This application claims priority to Finnish Patent Application No. 20225383, filed May 4, 2022, the contents of each of which are hereby incorporated by reference in its entirety.
The present disclosure relates to electronic components, and, more particularly, to electronic components where a die is protected by a surrounding package. The present disclosure further concerns the alignment of the die with other parts of the component.
Electronic dies, which may also be called chips, can be prepared by manufacturing electronic structures on a substrate and cutting the substrate into small pieces. The substrate may be a semiconductor substrate, for example, a silicon substrate. Each die that is cut from the substrate may be placed inside a protective package by attaching it to a support structure and then building the package around it. The die can also be electrically connected to other chips inside the same package and/or to leads which extend to the outside of the package. The package and its contents can thereby form an electronic component that can be mounted on a circuit board.
Some dies are orientation-sensitive and have to be carefully aligned inside the package to ensure that the output of the electronic component is accurate. Orientation-sensitive dies include magnetometer dies and dies that measure inertial variables such as acceleration or angular velocity. It is often convenient to attach the die to a die-attachment surface with a die-attach material and then build the rest of the package around the die-attachment surface. Any substantially flat surface can be used as a die-attachment surface. However, a frequent problem is that, due to the viscosity of the die-attach material, the die may rotate with respect to the die-attachment surface after it has been placed (or when it is placed) on the die-attach material. Even a small amount of flow can misalign the die before the die-attach material solidifies.
U.S. Patent Publication No. 2009/0166826 discloses an electronic component where a high wall surrounds an attachment area where a die is attached. A common problem with solutions where the die is fixed on all sides is that thermal expansion and other changes in the structures which surround the chip can subject the chip to mechanical stress and reduce the durability and/or the performance of the component.
Accordingly, it is an object of the present disclosure to alleviate the above problem with a method and an arrangement as described herein. The exemplary method and an arrangement are is based on the idea of aligning a die to a single die-alignment wall or to two die-alignment walls. An advantage of this arrangement is that the die can be perfectly aligned without fixing it on opposite sides. As a result, the risk of damage due to mechanical stress is thereby reduced.
Thus, in an exemplary aspect, an electronic component is provided that includes a support that includes a die-attachment surface that defines a horizontal plane, with a vertical direction being perpendicular to the horizontal plane; a first die that is vertically fixed to the die-attachment surface with a die-attach material, and a die aligning element that is adjacent to the die-attachment surface and that is integral with at least one of the support or a packaging structure that is rigidly attached to the support. Moreover, in this aspect, the die-aligning element comprises a first die-alignment wall that is horizontally fixed to a first side of the first die with the die-attach material, and a second side of the first die that is opposite to the first side of the first die is horizontally unfixed.
In another exemplary aspect, an electronic component is provided that includes a support that includes a die-attachment surface that defines a horizontal plane, with a vertical direction being perpendicular to the horizontal plane; a die-aligning element that is integral with the support and that includes a first die-alignment wall that vertically extends from the die-attachment surface; and a first die that is vertically fixed to the die-attachment surface with a die-attach material and that includes a first side that is horizontally fixed to the die-aligning element with the die-attach material. In this aspect, a second side of the first die that is opposite to the first side of the first die is horizontally unfixed.
In yet another exemplary aspect, a method for manufacturing an electronic component that includes one or more dies attached to a support that comprises a die-attachment surface defines a horizontal plane, with a vertical axis being perpendicular to the horizontal plane. In this aspect, the method include fixing a first die vertically to the die-attachment surface with a die-attach material, integrally forming a die aligning element with the support or as a packaging structure that is rigidly attached to the support, with the die-aligning element being adjacent to the die-attachment surface and including a first die-alignment wall; and fixing a first side of the first die horizontally to the first die-alignment wall with the die-attach material while leaving a side of the first die that is opposite to the first side of the first die horizontally unfixed.
In the following, the disclosure will be described in greater detail by means of exemplary embodiments with reference to the accompanying drawings, in which:
This disclosure describes an electronic component comprising a first die and a support. In particular, the support comprises a die-attachment surface that defines a horizontal plane. A vertical direction is perpendicular to the horizontal plane. The first die is vertically fixed to the die-attachment surface with a die-attach material. The component also comprises a die-aligning element which is adjacent to the die-attachment surface. The die-aligning element forms an integral part of the support of an integral part of a packaging structure which is rigidly attached to the support. The die-aligning element comprises a first die-alignment wall. A first side of the first die is horizontally fixed to the first die-alignment wall with the die-attach material. The side (e.g., a second side) of the first die which is opposite to the first side of the first die is horizontally unfixed.
