JP4831300B2 - Multi-die back-illuminated diode module assembly - Google Patents

Description

  The present invention relates generally to medical imaging systems, and more specifically to computed tomography (CT). Although the subject matter of this application has specific applications for X-ray systems, the present invention has applications related to other imaging modalities.

Current CT scanners typically use thousands of x-ray detectors to convert x-ray energy into electrical signals. A typical detector may include an array of scintillators, which are attached to an array of semiconductor photodiodes that detect light or other ionizing radiation in the front. Some implementations have configurable detectors that combine signal currents from multiple individual photodiodes to perform subsequent processing in a single amplifier channel. Can do. In this configuration, the detection area of each pixel can be changed using an externally controlled electrical switch (field effect transistor or FET). Bond pads for electrical connection to the FET are typically located at one or both ends of the photodiode, and the pixel array as a whole is from the center of the array to one or both edges near the FET. It must form a path towards you.
US Pat. No. 6,707,046

  As the number of elements in the array increases, the trace and bond pad density increases to an undesirably high level near the edge of the photodiode array. This places some physical limitations on the number and size of traces and bond pads that can be formed using the top contact. Available wiring and silicon processing techniques can only achieve up to 40-50 slices of a 0.625 mm pixel (as measured by the CT gantry isocenter).

  This document describes a method and apparatus that at least partially overcomes the aforementioned problems.

  In one aspect, a multilayer substrate having a plurality of scintillators, a plurality of back illuminated photodiodes optically coupled to the scintillators, and a plurality of substrate conductors to which the photodiodes are electrically coupled. A plurality of substrate conductors each connected to a different back-illuminated photodiode, and having a multilayer substrate and a plurality of flexible conductors to which the substrate is electrically coupled A computed tomography imaging scanner module comprising a flexible cable, wherein each of a plurality of flexible conductors is connected to a different output of a multilayer substrate.

  In another aspect, an imaging system is provided that includes an x-ray source and an x-ray detector module positioned to receive x-rays emitted from the source. The detector module is electrically coupled to the plurality of scintillators facing the X-ray source, the plurality of back illuminated photodiodes optically coupled to the scintillator, and the plurality of back illuminated photodiodes. And a flexible cable electrically coupled to the multilayer substrate.

  In yet another aspect, a method is provided. The method includes receiving a photon from a scintillator, converting the photon into an electrical signal, transmitting the electrical signal through a multilayer substrate, and transmitting the electrical signal through a multilayer flexible circuit. Steps.

  In yet another aspect, a method is provided for attaching a back-illuminated diode to a multilayer substrate, the method comprising connecting stud bumps to the surface of the back-illuminated diode, and applying an adhesive to the surface of the multilayer substrate. Positioning, aligning the surface of the stud bump with the surface of the adhesive on the multilayer substrate, heating the back illuminated diode and the substrate to the adhesive cure temperature, and the back illuminated diode And underfilling a gap formed between the substrate and the substrate.

  In another aspect, a method for attaching a flexible electrical circuit to a substrate is provided. The method includes the steps of placing a solder bump on the surface of the multilayer substrate, placing a reflow sealant on the surface of the flexible electrical circuit, and aligning the surface of the multilayer substrate with the surface of the solder bump. And heating the flexible electrical circuit and the substrate to a solder reflow temperature.

  This document provides radiation detection methods and apparatus useful in imaging systems such as, but not limited to, computed tomography (CT) systems. The apparatus and method will be described with reference to the drawings. In all of the drawings, like reference numerals indicate the same elements. Such drawings are intended to be illustrative rather than limiting and are included herein to facilitate the description of exemplary embodiments of the apparatus and method of the present invention.

  In some known CT imaging system configurations, the radiation source projects a fan-shaped beam, which is the XY plane of the Cartesian coordinate system, commonly referred to as the “imaging plane”. Collimated to lie in a plane. The radiation beam passes through the object being imaged, such as a patient. The beam enters the array of radiation detectors after being attenuated by the object. The intensity of the attenuated radiation beam received by the detector array depends on the amount of attenuation of the radiation beam by the object. Each detector element in the array produces a separate electrical signal that is a measurement of beam attenuation at the detector location. Attenuation measurements from all detectors are acquired separately to form a transmission profile.

