|Publication number||CA1099823 A|
|Application number||CA 304522|
|Publication date||21 Apr 1981|
|Filing date||31 May 1978|
|Priority date||30 Jun 1977|
|Also published as||CA1099823A1, DE2862024D1, EP0000286A1, EP0000286B1, US4190352|
|Publication number||CA 1099823 A, CA 1099823A, CA 304522, CA-A-1099823, CA1099823 A, CA1099823A|
|Inventors||John H. Bruning|
|Applicant||John H. Bruning, Western Electric Company, Incorporated|
|Export Citation||BiBTeX, EndNote, RefMan|
|Classifications (4), Legal Events (1)|
|External Links: CIPO, Espacenet|
The present invention relates to a method for patterning a photosensitive tape comprising the steps of translating the photosensitive tape between a tape-feeding source and a tape~
receiving source; and optically coupling an optical system between a predetermined pattern to be projected and the tape.
Up to a few years ago, wire-bonding was the most commonly used method for making connections from an integrated circuit (IC) chip to the outside world. An alternative to wire-bonding consists of using a tape carrier, similar to a movie filmS having lead frames formed alongs its surface. In this film-carrier approach, usually a polyimide film carries a copper lead pattern that repeats itself along the length of the film. The finger-like leads of an individual site on the film are bonded simultaneously to the pads of an IC chip, as for example, described in U.S. Patents No. 3,689,991, issued 12 September 1972 to A. D. Aird, and 3,968,563, issued 13 July 1975 to A. H. Hamlin.
These two known processes make use of a thin strip of a continuous electrically insulating tape having a plurality of prepunched apertures at regularly spaced intervals. A thin foil-like strip or layer of electrically conducting material is secured to the tape. By photolithographic masking and etching, portions of the layer are removed to form a plur-ality of sets of metallic finger-like leads. This subtractive technique, used to form the finger-like leads, is described in an article by S. ~. Grossman entitled "Film-carrier Technique Automates the Packaging of IC Chips" in Electronics r May 16, 1974, pages 89-95. According to this article, the technique consists in first bonding a l-ounce copper foil to a polyimide film by means of an adhesive. Photoresist
- 2 - ~ 823 ., techniques form the image of the desire~ lead frame in a step-and-repeat fashion along the film-mounted copper laminate. This step-and-repeat projection requires indeY.ing, . settlin~ and alignment, all of which are time-consuming and expensive operations. Moreover, such a projectiny technique is difficult if long lengths of tapes are needed since accelerations associated with high speed indexing are damaging to the fragile tape. Furthermore, the high price-per-pound of the polyimide carrier increases the cost per site of such a tape especially when small quantities of custom tapes are needed.
In accordance with one aspect of the invention there is provided a method for continuously patterning a photosensitive tape comprising the steps of; continuously projecting onto said tape a predetermined endless pattern that is defined entirely on the cylindrical surface of a transparent cylindrical body; translating said tape at a predetermined speed between a tape-feeding means and a tape-receiving means; ro-tating said body at said predetermined speed via a direct drive to synchronously lock the movements of said body and said tape to each other; optically coupling an optical system between ` said pattern and said tape; and illuminating said pattern through said transparent body for continuously projecting an ima~e of said pattern onto said tape via said optical system: wherein said optical system is characterized by a high-precision lens resolution relative to the surface of said tape, and the movements of said body and said tape are synchronously locked to each other by means of electrical circuit locking techniques to within the lens resolution of said optical system.
In accordance with another aspect of the invention there is provided apparatus for continuously patterning a photo-sensitive tape comprising: means for continuously translating .; ~ , .
