Sensor interposer employing castellation through-vias

Abstract

To provide a sensor interposer employing castellated through-vias formed in a PCB.SOLUTION: A sensor interposer includes: a planar substrate defining a plurality of castellated through-vias; a first electrical contact formed on the planar substrate and electrically coupled to a first castellated through-via; a second electrical contact formed on the planar substrate and electrically coupled to a second castellated through-via; the second castellated through-via electrically isolated from the first castellated through-via; and a guard trace having a first portion and a second portion, the first portion being formed on the first surface of the planar substrate and electrically coupling a third castellated through-via to a fourth castellated through-via, the second portion being formed on the second surface of the planar substrate and electrically coupling the third castellated through-via to the fourth castellated through-via, the guard trace providing electrical isolation between the first and second electrical contacts.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005] , , , ,

[0001] This application generally relates to wearable biosensors, and more specifically to sensor interposers that employ castellated through vias.

Background Art

[0002] Existing wearable biosensors, such as continuous glucose monitors, integrate an analyte sensor as a complete module assembly into a wearable device, and thus the device can be worn on the body and the sensor wires can be placed on the body simultaneously in one operation. As a result, the sensor wires need to be electrically connected to the device and mechanically assembled before placement during the manufacture or assembly of the device.

Summary of the Invention

Means for Solving the Problems

[0003] This application provides a planar substrate defining a plurality of castellated through vias, a first electrical contact formed on the planar substrate and electrically coupled to a first castellated through via, a second electrical contact formed on the planar substrate and electrically coupled to a second castellated through via, the second castellated through via being electrically insulated from the first castellated through via, and a guard trace formed on the planar substrate and electrically coupled between third and fourth through vias formed on the planar substrate, the guard trace insulating the first and second electrical contacts, and provides a sensor interposer including the same.

[0004] The accompanying drawings are incorporated herein and constitute a part hereof, showing one or more specific examples, and useful for explaining the principles and implementation of the specific examples together with the description of the examples.

Brief Description of the Drawings

[0005] [Figure 1] An exemplary sensor interposer employing castellated through-vias formed on a printed circuit board ("PCB") is shown. [Figure 2] An exemplary sensor interposer employing castellated through-vias formed on a printed circuit board ("PCB") is shown. [Figure 3A] This shows an exemplary sensor interposer employing castellated through-vias formed on a PCB. [Figure 3B] This shows an exemplary sensor interposer employing castellated through-vias formed on a PCB. [Figure 4] This shows an exemplary sensor interposer employing castellated through-vias formed on a PCB. [Figure 5A] This exhibits an exemplary wearable biosensor device, including a sensor interposer that employs castellated through-vias formed on a PCB. [Figure 5B] This exhibits an exemplary wearable biosensor device, including a sensor interposer that employs castellated through-vias formed on a PCB. [Figure 5C] This exhibits an exemplary wearable biosensor device, including a sensor interposer that employs castellated through-vias formed on a PCB. [Figure 6] This describes an exemplary method for manufacturing a sensor interposer that employs castellated through-vias formed on a PCB. [Modes for carrying out the invention]

[0006] This specification provides examples in the context of sensor interposers employing castellated through vias. Those skilled in the art will understand that the following description is illustrative and not intended to be limiting. Hereinafter, we refer in detail to the implementation of the example shown in the accompanying drawings. The same reference numerals are used throughout the drawings and the following description to refer to identical or similar items.

[0007] For clarity, not all of the everyday characteristics of the examples described herein are shown or explained. Naturally, in developing such actual implementations, it will be necessary to make numerous implementation-specific decisions to achieve the developer's particular goals, such as complying with application-related and business-related constraints, and it will be understood that these specific goals will differ from implementation to implementation and from developer to developer.

