SYSTEM AND METHOD FOR FABRICATING EXTENDED LENGTH FLEXIBLE CIRCUITS
20230422410 ยท 2023-12-28
Inventors
Cpc classification
H05K3/4635
ELECTRICITY
H05K2203/068
ELECTRICITY
International classification
Abstract
A method of manufacturing a flexible circuit comprised of conducting and insulating layers in an extended length format using multi-point registration to benefit subsequent processing and utilizing one pass printing for up to 110 inches in conjunction with a large format press or alternatively a combination of step press cycles.
Claims
1. A method for aligning at least one conductor trace along an entire length of an extended length flexible circuit with longitudinally opposed first and second ends, the method comprising: positioning a flexible laminate upon a surface; utilizing a multi-dimensional machine vision system, scan the entire length of the flexible laminate including a plurality of reference points; identifying in two-dimensions, with the multi-dimensional machine vision system, the location of each of the plurality of reference points; digitally segmenting the flexible laminate by defining a plurality of digital stitch lines between each of an adjacent longitudinally extending segment; following a subsequent flexible laminate fabrication step rescanning of the entire length of the flexible laminate including the plurality of reference points; applying a measuring algorithm to determine the magnitude and direction of the displacement of each of the reference point locations relative to the plurality of original reference point locations; positionally adjusting a subsequent fabrication process to account for the magnitude and direction of the displacement of the plurality of reference points to ensure continued alignment of the stitch lines between adjacent segments as well as alignment of the at least one conductor trace; and repeating as necessary the steps of scanning, numerically identifying, digitally segmenting, measuring and adjusting following each flexible laminate fabrication process to ensure continued precise alignment of the stitch lines and the at least one conductor trace between adjacent segments.
2. The method of claim 1, wherein the reference points each comprise a center of a through hole proximate an edge of the flexible laminate.
3. The method of claim 1, wherein the flexible circuit comprises a dielectric substrate film, electrical conductors, a protective finish, and adhesives.
4. The method of claim 1, wherein the longitudinal length of each of the digital segments is in the range of 10 to 20 inches.
5. The method of claim 1, wherein each demarcation line laterally spans in the range of 10 to 20 inches.
6. The method of claim 1, wherein the thickness of the at least one trace is in the range of 0.0001 inches to 0.010 inches.
7. The method of claim 1, wherein the multi-dimensional machine vision system comprises a digital camera.
8. The method of claim 1, wherein the step of digitally segmenting comprises application of an alignment optimization algorithm.
9. The method of claim 1, wherein the flexible laminate fabrication process step comprises large format press operations.
10. The method of claim 9, wherein large format press operations comprise presses of greater than 30 inches.
11. A system for aligning at least one conductor trace along an entire length of an extended length flexible circuit with longitudinally opposed first and second ends, the system comprising: a multi-dimensional machine vision system, the multi-dimensional machine vision system operable to scan the entire length of the flexible laminate including locating a plurality of reference points and stitch lines in multiple dimensions; an alignment optimization algorithm to digitally stitch together at the stitch lines a plurality of discrete segments of the extended length flexible circuit captured by the multi-dimensional machine vision system; a measurement algorithm to determine the magnitude and direction of the displacement of each of the reference point locations relative to the plurality of original reference point locations subsequent to another fabrication process step; and a fabrication process controller operable to positionally adjust a subsequent fabrication process to account for the magnitude and direction of the displacement of the plurality of reference points to ensure continued alignment of the multiple discrete segments as well as alignment of the at least one conductor trace.
12. A method for fabricating an extended length flexible circuit with longitudinally opposed first and second ends, the method comprising: installing tooling features consistent with an initial data set provided by computer aided design data, the tooling holes formed in a sized substrate laminate panel with an upper and a lower surface and combinations of longitudinally extending conducting and insulating layers at a repeating predefined distance along the substrate laminate panel; contemporaneous with the installation of the tooling features, creating an initial reference data set based upon the initial locations of the tooling features, wherein spacing intervals between both adjacent and non-adjacent holes are captured and the substrate laminate panel is digitally segmented into multiple sections each with a subset of a total number of tooling features; applying a photo-sensitive film across at least one of the upper surface and the lower surface; visually acquiring the location of the tooling features relative to one another to serve as reference points in each of the multiple sections of the substrate laminate panel; digitally recording the visually acquired location of the tooling features; utilizing a measurement algorithm on the visually acquired digital data of the multiple sections of the panel to determine any positional changes in the location of the tooling features relative to the initial two-dimensional data set following application of the photo-sensitive film; by referencing a stored digital dataset, directionally directing a beam of electromagnetic energy of one or more specific wavelengths to the applied photo-sensitive film to form a pre-defined flexible circuit pattern; chemically washing the sized substrate laminate to remove the uncured photo-sensitive film resulting in a pre-defined film mask; performing at least one of (i) plating with copper, or (ii) chemically etching to remove copper from a plurality of electrical connections on the pre-defined film mask; removing the remaining film mask with a chemical solution; covering with a protective dielectric cover film, the exposed copper electrical connections; placing the entire substrate laminate panel with protective dielectric cover film into a single static press where heat and pressure are applied to permanently bond the substrate material and the protective dielectric cover film to one another; visually re-acquiring the tooling features; digitizing the re-acquired tooling features; re-scaling the visually acquired data of the multiple sections to correlate the dimensional changes in each of the sections relative to the initial data set; transferring a re-scaled data set to an excising device; using the re-scaled data set to detect, and correct, any fabrication and environmentally induced distortion within each of the sections; and longitudinally excising the substrate laminate panel to produce a plurality of individual extended length flexible circuits.
