Sensor package and method for manufacturing the sensor package

Abstract

To provide a sensor package that can improve the combination of an existing sensor and a package.SOLUTION: A sensor package comprises: a sensor; at least one outer wall; and an interposer arranged between the sensor and the at least one outer wall. The sensor is wire-bonded to the interposer, and the interposer is wire-bonded to the at least one outer wall. The interposer wire-bonded to both the sensor and the at least one outer wall is used to improve an approach to electrically connect the sensor with the sensor package.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present disclosure relates to packaging sensors and maximizing the resilience of sensor packages under high stress.A sensor package and method of manufacturing the sensor package are disclosed. [Background technology]

[0002] Sensors, such as pressure sensors or inertial sensors (such as accelerometers and gyroscopes), are used in many applications including inertial navigation, robotics, avionics, and automotive. In inertial navigation applications, such sensors may be found in autonomous systems known as "inertial measurement units" (IMUs). IMUs typically contain multiple accelerometers and / or gyroscopes and provide estimates of an object's travel parameters, such as angular velocity, acceleration, altitude, position, attitude, and speed, based on the output of the gyroscope(s) and / or accelerometer(s). Each inertial sensor in an IMU is an autonomous package.

[0003] Microelectromechanical system (MEMS) based sensors can be used, for example, to measure pressure or temperature, or linear or angular motion, without a fixed point of reference. MEMS pressure sensors often operate on the principle of mechanical deformation of a MEMS structure due to fluid pressure. MEMS gyroscopes, or more precisely, MEMS angular rate sensors, can measure angular velocity by observing the response of an oscillating MEMS structure to a Coriolis force. MEMS accelerometers can measure linear acceleration by observing the response of a proof mass suspended on a spring in a MEMS structure. A high performance MEMS inertial sensor is defined by its bias and scale factor stability.

[0004] Due to the application of such sensors, they may be exposed to extremely large forces (e.g., accelerations > about 20,000 G) at times. Under such conditions, components inside the sensor package may begin to fail. Typically, the first failures inside the sensor package occur due to the wire bonds connecting the package to the sensor. The wire bonds may short to each other or experience bond failures where the wire bonds are bonded to pads on the sensor or package. This is clearly undesirable as it reduces the functional range of the sensor and further necessitates replacement of the unit in any of the failure scenarios described above. Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure seeks to address at least some of these shortcomings. [Means for solving the problem]

[0006] According to a first aspect of the present disclosure, A sensor; at least one exterior wall; a sensor package including: an interposer disposed between the sensor and the at least one outer wall; The sensor is wire bonded to the interposer. The interposer is wire bonded to at least one outer wall.

[0007] According to a second aspect of the present disclosure, there is provided a method of making a sensor package, the sensor package comprising: A sensor; at least one exterior wall; The method comprises: inserting an interposer into the sensor package between the sensor and at least one outer wall; Wire bonding the sensor to the interposer; wire bonding the interposer to at least one outer wall; Includes. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 shows a cross-sectional schematic diagram of a prior art sensor package. [Diagram 2] 1 illustrates a cross-sectional schematic diagram of a sensor package according to an example of the present disclosure. [Figure 3a] 1 illustrates a perspective view of an interposer according to an example of the present disclosure. [Figure 3b] 1 illustrates a perspective view of a sensor package according to an example of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present disclosure relates to a sensor package and a method for making the sensor package. It will be appreciated that the use of an interposer wire-bonded to both the sensor and at least one outer wall improves the approach of electrically connecting the sensor and the sensor package compared to the prior art. The interposer allows for shorter wire bonds from the sensor and at least one outer wall to the interposer, replacing the single long wire bond from the sensor to the at least one outer wall in the prior art. This results in improved resiliency of the sensor package under high stress. Furthermore, it allows for improvements to existing sensor and package combinations without the need to reconfigure any of the components.

[0010] Some non-limiting examples of sensor packages and methods of making sensor packages are described in further detail below.

[0011] 1 shows a cross-sectional schematic diagram of a prior art sensor package assembly 100. The sensor package includes a sensor 102, a package 104, wire bonds 106, conductive tracking 108, and a lid 110.

[0012] To protect the sensor 102 from external influences that may damage or destroy the sensor 102 during use, the sensor 102 is placed in a protective package 104 that surrounds the sensor 102. After the sensor 102 is placed in the package 104, it is wire-bonded to the package 104 to make an electrical connection from the sensor 102 to the outside world. The protective package 104 comprises conductive tracking 108, which allows making an electrical connection from the outside of the package 104 to the sensor 102. To completely seal the package 104 from external influences, a lid 110 is bonded to the package 104. This sealing of the internal space within the package 104 prevents any external influences from directly affecting the sensor 102.

