Multiaxial transducer interconnection apparatus

Abstract: An apparatus for use as a substrate assembly for providing electrical connections in a multiaxial transducer is disclosed. The multiaxial transducer includes transducer die elements, which are electrically connected to the substrate assembly. The transducer die elements each have a sensitivity axis and are mounted on the substrate such that their sensitivity axes are non-parallel. The substrate comprises at least two modules wherein each module is fabricated substantially identically to the other and further wherein each module is oriented along a different axis corresponding to the orientation of the sensitivity axes. A plurality of electrical pads are affixed to the substrate so as to allow for pad-to-pad connections from one module to the other and further provide a ratio of substrate module bonding pads to transducer die bonding. A multiaxial transducer interconnection apparatus. The apparatus comprises first, second and third substrate modules each having a plurality of electrical tracks thereon. A portion of the electrical tracks is structured and arranged to interconnect the substrate modules in an orthogonal relationship to each other. The plurality of tracks on each substrate module is further arranged to form a pattern identical to the plurality of tracks on the other substrate modules. The substrate modules each include a mounting region whereon transducer die elements are mounted. One alternate embodiment of the invention would include a base upon which the modules would mount. Another alternate invention of the invention employs a chip carrier to support the multiaxial transducer of the invention.

Description: BACKGROUND OF THE INVENTION I. Field of the Invention: The invention is directed generally to a multiaxial interconnection apparatus for transducers and, more particularly, to a multiaxial transducer interconnection apparatus for use in advanced rate adaptive cardiac pacemaker systems, defibrillators, cardioverters, heart monitors, metabolic need indicators and similar medical electronic devices. II. Discussion of the Prior Art: Heart and respiration activity generates mechanical energy. This energy propagates through the body and can be detected by appropriate transducers and may provide information useful for the control of organ functions such as heart rate pacing, for example. Current transducer technology does not address certain critical aspects of such medical electronics applications. Some prior approaches in the medical electronics art use active (piezoelectric) transducer elements which are well known such as Bruel & Kjaer Company's Type 4321 and Endevco Company's Model 2258-10/-100 devices. These devices are limited in their application, however, because they do not utilize the cost and size advantages of micromachining technology. Passive transducers are also known in the prior art. Passive transducers require excitation energy to operate. In the case of a multiaxial transducer, the number of supply lines is proportional to the number of uniaxial transducer components assembled together. The reduction in quantity of transducer terminals or wires is critical for many applications. A number of companies offer passive (piezoresistive) transducers such as IC Sensors, 1701 McCarthy Boulevard, Mulpitas, CA, for example. These devices are sensitive in one dimension only, but could be integrated into a multiaxial transducer. However, it is believed that the die substrates currently utilized in the industry, have no designed-in features to aid in substrate-to-substrate electrical connection. JP-A-63118667 discloses a three-dimensional acceleration sensor comprising a cubic block having a different acceleration sensor attached to each of the three of its faces which are mutually orthogonal. According to the present invention there is provided a multi-axial transducer interconnection apparatus comprising, either first and second, or first, second and third, substrate modules each having a plurality of electrical tracks thereon, the tracks on one module having an identical fabrication and identical pattern to the tracks on the other module or modules, the substrate modules being arranged in a mutually orthogonal relationship and being electrically interconnected, and the substrate modules each including a mounting region having a different transducer die element mounted thereon, each transducer die element being electrically connected with its respective substrate module. This invention provides a multiaxial transducer, useful for medical electronics applications, comprising transducer elements mounted on electrically interconnected modular substrates. The multiaxial transducer of the invention achieves a reduction in the quantity of terminals required for many applications as compared to other known devices. It is an object of the invention to provide a multiaxial transducer interconnection apparatus fabricated from identical substrate elements so as to allow use of identical masks for the basic substrate module fabrication. Other features, objects and advantages of the invention will become apparent to those skilled in the art through the description of the preferred embodiment, claims and drawings herein. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings like numerals refer to like elements. Figure 1 shows a plan view of one embodiment of a die substrate module according to the invention. Figure 2 shows a plan view of the interconnection scheme of one embodiment. Figure 3 shows a perspective view of one embodiment of a multiaxial transducer. Figure 4 is a diagram of the substrate module of the invention illustrating pad usage. Figure 5 shows a perspective view of an alternate embodiment of a multiaxial transducer including a base element for supporting the substrate modules. Figure 6 shows a perspective view of another alternative embodiment of a multiaxial transducer employing a chip carrier. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figure 1, a plan view of one embodiment of a die substrate module according to the invention is shown. The die substrate module 100 comprises a substrate material upon which printed circuit tracks 102 for carrying electrical power or signals are deposited by means well known in the art. In one example, the substrate module 100 includes tracks 1, 2, 3 and 4. Track 1 is a negative voltage power line, track 4 is the positive voltage potential power line, 2 is the first signal line and 3 is a second signal line for carrying information from the transducer device to other electronics (not shown). A test pad, T, may advantageously be included. While the transducer to be used in connection with the invention is not shown in Figure 1, the mounting surface 106 for the transducer is shown as part of the substrate module adjacent to the tracks 102 and as bordered by the corner markings 110. Broken line 112 denotes a cutting line for removing excess material from some of the modules prior to assembly as appropriate as shown in Figure 3 and as described below in detail. The substrate module may be comprised of ceramic substrate material, for example, which may be cut by means of a laser or other cutting device well known in the art. Referring now to Figure 2, a plan view of an interconnection scheme of one embodiment of a substrate assembly including three die substrate modules is shown. Three substrate modules, 100A, 100B and 100C, are shown arranged for the purposes of illustrating the interconnections for this embodiment. Each of the modules 100A, 100B and 100C initially is fabricated identically as a die substrate module 100. Depending on where the module is to be used, certain modifications are made by the removal of unwanted material. Crossed-hatched areas 200A and 200C are advantageously removed prior to assembly of the three modules into a multiaxial transducer as shown in Figure 3 by means of laser trimming or micromachine milling, for example. Note that Figure 2 is intended to be used as an interconnection illustration only and is not representative of a manufacturing process step. Each of the substrates 100A, 100B and 100C includes a mounting surface area. These are denoted as 106A, 106B and 106C, respectively. Transducer die elements 300A, 300B and 300C as shown in Figure 3 are advantageously affixed to the mounting surfaces prior to assembly of the modules into the multiaxial transducer. Each of the modules 100A, 100B and 100C have power and signal lines as described hereinabove with reference to module 100 in Figure 1. Referring now to Figure 3, a perspective view of one embodiment of the multiaxial transducer of the invention is shown. With continuing reference to Figure 2, it can be seen that the three substrate modules 100A, 100B and 100C have now been connected together to form a multiaxial transducer 202. Transducer devices 300A, 300B and 300C have been mounted to mounting surfaces 106A, 106B and 106C, respectively. The removed material is shown for reference purposes as 200A and 200C. No material is removed from module 100B. Modules 100A, 100B and 100C are oriented such that the mounting surfaces 106A, 106B and 106C abut each other in an orthogonal relationship. The transducer devices 300A, 300B and 300C have sensitivity axes 302A, 302B and 302C oriented in a perpendicular relationship for sensing, in this example, energy propagated in the X, Y and Z directions. Such transducer devices are well known in the art and may be, for example, accelerometers of the type as sold by IC Sensors, as for example, its 3000 Series accelerometer. Referring now to Figure 4, a diagram of the substrate module 100 is shown wherein each of the pad areas are designated by a reference numeral for the purposes of further clarifying the interconnections for the substrate assembly and multiaxial transducer. Those skilled in the art will recognize that this example is given by way of illustration and not limitation of the invention to the configuration shown. The table below defines the pad designations and module interconnections in accordance with the reference numerals in Figures 2 and 4. The following table enumerates the pad usages and ratios for the example embodiment of the substrate module shown in Figure 4. Triaxial Transducer Pad Configuration Ratios for this example are: E / C = 2 (E + F) / C = 3 (D + E + F) / C = 4 The above ratios would be smaller if E were equal to zero thereby providing no substrate interconnections via specially designed pads. Note that by utilizing a single substrate module 100 and a transducer 300, a unidirectional assembly can be fabricated utilizing edge connectors 19-22. Referring now to Figure 5, an alternate embodiment of the multiaxial transducer is shown in perspective view. This embodiment includes transducers 300A, 300B and 300C mounted to modular substrates 220A, 220B and 220C and further mounted to base 250. Interconnections are made by means of wire conductors or tracks 252. Referring now to Figure 6, yet another alternate embodiment is shown including a multiaxial transducer assembly 260 having transducers 300A, 300B and 300C (not shown) mounted on an integrated circuit chip carrier 262. Other pins 264 are then brought out from the chip carrier 262 for interfacing with external electronics. It is believed that this alternate configuration would be useful for certain applications. Those skilled in the art will recognize that the applications of the invention are not limited by the medical industry examples cited herein, but also have application to other fields utilizing multidirectional sensing devices, such as the automotive and aerospace arts.