2a ~ 3 the photosensitive tape in a predetermined direction at a predetermined speed between a tape-feeding means and a tape-receiving means; a cylindrical transparent body having its longitudinal axis perpendicular to said predetermined direction and its cylindrical surface adapted to have defined thereon in fixed relationship with respect to said body the entire extent of a first predetermined endless pattern to be projected; means including a direct drive for said cylindrical body, for synchronously coupling said translating means and said body via electrical ~ocking circuitry such that said pattern continuously rotates at sai~ predetermined speed; and an optical system for projecting an image of said pattern i onto said tape, whereby the rnovement of a projected image is in said predetermined direction; said optical system being characterized by a high-precision lens resolution relative to the surface of said tape, and said coupling means including said electrical circuitry serving to lock the movements of said tape and said pattern to each other within said lens resolution.
One advantage of the present invention is to achieve a highly accurate method and apparatus for continuously patterning a photosensitive tape or foil.
Another advantage of the present invention is to achieve a high-speed continuous patterning process of a tape or foil by means of projection exposure techni~ues.
Another advantage of the present invention is to realize a projection exposure system having a very long mask li~e.
Another advantage of the present invention is to realize a method and an apparatus for patterning a photosensitive ~ 30 tape or foil while pre~enting undue tensions on the tape or ; foil during the patterning process.
~ ~; g A further advantaye of the present invention i.s to achieve a simple, flexible and high-speed projection exposure system for photosensitive tapes or foils.
A still further advantage of the present invention . , . : , .
- 3 - J. s. !3runin l r~
1 is to continuously pattern a photosensitive tape or foil~
2 thereby preventing the tape or foil from breakiny and 3 achieving an economically attractive projecting process.
4 In the Draw n~
. . . _ _ .
FIG. 1 shows an illustrative embo~iment of an 6 apparatus made according to the present invention;
7 FIG. 2 is an enlarged view of a portion of the 8 apparatus shown in FIG.l including its optical syster~;
9 FIG. 3 shows a circuit diagram of the phase~
locking system of the apparatus shown in FIG. l;
11 FIGS. 4 and 5, respectively, illustrate a front 12 and si~e view oE another illus~rative embodiment of an 13 apparatus made according to the present invention;
14 FIG. 6 shows a further illustrative embodirnent of an apparatus according to the present invention;
16 FIG. 7 is an enlarged view of a portion of the 17 apparatus shown in ~G. 6 including its optical syste~; and 18 FIG. B shows a still further illustrative 19 embodiment of an apparatus accor~ing to the present inventin 21 In accordance with an illustrative 22 embodiment of the present invention, a method 23 for continuously patterning a photosensitive tape 24 comprises the steps of translating the photosensitive tape at a predetermined speed between a tape-feeding source and 26 a tape-receiving source, rotatiny at the predetermined 27 speed a cylindrical transparent body having on its 28 cylindrical surface a predetermined pat~ern, optically 29 coupling an optical system between the pattern and the tape, and illuminating the pattern throu~h the ~ransparent 31 body for continuously projecting an image of the pattern 32 onto the tape.
33 In a particular illustrative ernbodirnent of the 34 present invention, the rotating step comprises the step of synchronously locking the cylindrical body and the tape to 36 each o~her to within the lens resolution of the optical .
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- 4 - J. ~ Lunin~J 5 l system. Also, the translating step comprises the step of 2 engagÓny ~he tape on a cylindrical drum having its axis 3 parallel to the axis of the cylindrical transparent body.
4 An illustrative embodirnent of an apparatus for continuously patterning a photosensitive tape according to 6 the present invention comprises an arrangement for 7 translatin~ the photosensitive tape in a predetermined 8 direction at a predetermi~ed speed between a tape-~eeding 9 source and a tape-receiving source, a cylindrical transparent body having its longitudinal axis perpendicular 11 to the predetermined direction and its cylindrical surface 12 adapted to receive a predetermined pattern to be projected, 13 circuitry for synchronously coupling the translating 14 arrangement and the cylindrical body such that the pattern rotates at the predetermined speed, and an optical system 16 for projecting an image of the pattern onto the tape, 17 whereby the movernent of a projected image is in the 18 predetermined direction.