  In the third generation CT system, the radiation source and detector array rotate with the gantry around the object in the imaging plane so that the angle at which the radiation beam intersects the object changes constantly. A group of radiation attenuation measurements or projection data from a detector array at one gantry angle is called a “view”. A “scan” of an object includes a set of views that are formed at various gantry or view angles during one revolution of the radiation source and detector.

  In an axial scan, the projection data is processed to reconstruct an image corresponding to a two-dimensional slice obtained through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered backprojection method. This method converts attenuation measurements from the scan into integers called “CT numbers” or “Hansfield units” and uses these integers to control the brightness of the corresponding pixels on the display.

  To shorten the total scan time, a “helical” scan (spiral scan) can also be performed. In order to perform a “helical” scan, data of a predetermined number of slices are acquired while moving the patient. Such a system generates a single helix from a single fan beam helical scan. Projection data is obtained from the helix mapped by the fan beam, and an image at each predetermined slice can be reconstructed from the projection data.

  As used in this document, the term element or step written in the singular and followed by the singular indefinite article should be understood as not excluding the presence of a plurality of such elements or steps unless explicitly stated otherwise. . Furthermore, references to “one embodiment” of the present invention should not be construed as excluding the existence of other embodiments that also incorporate the recited features.

  Also, the expression “reconstruct an image” as used in this document does not exclude embodiments of the invention in which data representing the image is generated but no visible image is formed. Accordingly, as used herein, the term “image” broadly refers to both the visible image and the data representing the visible image. However, many embodiments form (or are configured to form) one or more visible images.

  FIG. 1 is a sketch of a CT imaging system 10. FIG. 2 is a block schematic diagram of the system 10 shown in FIG. In the exemplary embodiment, a computed tomography (CT) imaging system 10 is shown as including a gantry 12 typical of a “third generation” CT imaging system. The gantry 12 has a radiation source 14 that projects an x-ray cone beam 16 toward a detector array 18 on the opposite side of the gantry 12.

  The detector array 18 is formed by a plurality of detector rows (not shown in FIGS. 1 and 2) that include a plurality of detector elements 20, which are collectively shown in FIG. A projected X-ray beam transmitted through the object is sensed. Each detector element 20 generates an electrical signal that represents the intensity of the incident radiation beam and thus represents the attenuation of the beam as it passes through the subject or patient 22. Imaging system 10 having multi-slice detector 18 is capable of forming a plurality of images representing the volume of object 22. Each of these multiple images corresponds to a separate “slice” of space. The “thickness” or aperture of the slice is determined by the thickness of the detector row.

  The gantry 12 and components mounted on the gantry 12 rotate around the center of rotation 24 during a single scan to acquire radiation projection data. FIG. 2 shows only a single row of detector elements 20 (ie, a detector row). However, the multi-slice detector array 18 provides a plurality of parallel detector rows of detector elements 20 so that projection data corresponding to multiple quasi-parallel or parallel slices can be acquired simultaneously during a single scan. Contains.

  The rotation of the gantry 12 and the operation of the radiation source 14 are controlled by the control mechanism 26 of the CT system 10. The control mechanism 26 includes a radiation controller 28 that supplies power and timing signals to the radiation source 14 and a gantry motor controller 30 that controls the rotational speed and position of the gantry 12. A data acquisition system (DAS) 32 provided within the control mechanism 26 samples the analog data from the detector element 20 and converts this data into a digital signal for subsequent processing. An image reconstructor 34 receives sampled and digitized radiation data from DAS 32 and performs high speed image reconstruction. The reconstructed image is applied as an input to the computer 36, which causes the mass storage device 38 to store the image.

  The computer 36 also receives commands and scanning parameters from an operator via a console 40 having a keyboard. The attached cathode ray tube display 42 allows the operator to observe the reconstructed image and other data from the computer 36. The commands and parameters supplied by the operator are used by the computer 36 to supply control signals and information to the DAS 32, radiation controller 28 and gantry motor controller 30. In addition, the computer 36 operates a table motor controller 44 that controls the motorized table 46 to place the patient 22 in the gantry 12. Specifically, the table 46 moves each part of the patient 22 through the gantry opening 48.