13. The method of claim 12, wherein the extended length flexible circuit is at least 36 inches from the first end to the second end.
14. The method of claim 13, wherein the extended length flexible circuit is at least 50 inches from the first end to the second end.
15. The method of claim 12, wherein the step of installing tooling features comprises using at least one of a laser, mechanical drilling and tooling die set.
16. The method of claim 12, wherein at least one of a charged coupled device (CCD) camera or a video camera digitally captures the initial location of the tooling features.
17. The method of claim 12, wherein the static press imparts a pressure onto the flexible circuit substrate materials with protective dielectric cover film in the range of about 200 to 400 psi.
18. The method of claim 12, wherein the static press increases the temperature of the substrate with protective dielectric cover film into the range of about 300 to 800 F.
19. The method of claim 12, wherein the cycle time of the static press is in the range of about 3 to 5 hours.
20. The method of claim 12, wherein the original location of the tooling holes is determined by a computer aided design data set.
21. The method of claim 12, wherein the excising device comprises at least one of a laser, a water jet, a numerically controlled knife or a numerically controlled routing machine.
22. The method of claim 12, wherein the step of referencing a stored digital dataset and directionally directing a beam of electromagnetic energy of one or more specific wavelengths to the applied photo-sensitive film to form a pre-defined flexible circuit pattern is performed in a single pass.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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[0031]
DETAILED DESCRIPTION
[0032] Flexible laminates are known to have dimensional variation, and extended length flexible circuits which are fabricated from flexible laminates can encounter movement and distortion during the fabrication process causing fine features and tight tolerances to be very difficult to achieve. The use of digital imaging methodologies and systems to create patterned features on dry film in standard size formats and subsequently step and repeat sequences has resulted in stitching errors due to these material changes and errors in reference point systems.
[0033] These stitching errors can create undesirable misalignment of the copper trace conductors that extend between digitized sections of the long flexible laminate. It has also been shown that standard size format static press systems are poorly suited to the lamination of extended length circuits, i.e., those over 24 inches in length.
[0034] Disclosed herein are a system 10 and method that utilize digital imaging technology to identify multiple reference points along the entirety (entire perimeter) of an extended length flexible laminate 12 and perform a digital transformation of each of multiple sections, precisely digitally stitching the sections together at demarcation lines L1-LX spanning between the laterally opposed edges. Disclosed herein is a system and method for use of multiple reference features 14 to create a seamless digital map 16 of multiple adjacent sections 18 separated by demarcation lines L1-LX, passing through the center of opposed reference features that are unencumbered by multiple exposure stitching and the errors that can arise from it.
[0035] Multiple exposure stitching errors arise when a point, or a digitally imposed line, on the flexible laminate no longer resides at the location originally identified by the CAD software data specifying the physical attributes of the flexible laminate 12. This multi-point reference methodology is also translated to subsequent fabrication processes allowing multi-dimensional digital images to be taken at the same reference points along the entirety of the length of a panel and have the transformation demarcation lines (also known as hinge lines) remain constant. This results in an ideal fluid transformation of all process data, matching any distortions inherited by the flexible laminates 12.
[0036]
[0037] The digital demarcation lines L2-L4 as shown in
[0038] A greater number as well as a fewer number of sections S1-SX (with X serving as a variable) are also contemplated by this disclosure with the number of sections generally dependent upon the customer specified overall length of the flexible laminate 12. Section longitudinal span is a parameter that can readily be adjusted within the controlling software to align with the specifications for fabrication of the flexible circuit. As previously noted, the original reference features 14 coincide with for example, tooling holes, that are placed within the laminate panel 12 based upon the laminate panel design specifications that are loaded into the software database that then controls the placement of the reference features (i.e., tooling holes).
[0039]
[0040] These reference feature displacements are induced through chemical, physical or environmental influences (e.g., temperature changes or due to vibration of the associated fabrication equipment, etc.) and from fabrication processes that alter ever so slightly the original reference feature 14 locations. The subsequently captured digital data reveals the change in position along for example, a cartesian coordinate system (X, Y, Z) or a polar coordinate system (R, ). It is also contemplated that rotation of each of the reference features 14 following a fabrication step are also optionally calculated. Rotation information may also be utilized in the stitching together of the various segments S1-SX along the demarcation lines L1-LX.