[0008] Some wearable biosensors employ one or more invasive sensor wires that are inserted into the wearer's skin. The sensor wire typically contains at least two separate electrodes and has a certain amount of chemical, such as glucose oxidase ("GOX"), deposited at the end of the sensor wire inserted into the wearer's skin. The chemical then reacts with an analyte present in the wearer's interstitial fluid, generating an electric current that can be sensed by the biosensor's electronics. However, the amount of current generated can be very small, for example, on the order of tens of nanoamperes, and these chemicals can be heat-sensitive, making the design and manufacture of biosensors challenging. For example, biosensors need to be designed to prevent leakage currents that could interfere with the current generated by the reaction between the chemical and the analyte. In addition, manufacturing processes involving high-temperature steps, such as soldering, can damage the chemicals when heated.

[0009] To address these and other challenges, an exemplary wearable biosensor may employ a main PCB containing electronic components such as a microcontroller or wire transceiver, battery, etc. In addition, the exemplary device may employ an auxiliary PCB assembly (commonly referred to as an "interposer") for mechanically securing the sensor wires, while also providing electrical contacts to different electrodes present on the sensor wires. The interposer may then be electrically and physically coupled to the main PCB, for example, by soldering. To help reduce the amount of heat transferred to the interposer during soldering, the exemplary interposer may employ castellated through-vias to provide an electrical connection between the main PCB and the interposer, providing a soldering location that is relatively thermally isolated from the sensor wires themselves.

[0010] In this example, the interposer has through-vias formed around the interposer footprint. The interposer is then cut from a larger PCB board, and thus the through-vias are cut, exposing the inner portions of the through-vias. The exposed inner portions of the through-vias can be aligned with corresponding electrical contacts on the main PCB and soldered to each other. Because the soldering points are located inside the through-vias and essentially on the opposite side of the PCB from the electronics on the interposer PCB, heat transfer from the soldering process to the interposer electronics, including the sensor wires, is significantly reduced. In addition, the use of through-vias makes it possible to form one or more guard rings surrounding the interposer, providing electrical insulation between different electrical contacts formed on the interposer, such as electrical contacts to different electrodes formed within the sensor wires.

[0011] The example in this figure is provided to introduce the reader to the general subject matter described herein, and this disclosure is not limited to this example. The following sections describe various additional non-limiting examples for sensor interposers employing castellation through vias formed in a PCB, as well as examples of systems and methods.

[0012] Referring now to Figure 1, which shows an exemplary sensor interposer 100 employing castellation through vias. In this example, the sensor interposer is a planar substrate, i.e., a PCB in this example. Any suitable PCB material may be employed, including FR4, polyimide, etc. Two electrical contacts 112, 114 are formed on the top surface of the PCB. Each electrical contact 112, 114 is sized and shaped such that a sensor wire 120 can be electrically and physically coupled to it by, for example, a clamp, adhesive, or any other suitable physical coupling technique. In this example, the sensor wire is formed from two electrodes formed coaxially, and before use, a sensor chemical (e.g., glucose oxidase) may be deposited on the distal end of the sensor wire, i.e., the end of the sensor wire, which is inserted into the wearer's skin. The proximal end of the sensor wire exposes each electrode, allowing each electrode to be electrically and physically coupled to one of the different electrical contacts 112, 114. In this example, the working electrode ("WE") is coupled to electrical contact 114, while the counter electrode ("CE") is coupled to electrical contact 112. In addition, each electrical contact 112, 114 is electrically coupled to a castellar through-via formed on the periphery of the PCB material. Once the interposer 100 is physically and electrically coupled to the main PCB, the castellar through-via 118 provides an electrical connection between the electrical contacts 112, 114 and the sensor electronics located on the main PCB. In this example, the interposer 100 has two electrical contacts 112, 114, but some examples may employ multiple sensor wires and may require additional electrical contacts depending on the type(s) of sensor wires employed. Furthermore, in some examples, the sensor wires may include three or more electrodes. For example, multiple electrodes may be formed overlapping in a series of planar layers. Each layer may be coupled to a different electrical contact formed on the planar substrate. Furthermore, different electrodes may have different sensor chemicals coated on them.Suitable sensor chemicals include chemicals for sensing acetylcholine, amylase, bilirubin, cholesterol, chorionic gonadotropin, creatine kinase (e.g., CK-MB), creatine, DNA, fructosamine, glucose, glutamine, growth hormone, hormones, ketones, lactates, peroxides, prostate-specific antigen, prothrombin, RNA, thyroid-stimulating hormone, or troponin.

