US20090269976A1 - Bridge connector for connecting circuit boards - Google Patents

Abstract

A bridge connector that is configured to electrically and mechanically couple first and second circuit boards is provided. Each circuit board includes a board surface having through-holes. The connector includes a housing having a coupling side configured to interface with the board surfaces when the housing is coupled to the first and second circuit boards. The connector also includes a plurality of bridge contacts that are held within the housing. Each contact includes tail portions that project from the coupling side. Each tail portion is configured to form an interference fit with a corresponding through-hole in order to couple the first and second circuit boards. The tail portions are arranged to hold the first and second circuit boards along the coupling side.

Description

BACKGROUND OF THE INVENTION
• The subject matter herein relates generally to electrical connectors and more particularly to bridge connectors that mechanically and electrically couple two or more circuit boards together.
• Some electrical devices or systems use circuit board assemblies in which two or more circuit boards are fastened together. The circuit boards may be electrically coupled together in order to allows the circuit boards to transmit information between each other. For example, some known touchscreen systems utilize a display panel having multiple layers stacked upon each other. One of the layers may be a circuit board assembly having several circuit boards fastened together in a frame that forms the perimeter of a touchscreen area. The circuit boards are typically co-planar and include LEDs and phototransistor receivers. The LEDs and receivers form an optical grid along the touchscreen area that is used to determine the location of a touch. When a user touches the touchscreen area, the optical grid registers the touch information and relays the information through the circuit board assembly to a controller of the touchscreen system.
• In one known method for coupling circuit boards together, a first circuit board is positioned adjacent to a second circuit board such that edges of the circuit boards are proximate to each other. Each circuit board includes a plurality of contact areas, such as bonding pads, that are formed along a corresponding edge. The contact areas of the first circuit board are aligned with the corresponding contact areas of the second circuit board. A conductive band formed from a conductive material is used to electrically couple the associated contact areas. However, although the circuit boards are electrically coupled to each other through the conductive bands, the conductive bands may not provide sufficient support to facilitate maintaining the positions of the circuit boards.
• Other methods include soldering contacts to the surfaces of adjacent circuit boards and/or using resins or adhesives to couple the circuit boards together. However, these methods may have a limited ability to mechanically couple the circuit boards together such that the circuit boards maintain their spatial relationship. Furthermore, other methods generally involve using multiple steps in order to connect the circuit boards together.
• Thus, there is a need for connectors that both electrically and mechanically couple two or more circuit boards together. There is also a need for a connector that may be applied to the circuit boards in order to couple the circuit boards together using fewer steps than at least some known connectors.
BRIEF DESCRIPTION OF THE INVENTION
• In one embodiment, a bridge connector that is configured to electrically and mechanically couple first and second circuit boards is provided. Each circuit board includes a board surface having through-holes. The connector includes a housing having a coupling side configured to interface with the board surfaces when the housing is coupled to the first and second circuit boards. The connector also includes a plurality of bridge contacts that are held within the housing. Each contact includes tail portions that project from the coupling side. Each tail portion is configured to form an interference fit with a corresponding through-hole in order to couple the first and second circuit boards. The tail portions are arranged to hold the first and second circuit boards along the coupling side.
• Optionally, the tail portions are configured to hold the circuit boards co-planar with respect to each other. Also, the tail portions may be configured to hold the circuit boards such that edges of the circuit boards directly abut each other and form an edge interface. Furthermore, the connector may also include a plurality of bridge contacts that are configured to mechanically and electrically couple the first circuit board to a third circuit board. Optionally the connector is only formed from the housing and the contacts.
