mount 132 directly to window 124 , the area of upper surface 102 U of substrate 102 is minimized. More generally, the size of substrate 102 is reduced compared to a substrate of an optical module in which the mount is mounted to the substrate laterally adjacent to and around the image sensor. Accordingly, optical module 100 has a small size, sometimes called a small footprint, allowing miniaturization of devices such as digital cameras or camera phones using optical module 100 .

Mount 132 includes a central aperture 138 having a longitudinal axis LA perpendicular to upper surface 114 U of image sensor 114 . Central aperture 138 extends upwards and is aligned above active area 118 .

Mount 132 supports a barrel 140 . In one embodiment, barrel 140 is threadedly attached to mount 132 such that rotation of barrel 140 moves barrel 140 relative to mount 132 . For example, mount 132 includes an inner cylindrical threaded surface 142 that defines central aperture 138 . Barrel 140 includes an outer cylindrical threaded surface 144 that is threadedly attached to inner cylindrical threaded surface 142 of mount 132 . However, in another embodiment, barrel 140 is fixedly attached to mount 132 , e.g., with adhesive.

Barrel 140 includes at least a single lens such as a single lens or multiple lenses, e.g., one, two, three, four or more lenses made of plastic or glass, stacked together to form a lens system. In this embodiment, barrel 140 includes three lenses 146 A, 146 B, 146 C, collectively referred to as lenses 146 or a lens assembly. Lenses 146 focus light on active area 118 .

FIG. 2 is a cross-sectional view of optical module 100 of FIG. 1 during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 2 , lower surface 114 L of image sensor 114 is attached to upper surface 102 U of substrate 102 by adhesive 116 . Bond pads 120 of image sensor 114 are electrically connected to upper traces 104 by bond wires 122 . In one embodiment, bond wires 122 are formed by reversed stand off stitch bonding (RSSB).

Window adhesive 126 is applied to the periphery of upper surface 114 U of image sensor 114 and directly on and over bond pads 120 . Window 124 is moved relative to image sensor 114 in the direction of arrow 202 and into window adhesive 126 . Window adhesive 126 is cured, e.g., optically or thermally cured, thus mounting window 124 to image sensor 114 as shown in FIG. 3A . In one embodiment, a normal die bonder is used for attachment of window 124 to image sensor 114 .

FIG. 3A is a cross-sectional view of optical module 100 of FIG. 2 at a further stage during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 3A , window adhesive 126 mounts the periphery of lower surface 124 L of window 124 to the periphery of upper surface 114 U of image sensor 114 . In another embodiment, window adhesive 126 entirely covers bond wires 122 as indicated by the dashed lines. In accordance with this embodiment, window adhesive 126 also encloses sides 114 S of image sensor 114 as well as the adjacent portion of upper surface 102 U of substrate 102 .

FIG. 3B is a cross-sectional view of an optical module 100 A similar to optical module 100 of FIG. 1 during fabrication in accordance with another embodiment of the present invention. Referring now to FIG. 3B , a window 124 A is mounted to upper surface 114 U of image sensor 114 by a window adhesive 126 A. More particularly, window adhesive 126 A is applied to upper surface 114 U between bond pads 120 and active area 118 . Thus, window adhesive 126 A does not cover bond pads 120 , bond wires 122 or active area 118 in accordance with this embodiment.

Further, the total area of lower surface 124 L of window 124 A is less than the total area of upper surface 114 U of image sensor 114 in accordance with this embodiment. More particularly, window 124 A fits entirely inwards of bond pads 120 although window 124 A extends over bond pads 120 in another embodiment.

In one embodiment, window 124 A is attached to image sensor 114 while image sensor 114 is still in wafer form. Window 124 A and window adhesive 126 A protect active area 118 from particulates generated during singulation of image sensor 114 from the wafer in accordance with this embodiment. However, in another embodiment, window 124 A is attached to image sensor 114 after singulation of image sensor 114 from the wafer.