[0013] In this example, the planar substrate 110 (or interposer substrate) also defines an opening 124 between the two electrical contacts. The opening provides physical separation between the two electrical contacts 112, 114, thereby providing some electrical insulation between them. In addition, the opening allows for the formation of guard traces 116a-b that do not intersect or contact the sensor wire 120. In some examples, the opening may be formed to have a shape corresponding to one or more features formed on the main PCB, allowing for alignment. However, it should be understood that such openings are not necessary in all examples and may be omitted based on design considerations.

[0014] In addition to the electrical contacts 112 and 114, two guard traces 116a and 116b are formed on the interposer PCB. Each guard trace 116a and 116b surrounds a portion of the interposer PCB, providing electrical isolation between the two electrical contacts 112 and 114. In this example, each guard ring includes a portion formed on the upper surface of the interposer PCB 110 that electrically connects two corresponding castellation through vias. Each guard ring 116a and 116b also includes a portion formed on the lower surface of the interposer PCB 110 that is also connected to the same corresponding castellation through vias, providing a closed loop of material surrounding the portion of the interposer PCB. Combined with the openings, the two guard rings 116a and 116b electrically isolate the two electrical contacts 112 and 114 from each other. In some examples, one or both of the guard rings 116a and 116b may be connected to a ground plane to help dissipate leakage current.

[0015] In this example, the interposer 100 also includes a sensor wire 120 coupled to two electrical contacts 112, 114. The sensor wire 120 in this example has two coaxially arranged wire members, one of which acts as the working electrode and the other as the reference electrode or counter electrode. To allow the two different coaxial portions of the sensor wire to be coupled to different electrical contacts, the inner wire member extends beyond the end of the outer wire member, a portion of which is covered with a polyurethane insulator 122. In this example, the inner wire member is physically and electrically coupled to one electrical contact 114, and the outer wire member is physically and electrically coupled to the other electrical contact 112.

[0016] In this example, the sensor wire material consists of (1) an inner wire material, which is a platinum or platinum-coated wire, and (2) an outer wire material, which is a silver / silver chloride (Ag / AgCl) material. One end of the sensor wire 120 and a portion of the Ag / AgCl material are inserted into the patient's skin, and the other end of the sensor wire 120 is attached to an electrical contact. The Ag / AgCl material is coupled to a first electrical contact 112, and the platinum material is coupled to a second electrical contact 114.

[0017] Referring now to Figure 2, which shows another exemplary sensor interposer 200 employing castellation through vias. In this example, the interposer 200 is formed from a planar substrate, which is PCB 210. Similar to the example shown in Figure 1, the interposer 200 has two electrical contacts 230a-b formed thereon. The sensor wire 250 is physically and electrically coupled to the electrical contacts 230a-b. In particular, the sensor wire has two coaxial electrodes 252a-b, which are physically and electrically coupled to their respective electrical contacts 230a-b. Each electrical contact 230a-b is electrically coupled to the corresponding castellation through vias 220b, 220c by electrical traces formed on PCB 210. The castellation through vias can later be physically and electrically coupled to electrical contacts on another PCB, allowing electrical signals from the sensor wire 250 to be communicated to another PCB.

[0018] The interposer 200 also includes guard traces 240 formed on the PCB 210. The guard traces 240 traverse the PCB 210 between two castellation through vias 220a, 220d and between two electrical contacts 230a-b, thereby electrically insulating them from each other. In this example, the guard traces 240 are formed on both the top surface of the PCB (shown in Figure 2) and the bottom surface opposite the top surface, where further electrical traces are formed between the castellation through vias 220a, 220d. However, in some examples, the guard traces 240 may be formed only on the same surface as the electrical contacts 230a-b. In this example, unlike the example shown in Figure 1, the PCB does not define a central opening. Therefore, the guard traces 240 must pass beneath the sensor wires 250 without contacting them, which could interfere with the electrical signals supplied to the electrical contacts 230a-b by the sensor wires 250.