l9 Referring now to an illustrative embodiment of the invention, as shown in FIG. l, an apparatus ~or 21 continuously patterning a photosensitive tape l comprises a 22 tape-feeding reel 2~ a tape-receiving reel 3, and a tape-23 translating drum 4 for translating the tape l a~ a 24 predetermined speed and in a predetermined direction between reels 2 and 3. The drum 4 is rnechanically coupled 26 to a driving mechanism 5 comprising, for example, a motor 27 having its shaft directly coupled to the drum 4~ However, 28 other translating mechanisms may be substituted for drurn 4 29 as will be explained in connection with another illustrative embodiment of the invention, without departing 31 from the spirit and scope of the present invention. A
32 cylindrical transparent body ~ is positioned with its 33 longitudinal axis perpendicular to the direction of 34 translation of tape l on the drum 4. In other words, in the embodiment of EIG. 1, the axes of body 6 and drum 4 are 36 parallel, Transparent cylindrical body 6 carries on its 37 cylindrical surface 7 a predetermined pattern or mask 8 to --: , . : :
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- 5 - J. H. Brurling 5 1 ~e projected on the photosensitive tape 1.
2 The pattern 8 may be formed directly on the 3 cylindrical surface 7 b~ first coating the surface Wi'Lh a 4 thin metal film and then selectively removing portions thereof ~y thermal rnachining oE the film~ Another
6 alternative for depositing pattern 8 onto the cylin~rical
7 surface 7 consists in first producing a predetermined
8 pattern on a 16 mm or 35 mm filmstrip by means of
9 conventional techni~ues. ~rhe filmstrip comprising a plurality of individual frames or patterns could be wrapped 11 around the cylindrical body ~ and held by vacuum against 12 the surface 7. Both ends of ~he filmstrip would he butted 13 to produce a contiguous set of patterns on the cylindrical 14 surface 7. The cylindrical body ~ is mechanically coupled to a driving mechanism 9 comprising, for example, a motor 16 having its shaft directly coupled to the body 6.
17 In accordance with the principles of the present 18 invention, the cylindrical transparent body 6 and the 19 drum 4 are synchronously coupled by means of a coupling circuit 10 responsive to a reference frequency signal fOO
21 1'he coupling circuit 10 may comprise a pair of phase-locked 22 loops arranged such that the cylindrical transparent body 6 23 is the "slave". Thus, both cylinders 4 and 6 rotate at.
24 precisely the same rate but in opposite directions as sho-~n by the arrows in FIG. 1. In effect, an electrical link 26 exists between drum 4 and cylinder 6 resulting in locking 27 of both cylinders to each other. The apparatu~s according 28 to the present invention further comprises an optical 29 system 11 positioned between cylindrical body 6 and drum 4 for projecting an lmage of the pattern 8 onto the tape 1.
31 The optical system 11 ~ay be positioned as shown in FIG. 1 32 ~etween body 6 and drum 4, or may ~e rotated by a 90~degree 33 angle such ~hat its axis is parallel to the axes of the 34 body and the drum. In the latter, object and image have the same orientation in the direction of the width of 36 tape 1, but have opposite orientation in the longitudinal 37 direction of tape 1~ Also, object and image would be `:
., ' ~ .
- 6 - ,J. H. Bruning 5 1 offset in the la~ter direction.
2 Shown in ~IG. 2 is an enlarc~ed portion of the 3 illustrative eMbodirnent of FIG. 1 includiny the structural 4 details of the optical systeM ll. By way of background, a known one-to-one i~aging optical system is described in an 6 article by J. Dyson entitled "Unit Magnification Optical 7 System without Seidel Aberrations,7' published in IJour~al of 8 the ~ cal Society of America, Volume ~9, No. 7, 9 July 1959, pages 713-716. I~his known Dyson system consists of two components, namely, a concave s~herical mirror of 11 radius R, and a thick plano-convex lens of radius r, 12 index n and ~hickness equal to r. The centers of curvature 13 of both spherical surEaces are substantially coincident, 14 and r is chosen so that parallel rays incident on the plano surface are focused on the mirror surface, i.e., 16 r = n - 1 R n 17 In this known system, object and image surfaces lie on or 18 close to the plane face of the lens, and object and image 19 are of opposite directions.