  In one embodiment, the computer 36 is a device 50 that reads instructions and / or data from a computer readable medium 52 such as a flexible disk, CD-ROM, DVD or other digital source such as a network or the Internet, eg, Any other digital device including a network connection device such as a flexible disk drive, CD-ROM drive, DVD drive, magneto-optical disk (MOD) device, or Ethernet device, and digital means under development Is included. In other embodiments, computer 36 executes instructions stored in firmware (not shown). Generally, at least one processor of DAS 32, reconstructor 34, and computer 36 shown in FIG. 2 is programmed to perform the steps described below. Of course, the method is not limited to being implemented in the CT system 10 and can be utilized with many other types and variations of imaging systems. In one embodiment, computer 36 is programmed to perform the operations described herein, so the term computer as used herein is not limited to an integrated circuit referred to in the art as a computer, Broadly refer to processors, microcontrollers, microcomputers, programmable logic controllers, application specific integrated circuits, and other programmable circuits. Although the methods described herein are described in a medical environment, such as systems typically used in industrial or transport environments, such as, but not limited to, baggage scanning CT systems at airports or other transport locations, etc. It is envisioned that medical imaging systems will also benefit from the present invention.

  As shown in FIGS. 3 and 4, the known detector array 118 includes a plurality of detector module assemblies 150 (also referred to as detector modules), each module comprising an array of detector elements 120. Yes. Each detector module 150 includes a high density photosensor array 152 and a multidimensional scintillator array 154 located adjacent to the top of the photosensor array 152. Specifically, the scintillator array 154 includes a plurality of scintillators 156, and the photosensor array 152 includes a photodiode 158, a switch device 160, and a decoder 162. A material such as epoxy with titanium dioxide as a filler fills the small space between the scintillator elements. The photodiode 158 is an individual photodiode or an integral multidimensional diode array. Photodiodes 158 are dispersed, deposited or formed on a silicon substrate. The scintillator array 154 is placed over or adjacent to the photodiode 158 as is known in the art. Photodiode 158 is optically coupled to scintillator array 154 and has an electrical output line that transmits a signal representative of the light output by scintillator array 154. Each photodiode 158 generates a separate low level analog output signal that is a measurement of beam attenuation for a particular scintillator in scintillator array 154. Photodiode output lines (not shown in FIG. 3 or FIG. 4) may be physically located on one side of module 120 or on multiple sides of module 120, for example. As shown in FIG. 4, the photodiode outputs are located on both sides of the photodiode array.

  As shown in FIG. 3, detector array 118 includes 57 detector modules 150. Each detector module 150 includes a photosensor array 152 and a scintillator array 154 that typically conforms to the array 152. As a result, the array 118 is divided into 16 rows × 912 columns (16 × 57 modules), for example, with the current technology, assuming that the z axis is the gantry rotation axis, N rotations along the z axis with each rotation of the gantry 12 = 16 slice data can be collected simultaneously.

  The switch device 160 is a multidimensional semiconductor switch array. Switch device 160 is coupled between photosensor array 152 and DAS 32. The switch device 160 in one embodiment includes two semiconductor switch arrays 164 and 166. Switch arrays 164 and 166 each include a plurality of field effect transistors (FETs) (not shown) arranged as a multidimensional array. Each FET includes an input electrically connected to one of the respective photodiode output lines, an output, and a control (not shown). The FET outputs and controls are connected to lines that are electrically connected to DAS 32 via flexible electrical cable 168. Specifically, about half of the photodiode output lines are electrically connected to each FET input line of the switch 164, and the other half of the photodiode output lines are electrically connected to the FET input line of the switch 166. Yes. Thus, the flexible electrical cable 168 is electrically connected to the photosensor array 152, for example, by connection from the flexible cable 168 to the switch device 160, and from the switch device 160 and decoder 162 to the photodiode 158. Has been.

  The decoder 162 controls the operation of the switch device 160 to enable, disable, or combine the output of the photodiode 158 depending on the desired number of slices and the desired resolution of each slice. The decoder 162 is, in one embodiment, an FET controller as is known in the art. Decoder 162 includes a plurality of output lines and control lines coupled to switch device 160 and DAS 32. Specifically, the decoder output is electrically coupled to the control line of the switch device to enable the switch device 160 to transmit the appropriate data from the switch device input to the switch device output. A decoder 162 is used to selectively enable or disable a particular FET within the switch device 160 so that the output of a particular photodiode 158 is electrically connected to the DAS 32 of the CT system. Or combine. The decoder 162 enables the switch device 160 so that the rows of the photosensor array 152 of the selected number of columns are connected to the DAS 32, and then the data for the selected number of slices are electrically connected to the DAS 32. To be processed.