[0019] Next, referring to FIGS. 3A - 3B, FIG. 3A shows an exemplary sensor interposer 300 that employs castellated through - vias formed within a PCB. In this example, the interposer 300 has a planar substrate of PCB 310 that defines a central opening 322. Additionally, PCB 310 has four castellated through - vias formed around its perimeter, while two castellated through - vias are formed around the central opening 322.

[0020] Two electrical contacts 312, 314 are formed on the upper surface of the PCB and are each electrically coupled to a corresponding castellated through - via formed around the central opening 322. The electrical contacts 312, 314 are arranged to physically and electrically couple to the sensor wire 220.

[0021] In addition to the electrical contacts 312, 314, two "wrap - around" guard traces 316a - b are formed on the PCB 310. Each guard trace 316a - b surrounds a portion of the PCB 310 and provides electrical insulation between the two electrical contacts 312, 314. In this example, each guard trace 316a - b includes a portion formed on the upper surface of the PCB 310 that electrically couples the corresponding two castellated through - vias. Each guard trace 316a - b also includes a portion formed on the lower surface of the PCB 310 that is also coupled to the same corresponding castellated through - via, providing a closed loop of material that surrounds a portion of the PCB 310. In combination with the opening, the two guard traces 316a - b electrically insulate the two electrical contacts 312, 314 from each other. In some examples, one or both of the guard traces 316a - b may be coupled to a ground plane to help dissipate leakage current.

[0022] Figure 3B shows the bottom surface of PCB 310. The diagram shown in Figure 3B also illustrates wrap-around guard traces 316a and 316b, which are electrically coupled by guard trace 316c, which connects two castellation through vias formed around the opening. In some examples, guard trace 316c is not included, so the two wrap-around guard traces 316a and 316b are electrically isolated from each other on PCB 310, but in some examples, they may be coupled to a common ground surface, such as a common ground surface formed on the main PCB of the biosensor.

[0023] Referring next to Figure 4, Figure 4 shows an exemplary sensor interposer 400 employing castellation through-vias formed within a PCB. Such an exemplary sensor interposer 400 can be integrated within a wearable biosensor such as a continuous glucose monitor ("CGM"). The exemplary CGM may include a main PCB containing various electronic components, including a processor, discrete electronic components, and a wireless transceiver. A battery may be mounted on the main PCB of the CGM and electrically coupled to power the electronic components of the CGM.

[0024] An exemplary sensor interposer 400 may be physically and electrically coupled to the main PCB, allowing signals from the sensor wires of the CGM, which are physically and electrically coupled to the sensor interposer 400, to be supplied to electronic components on the main PCB, such as a processor.

[0025] In this example, the sensor interposer 400 includes two electrical contacts 412, 414 formed on one side of the interposer 400, which are physically separated by an opening 422 defined around the interposer 400. Each electrical contact 412, 414 is electrically coupled to a castellation through via. In addition, a guard trace 416 is formed on the same surface of the PCB 410 as the two electrical contacts 412, 414, providing electrical insulation between the two electrical contacts 412, 414.

[0026] In addition to electrical contacts and guard traces 416, the interposer 400 also includes additional electrical features. In this example, an electrical tracer designed as an antenna 430 is formed on PCB 410 and electrically coupled to a castellation through via, enabling electrical and physical coupling of the CGM to the main PCB. In some examples, even more electrical features may be provided on the PCB, including additional electrical contacts for physically and electrically coupling one or more additional sensor wires.

[0027] In some examples, the interposer 400 may be formed separately from the main PCB, and the sensor wires may be physically and electrically coupled to the interposer 400 before the interposer 400 is physically and electrically coupled to the main PCB of the CGM; however, other sequences may also be adopted, as illustrated with respect to Figure 6.