Fabrication of optical module 100 A of FIG. 3B is similar to fabrication of optical module 100 of FIG. 1 and so is not discussed further to avoid detracting from the principles of the invention.

FIG. 4 is a cross-sectional view of optical module 100 of FIG. 3A at a further stage during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 4 , encapsulant 130 , e.g., a liquid encapsulant, is applied, e.g., dispensed, to the periphery of upper surface 102 U of substrate 102 . Encapsulant 130 is applied to enclose image sensor 114 , window adhesive 126 , sides 124 S of window 124 , and bond wires 122 . In accordance with another embodiment, encapsulant 130 , sometimes called mold or molding compound, is formed using a mold as those of skill in the art will understand and the particular molding technique used is not essential to this embodiment of the present invention.

In one embodiment, optical module 100 is fabricated simultaneously with a plurality of optical modules in an array. After application of encapsulant 130 , optical module 100 is singulated from the array, e.g., using a saw or by punch singulation. Active area 118 is protected by window 124 , window adhesive 126 and encapsulant 130 from particulates generated during the sawing and removal of the particulates.

FIG. 5 is a cross-sectional view of optical module 100 of FIG. 4 at a further stage during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 5 , interconnection balls 112 are formed. In other embodiments, interconnection balls 112 are formed at an earlier or later stage of fabrication of optical module 100 .

Mount 132 is pressed into encapsulant 130 and on to upper surface 124 U of window 124 . As mount is pressed into encapsulant 130 , slanted surface 137 B of protruding lip 136 causes encapsulant 130 to flow away from window 124 as indicated by the arrows 139 . Encapsulant 130 is cured, e.g., optically or thermally, thus mounting mount 132 to window 124 . Barrel 140 ( FIG. 1 ) is mounted to mount 132 thus completing fabrication of optical module 100 .

FIG. 6 is a cross-sectional view of an optical module 600 in accordance with another embodiment of the present invention. Optical module 600 of FIG. 6 is similar to optical module 100 of FIG. 1 and only the significant differences between optical module 600 and optical module 100 are discussed below.

Referring now to FIG. 6 , a mount 132 A includes a planar rectangle annular mounting surface 134 A, i.e., does not include a protruding lip. Mount 132 A is mounted to upper surface 124 U of window 124 and encapsulant 130 by a mount adhesive 648 . In one embodiment, mount adhesive 648 entirely covers mounting surface 134 A of mount 132 A.

FIG. 7 is a cross-sectional view of an optical module 700 in accordance with another embodiment of the present invention. Optical module 700 of FIG. 7 is similar to optical module 600 of FIG. 6 and only the significant differences between optical module 700 and optical module 600 are discussed below.

Referring now to FIG. 7 , a window 124 B is mounted by encapsulant 130 A above and to image sensor 114 . In one embodiment, encapsulant 130 A is a cured liquid encapsulant. In accordance with this embodiment, encapsulant 130 A directly adheres to lower surface 124 L of window 124 B. In another embodiment, encapsulant 130 A is mold. In accordance with this embodiment, window 124 B is mounted to encapsulant 130 A by window adhesive 126 B as indicated by the dashed lines.

As shown in FIG. 7 , window 124 B has a greater surface area than the surface area of image sensor 114 . Accordingly, window 124 B extends laterally outwards past sides 114 S of image sensor 114 .

In accordance with this embodiment, mount 132 A is mounted to upper surface 124 U of window 124 B by mount adhesive 648 . More particularly, mounting surface 134 A of mount 132 A is mounted to upper surface 124 U of window 124 B by mount adhesive 648 . Window 124 B is between mount 132 A and encapsulant 130 A.

FIG. 8 is a cross-sectional view of optical module 700 of FIG. 7 during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 8 , lower surface 114 L of image sensor 114 is attached to upper surface 102 U of substrate 102 by adhesive 116 . Bond pads 120 of image sensor 114 are electrically connected to upper traces 104 by bond wires 122 . In one embodiment, bond wires 122 are formed by RSSB.