[0013] However, in an extremely stressful event (e.g., extremely high acceleration), failure or malfunction may occur internal to the sensor package assembly 100. Typically, the initial failure internal to the sensor package assembly 100 due to such a high stress event will be the failure of one or more of the wire bonds 106. Wire bond 106 failure may occur when one wire bond 106 shorts to another, or the entire wire bond 106 may crush. Crushing may occur when there is a bond failure (i.e., when the wire bond 106 is bonded to the sensor 102 or metal tracking 108).

[0014] 2 illustrates a cross-sectional schematic view of a sensor package 200 according to an example of the present disclosure. The sensor package 200 includes a sensor 202, a base 204, an interposer 206, wire bonds 208, conductive tracking 210, 212, a lid 214 sealed to an outer wall 213, and a selective adhesive 216 between the interposer 206 and the outer wall 213.

[0015] In this example, the interposer 206 is inserted between the sensor 202 and the outer wall 213 such that it is on top of the package base 204. Conductive tracking 210 is placed on the interposer 206 before it is added to the sensor package 200, allowing for an electrical connection to be made from one side of the interposer 206 to the other. The sensor 202 can then be wire bonded (208) to the conductive tracking 210 of the interposer 206, which in turn can be wire bonded (208) to the conductive tracking 212 on the outer wall 213. This creates an electrical connection from the sensor 202 through the interposer 206 to the outside of the package 200.

[0016] The present inventors have discovered that the failure rate of wire bond 208 is correlated to the weight, and therefore the length, of wire bond 208. It is contemplated that other modifications, such as reducing the diameter of wire bond 208 or changing the material of wire bond 208, may also affect the weight of wire bond 208, but this disclosure focuses on the length of wire bond 208 because this approach also provides other advantages that are described in more detail below.

[0017] The insertion and fitting of the interposer 206 in this example allows the wire bonds 208 to be extremely short inside the package 204 while maintaining an electrical connection between the sensor 202 and the conductive tracking 212 on the package 204. These short wire bonds 208 are significantly more resilient to high stresses than the long wire bonds 106 of Figure 1. This allows the sensor package 200 to be more resilient against bumps and / or damage and maintains an increased operating range.

[0018] Furthermore, the addition of the interposer 206 allows for the use of existing package 204 designs along with existing package 204 manufacturing methods, such that the interposer 206 can be incorporated into such packages 204, eliminating the need to redesign the entire package 204 to achieve the same reduction in wire bond 208 length.

[0019] In this example, the interposer 206 is adhesively bonded to the package 204 by an adhesive layer 216. This may increase the resiliency of the sensor package 200 by ensuring that the interposer 206 remains in place under high stress.

[0020] 3a and 3b show perspective views of an interposer 300 and a sensor package 310, respectively, according to an example of the present disclosure.

[0021] FIG. 3a illustrates an interposer 300 according to an example of the present disclosure. The interposer 300 is formed to be patterned with conductive tracking 302, which allows for making connections (e.g., wire bonds) to the interposer 300. As shown, the interposer 300 includes a cutout 304, which allows for adhesive to be dispensed without the adhesive contacting the conductive tracking 302. This may prevent any possible contamination of the conductive tracking 302 and may also prevent any possible wire bonding process from occurring. As mentioned above, the adhesive may also bond the interposer 300 to one or more outer walls of the package, increasing the resiliency of the sensor package.

[0022] 3b shows a sensor package 310 according to an example of the present disclosure. The sensor package 310 includes the interposer 300 of FIG. 3a that fits inside its outer wall 313 and a sensor 316 that fits inside or is surrounded by the interposer 300.

[0023] Package 310 is an existing mass-produced design, and thus interposer 300 is specifically designed to fit inside package 310. As mentioned above, this avoids redesigning package 310.

[0024] As shown, interposer 300 is inserted into package 310, surrounding sensor 316 and occupying most of the space between sensor 316 and package 310. In this example, it can be seen how interposer 300 is shaped to conform to the shape defined by outer walls 313 of package 310 and is positioned to contact outer walls 313 at least at the corners of its rectangular shape.

[0025] Adhesive may be dispensed into the cutout 304 as described above to secure the interposer 300 in place inside the package 310. The cutout 304 prevents the interposer 300 from moving upward past the hardened adhesive, which increases the resiliency of the sensor package 310.

[0026] As shown, the sensor 316 is wire bonded (318) to the conductive tracking 302 on the interposer 300. The conductive tracking 302 on the interposer 300 is further wire bonded (320) to the conductive tracking 314 that is supported by the outer wall 313 of the package 310. As explained above, this allows an electrical connection to be made between the sensor 316 and the package 310. As previously mentioned, the reduced length of the wire bonds 318, 320 increases the resiliency of the sensor package 310 under high stress.