[0041] As illustrated at
[0042] Once the multi-dimensional machine vision system 32 has acquired the dataset 30 for the original flexible laminate panel 12 a second scan of the post-fabrication-step flexible laminate panel 12 (as best seen in
[0043] With multi-dimensional machine vision, robust dimensional data is available from the captured images of the shifted reference features R1-R10 upon the flexible laminate 12. It is well understood in the art area of machine vision how to determine the shifting (direction and magnitude) of reference features from the original visually acquired reference features 14 following one or more fabrication steps. Dimensional inspection with image processing produces not only pass/fail judgments, but also numerical data for the specific dimensions of various components. Another advantage is that manufacturers can measure components and save all data acquired by the machine vision system for statistical process control.
[0044] The machine vision algorithm 38 calculates the displacement of each of the reference points from their original location as determined by the original dataset 30 relative to R1-R10 respectively and provides the adjustments needed for subsequent fabrication processes to maintain the highly precise alignment of each section S1-S4 with the adjacent sectionsin effect stitching the sections together. For example, and as illustrated at
[0045] As previously noted, there exists a requirement to maintain continuity of trace lines 26 as narrow as 0.002 inches along the entire longitudinal expanse of the flexible laminate 12 without deviation. Maintaining very tight tolerances to achieve this conductor trace 26 continuity is vital to the functionality of the fully fabricated flexible laminate 12. The system and method 10 disclosed herein can accommodate these reference point R1-R10 displacements along the entire longitudinal expanse of the flexible laminate 12 and specifically between adjacent sections S1-S4 at the digitally imposed demarcation (stitch) lines L1-L5. As noted above, maintaining positional knowledge of the entire span of the digital demarcation (stitch) lines L1-LX that extend between the center of the reference features R1-RX that are disposed laterally opposite one another along the entire longitudinal span is central to the system and method 10 disclosed herein.
[0046] The multi-dimension machine vision system 32 scans the flexible laminate 12 following subsequent fabrication processes (steps) utilizing the same initially assigned reference features 14 and compares those initial reference features with the location of each reference feature R1-R10 following the subsequent fabrication process as illustrated at
[0047] Subsequent fabrication processes (steps) utilize the same transformation technique as disclosed above. This allows the subsequent processes to maintain alignment continuity throughout the entire fabrication process. This method can be applied to all construction types, single conducting layer, double sided with or without electrically connecting conductive traces, and multilayer construction.
[0048] As illustrated at
[0049] Disclosed herein and as set forth in the process flow diagram of
[0050] A computer numerically controlled (CNC) drill system, a laser or a tooling die set are all options available to precisely position holes (reference features 14) in the locations consistent with the CAD data set. As illustrated at
[0051] Contemporaneous with the installation of the tooling hole reference features 14 an initial reference data set 30A is created based upon the initial locations of the reference feature tooling holes 14. While the original CAD data set 30 and the supplemental data set 30A should be nearly identical in terms of spatial arrangement of the reference features 14 it is possible that nominal variations on the location of the reference features 14 possibly induced by, for example, ambient temperature fluctuations, may exist and it is critical that the actual reference feature locations R1-RX be fully digitized for use in determining the demarcation (stitch) lines L1-LX. The spacing intervals between both adjacent and non-adjacent reference feature tooling holes R1-RX are captured as dataset 30A using a multi-dimensional vision system as detailed at Step B in
[0052] Step C requires the utilization of an algorithmic methodology to digitally segment the substrate laminate panel 12 into multiple sections S1-SX, each with a subset of the total number of the reference feature tooling holes 14. The sections S1-SX are separated at digital demarcation lines L1-LX as best illustrated at
[0053] Next, at Step D a photo-sensitive dry film or alternatively a wet film 60 (henceforth film) is applied across at least one of the upper surface 55 and the lower surface 57 of the substrate panel 14. Next at Step E, following the application of the film 60, the location of the reference feature tooling holes R1-RX are again visually acquired by the multi-dimensional machine vision system 32 creating yet another dataset 30A. Specifically, the locations of the tooling holes 14 relative to one another are visually acquired and digitally recorded to serve as reference points R1-RX in each of the multiple sections S1-SX of the substrate laminate panel 12. At Step F a measurement algorithm 38 is then applied to the newly acquired data 30A of the multiple sections S1-SX of the panel. The measurement algorithm 38 calculates the change in location, or displacement, of each of the reference features R1-RX relative to the initial two-dimensional data set 30 reference feature locations 14 and determines the precise location of each of the demarcation (stitch) lines L1-LX.