• In another embodiment, a bridge connector configured to electrically and mechanically couple first and second circuit boards is provided. Each circuit board includes a board surface having through-holes. The connector includes a housing that has a coupling side configured to interface with the board surfaces when the housing is coupled to the first and second circuit boards. The connector also includes at least one contact row that includes upper and lower bridge contacts held within the housing. Each of the upper and lower bridge contacts has tail portions that project from the coupling side, and each tail portion is configured to form an interference fit with a corresponding through-hole to couple the first and second circuit boards. The tail portions are arranged to hold the first and second circuit boards along the coupling side.
• Optionally, the tail portions may extend along a common plane. Furthermore, the at least one contact row may include a plurality of contact rows that extend along a length of the housing. The contact rows may be spaced apart from each other along the width of the body. Also, the housing may include a plurality of slots that are configured to receive the contacts. The contacts may be held within slots that extend along a common plane that is substantially perpendicular to the board surfaces.
• In vet another embodiment, a circuit board assembly is provided. The circuit board assembly includes a plurality of circuit boards where each circuit board includes a board surface having through-holes. The circuit board assembly also includes at least one bridge connector that is configured to electrically and mechanically couple adjacent circuit boards to each other. The connector includes a coupling side that is configured to interface with the board surfaces of adjacent circuit boards when the coupling side is mounted onto the adjacent circuit boards. The connector also includes a plurality of bridge contacts that are held within the connector. Each contact has tail portions that project from the coupling side, and each tail portion is configured to form an interference fit with a corresponding through-hole to couple the adjacent circuit boards. The tail portions are arranged to hold the adjacent circuit boards along the coupling side.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a bridge connector formed in accordance with one embodiment.
• FIG. 2 is a top perspective view of the connector shown inFIG. 1.
• FIG. 3 is a bottom perspective view of the connector shown inFIG. 1.
• FIG. 4 is a cross-sectional view of the housing taken along the line4-4 shown inFIG. 2.
• FIG. 5 is a bottom planar view of the connector shown inFIG. 1.
• FIG. 6 is a top planar view of a circuit board assembly formed in accordance with one embodiment.
• FIG. 7 is a side view of a bridge connector system formed in accordance with one embodiment.
DETAILED DESCRIPTION OF THE INVENTION
• FIG. 1 is a perspective view of abridge connector100 formed in accordance with one embodiment and a pair ofcircuit boards102 and104. As will be discussed in greater detail below, theconnector100 is configured to mount and engage thecircuit boards102 and104 in order to mechanically and electrically couple thecircuit boards102 and104 together. In some embodiments, theconnector100 may be included as one part or component of an electrical device or the features of theconnector100 may be incorporated into a larger system or structure. However, in the illustrated embodiment, the exclusive function of theconnector100 is to mechanically and electrically couple thecircuit boards102 and104 together. By way of example, theconnector100 may be used in constructing a circuit board assembly for use in an infrared (IR) touch system such as modular flat panels by Elo Touch Systems. Furthermore,FIG. 1 illustrates twocircuit boards102 and104, however, alternative embodiments of theconnector100 may be configured to engage more than two circuit boards (for example, three or four circuit boards). Also, as described above, a plurality ofconnectors100 may be used to interconnect several circuit boards into a circuit board assembly. For example, several circuit boards may be connected in a linear arrangement or several circuit boards may be connected to each other to form a frame that extends along a perimeter of a touchscreen.
• As shown inFIG. 1, theconnector100 may include ahousing106 that holds a plurality ofbridge contacts140 and150 (FIGS. 2-4) therein. Thehousing106 may be formed from a dielectric material during, for example, an injection molding process. In one embodiment thehousing106 has a rigid body or structure. Thehousing106 may also have a substantially rectangular body and include a length L, a width W, and a thickness T. Alternatively, thehousing106 may have other shapes configured to hold the plurality ofcontacts140 and150 and, optionally other components for an electrical device. Thehousing106 may be shaped to have a plurality of sides including a coupling side S₂that interfaces with thecircuit boards102 and104 when theconnector100 is mounted thereon. Thecontacts140 and150 may extend lengthwise (i.e., parallel to a longitudinal axis191) through thehousing106 and includetail portions110 that project from the coupling side S₂in a perpendicular manner (i.e., parallel to a vertical axis192). Thetail portions110 may form any predetermined or desired arrangement on the coupling side S₁. As will be discussed in greater detail below, thetail portions110 may form an arrangement that facilitates mechanically holding thecircuit boards102 and104 in a desired spatial relationship.