In accordance with the principles of the present 21 invention, the optical system 11 of FIG. 2 is a modified 22 Dyson-type system comprising a plano-convex lens 111 of 23 radius r and index n and a spherical concave mirror 112 of 24 radius R having substantially coincident centers of curvature. The plane face of the plano-convex lens 111 is 26 cemented to two right-angle prisms 113 and 114 in order to 27 bring object and image to usable posi~ions. The pattern 8 28 to be imaged on the tape 1 is placed or formed on the 29 cylindrical transparent body 6 which is made, for exa~ple, of quartz. A narrow strip of this pattern 8 is irnaged by 31 the system onto the photosensitive resist coated tape which 32 is held in the proper focal plane by the lower drum 4. I~
33 the two drums 4 and 5 rotate in synchronism, the pattern 34 is continuously transferred to the resist coated tape 1.
The optical system 11 can image the ~ull tape width, and ', .
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- 7 - J~ H. Bruning 5 1 utilizes a very small field size in the scan direction.
2 The narrow stripe object and image can thus lie close to 3 the optical axis obviating the need for a beamspli-tter.
4 This permits an optical system desiyn completel~ made of 5 fused silica with its attendant high transmission in the 6 ultraviolet range. The optical system 11 is telecentric 7 and hence insensitive to first-order distortions due to 8 focal plane shifts. Since the desiyn is completely 9 symmetric, distortion, coma, and lateral color are zero.
10 Resolution is nearly diffraction limited over a
11 2 mm x 16 mm field at E/2.5 and still has acceptable
12 resolution at a 2 x 22 mm field at F/4. ~esolution in all
13 cases is better than 5 ~m which is adequate for lead
14 patterns whose narrowest feature would be larger than
15 50 ~m. Over the range of 3000-4400 Angstroms the optical
16 system is nearly achromatic.
17 Illumination is provided, for example, by a 1 kW
18 water-cooled mercury capillary arc 12~ However, other
19 light sources may be used without departing from the spirit
20 and scope of the invention. Water cooling filters out most
21 of the infrared radiation beyond 1 ~m and assures cool
22 operation. A combination of lenses and mirrors
23 schematically sho~n in FIG. 2, is coupled to the arc for
24 directing the arc's rays onto the cylindrical surface 7.
25 The operation of the optical system is such that an
26 object 13 that is part of the pattern 8, when illuminated
27 by light source 12, is projected onto an image plane
28 corresponding to the tape 1. The incoming object 2~ radiations 15 are first reflected by right-angle prism 113 30 and directed to lens 111 and mirror 112. The rays from 31 mirror 112, after reflection by right-angle prism 114, are 32 directed to the tape 1 to form the image 14 thereon. ~s 33 shown in FIG. 2, object 13 and image 14 have the same 34 orientation in the direction of translation of the tape 1.
35 However, in a direction corresponding to the width of the 36 tape, i.e., in a plane perpendicular to the page in FIG. 2, 37 there is an inversion between object and image.
... . . .. ~ . - . . . -.
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- 8 - J. fl. sruniny 5 1 Furthermore, as the pattern 8 rotates, the movement of the 2 inlage 14 is in the same direction as the movement of the 3 tape 1, thus enabling a continuous projection patterning of 4 the tapeO
Since in the present case, scanning of the 6 pat-tern takes place in the direction of movement of the 7 tape 1, -there is no inversion in the scanning direction and 8 no need for image reversion.