[0027] It can thus be seen that in accordance with the present disclosure, a sensor package is provided that can facilitate reducing the length of the wire bonds. The inventors of the present invention have understood that a reduced length of the wire bonds corresponds to a reduced likelihood of breakage under high stress. When an interposer is disposed between the outer wall and the space between the sensor, typically, the wire bonds that directly couple the sensor to the outer wall can be shortened to two wire bonds, one between the sensor and the interposer and one between the interposer and the outer wall. These shortened wire bonds can be less susceptible to high acceleration shocks or crashes, increasing the resilience and operating range of the sensor package. The inventors of the present invention have understood that there is a correlation between the weight of a wire bond and its susceptibility to breakage under high stress. Thus, by reducing the length of the wire bonds, their weight is also reduced, which in turn reduces their likelihood of breakage under high stress. It is contemplated that other modifications, such as reducing the diameter of the wire bond or changing the material of the wire bond, may also affect the weight of the wire bond, but this disclosure focuses on the length of the wire bond.

[0028] Use of the present disclosure may further allow for the use of existing package designs along with existing package manufacturing methods. Thus, the interposer can be incorporated into such existing packages, eliminating any need to redesign the entire package. This saves both the cost and time of such redesigns.

[0029] Use of the present disclosure may also enable existing sensors to be used in emerging markets that require extreme robustness, where such devices, as discussed above, may not be suitable.

[0030] In accordance with one or more examples of the present disclosure, the interposer includes conductive tracking, the sensor is wire bonded to the conductive tracking, and the conductive tracking is wire bonded to at least one outer wall. This may allow the sensor to be electrically connected to at least one outer wall via the conductive tracking of the interposer. This may allow the signal from the sensor to be accessed from outside the package. This may also allow a further reduction in the length of the wire bond, since the conductive tracking may span the width of the interposer. The wire bond may then be bonded to the interposer at an edge. Furthermore, the tracking may be designed to optimize the distance between where the connection is made from the sensor and where the connection is made from the interposer. Also, the tracking may be designed to optimize the distance between where the connection is made from the package and where the connection is made from the interposer. Thus, in one or more examples, the sensor is wire bonded to the conductive tracking, and the conductive tracking is wire bonded to at least one outer wall.

[0031] Additionally or alternatively, according to one or more examples of the present disclosure, at least one outer wall is made of a first material and the interposer is made of a second material, the first and second materials being different. In some examples, the first or second material is a ceramic, e.g., alumina. In some examples, the second material is a resin. In some examples, the second material is FR-4.

[0032] In accordance with one or more examples of the present disclosure, additionally or alternatively, the interposer is formed by injection molding. This may allow existing manufacturing techniques (e.g., molded interconnect device techniques) to be utilized, simplifying manufacturing and reducing costs. In some examples, the interposer is a molded integrated circuit device (MID).

[0033] In accordance with one or more examples of the present disclosure, additionally or alternatively, the interposer contacts at least one outer wall. This means that the interposer may be in physical contact with the at least one outer wall and wire bonded to the at least one outer wall for electrical contact. This physical contact of the interposer and the at least one outer wall may increase the robustness of the package by reducing the possibility of the interposer moving or becoming misaligned inside the sensor package during use. For example, the interposer may fit inside the package to contact the at least one outer wall. Preferably, the interposer is molded to fit a shape defined by the at least one outer wall. In some examples, the sensor package comprises at least four outer walls forming a square, rectangular, or polygonal shape. In such examples, the interposer may be molded to have a corresponding square, rectangular, or polygonal shape such that the interposer fits inside the package to at least partially contact the at least four outer walls. In such examples, the interposer preferably contacts the exterior wall at least at the corners of its square, rectangular, or polygonal outline.

[0034] In accordance with one or more examples of the present disclosure, the interposer may additionally or alternatively be adhesively bonded to at least one outer wall, which may further improve the stability and resilience of the sensor package under stress.

[0035] In accordance with one or more examples of the present disclosure, additionally or alternatively, the interposer is shaped to accommodate an adhesive used to adhesively bond the interposer to at least one outer wall. In some examples, the interposer may include a cutout shaped to accommodate the adhesive. In some examples, the adhesive accommodated by the cutout may increase the resiliency of the sensor package under stress. In these examples, the interposer may conform to the inside of the package to contact at least one outer wall, e.g., to contact corners defined by the outer wall, and the cutout may be arranged between the contact areas, e.g., between the corners. In such examples, the sensor package may benefit from a highly stable fit with the interposer and bond provided by the adhesive.