[0028] Referring next to Figures 5A-5C, Figure 5A shows an exemplary wearable biosensor device 500 including a sensor interposer 520 employing castellated through-vias. In this example, the wearable biosensor device 500 includes a main PCB 510 on which the sensor interposer 520 and sensor controller 540 are located. This exemplary device 500 includes the exemplary sensor interposer shown in Figure 3, however, any suitable sensor interposer employing castellated through-vias may be employed.

[0029] In this example, the main PCB 510 also defines surface features 512, such as pins, that engage with openings defined in the sensor interposer 520. Figure 5B illustrates the main PCB 510, which has surface features 512 defined thereon. The surface features 512 provide alignment features to enable alignment between the sensor interposer 520, the main PCB 510, and one or more electrical contacts formed on the main PCB 510. Figure 5C illustrates a top-down view of the main PCB 510, which has surface features 512 formed and positioned to engage with the sensor interposer 520. In addition, the main PCB 510 has four electrical contacts 514a-d formed to engage with castellation through vias 522a-d of the sensor interposer.

[0030] Referring next to Figure 6, Figure 6 shows an exemplary method 600 for manufacturing a sensor interposer employing castellation through vias formed in a PCB. The exemplary method 600 is described in relation to the exemplary sensor interposer 100 shown in Figure 1, however, the exemplary method according to the Disclosure may be employed to manufacture any suitable exemplary sensor interposer according to the Disclosure.

[0031] Block 610 provides a suitable planar substrate 110. In this example, the planar substrate 110 is a PCB formed from a suitable material such as FR4 or polyimide. The planar substrate 110 in this example is larger in size than the designed sensor interposer 100. Therefore, in a later step, the planar substrate 110 can be cut to the size designed for the sensor interposer 100.

[0032] In block 620, one or more through vias 118 are formed on the planar substrate 110, such as in locations corresponding to the designed perimeter of the sensor interposer 100. Such through vias 118 may be formed to have a substantially circular (or other) cross-section, with a portion of the through via extending outside the designed perimeter of the sensor interposer 100. In some examples, one or more through vias 118 may also be formed on the inner portion of the sensor interposer 100. Such through vias 118 may be formed around the designed perimeter of an opening defined in the sensor interposer 100. For example, referring again to Figure 1, two through vias are formed on the PCB 110 and cut to form castellation through vias when the central opening of the PCB 110 is formed. Any appropriate number of through vias may be formed according to different examples. In this example, four through vias are formed around the designed perimeter of the sensor interposer, while two additional through vias are formed around the designed perimeter of the central opening of the sensor interposer 100.

[0033] In block 630, the planar substrate 110 is cut along the designed perimeter of the sensor interposer 100, and through vias are cut to form castellation through vias 118. In this example, the planar substrate 110 is further cut to form a central opening 124 and castellation through vias around the central opening 124.

[0034] In block 640, two electrical contacts 112 and 114 are formed on the PCB 110 within the designed periphery of the sensor interposer 100. In this example, the electrical contacts 112 and 114 are formed on either side of the designed central opening 124, enabling the physical and electrical coupling of the sensor wires 120. In this example, both electrical contacts 112 and 114 are formed on the same surface of the PCB 110; however, in some examples, they may be formed on either side of the PCB 100. For example, if each electrode of the sensor wire is formed on a separate wire, they may be coupled on either side of the PCB 110. And in this example, two electrical contacts are formed, but in some examples, three or more electrical contacts may be formed. For example, if multiple sensor wires are attached to the sensor interposer, a pair of electrical contacts may be formed for each sensor wire or each sensor electrode.

[0035] In addition to forming electrical contacts in block 640, electrical traces are formed from each electrical contact 112, 114, electrically coupling each electrical contact 112, 114 to the corresponding castellation through via. In some examples, the electrical traces are curved to extend their length, which can reduce heat transfer from the castellation vias to the electrical contacts when the interposer is later soldered to the main PCB.