Claims: A multi-axial transducer interconnection apparatus comprising, either first and second, or first, second and third, substrate modules (100A-C, 220A-C) each having a plurality of electrical tracks (1,2,3,4,252) thereon, the tracks on one module having an identical fabrication and identical pattern to the tracks on the other module or modules, the substrate modules (100A-C,220A-C) being arranged in a mutually orthogonal relationship and being electrically interconnected, and the substrate modules (100A-C,220A-C) each including a mounting region (106A-C) having a different transducer die element (300A-C) mounted thereon, each transducer die element (300A-C) being electrically connected with its respective substrate module (100A-C,220A-C). The apparatus according to Claim 1 wherein the electrical tracks (1,2,3,4,) electrically interconnect the modules (100A-C) The apparatus according to Claim 1 comprising a base (250,260) having orthogonal mounting surfaces, wherein each mounting surface has a different one of said modules (220A-C) mounted thereon. The mounting apparatus of Claim 3 which further comprises an IC chip carrier (262) upon which the base (260) is mounted. The apparatus of any preceding claim, wherein the transducer die elements (300A-C) each have a sensitivity axis (x,y,z) and are mounted so as to orientate the sensitivity axes (x,y,z) in a mutually orthogonal relationship The apparatus of Claim 5, wherein the transducer die elements (300A-C) are accelerometers. The apparatus according to claim 5 or 6, wherein the transducer die elements (300A-C) have bonding pads. The apparatus according to any preceding claim, wherein each module has a plurality of electrical pads (1-22,T). The apparatus of any preceding claim wherein the substrate modules (100A-C,220A-C) are fabricated from ceramic material. The apparatus of any preceding claim wherein the plurality of electrical tracks (1,2,3,4,252) of each module (100A-C,220A-C) comprise at least two tracks (1,4) for carrying electrical power and at least two tracks (2,3) for carrying an electrical signal.

Inventors: SILVERMINT EMANUEL H, SILVERMINT, EMANUEL H.
Applicants: CARDIAC PACEMAKERS INC, CARDIAC PACEMAKERS, INC.
Application year: 1990
Main classification: G01P15
IPC codes: A61N1, H01L29, G01P15