• Thecircuit boards102 and104 may have substantially rigid bodies and include board surfaces103 and105, respectively. Thecircuit boards102 and104 may be of a common type or structure, however, in alternative embodiments, thecircuit boards102 and104 are not similar and may include, for example, different dimensions or are formed from a different substrate material. As shown inFIG. 1, the board surfaces103 and105 may form planes that are substantially co-planar and parallel with respect to a plane formed by theaxes191 and190. The board surfaces103 and105 may includeengagement areas112 and114, respectively, having associated through-holes116 extending therethrough. When thecircuit boards102 and104 are aligned, theengagement areas112 and114 indicate aninterfacing area115 of thecircuit boards102 and104 where thehousing106 may engage and interface with. Optionally theengagement areas112 and114 may be marked or delineated on the board surfaces103 and105, respectively, to indicate to an operator where thehousing106 should be positioned. In the illustrated embodiment, the through-holes116 form a pattern or an array that is similar to the arrangement oftail portions110 projecting from the coupling side S₁. Furthermore, the through-holes116 andcorresponding tail portions110 may be configured to form a press or interference fit.
• In order to engage thecircuit boards102 and104, theconnector100 may be aligned with theengagement areas112 and114 such that thetail portions110 may be inserted into the corresponding through-holes116. When thetail portions110 are inserted into the corresponding through-holes116, the combined interference fits may provide a tactile indication (i.e., snap-fit) to an operator that theconnector100 has been mounted to thecircuit boards102 and104. As such, theconnector100 may provide a simple method for mechanically and electrically coupling thecircuit boards102 and104 together.
• Also shown inFIG. 1, thecircuit boards102 and104 may includeedges122 and124, respectively. Optionally when thecircuit boards102 and104 are coupled to theconnector100, theedges122 and124 may directly abut each other along anedge interface120. As shown inFIG. 1, theedge interface120 may be substantially linear. However, alternative embodiments may include theedges122 and124 having complementary protrusions or teeth such that thecircuit boards102 and104 may mate with each other before theconnector100 is mounted thereon.
• FIGS. 2 and 3 provide top and bottom perspective views, respectively, of thehousing106. Thehousing106 may include a plurality of sides S₁-S₆. As shown, the thickness T of thehousing106 extends between the coupling side S₂and an opposing upper side S₁. As shown inFIG. 2, the length L extends between opposing sides S₆and S₅and is parallel to the longitudinal axis191 (FIG. 1). The width W extends between opposing sides S₃and S₄and is parallel to a z-axis190 (FIG. 1). Also shown, thehousing106 may include a plurality of upper slots130 (FIG. 2) and lower slots132 (FIG. 3) that extend lengthwise along thehousing106. The upper and lower slots130 and132 are configured to receive thecontacts140 and150, respectively. The upper and lower slots130 and132 may be formed in the dielectric material of thehousing106 during a molding process. In alternative embodiments, the upper slots130 and the lower slots132 may extend widthwise or diagonally across thehousing106.
• In one embodiment, theconnector100 may be a low-profile connector. As used herein, the term “low-profile” generally means that the thickness T of theconnector100 is configured to take up a minimal amount of space. As one example, the thickness T of theconnector100 is substantially equal to a sum of the widths of thecontacts140 and150 plus the thickness of the housing material that separates thecontacts140 and150. However, embodiments of theconnector100 are not required to be low-profile.