[0054] Step G requires the system 10 to access and execute a digital instruction dataset 66. This digital instruction dataset 66 contains instructions for precisely delivering a narrowly focused beam of electromagnetic energy 70 onto a photo-sensitive film 72. These instructional datasets 66 are specifically developed with software that is widely available to guide the beam of energy 70 on a particular substrate laminate panel 12. As illustrated at
[0055] Once the electromagnetic energy 70 is applied as directed by the dataset 66 instructions, the flexible circuit pattern 74 is complete. Next, at Step H the substrate laminate 12 is chemically washed to remove the uncured photo-sensitive film 72 resulting in the pre-defined film mask 76. Next, Step I requires at least one of (i) plating with copper (Step I), or (ii) chemically etching (Step J) to remove copper (Step K) from a plurality of electrical connections 78 on the pre-defined film mask 76. Following completion of Steps I or J and K, Step L requires removal of the remaining film mask 76 with a chemical solution wherein the exposed copper electrical connections are covered with a protective dielectric cover film.
[0056] Step M requires that the entire substrate laminate panel 12 with the protective dielectric cover film is placed into a single longitudinally extending static press, an exemplary static press is produced by French Oil Mill Machinery Company, where heat and pressure are applied to permanently bond the copper traces and the protective dielectric cover film to one another. The static press imparts a pressure in the range of 200 to 400 psi onto the flexible circuit substrate materials with protective dielectric cover film while the temperature of the copper traces and protective dielectric cover film are raised into the range of 300 to 800 F. with a static press cycle time in the range of 3 to 5 hours.
[0057] Once the cycle time in the static press is completed, the multi-dimensional machine vision system 32 re-reacquires and digitizes the plurality of reference features R1-RX. The system 10 then applies the measurement algorithm 38 to the multi-dimensional vision system acquired digital data sets 30, 30A to correlate the position of each demarcation (stitch) lines L1-LX relative to the initial data set 30.
[0058] The objective of employing the measurement algorithm 38 of the multi-dimensional machine learning system 32 is to align with high precision the demarcation lines L1-LX separating the sections S1-SX to ensure trace 26 continuity along all sections S1-SX of the entire substrate laminate panel 12. Without proper alignment of the demarcation lines L1-LX identifying the terminus of each section S1-SX, the fully fabricated flexible circuit may lack electrical continuity effectively rendering the component non-functional.
[0059] The system 10 then transfers a positionally adjusted instruction set to an excising device, such as a laser or a computer numerically controlled (CNC) machine, where the positionally adjusted data set is used to detect, and correct, any fabrication and environmentally induced distortions within each of the panel sections S1-SX such as those shown in
[0060] The disclosed system and method should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed method, alone and in various combinations and sub-combinations with one another. The disclosed method is not limited to any specific aspect or feature or combination thereof, nor do the disclosed method require that any one or more specific advantages be present, or problems be solved.
[0061] In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only examples of the disclosure and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope of these claims.
[0062] The disclosure presented herein is believed to encompass at least one distinct invention with independent utility. While the at least one invention has been disclosed in exemplary forms, the specific embodiments thereof as described and illustrated herein are not to be considered in a limiting sense, as numerous variations are possible. Equivalent changes, modifications, and variations of the variety of embodiments, materials, compositions, and methods may be made within the scope of the present disclosure, achieving substantially similar results. The subject matter of the at least one invention includes all novel and non-obvious combinations and sub-combinations of the various elements, features, functions and/or properties disclosed herein and their equivalents.
[0063] Benefits, other advantages, and solutions to problems have been described herein regarding specific embodiments. However, the benefits, advantages, solutions to problems, and any element or combination of elements that may cause any benefits, advantage, or solution to occur or become more pronounced are not to be considered as critical, required, or essential features or elements of any or all the claims of at least one invention.
[0064] Many changes and modifications within the scope of the instant disclosure may be made without departing from the spirit thereof, and the one or more inventions described herein include all such modifications. Corresponding structures, materials, acts, and equivalents of all elements in the claims are intended to include any structure, material, or acts for performing the functions in combination with other claim elements as specifically recited. The scope of the one or more inventions should be determined by the appended claims and their legal equivalents, rather than by the examples set forth herein.
[0065] Benefits, other advantages, and solutions to problems have been described herein regarding specific embodiments. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the inventions.
[0066] The scope of the inventions is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean one and only one unless explicitly so stated, but rather one or more. Moreover, where a phrase similar to at least one of A, B, or C is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
[0067] In the detailed description herein, references to one embodiment, an embodiment, an example embodiment, etc., indicate that the embodiment described may include a feature, structure, or characteristic, but every embodiment may not necessarily include the feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a feature, structure, or characteristic is described relating to an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic relating to other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
[0068] Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase means for. As used herein, the terms comprises, comprising, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
[0069] The invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.