  As shown in FIGS. 3 and 4, the detector module 150 is fitted to the detector array 118 and fixed in place by rails 170 and 172. FIG. 3 shows that the rail 172 is already fixed in place and the rail 170 is being fixed above the electrical cable 168 and above the substrate 174, flexible cable 168 and mounting bracket 176 of the module 150. It shows a state. A screw (not shown in FIGS. 3 and 4) is then screwed through the holes 178 and 180 into the screw holes 182 of the rail 170 to secure the module 150 in place. The flange 184 of the mounting bracket 176 is held in place by compression against the rails 170 and 172 (or in one embodiment by gluing) to prevent “swing” of the detector module 150. The mounting bracket 176 also clamps the flexible cable 168 to the substrate 174, or in one embodiment the flexible cable 168 is also glued to the substrate 174.

  Traditionally, however, traces or electrical paths can only be drawn from one end of the photodiode array, which places some physical limitations on the number and size of traces and bond pads that can be formed using the top contacts. Have joined. Physical limitations on the number and size of traces and bond pads can be avoided by inverting the diodes and placing surface contacts on the back side of the photodiode array. This technique is described, for example, in US Pat. No. 6,707,046 (ie, back illuminated or “backlit” diode). Electrical connections are made directly from each pixel of the back-illuminated diode array to a ceramic substrate or printed wiring board (PWB) or the like. The substrate is multilayered and transmits electrical signals from the photodiode array through the multilayer substrate to the opposite side of the substrate. Pads capable of electrical bonding are disposed on each side of the substrate to facilitate electrical interconnection. The backside connection design eliminates the requirement that traces have to be routed to the edges of the diode array, and allows unlimited tiling of elements in the z and x dimensions of a CT scanner.

  FIGS. 5 and 6 show a diode-substrate assembly 200 assembled by placing a back-illuminated diode array 202 on a multilayer substrate 204. Prior to the alignment and attachment of the back-illuminated diode array 202 to the substrate 204, an array of conductive epoxy 206 is applied loosely on the substrate 204, applied to one side, or dispensed quantitatively. A plurality of stud bumps 208 are bonded to the patterned metallized surface of the back-illuminated diode array 214 by ultrasonic thermocompression and placed substantially at the center of each of the pixels of the array 202. The stud bump 208 is metallic and in one embodiment is gold. The conductive adhesive 206 is patterned on the surface of the substrate 204 with an opposing pattern 216 that is the same as and compatible with the stud bump array 206. The diode array 202 is precisely aligned with the substrate 204 using pick and place flip chip technology and crimped until the stud bumps 208 reach the pads of the array 216. The conductive adhesive is cured according to the manufacturer's instructions for time and temperature requirements. The stud bump 208 controls the back-illuminated diode array 202 to a uniform height and facilitates application of the underfill material 210 to the gap 212. The stud bump 208 is in contact with the surface of the substrate 204 throughout the array of contact areas and is substantially the same height so that the diode array has substantially the same surface flatness as the substrate 204. Makes it possible to fit. The stud bumps also form a gap 212 that is filled with the underfill material 210 by capillary action. The underfill 210 helps to strengthen the bond between the back illuminated diode array 202 and the substrate 204. The underfill 210 also helps prevent ionic and other contamination from entering the array mounting area and adds low signal robustness to the junction.

  FIG. 7 shows the flexible circuit 308 attached to the substrate 204 on the opposite side of the back illuminated diode array 202 (not shown). A plurality of eutectic solder balls 302 are arranged on the substrate 204 in a pattern according to the plurality of electrical output pads 304 of the substrate 204. A no-flow method is then used to first apply the sealant 312 onto the flexible circuit 308 using a pick and place facility to bond the flexible circuit 308 to the substrate 204 and then assembly. Is heated to a predetermined temperature required for soldering to cause the solder balls 302 to flow, thereby filling the gap 310. The encapsulant cures as part of the solder flow heating. The flexible circuit 308 has a corresponding pattern of electrical contact pads 306 that matches the opposing pattern 304 on the substrate 204. The no-flow method refers to applying a sealant on the flexible circuit 308 before joining the two surfaces and then heating to the solder melting temperature.