• FIG. 4 is a cross-sectional view of theconnector100 taken along the line4-4 shown inFIG. 2 when engaged with thecircuit boards102 and104. The coupling side S₂and the board surfaces103 and105 share and extend along a side interface195. As shown, the upper andlower slots130B and132B are configured to receive thecontacts140 and150, respectively. The upper andlower slots130B and132B may form a contact row200 (shown inFIG. 5). In the illustrated embodiment, theupper slots130B andlower slots132B of the contact row200 extend along a common plane that is parallel to a vertical plane formed by theaxes192 and191 and are perpendicular to the board surfaces103 and105. Although the following description is with reference toslots130B and132B inFIG. 4, the description may be similarly applied toslots130A and132A shown inFIGS. 2 and 3, respectively. As shown, theupper slot130B opens onto the side S₁and may have sections or leg portions that extend completely through the thickness T of thehousing106 such thattail portions144 and146 of thecontact140 may extend completely therethrough. As shown inFIG. 4, theupper slot130B extends between a point C, which is a distance X₁from the side S₅, and point D, which is a distance X₂from the side S₆. Although in some embodiments X₁and X₂may be substantially equal, in the illustrated embodiment, X₁is greater than X₂. As will be discussed in greater detail below, the contact rows200 alternate between being the distance X₁and a distance X₃(FIG. 5) from the side S₅and between being X₂and X₄(FIG. 5) from the side S₆.
• Thelower slot132B extends a portion into the thickness T of thehousing106 and may open onto the coupling side S₂. Thecontacts140 and150 include tail portions110 (FIG. 1). More specifically as shown inFIG. 4, thecontact140 includes thetail portions144 and146, and thecontact150 includestail portions154 and156. In one embodiment, thetail portions144,154,156, and146 project from the coupling side S₂along a common plane that is parallel to the vertical plane. Also shown, thetail portions144 and154 are separated by the housing material a distance Y and thetail portions146 and156 are also separated from each other the distance Y. However, in alternative embodiments, the distance separating thetail portions144 and154, and the distance separating thetail portions146 and156 may be different.
• Thecontacts140 and150 may be held within thehousing106 in a stacked relationship. Thecontacts140 and150 may be inserted into the upper andlower slots130B and132B. respectively, and form an interference fit with the correspondingslots130B and132B. As shown, thecontact140 includes abody portion142 that extends parallel to the board surfaces103 and105. Thebody portion142 may be exposed to the surrounding environment along the side S₁. Thecontact140 also includes thetail portions144 and146 that may extend from ends of thecorresponding body portion142 in a direction substantially perpendicular to thebody portion142. In the illustrated embodiment thecontact150 includes abody portion152 that extends parallel to the board surfaces103 and105. Thebody portion152 may be exposed to the surrounding environment along the coupling side S₁. Thecontact150 also includes thetail portions154 and156 that extend from ends of thebody portion152.
• As shown, thebody portions142 and152 extend substantially parallel with respect to each other and thetail portions144,146,154, and156 extend substantially parallel to each other. Also, thecontact140 may surround thecontact150. Thebody portion152 may be shorter than thebody portion142 and extend along a portion of a distance between thetail portions144 and146. As such, thetail portions154 and156 may be positioned between thetail portions144 and146.
• However, in alternative embodiments, thebody portions142 and152 may have non-linear paths that may or may not extend along with one another. For example, thebody portion152 may jog or deviate from a path made by thebody portion142 in order to make the electrical paths of thecontacts140 and150 substantially equal. Furthermore, in alternative embodiments, thecontacts140 and150 may not be exposed to surrounding environment but may be embedded within thehousing106.
• FIG. 5 is a bottom planar view of theconnector100. As described above, thecontacts140 and150 (FIG. 4) of each associated pair of upper and lower slots130 and132 (FIG. 4) may form a contact row200. As such, theconnector100 may include a plurality of contact rows200 that are spaced apart from each other a distance Z along the width W (FIG. 1) of thehousing106. More specifically thecontact rows200A include the upper andlower slots130A and132A, and thecontact rows200B include the upper andlower slots130B and132B. Each contact row200 includes a set of tail portions formed by thetail portions144,146,154, and156 (FIG. 4).
• As described above, thecontact rows200A and200B may alternate in position along the length L (FIG. 1) of thehousing106. More specifically thetail portion144 ofcontact row200A is the distance X₁from the side S₅and thetail portion144 of thecontact row200B is the distance X₃from the side S₅. As such, thetail portions144,146,154, and156 of thecontacts140 and150form contact grids210 and212 having multiple rows and columns of tail portions. In particular, thecontact grid210 includes thetail portions144 and154, and thecontact grid212 includes thetail portions146 and156. As such, thecontact grids210 and212 provide multiple points throughout the interface195 (FIG. 4) where an interference fit is formed between theconnector100 and the corresponding circuit board. As such, theconnector100 facilitates making a rigid connection that mechanically couples thecircuit boards102 and104 to each other.