As described in more detail below, the die-aligning element can either be formed in the support or on a fixed structure which is adjacent to the support. The die-aligning element may be a protrusion which extends in the vertical direction from the die-attachment surface. Alternatively, it may be a protrusion which extends in a horizontal or a vertical direction from the fixed structure which is attached to the support. The horizontal plane is illustrated as the xy-plane in this disclosure. The vertical direction is indicated with a z-axis. The term “horizontal” refers in this disclosure to directions which are parallel to the xy-plane. Terms such as “vertical”, “top”, “bottom”, “up”, “down”, “below” and “above” refer in this disclosure to the direction which is perpendicular (e.g., orthogonal) to the xy-plane and to relative positions and distances in that direction. These terms do not indicate anything about how the component should be oriented with regard to the Earth's gravitational field when the component is manufactured or when it is being used.
Moreover, for purposes of this disclosure, the “side” of a die is an external surface of the die which is vertical or at least approximately vertical when the die is placed on the die-attachment surface. A side which is opposite to another side lies on the other side of the die in a horizontal direction. The die also has a top surface and a bottom surface which are substantially horizontal when the die is placed on the die-attachment surface, and which are opposite to each other in the vertical direction. It should also be appreciated that the term “substantially” takes into account minor differences due to possible manufacturing variances as would be appreciated to one skilled in the art.
For purposes of this disclosure, the term “vertically fixed” refers to a situation where a bottom surface of a die is firmly attached with the die-attach material to the underlying die-attachment surface in the vertical direction (the z-direction). The term “horizontally fixed”, on the other hand, refers to a situation where a side of the die is firmly attached with the die-attach material to a die-aligning element which is adjacent to the die in the horizontal direction (a direction parallel to the xy-plane). The term “horizontally unfixed”, on the other hand, refers to a situation where a side of the die is not firmly attached to any fixed structure in a given the horizontal direction. The term “horizontally unfixed” may also be expressed as “not horizontally fixed”.
For purposes of this disclosure, the word “length” is used in this disclosure as a general term for a distance measure in the horizontal plane. Lengths can for example be measured in the direction of the x-axis, or in the direction of the y-axis, or in any other direction in the xy-plane. The alignment walls and the sides of the die are illustrated as straight walls/sides in the figures of this disclosure, and the corresponding lengths are then linear measures.
The die-alignment walls illustrated in the figures of this disclosure are straight in that they have a linear shape in the xy-plane. The sides of the die are correspondingly illustrated with a linear shape. However, if the side of the die is curved, then the die-alignment wall can also be curved. The length of the wall and the length of the side may in this case be measured along the curve.
In any exemplary embodiment, the first die may, for example, be an accelerometer configured to measure acceleration, a gyroscope configured to measure angular rotation, or a magnetometer, or any other orientation-sensitive die. The accelerometer or gyroscope may be a MEMS accelerometer/gyroscope.
The electronic component may comprise a package that provides protection for the dies inside the component. The electronic component may alternatively be without a package. The electronic component may comprise external contacts and mounting elements which allow the component to be attached and electrically connected to a circuit board. The component may be mounted on a circuit board so that the circuit board is closer to the die-attachment surface than to the die, or it may be mounted the other way around so that the circuit board is closer to the die than to the die-attachment surface.
To facilitate a simple illustration of die alignment in the figures of this disclosure, both the die itself and the die-attachment surface are illustrated as rectangular blocks with straight edges extending parallel to the x-axis and the y-axis. The die is then assumed to be oriented correctly when the four edges of the rectangular die are parallel to the four edges of the die-attachment surface, as
It should be appreciated that the general principles of alignment are the same regardless of the shape of the die. When the directional alignment of the die is correct, the relevant measurement axes on the die (such as axes i and j in
The die-aligning element 241 may be a protrusion in the die-attachment surface 22. It may be formed from the same material as the die-attachment surface 22 in an exemplary aspect. However, it is noted that the die-aligning element 241 and the die-attachment surface 22 can be made of any material, and the material of the die-aligning element may be either the same as the material of the die-attachment surface, or different from the material of the die-attachment surface. Even though the die-aligning element may be an integral part of the support, the die-attachment surface 22 and the die-aligning element 241 are for reasons of clarity illustrated with a different color in the figures of this disclosure.