  FIG. 8 shows a flexible circuit 308 configured with an array pattern 306, which is also configured with a sacrificial pad 330, which is pivoted between stitches. Stitch welding is performed with the directional gap 332 provided. Similar metallized sacrificial stitches are placed on a substrate (not shown) in a similar manner to the pattern of contact pads 304. When the flexible circuit 308 is bonded to the substrate 204, the opposing stitch pattern forms opposing metallized surfaces that perform at least three functions. FIG. 9 shows sacrificial pads 330. When these sacrificial pads 330 are joined in a subsequent bonding process, the adhesion of the mating surface to which the sealant adheres is enhanced. The sacrificial pad 330 also helps to prevent the sealant 312 from flowing beyond the sacrificial pad 330. The flow region of the sealant 312 is limited by the groove 334, and the groove 334 is arranged and dimensioned such that capillary action ends in the groove region 334. With the flow thus restricted, the sacrificial pad 330 also serves to define the bend line 336 of the flexible circuit 308. The axial gap 332 allows the release of gas formed during the heating process of the solder bumps 304.

  One of the technical advantages of the methods and apparatus described herein is that they provide a back-illuminated diode on a multilayer substrate and a flexible circuit attached to the lower surface of the substrate. That is. Another technical advantage is that the method and apparatus described herein uses a multilayer ceramic substrate or printed wiring board as the substrate material. Another technical advantage is that the method and apparatus described herein uses solder and reflow sealant for flexible circuit attachment and bend line control. Another technical advantage is that the methods and apparatus described herein use sacrificial pads for underfill material control and improved CT detector module reliability.

  The invention has been described with reference to the preferred embodiment. Modifications and variations will occur to those skilled in the art upon reading and understanding the above detailed description. The present invention should be construed to include all such modifications and variations as long as they fall within the scope of the claims or their equivalents. In the claims, reference numerals corresponding to reference numerals in the drawings are for the purpose of facilitating the understanding of the claimed invention and are not intended to narrow the scope of the claimed invention. . The matters described in the claims of this application are incorporated into the specification as a part of the description of the specification.

1 is a sketch of an embodiment of a CT imaging system. It is a block schematic diagram of the system shown in FIG. FIG. 2 shows an array of known detector modules. It is a figure which shows the well-known detector module shown in FIG. It is a figure which shows arrangement | positioning with respect to the base material of a back irradiation type diode array. FIG. 3 is a diagram showing adhesive bonding between a substrate and a back illuminated diode array. It is a figure which shows the adhesive joining between a base material and a flexible circuit. FIG. 6 is a plan view of a sacrificial pad on a flexible circuit. FIG. 6 is a view of a flexible circuit attached to a substrate, wherein the flex circuit bend line is defined by the position of the sacrificial pad.

Explanation of symbols

10 CT system 12 Gantry 14 Radiation source 16 X-ray cone beam 18 Detector array 20 Detector element 22 Patient 24 Center of rotation 26 Control mechanism 42 Display 46 Motorized table 48 Gantry aperture 50 Media reader 52 Media 118 Known detection Detector array 150 detector element 150 detector module assembly 152 photosensor array 154 scintillator array 156 scintillator 158 photodiode 160 switch device 162 decoder 164, 166 semiconductor switch array 168 flexible electrical cable 170, 172 rail 174 base Material 176 Mounting bracket 178, 180, 182 Screw hole 184 Flange 200 Diode-substrate assembly 202, 214 Back-illuminated diode array 20 4 Multilayer Substrate 206 Conductive Adhesive 208 Stud Bump 210 Underfill Material 212 Gap 216 Adhesive Opposing Pattern 302 Eutectic Solder Ball 304 Substrate Side Contact Pad Pattern 306 Circuit Side Contact Pad Pattern 308 Flexibility Circuit 310 gap 312 sealant 330 sacrificial pad 332 axial gap 334 groove 336 bending line

Claims (10)