• With reference again toFIG. 4, thetail portions144,146,154, and156 may include eve-of-needle shaped pins for forming an interference fit with the corresponding through-holes136. However, thetail portions144,146,154, and156 may have a variety of shapes for being inserted into and engaging the corresponding through-holes. In one alternative embodiment, thetail portions144,146,154, and156 do not include eve-of-needle shaped pins, but have solder balls (not shown) for soldering thetail portions144,146,154, and156 to corresponding contact pads (not shown) on thecircuit boards102 and104.
• In the illustrated embodiment, the interface195 does not include a resin or adhesive between the coupling side S₂and the board surfaces103 and105. However, in alternative embodiments, a resin or adhesive may be applied along the interface195 to facilitate bonding between theconnector100 and thecircuit boards102 and104.
• FIG. 6 is a top planar view of acircuit board assembly320 formed in accordance with one embodiment. Thecircuit board assembly320 includes a plurality of circuit boards302-306 that may be positioned adjacent to one another andbridge connectors300 and315. Theconnectors300 and315 electrically and mechanically couple the circuit boards302-306 to each other and may have similar features as described above with reference to theconnector100. As shown, theconnector300 may be configured to mechanically and electrically couple the adjacent circuit boards302-305 in a square arrangement or structure. Each circuit board302-305 may be mechanically and electrically coupled to two or more of the other circuit boards via sets of bridge contacts308-312. The contacts of each set308-312 may have similar features as described above with respect to thecontacts140 and150 and may be arranged in contact rows, such as the contact rows200 described above. Furthermore, each set of contacts308-312 may have a staggered arrangement, such as in the sets ofcontacts311 and312, or the contacts may be aligned with each other, such as in the sets of contacts308-310. Also shown, theconnector315 may couple theadjacent circuit boards303 and306 to each other. As such, thecircuit board assembly320 usesmultiple connectors300 and315 and multiple sets of contacts308-313 to form a unitary circuit board structure. In one embodiment, all of the circuit boards302-306 are co-planar and in a fixed relationship with respect to each other. Although thecircuit board assembly320 is shown as having several circuit boards302-306, alternative embodiments of thecircuit board assembly320 may have only taco circuit boards held together by a bridge connector.
• FIG. 7 is a side view of aconnector assembly350 formed in accordance with one embodiment. Theconnector assembly350 may includebridge connectors400 and500, which may have similar features as the connectors100 (FIG. 1) and 300 (FIG. 6) described above. Theconnectors400 and500 may be used to mechanically and electricallycouple circuit boards402 and502 together. As shown, theconnectors400 and500 may mount and engage thecircuit boards402 and502 from opposing board surfaces such that thecircuit boards402 and502 are sandwiched therebetween. Furthermore, thecircuit boards402 and502 may form a gap G therebetween. As shown, theconnectors400 and500 may be staggered with respect to each other. In the staggered arrangement, theconnector assembly350 may allow a greater density of contacts for mechanically and electrically coupling thecircuit boards402 and502 together. Furthermore, by forming interference fits with eachcircuit board402 and502 from each side of the circuit boards, theconnector assembly350 may provided a stronger interlocking mechanism than using just one connector.
• Embodiments described herein include bridge connectors having a housing and bridge contacts that electrically and mechanically couple two or more circuit boards together. The bridge connectors may be constructed and mounted to circuit boards using less steps that at least some other known connectors. Furthermore, embodiments described herein include circuit board assemblies that utilize the bridge connectors in holding a plurality of circuit boards together.
• It is to be understood that the above description is intended to be illustrative, and not restrictive. As such, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. For example, theconnectors300,315,400, and500 may have features similar to those described with respect to theconnector100. Furthermore, although the above description referred to coupling circuit boards in touch systems, embodiments described above may be used in a variety of electrical devices and systems that require mechanically and electrically coupling two or more circuit boards together.
• In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by no means limiting and are merely exemplary embodiments.
• Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.