9 As described above, the tape-carrying drum ~ and the cylindrical transparent body ~ are synchronously 11 coupled by means of coupling circuit 10. The latter is 12 schematically illustrated in FIG. 3 wherein the drum 4 and 13 the c~lindrical body 6 are mechanically driven b~ electric 14 motors 5 and 9, respectively. The drum 4 and the body 6, in accordance with ~he principles of the present invention, 16 must rotate at precisely the same rate, but in opposite 17 directions. Moreover, the drum 4 and the body 6 are locked 18 to each other within the lens resolution of the optical 19 system on the circumference~ i.e., within less than 5 ~m.
This corresponds to a rotational tolerance of approximately 21 20 arc seconds. By usin~ precision optical encoders 31 and 22 32 and phase-locked loop techniques, the body 6 can move 23 with respect to the tape-carrying drum 4 with a speed 24 accuracy of 0.~01%. In this illustrative embodiment, the drum 4 is locked to a predetermined speed by means of a 26 reference frequency signal fO coupled to one ;nput terminal 27 of phase detector 33. The other input terminal of the 28 phase detector 33 is coupled to the output terminal of
29 optical encoder 31. ~ low-pass filter 35 has its input 3 terminal coupled to the phase detector 33 output terminal, 31 and its output terminal coupled to one input terminal of 32 operational arnplifier 37 The other input terrninal o~
33 operational amplifier 37 is coupled to the output terminal 34 of optical encoder 31 via a frequency-to-amplitude 3~ converter 39. The output terminal of amplifier 37 is 36 coupled to the driving motor 5 of the tape-carrying drum ~.
37 The upper half of the couplin~ circuit 10 coupled to the :
: . ' .
- 9 ~ J~ HA Bruniny 5 1 cylindrical transparent bod~ 6 and its driving mo~or 9 is 2 identical to ~he lower half of the loop lO, i.e., it 3 comprises a phase detector 34, a low-pass filter 36, an 4 operational amplifier 38 and a frequency-to-amplitude 5 converter 40.
6 In this illustrative embodirnent of the coupling 7 circuitl the motion of tape-carrying drum 4 serves as the 8 "masterl'. The ou~put of the optical encoder 31 serves as 9 the reference frequency to which the cylindrical 10 transparent body 6 is the "slave". Thus, low frequency 11 torque disturbances on the drum 4 are tracked by the body 12 6, and high frequencies are damped by the inertia of the 13 loop and motors. The system comprising the drum 4, the 14 body 6, the motors 5 and 9, and the coupling circuit 10 is 15 stiff enough so that torque disturbances of several ounces 16 in ~he tape disturb the tape position by less than the 17 image resolution. In the illustrative embodiment of the 18 coupling circuit 10, the reference frequency signal fO is, 19 for example, a 1000 ~z signal and the optical encoders 31 20 and 32 are 16-bit encoders generating 21 or 6S,536 21 pulses/revolution. The phase detectors 33 and 34, the 22 filters 35 and 36, the amplifiers 37 and 38, and the 23 eonverters 39 and 40 may be selected Erom conventional and 24 commercially available components.
In accordance with the principles of -the present 26 invention~ the tape-carrying drum 4 and the cylindrical 27 -transparent body 6 can both be the "slaves" of the 28 reference ~requeney signal f . This is achieved by 29 coupling the reference signal f to phase detectors 33 and
30 34, and by connecting the optical eneoder 31 output signal
31 only to the other input terminal of phase deteator 33,
32 Thus, instead o~ having a "master-slave" arrangement as
33 shown in FIG. 3, the drum and the body would be "slaves"
34 and loeked to f .
Another illustrative ernbodiment of the present 36 invention for patterning both sides o~ a photoresist eoated 37 tape is shown in ~IGS. 4 and 5. The apparatus for , ~ 10 ~ ~. H. Bruning 5 1 projectin~ an image onto the con~inuous tape 1 comprises 2 the first cylindrical transparent body or drum 6 having on 3 its cylindrical surface 7 the prede~ermine~l pattern 8 to be 4 projected. A first optical system 11 is positioned between the drum 6 and the tape 1 as described in connection wi-th 6 the embodiment shown in FIG. 1. In order to achieve 7 projection printing onto the other side of photosensitive 8 tape 1, a second cylindrical transparent drum 6' is 9 positioned with its longitudinal axis parallel to -the axis of drum 6. A second predetermined pattern 8' is formed on 11 cylindrical surface 7' of drum 6'. A second optical 12 system 11' identical to the optical system 11, is 13 positioned between the drum 6' and -the tape 1.