For simplicity, the die-aligning element is illustrated as a cuboid in
Also, although the die-alignment walls illustrated in the figures of this disclosure are parallel to the illustrated edges of the die-attachment surface 22, the die-alignment wall can be oriented in any direction on the surface. It is only important that the orientation of the die-alignment allows the die to be oriented correctly when it attaches to the die-alignment wall.
If the side of the die 21 is close to being parallel to the die-alignment wall when the die is placed near the die-aligning element, but not perfectly parallel—that is, if the die is slightly misaligned—then the capillary and surface tension forces which act on the viscous die-attach material 23 will strive to automatically correct this error by equalizing the thickness (both in the x-direction and the z-direction) of the die-attach material interface layer which is formed between the wall and the side of the die. The die-attach material 23 will thereby rotate the die 21 slightly and bring the side of the die into perfect alignment with the die-alignment wall. This effect can be obtained as long as the initial misalignment is not too large and the distance between the die and the die-aligning element when the die is placed on the die-attachment surface is sufficiently small. The maximum amount of initial misalignment which can still be corrected will depend at least on the size of the die 21, the viscosity of the die-attach material 23 and the height of the die-aligning element 241.
The horizontal bond line between the die-attach material 23 and the die 21 is illustrated in
In other words, the vertical distance from the die-attachment surface to the bond line between the first die and the die-attach material may be D, and the vertical height of the first die may be H, and the first die-alignment wall may have a first wall height in the vertical direction, and the first wall height may be greater than D and less than D+H/2. In general, a die has multiple sides, with some of these sides being opposite to each other, as for example the left and right sides of the die in
Moreover, the length 249 of the die-alignment wall is illustrated in
However, the length 249 of the first die-alignment wall does not necessarily have to be equal to the length of the first side of the first die. In alternative aspects, longer or shorter walls can be used in applications where positional alignment is not critical.
The die-aligning element may, but does not necessarily have to be, in contact with the sidewall of a package which surrounds the die.
Furthermore, the die-alignment wall does not necessarily have to extend all the way down to the die-attachment surface.
The package structure 27 is fixed to the support, and to the die-attachment surface 22. The package structure may for example be a cap which forms an enclosure around the chip. The die-aligning element could alternatively be a protrusion that extends downward in the vertical from the ceiling of the package structure. This exemplary aspect has not been illustrated. All geometry options discussed above with reference to
It is noted that the directional and positional alignment of the die can in some applications be improved by using two die-alignment walls which are not parallel to each other. Two different sides of the die can then be attached to these two walls. The die-aligning element may also comprise a second die-alignment wall that is not parallel to the first die-alignment wall. A second side of the first die may be horizontally fixed to the second die-alignment wall with the die-attach material. The second side of the first die is not opposite to the first side of the first die. The side of the first die which is opposite to the second side of the first die is horizontally unfixed.
The flow of the die-attach material into the space between the die and the die-alignment wall and the tendency of the die-attach material to minimize its surface tensions will act to align the die 31 with the second die-alignment wall, just as it aligns the die with the first die-alignment wall. This is illustrated in
The length of the second die-alignment wall may be substantially equal to the length of the second side of the first die. However, as in the case of the length of the first die-alignment wall discussed above with reference to
The first wall height may be substantially equal to the second wall height. However, this configuration does not necessarily have to be the case in alternative aspects. The alignment can be just as accurate if one of the walls is higher than the other, and it may in some cases be advantageous to make one of the walls higher so that it can serve as a primary die-alignment wall while the other is lower so that the risk of mechanical stress on the die is reduced.
The first and second die-alignment walls are orthogonal (e.g., 90 degrees) in
The die-aligning element 341 illustrated in
In general, it should be appreciated that the exemplary aspects and alternatives that have been explained above with reference to
A die-aligning element may be used to align multiple dies. The component may comprise a second die which is attached to the die-attachment surface with an additional die-attach material. The die-aligning element may comprise an additional die-alignment wall. A first side of the second die may be horizontally fixed to the additional die-alignment wall with the additional die-attach material. The side of the second die which is opposite to the first side of the second die may be horizontally unfixed.
The second die 412 has a first side (e.g., the right side in
In the exemplary aspect, the additional die-alignment wall may be parallel to the first die-alignment wall as
The length 429 of the additional die-alignment wall may be equal to the length of the first side of the second die. However, the length of the first side of the second die may alternatively be shorter, as
The vertical distance from the die-attachment surface to the bond line between the second die and the additional die-attach material may be D*. The vertical height of the second die may be H*. The additional die-alignment wall may have a third wall height in the vertical direction, and the third wall height may be greater than D* and less than D*+H*/2.