Encapsulant 130 A is applied to the periphery of upper surface 114 U and sides 1145 of image sensor 114 and covers the exposed portions of upper surface 102 U of substrate 102 . In various embodiments, encapsulant 130 A is applied by being dispensed, e.g., when encapsulant 130 A is a liquid encapsulant, or by being molded, e.g., when encapsulant 130 A is molding compound. As shown in FIG. 8 , encapsulant 130 A does not cover bond pads 120 . However, as illustrated by the dashed lines, in one embodiment, encapsulant 130 A covers bond pads 120 and entirely encloses bond wires 122 .

FIG. 9 is a cross-sectional view of optical module 700 of FIG. 8 at a later stage during fabrication in accordance with one embodiment of the present invention. Referring now to FIG. 9 , interconnection balls 112 are formed. In other embodiments, interconnection balls 112 are formed at an earlier or later stage of fabrication of optical module 700 .

Window 124 B is moved toward image sensor 114 and into contact with encapsulant 130 A. Encapsulant 130 A is cured, e.g., optically or thermally cured, thus mounting window 124 B above image sensor 114 as shown in FIG. 9 . In accordance with this embodiment, encapsulant 130 A directly adheres to lower surface 124 L of window 124 B.

In another embodiment, encapsulant 130 A is mold. In accordance with this embodiment, window 124 B is mounted to encapsulant 130 A by window adhesive 126 B as indicated by the dashed lines.

Mount 132 A is mounted to upper surface 124 U of window 124 B by mount adhesive 648 . In one embodiment, mount 132 A is mounted to window 124 B prior to mounting of window 124 B to encapsulant 130 A. In another embodiment, window 124 B is mounted to encapsulant 130 A, and then mount 132 A is mounted to window 124 B. Barrel 140 ( FIG. 7 ) is mounted, e.g., threaded or screwed, to mount 132 A thus completing fabrication of optical module 700 .

FIG. 10 is a cross-sectional view of an optical module 1000 in accordance with another embodiment of the present invention. Optical module 1000 of FIG. 10 is similar to optical module 100 of FIG. 1 and only the significant differences between optical module 1000 and optical module 100 are discussed below.

Referring now to FIG. 10 , optical module 1000 includes an electronic component 1002 , e.g., an integrated circuit or controller chip. More particularly, a lower, e.g., first, surface 1002 L of electronic component 1002 is mounted to upper surface 102 U of substrate 102 by an adhesive 1004 . An upper, e.g., second, surface 1002 U of electronic component 1002 includes bond pads 1006 . Bond pads 1006 are electrically connected to upper traces 104 by bond wires 1008 .

Image sensor 114 is mounted, sometimes called stacked, above electronic component 1002 by an image sensor spacer 1010 . More particularly, lower surface 114 L of image sensor 114 is mounted above electronic component 1002 with image sensor spacer 1010 , e.g., a cured liquid encapsulant or mold.

In one embodiment, image sensor spacer 1010 is applied as a liquid encapsulant. Image sensor 114 is placed into image sensor spacer 1010 , which is then cured. In accordance with this embodiment, image sensor spacer 1010 directly adheres to image sensor 114 .

In another embodiment, image sensor spacer 1010 is mold formed using a mold. Image sensor 114 is then adhered to image sensor spacer 1010 using an adhesive 116 A indicated by the dashed line.

As shown in FIG. 10 , lower surface 114 L of image sensor 114 has a greater total surface area than upper surface 1002 U of electronic component 1002 . Stated another way, image sensor 114 has a greater surface area, i.e., is larger, than electronic component 1002 . However, in other embodiments, electronic component 1002 is the same size, or larger, than image sensor 114 .

In accordance with this embodiment, image sensor spacer 1010 mounts the periphery of lower surface 114 L of image sensor 114 to the periphery of upper surface 1002 U of electronic component 1002 . Image sensor spacer 1010 is applied directly on and covers bond pads 1006 and bond wires 1008 .