14 Photosensitive -tape 1 is translated at a constant and predetermined speed by means of guiding rolls ~1 and 42 16 between a tape~feeding reel and a tape~receiving reel (not 17 shown). In accordance with the principles of the present 18 invention, the motion of guiding rolls 41 and 42 serves as 19 the "master" reference frequency in the phase~locked loops of FIG. 3. Both drums 6 and ~', rotating in opposi-te 21 directions, are locked to the guiding rolls 41 and 42 and 22 are, thereEore, the "slaves" in the coupling circuit 10 of 23 FIG. 3.
24 As shown in ~IG. 5, in order to achieve simultaneous and continuous projection of patterns 8 and 8' 26 onto both sides of the tape 1, double~sided illumination of 27 the tape is re~uired. This may be realized by using a 28 single light source 12, such as a 1 kW water~cooled mercury 2~ capillary arc, coupled to a pair of mirrors 51 and 52 for directin~ the radiations from source 12 toward the 31 patterns 8 and 8' on drums 6 and 6'. The foregoing is 32 achieved by interposing a condenser 53 and a mirror 57 33 between mirror 51 and pattern 8. Also, another 34 condenser 54 and a second mirror 58 are interposed between mirror 52 and pattern 8' of drum 6'. Condensers 53 and 54 36 may, for example, comprise all reflecting optical 37 components such as a spherical concave mirror Eor receiving - 11 - ;J. ~ ,runit3~J 5 1 tl-,e radiations reflected by rilirrors ',1 or 52, ar\d a 2 s~j`nerical conve~ n~irror for re~lectincj the incor~ing 3 ra,liations fron, the concave lilirror an~ ~irectiny the~n to -the 4 ~irrors 57 or ~a. ~o"~ever, other types oE con~iensers may be 5 used without cie~arting from tlle spiri~ of tne invention.
6 Bot~l m,irrors 57 and 58 are positioned within t~le transparent 7 drums ,~ and 6' in order to reflect the inco~ing radia'cions 8 Erom source 12 by a 90-degree angle~ ith the arrangement 9 sho~"Jn in E~IG. 5, illumination for -tape e~posure frorn both 10 sides is available from the same source 12. ~oth drurns ~
11 and 6' are prefera~ly made o~ quartz yround ancl polishe(-l to 12 ~lig~ accuracy. l~he c~uartz drums ~ and ~' have, for example, 13 approxilllately a 3~1 mm circurnfere~nce ~hich is a convenient 14 multiyle of standarc~ tape pitches. ~s explained in 15 connectiorl with the embocli~ent of E~IG. 1, the patterns 8 and 16 81 miay be ~ormed, for exampler directly OlJ sur~aces 7 and 7' 17 by thermal machinin~. Alternatively, patterns 8 and 8' may 18 be formed on a films~rip wrapped around the dru~ls 6 and 6' ~9 and held by vacuum against surfaces 7 anc1 7'. Ilo-"~ever, 20 other l~eans o forllling a pattern onto a cylindrical surface 21 can be used wit~out departing froln the teachiny oE the 22 present invention.
23 Referriny now to FIGS. 6 and 7, wherein double-24 sicled patterniny of photoserlsitive ta~e 1 is shown, 25 ic,entical nwllerals correspondin~ -to the numerals of the 26 previous fi,-3ures are utilized to illustrata the 27 similarities oE the illustrative embodiments. In tllis 28 illustrative embodilnent, topside exposure of photosensitive 29 tape 1 is obtained by projection printin~ frorn the drum 5 30 o~ pattern 8 as explained in connectiorl ~7ith the previously 31 described embocliments. The back or other side of tape 1 is 32 patterned by means of contact printing oE a patterrl 60 onto 33 the tape. The pattern 60 on drwn 6' ancl pattern 8 on 34 drum 6 may be identical. Elo~Jever, di~ferent patterns may
35 be used when it is ~esirable to project on both si,;les of
36 the ~ape a diferent be,am lead pattern. Contact printin~
37 consists of first forming a l~ask 6U accordiny to :~ , .