Finally, the die-aligning element which comprises a first die-alignment wall and an additional die-alignment wall may also comprise the second die-alignment wall which was discussed above with reference to
In an exemplary aspect, a method is also provided for manufacturing an electronic component comprising one or more dies attached to a support. The support comprises a die-attachment surface which defines a horizontal plane. A vertical axis is perpendicular to the horizontal plane. The method comprises the step of fixing a first die vertically to the die-attachment surface with a die-attach material. The method also comprises the step of forming a die-aligning element as an integral part of the support or as an integral part of a packaging structure which is rigidly attached to the support. The die-aligning element is adjacent to the die-attachment surface. The die-aligning element comprises a first die-alignment wall. The method also comprises the step of fixing a first side of the first die horizontally to the first die-alignment wall with the die-attach material while leaving the side of the first die which is opposite to the first side of the first die horizontally unfixed.
The step of attaching a first side of the first die to the first die-alignment wall with the die-attach material may comprise the following sub-steps: (A) placing the die-attach material on the support close to the die-aligning element, and (B) placing the first die onto the die-attach material so that the first side of the first die is in close proximity to the first die-alignment wall.
In general, it is noted that all exemplary aspects described above with reference to 2a-2g apply also to this method.
If the first die is initially misaligned, the die can (as long as the initial misalignment is not too large) be brought into perfect alignment as the die-attach material creeps up between the die and the die-alignment wall and forms an intermediate layer between the die and the wall. The initial distance DD between the die and the die-aligning element when the die is placed on the die-attachment surface should not be too large. This distance DD may preferably the shorter than the distance DO between the die and any other adjacent fixed element on the support surface. DD may for example be less than half of DO or less than three quarters of DO. The minimum value for DD, as well as the maximum amount of initial misalignment which can be corrected, will depend at least on the size of the die, the viscosity of the die-attach material and the height of the die-aligning element.
It is also noted that the exemplary aspects presented above with reference to 3a-3b may also be implemented in the method. In other words, the die-aligning element may comprise a second die-alignment wall which is not parallel to the first die-alignment wall, and the method may comprise the step of fixing a second side of the first die horizontally to the second die-alignment wall with the die-attach material while leaving the side of the first die which is opposite to the second side of the first die horizontally unfixed, wherein the second side of the first die is not opposite to the first side of the first die.
The step of fixing the first and second sides of the first die to the first and second die-alignment wall, respectively, may in this case comprise the following sub-steps: (A) placing the die-attach material on the support close to the die-aligning element, and (B) placing the first die onto the die-attach material so that the first side of the first die is in close proximity to the first die-alignment wall and the second side of the first die is in close proximity to the second die-alignment wall.
Finally, the exemplary aspects presented above with reference to 4a-4d may also be implemented in the method. In other words, the first die-aligning element may also comprise an additional die-alignment wall and the method may comprise the step of fixing a second die vertically to the die-attachment surface and fixing a first side of the second die horizontally to the additional die-alignment wall with an additional die-attach material, while leaving the side of the second die which is opposite to the first side of the second die horizontally unfixed.
The step of fixing the first side of the second die to the additional die-alignment wall, may in this case comprise the following sub-steps: (A) placing the additional die-attach material on the support close to the die-aligning element, and (B) placing the second die onto the additional die-attach material so that the first side of the second die is in close proximity to the additional die-alignment wall.
Any of the exemplary aspects described above relating to the heights of the first and second die-alignment walls, the additional die-alignment wall, the bond line and the first and second dies can be applied in these methods as well.
In general, it is noted that the exemplary embodiments described above are intended to facilitate the understanding of the present invention, and are not intended to limit the interpretation of the present invention. The present invention may be modified and/or improved without departing from the spirit and scope thereof, and equivalents thereof are also included in the present invention. That is, exemplary embodiments obtained by those skilled in the art applying design change as appropriate on the embodiments are also included in the scope of the present invention as long as the obtained embodiments have the features of the present invention. For example, each of the elements included in each of the embodiments, and arrangement, materials, conditions, shapes, sizes, and the like thereof are not limited to those exemplified above, and may be modified as appropriate. It is to be understood that the exemplary embodiments are merely illustrative, partial substitutions or combinations of the configurations described in the different embodiments are possible to be made, and configurations obtained by such substitutions or combinations are also included in the scope of the present invention as long as they have the features of the present invention.
Number | Date | Country | Kind |
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20225383 | May 2022 | FI | national |