[0036] In accordance with one or more examples of the present disclosure, additionally or alternatively, at least two of the interposer, the sensor, and the at least one outer wall are coplanar. This may allow for a further reduction in the length of the wire bonds between the sensor and the interposer. This may also allow for a further reduction in the length of the wire bonds between the interposer and the at least one outer wall. In some examples, the interposer, the outer wall, and the sensor are coplanar.

[0037] In accordance with one or more examples of the present disclosure, additionally or alternatively, the interposer surrounds the sensor, which may allow for a reduction in the length of the wire bond made between the interposer and the sensor. In some examples, at least one outer wall surrounds the interposer, which may allow for a reduction in the length of the wire bond made between the at least one outer wall and the interposer.

[0038] In accordance with one or more examples of the present disclosure, additionally or alternatively, the interposer fills at least 50% of the space between the sensor and the at least one outer wall. This may allow for a reduction in the length of wire bonds connecting the interposer and the sensor and / or the interposer and the at least one outer wall. In some examples, the interposer fills at least 75% of the space between the sensor and the at least one outer wall.

[0039] Additionally or alternatively, according to one or more examples of the present disclosure, the sensor is a MEMS sensor. In some examples, the MEMS sensor is silicon-based. In some examples, the MEMS sensor is an inertial sensor. In some examples, the MEMS sensor is an accelerometer, a gyroscope, or a pressure sensor.

[0040] According to one or more examples of the present disclosure, the sensor package further comprises a potting or lid for sealing the package. In this way, the interposer does not seal the package. Sealing the sensor package with a potting or lid may protect the sensor from any direct external influences that may damage or destroy the sensor. Sealing the sensor package further allows for control of the internal environment of the package, which may be optimized depending on the sensor.

[0041] Also disclosed is a method of making a sensor package. In one or more examples, the interposer includes conductive tracking, the method further including wire bonding the sensor to the conductive tracking and wire bonding the conductive tracking to at least one outer wall.

[0042] Additionally or alternatively, in one or more examples, the method further includes arranging at least two of the interposer, the sensor, and the at least one exterior wall in a coplanar manner.

[0043] Additionally or alternatively, in one or more examples, the method further includes adhesively bonding the interposer to the at least one exterior wall.

[0044] Although the present disclosure has been illustrated by describing one or more specific examples thereof, it will be recognized by those skilled in the art that it is not limited to these examples and that many variations and modifications are possible within the scope of the appended claims. Features of any aspect or example described herein may be applied to any other aspect or example described herein, where appropriate. When referring to different examples or sets of examples, it should be understood that these are not necessarily different, but may be partially consistent.

Claims

1. 1. A sensor package comprising: A sensor; at least one exterior wall; an interposer disposed between the sensor and the at least one outer wall; Equipped with the interposer, the sensor, and the at least one exterior wall are coplanar; the sensor is wire bonded to the interposer; the interposer is wire bonded to the at least one outer wall; a portion of the interposer to which the wire bonding is connected, a portion of the sensor to which the wire bonding is connected, and a portion of the outer wall to which the wire bonding is connected are located in the same plane; the interposer is fitted inside the package so as to contact the at least one outer wall; The interposer is adhesively bonded to the at least one outer wall.

2. 10. The sensor package of claim 1, wherein the interposer comprises conductive tracking, the sensor is wire bonded to the conductive tracking, and the conductive tracking is wire bonded to the at least one outer wall.

3. The sensor package of claim 1 or 2, wherein the at least one outer wall is made from a first material and the interposer is made from a second material, the first and second materials being different.

4. The sensor package of claim 3 , wherein the second material is a resin, and optionally, the interposer is formed by injection molding.

5. The sensor package of claim 4 , wherein the interposer is a molded interconnect component (MID).

6. The sensor package of claim 1 , wherein the interposer is molded to accommodate an adhesive.

7. The sensor package of claim 1 , wherein the interposer fills at least 50% of a space between the sensor and the at least one outer wall.

8. The sensor package of claim 1 , further comprising a potting or a lid for sealing the package.

9. A method for manufacturing a sensor package, the sensor package comprising: A sensor; at least one outer wall; The method comprises: inserting an interposer into the sensor package between and flush with the sensor and the at least one outer wall; wire bonding the sensor to the interposer; wire bonding the interposer to the at least one outer wall; Including, adhesively bonding said interposer to said at least one outer wall. Further comprising: A method according to claim 1, wherein the location where the wire bonding is connected on the interposer, the location where the wire bonding is connected on the sensor, and the location where the wire bonding is connected on the outer wall are in the same plane.

10. The interposer includes conductive tracking, and the method further comprises: wire bonding the sensor to the conductive tracking; wire bonding the conductive tracking to the at least one outer wall; 10. The method of claim 9, comprising:

11. The method of claim 9 or 10, further comprising arranging at least two of the interposer, the sensor, and the at least one outer wall in a same plane.

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