Claims (21)

1. (canceled)

2. The connector in accordance withclaim 7 wherein the tail portions are configured to hold the circuit boards such that edges of the circuit boards directly abut each other and form an edge interface.

3. The connector in accordance withclaim 7 wherein the tail portions and the coupling side are configured to hold the first and second circuit boards such that the first and second circuit boards are coplanar with respect to each other.

4. The connector in accordance withclaim 7 wherein the connector is formed from only the housing and the contacts.

5. The connector in accordance withclaim 7 wherein each said slot is configured to receive a length of a corresponding contact.

6. The connector in accordance withclaim 5 wherein the contacts are held in a stacked relationship when inserted into the housing.

7. A bridge connector configured to electrically and mechanically couple first and second circuit boards, each circuit board including a board surface having through-holes, the connector comprising:

a housing having a coupling side configured to interface with the board surfaces when the housing is coupled to the first and second circuit boards;

a plurality of bridge contacts held within the housing, each said contact having tail portions projecting from the coupling side and each said tail portion configured for an interference fit with a corresponding said though-hole to couple the first and second circuit boards, wherein the tail portions are arranged to hold the first and second circuit boards along the coupling side;

wherein the housing includes a plurality of slots configured to receive the contacts, the plurality of slots including first and second slots extending along a common plane that is substantially perpendicular to the board surfaces, the first slot opening onto the coupling side and the second slot opening onto a side that is opposite the coupling side.

8. The connector in accordance withclaim 7 wherein each contact further comprises a body portion extending parallel to the board surfaces, the tail portions extending from the body portions along the common plane.

9. A bridge connector configured to electrically and mechanically couple first and second circuit boards, each said circuit board including a board surface having through-holes, the connector comprising:

a housing having a coupling side configured to interface with the board surfaces when the housing is coupled to the first and second circuit boards; and

at least one contact row including upper and lower bridge contacts held within the housing, each of the upper and lower bridge contacts configured to electrically couple the first and second circuit boards through a pair of tail portions that project from the coupling side, each said tail portion configured to form an interference fit with a corresponding said through-hole, wherein the interference fits of said upper and lower bridge contacts combine to form a rigid connection to the first and second circuit boards that mechanically holds the first and second circuit boards along the coupling side;

wherein the housing includes a plurality of slots, each said slot configured to receive a length of a corresponding bridge contact and configured for interference fit with the corresponding bridge contact, said slots opening to one of the coupling side and a side that is opposite the coupling side, the length extending substantially parallel to the board surfaces and the tail portions extending substantially perpendicular to the board surfaces when the corresponding bridge contact is inserted into and held by said slot.

10. The connector in accordance withclaim 9 wherein the tail portions extend along a common plane that is perpendicular to the board surfaces.

11. The connector in accordance withclaim 9 wherein the connector is formed from only the housing and the bridge contacts.

12. The connector in accordance withclaim 11 wherein the tail portions and the coupling side are configured to hold the first and second circuit boards such that the first and second circuit boards are coplanar with respect to each other.

13. (canceled)

14. The connector in accordance withclaim 9 wherein the plurality of slots includes first and second slots extending along a common plane that is substantially perpendicular to the board surfaces, the first slot opening onto the coupling side and the second slot opening onto a side that is opposite the coupling side.

15. The connector in accordance withclaim 9 wherein the at least one contact row includes a plurality of contact rows extending along a length of the housing, said contact rows being spaced apart from each other along the width of the housing.

16. The connector in accordance withclaim 11 wherein the upper and lower bridge contacts of each contact row are stacked with respect to each other in the housing such that the upper and lower bridge contacts extend along a common plane that is perpendicular to the board surfaces.

17-20. (canceled)

21. The connector in accordance withclaim 7 wherein the housing is mounted onto the board surfaces.

22. The connector in accordance withclaim 21 wherein the housing extends over only a portion of each board surface.

23. The connector in accordance withclaim 7 wherein at least two of said contacts are held in a stacked relationship within the first and second slots along the common plane, and wherein said stacked contacts have a width and said housing has a housing thickness that extend along the common plane, the housing thickness being substantially equal to a sum of the widths of said stacked contacts and a thickness of housing material that separates the said stacked contacts.

24. The connector in accordance withclaim 7 wherein the housing has a substantially rectangular body that includes a length and a width that extend along and form an interface with the board surfaces and a thickness that extends away from the board surface, wherein both the length and the width are greater than the thickness.

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