A plurality of scintillators (156);
A plurality of back illuminated photodiodes (202) optically coupled to the scintillator (156);
A multi-layer substrate having a first surface, a second surface parallel to the first surface and disposed opposite to the first surface, and a groove (334) provided in the first surface A plurality of base material conductors (204) to which the photodiodes (202) are electrically coupled are disposed on the first surface, and each of the plurality of base material conductors is different from each other. A multilayer substrate (204) connected to a back illuminated photodiode (202);
A flexible electrical circuit (308) having a plurality of flexible conductors to which the multilayer substrate is electrically coupled on the second surface, wherein each of the plurality of flexible conductors is A flexible electrical circuit (308) connected to different outputs of the second surface of the multilayer substrate (204);
A plurality of metallized sacrificial pads (330) adjacent to the groove (334) of the multilayer substrate (204) and bonded between the multilayer substrate (204) and the flexible electrical circuit (308); ,
A sealant (312) that joins the flexible electrical circuit (308) to the multilayer substrate (204);
Equipped with a,
A computed tomography imaging scanner (10) module wherein each of the plurality of metallized sacrificial pads (330) is spaced from an adjacent metallized sacrificial pad (330) . The module of claim 1, wherein the plurality of scintillators (156) comprise a two-dimensional array (154). Wherein the plurality of back-illuminated photodiode (202) constitutes a two-dimensional array aligned with the array of the plurality of scintillators (156) (214), according to claim 2 module. It said plurality of base conductors constitute a two-dimensional array aligned with the array of the back-illuminated photodiode (202), according to claim 3 modules. Each of the plurality of back-illuminated photodiode (202) includes a stud-bumps, module according to any one of claims 1 to 4. The plurality of metallized sacrificial pads (330), wherein the sealant (312) prevents the sealant (312) from flowing beyond the plurality of metallized sacrificial pads (330). Modules. An X-ray source (14);
An X-ray detector module (18) arranged to receive X-rays emitted from the source;
An imaging system (10) comprising:
A plurality of scintillators (156) facing the X-ray source;
A plurality of back illuminated photodiodes (202) optically coupled to the scintillator (156);
A multilayer substrate having a first surface, a second surface parallel to the first surface and disposed opposite to the first surface, and a groove (334) provided in the first surface A multilayer substrate (204), the material (204) , wherein the plurality of back illuminated photodiodes are electrically coupled to the first surface ;
A flexible electrical circuit (308) electrically coupled to the multilayer substrate (204) on the second side ;
A plurality of metallized sacrificial pads (330) adjacent to the groove (334) of the multilayer substrate (204) and bonded between the multilayer substrate (204) and the flexible electrical circuit (308); ,
A sealant (312) that joins the flexible electrical circuit (308) to the multilayer substrate (204);
The includes,
The imaging system (10), wherein each of the plurality of metallized sacrificial pads (330) is spaced from an adjacent metallized sacrificial pad (330 ). Bonding a plurality of back illuminated photodiodes to the first surface of the multilayer substrate (204);
Providing a groove (334) in a second surface disposed parallel to the first surface of the multilayer substrate (204) and opposite the first surface;
Coupling a multilayer flexible electrical circuit (308) to the second surface of the multilayer substrate (204);
With
Coupling the multilayer flexible electrical circuit (308) to the second surface;
A plurality of metallized sacrificial pads (330) are coupled between the multilayer substrate (204) and the multilayer flexible electrical circuit (308) adjacent to the groove (334) of the multilayer substrate (204). Steps,
Applying a sealant (312) onto the flexible circuit (308) to bond the flexible circuit (308) to the multilayer substrate (204);
Each of the plurality of metallized sacrificial pads (330) is spaced apart from an adjacent metallized sacrificial pad (330). Placing a plurality of solder balls (302) on the multilayer substrate (204) in a pattern according to the plurality of electrical output pads (304) of the multilayer substrate (204) on the second surface;
Heating and flowing the solder balls (302) and the sealant (312), and curing the sealant (312);
Including
The flow area of the sealant (312) is limited by the groove (334),
The plurality of metallized sacrificial pads (330) prevent the sealant (312) from flowing beyond the plurality of metallized sacrificial pads (330);
The method of claim 8, wherein the spacing between the adjacent metallized sacrificial pads (330) allows for the release of gas formed during the heating. Receiving the photons from the scintillator (156) by the plurality of back-illuminated photodiodes ;
Converting the photons into electrical signals;
Transmitting said electrical signal through said multilayer substrate (204),
Transmitting said electrical signal through said multi-layer flexible circuit (308),
10. The method according to claim 8 or 9, comprising :

Images