Image sensor spacer 1010 does not cover a central region inward of bond pads 1008 of upper surface 1002 U of electronic component 1002 in accordance with this embodiment. Accordingly, a cavity 1012 is formed by upper surface 1002 U of electronic component 1002 , lower surface 114 L of image sensor 114 , and image sensor spacer 1010 . However, in another embodiment, image sensor spacer 1010 entirely covers electronic component 1002 such that cavity 1012 is not formed.

Bond wires 1008 are enclosed in image sensor spacer 1010 . More particularly, image sensor spacer 1010 spaces image sensor 114 above the loop height of bond wires 1008 , i.e., apart from bond wires 1008 . Further, image sensor spacer 1010 covers at least the periphery of upper surface 1002 U and sides 10025 of electronic component 1002 and a portion of upper surface 102 U of substrate 102 adjacent electronic component 1002 . Encapsulant 130 covers the exposed portion of upper surface 102 U of substrate 102 , sides 114 S of image sensor 114 , window adhesive 126 , bond wires 122 and image sensor spacer 1010 .

By stacking image sensor 114 above electronic component 1002 , use of surface area of substrate 102 around image sensor 114 for electronic component 1002 is avoided. More generally, the size of substrate 102 is reduced compared to a substrate of an optical module in which an electronic component is mounted laterally adjacent to the image sensor. Accordingly, optical module 1000 has a small footprint allowing miniaturization of devices such as digital cameras or camera phones using optical module 1000 .

FIG. 11 is a cross-sectional view of an optical module 1100 in accordance with another embodiment of the present invention. Optical module 1100 of FIG. 11 is similar to optical module 1000 of FIG. 10 and only the significant differences between optical module 1100 and optical module 1000 are discussed below.

Referring now to FIG. 11 , optical module 1100 includes an image sensor spacer 1110 . Image sensor spacer 1110 mounts image sensor 114 above electronic component 1002 . More particularly, image sensor spacer 1110 is mounted to a central region of upper surface 1002 U of electronic component 1002 inward of bond pads 1006 . Further, image sensor spacer 1110 is mounted to lower surface 114 L of image sensor 114 . Image sensor spacer 1110 spaces image sensor 114 above the loop height of bond wires 1008 , i.e., apart from bond wires 1008 .

In one embodiment, image sensor spacer 1110 includes a rigid spacer 1112 , e.g., silicon, ceramic, laminate, and/or tape, with a lower, e.g., first, adhesive 1114 and an upper, e.g., second, adhesive 1116 . More particularly, lower adhesive 1114 mounts upper surface 1002 U of electronic component 1002 to a lower, e.g., first, surface 1112 L of rigid spacer 1112 , sometimes called a central spacer. Upper adhesive 1116 mounts lower surface 114 L of image sensor 114 to an upper, e.g., second, surface 1112 U of rigid spacer 1112 . For example, image sensor spacer 1110 is a double sided sticky tape.

In another embodiment, image sensor spacer 1110 , e.g., a cured liquid encapsulant, is itself the adhesive that mounts image sensor 114 above electronic component 1002 . In accordance with this embodiment, image sensor spacer 1110 does not include upper and lower adhesive 1114 , 1116 .

As shown in FIG. 11 , bond pads 1006 and bond wires 1008 are uncovered. However, in another embodiment, encapsulant 130 covers bond pads 1006 , bond wires 1008 , and encloses image sensor spacer 1110 .

By stacking image sensor 114 above electronic component 1002 , use of surface area of substrate 102 around image sensor 114 for electronic component 1002 is avoided. More generally, the size of substrate 102 is reduced compared to a substrate of an optical module in which an electronic component is mounted laterally adjacent to the image sensor. Accordingly, optical module 1100 has a small footprint allowing miniaturization of devices such as digital cameras or camera phones using optical module 1100 .

The drawings and the forgoing description gave examples of the present invention. The scope of the present invention, however, is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of the invention is at least as broad as given by the following claims.