, ' , .
- 12 - J. ~ runiny 5 1 conventional mask producing techniques, and wrapping the 2 mask around the cylindrical sur~ace 7' of drum 6'. In this 3 illustrative embodiment, as in the embodiment of EIG. 1, 4 both drums 6 and 6' are synchronously coupled and locked to 5 each other by means of coupling circuit 10. Condensers 53 6 and 54, as shown in FIG. 6, each comprise all r~flecting 7 optical components. It should be noted that other types o~
8 optical components can be substituted without deyarting 9 from teachings of the presen-t invention.
Double-sided exposure either through projection 11 printing as shown in FIG. 4, or through projection printing 12 on one side and contact printing on the other as shown in 13 FIG. 6, is required for etching with negative photoresistsO
14 Contact printing requires changing of the mask ~0 after a 15 predetermined number of runsO Projection printing, 16 instead, offers the advantage of avoidiny contact between 17 the mask and the resist coated tape. The apparatus o~
18 FIGS. 6 and 7 enables the combination of these two 19 patterning techniques for double-sided patterning by using 20 only one optical system 11.
21 ~ still ~urther illustrative embodiMen-t of the 22 present invention is shown in ~IGo 8 wherein the 23 photosensitive tape 1 and the predetermined pattern 8 to be 24 projected are driven by the same motor. This illustrative 25 embodiment is useful when single or double sided exposure 26 of the tape is needed. The photosensitive tape l and the 27 predetermined pattern 8 are mounted on the same cylindrical 28 transparent drum 81. The drum is rotated at a constant 29 speed by means of a motor 82 having its sha~t 83 coupled by 30 means o~ two end plates 84 and 85 to the cylindrical 31 druM 81. A source o~ light 12, similar to the one 32 described in connection with the other embodiments, 33 generates radiations that are directed inside the 34 cylindrical drum 81 by means of lenses 8~ and 87. A
35 mirror 88 is positioned within the drum 81 for directing 36 the radiations ~rom lens 87 onto the pattern 8. In order 37 to project an image o~ the pattern onto the photosensitive . . ~ , - . , .:
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- 13 - J. H. Bruning 5 1 tape 1, an optical sys-te~n comprisiny a plane mirror 89, a 2 1:1 lens 90 and a roof mirror 91 is optically coupled 3 between the pattern 8 and the photosensitive tape 1. Since 4 both tape 1 and pattern 8 are driven by the same ~lotor 82 there is no need for phase-locked loops of the type 6 described above. Furthermore, by using a cylindrical 7 drum 81 having in its longitudinal ~irection a first 8 cylindrical surface of diameter Dl and the second 9 cylindrical surface of diarneter D2 for respectively carrying the pattern 8 and the tape 1, magnifications given 11 by:
12 Dl 13 are implemented~ As described in connection with the other 14 embodiments, the pattern ~ may be formed according to the above-described methods.
16 In all of the above illustrative embodiments of 17 the present invention, the pho-tosensitive tape 1 may be a 18 photoresist coated copper tape or a photoresist coated 19 continuous metal-composite tape. Use of either negative photoresists or positive photoresists is within the spirit 21 and scope of the invention. After patterning the 22 photosensitive copper tape by using any of the abova-23 described method and apparatus, the copper is etched where 24 exposed (if positive resist is used) leaving a set of thin copper leads suitable for "gang" or simultaneous bonding to 26 a chip.
', .~ ~ ', ' :
|International Classification||G03B27/32, G03B27/46, H01L21/60|