[0036] In block 650, one or more guard traces 116a-b are formed on PCB 110. In this example, electrical traces are formed to connect the castellation through vias to each other and electrically insulate the electrical contacts. Referring to Figure 3A, for example, an electrical trace is formed between the castellation through vias formed around the central opening 322 and the corresponding castellation through vias formed around PCB 310. Such traces are formed on both the top and bottom surfaces of PCB 310, creating a guard trace surrounding PCB 210. In addition, in this example, a guard trace 316c is formed between the castellation through vias formed around the central opening 322, connecting the two wrap-around guard traces 316a-b; however, guard trace 316c is optional and may be omitted in some examples.

[0037] In block 660, the sensor wire 120 is coupled to electrical contacts 112 and 114. As described above, the sensor wire 120 may be a coaxial sensor wire 120 having two different wire materials, the inner wire material extending beyond the outer wire material at one end of the sensor wire 120. The exposed portion of the inner wire material may be physically and electrically coupled to one of the electrical contacts 114 by soldering or by using clips or other electrical coupling means. The portion of the outer wire material may be coupled to the other electrical contact 112 using any suitable electrical coupling means.

[0038] In block 670, appropriate sensor chemicals, such as glucose oxidase, are deposited on the end of the sensor wire 120 distal to the sensor interposer 100.

[0039] In block 680, the sensor interposer 100 is coupled to the main PCB of the biosensor. In this example, the sensor interposer 100 is soldered to the main PCB using each of the castellation through vias formed around the sensor interposer. In some examples, castellation through vias formed around the central opening may be soldered instead or in addition.

[0040] Although the steps of Method 600 described above were presented in a specific order, it should be understood that different orders may be adopted depending on the example. For example, block 630 may be executed after block 650, or block 650 may be executed before block 640 or block 630.

[0041] The above-mentioned examples are provided for illustrative and illustrative purposes only and are not intended to be exhaustive or to limit this disclosure to the exact form disclosed. Numerous modifications and adaptations thereto will be apparent to those skilled in the art without departing from the nature and scope of this disclosure.

[0042] Any reference in this specification to an example or implementation means that a particular feature, structure, operation, or other characteristic described in relation to the example may be included in at least one implementation of this disclosure. This disclosure is not limited to the specific example or implementation described in this specification. Occurrences of the phrases "in one example," "in an example," "in one implementation," "in an implementation," or variations thereof in various places in this specification do not necessarily refer to the same example or implementation. Any particular feature, structure, operation, or other characteristic described herein in relation to one example or implementation may be combined with other features, structures, operation, or other characteristics described in relation to any other example or implementation.

[0043] The use of the term "or" in this specification is intended to encompass inclusive and exclusive OR conditions. In other words, A or B or C, depending on the specific use, includes, namely A only, B only, C only, A and B only, A and C only, B and C only, and any or all of A, B and C. [Explanation of Symbols]

[0044] 100 Sensor Interposer 110 Planar board 112, 114 Electrical contacts 116a, 116b Guard Trace 118 Castellation through vias 120 Sensor Wire 122 Polyurethane insulator 124 Opening 200 Sensor Interposer 220a~220d Castellation through via 230a, 230b electrical contacts 240 Guard Trace 250 sensor wires 252a, 252b coaxial electrode 300 Sensor Interposer 310 PCB 312, 314 Electrical contacts 316a~316c Guard Trace 322 Central opening 400 Sensor Interposer 410 PCB 412, 414 Electrical contacts 416 Guard Trace 430 Antenna 500 Wearable Biosensor Devices 510 Main PCB 512 Surface Features 514a~514d Electrical contacts 520 Sensor Interposer 522a~522d Castellation through via

Claims

[Claim 1] A planar substrate defining multiple castellation through vias, A first electrical contact formed on the planar substrate and electrically coupled to the first castellation through via, A second electrical contact formed on the planar substrate and electrically coupled to a second castellation through via, wherein the second castellation through via is electrically insulated from the first castellation through via, A sensor interposer comprising a guard trace formed on the planar substrate, which is electrically coupled to third and fourth through vias formed on the planar substrate and insulates the first and second electrical contacts.

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