TAPE AUTOMATED BONDED LEAD PACKAGE AND REUSABLE TRANSPORT TAPE FOR USE THEREWITH

Abstract: A lead pack which includes a rectangular frame (18, 28) of polymer insulating material and a plurality of leads (34) imbedded in said frame and extending inwardly and outwardly therefrom for attachment to an associated integrated circuit and for attachment of the leaded integrated circuit to an associated printed wiring board or like circuit. The insulating frame serves as a dam or sealing means in an encapsulating process. An additional frame (29) stabilizes and positions. The outwardly extending ends of the leads (34). A reusable transport and test tape (12) which includes a plurality of leads (62) adapted to receive and connect to the leads (34) of the lead pack and the position the lead pack for reception of an integrated circuit for bonding of lead pack leads to the contact pads of the integrated circuit and to move the lead pack and integrated circuit into succeeding processing stations where the circuit is packaged and tested, and then excised.

Description: TAPE AUTOMATED BONDED LEAD PACKAGE AMD REUSABLE TRANSPORT TAPE FOR USE THEREWITH Field of the Invention This invention relates generally to a tape automated lea bonding process for lead attachment to integrated circui devices and more particularly to a lead package and a reus able transport and test tape for receiving and transportin said lead package during fabrication of packaged integrate circuits. Background of the Invention Tape automated bonding is becoming the choice for packagin integrated circuits having high lead count. In this pro cess, thin copper or metal films are etched to define thi film beam conductors which are bonded to the chip contac pads and provide connections to associated printed circui boards or other circuits. The thin conductive film, i certain instances, has been bonded to an insulating tape t provide testability, transportability and structural rigid ity to the thin film conductors. The format for the thin metal film or thin film layere tape, includes an elongated tape with sprocket holes fo indexing the tape as the semiconductor chip is bonded t the thin leads and then advanced to various processin stations for encapsulation, testing and the like. Th tapes have widths ranging from 8 to 70 millimeters and ar provided on reels or strips. The tape portions which d not form leads for the integrated circuit package ar discarded when the integrated circuit package is severe from the tape. Generally, the discarded materials repre sent a significant cost of packaging. Summary and Obiects of theInvention This invention provides a tape automated bonding process i which the lead package (lead pack) is a separate componen secured to a reusable transport tape. It is an object of the present invention to provide a lea pack for connecting an integrated semiconductor circuit t an associated printed circuit board or the like. It is another object of the present invention to provide lead pack for use with a reusable transport tape in a automated bonding system. It is a further object of the present invention to provid a reusable transport tape for a tape automated bondin system. It is a further object of the present invention to provid a lead pack in which the leads are embedded in a fram which stabilizes and positions the leads. t is a further object of the present invention to provid a reusable tape for receiving a lead pack, presenting th lead pack to an integrated circuit for bonding the leads o the lead pack to the integrated circuit and then presentin the lead pack and integrated circuit to succeeding station for testing and encapsulation. The foregoing and other objects of the invention ar achieved by a reusable transport and test tape which in cludes a plurality of leads adapted to receive and connec to the leads of the lead pack and to position the lead pac for reception of an integrated circuit for bonding of lea pack leads to the contact pads of the integrated circui and to move the lead pack and integrated circuit int succeeding processing stations where the circuit is pac aged and tested, and then excised. Further, there is provided a lead pack which includes rectangular frame of insulating material and a plurality leads imbedded in said frame and extending inwardly a outwardly therefrom for attachment to an associated int grated circuit and for attachment of the leaded integrat circuit to an associated printed wiring board or like ci cuit. The insulating frame serves as a dam or seali means in an encapsulating process. An additional fra stabilizes and positions the outwardly extending ends the leads. The foregoing and other objects of the invention will more clearly understood from the following description wh read in connection with the drawings. Brief Description of the drawings Figures 1A and IB show a flow chart illustrating t formation of a lead pack and transport of the lead pack the transport and test tape and insertion and testing of integrated circuit and protective encapsulation thereof. Figure 2A shows an insulating tape which has been pe forated to define a lower lead frame. Figure 2B shows a lower lead. frame excised from t tape of Figure 2A. Figure 3A shows an insulating tape which has be perforated to define an upper lead frame and upper le support. Figure 3B shows the upper lead frame and upper le support excised from the tape of Figure 3A. Figure 4 shows a portion of a thin metal film such a copper perforated to define leads. Figure 5 is a sectional view taken along the line 5 of Figure 4. Figure 6 is a sectional view taken along the line 6 in Figure 4, showing the forming of a lead bump or dimp that will become the inner end of the lead pack lead. Figure 7 is a sectional view of a lead with protective plating. Figure 8 is a view showing a portion of the perforated metal film with a lower insulating frame attached. Figure 9 is a sectional view taken along the line 9-9 of Figure 8. Figure 10 is a view showing a portion of perforated metal film with both the lower and the upper insulating frame attached. Figure 11 is a sectional view taken along line 11-11 of Figure 10. Figures " 12A-12F show the steps in imbedding the leads in the lower insulating frame. Figure 13 shows the perforated metal film with the center portion excised to provide cantilevered and plated lead portions. Figure 14 is a sectional view taken along the line 14- 14 of Figure 13. Figure 15 is a sectional view showing the lead of Fig. 14 with a conductive adhesive applied. Figure 16 is a sectional view showing outer leads ex¬ cised from the perforated metal film to thereby form a lead pack. Figure 17 is an enlarged view of a portion of the tape transport illustrating the conductive pattern between the center window and the outer test pads. Figure 18 shows the lead pack with the leads secured to the tape transport conductors with a conductive adhesive. Figure 19 is a sectional view taken along the line 19- 19 of Figure 18 showing the connection of the lead pack leads to the transport tape leads. Figure 20 is a partial view showing the cantilevered lead pack inner leads attached to a semiconductor chip. Figure 21 is a sectional view taken along the line 21- 21 of Figure 20 showing the connection of a bumped o dimpled inner lead to a chip contact pad. -5- Figure 22 shows a lower package body attached to th lead pack frame. Figure 23 is a sectional view taken along the line 23 23 of Figure 22 showing the lower housing. Figure 24 is a view showing the application of th upper housing body to the lead pack frame. Figure 25 is a sectional view taken along the line 25 25 of Figure 24 showing the upper housing portion. Figure 26 shows the leads severed from the transpor tape. Figure 27 shows bending of the outwardly extendin lead portions to form feet for attachment to an associate circuit. Figure 28 is an enlarged view of a portion of packaged semiconductor device attached to a printed wirin board. Description of a Preferred Embodiment The tape automated bonding processing of this inventio employs a novel lead package schematically illustrated a ii in Figure 1, to be presently described. Briefly, th lead package includes a frame of insulating material whic supports conductors in spaced relationship with one en cantilevered inside the frame and one end extending out wardly. A transport tape 12, Figures 1A, IB, whic includes a plurality of windows 13.receives the lead pack The transport tape includes leads, to be described present ly, which splay outwardly from the window to test pads. The process of the present invention comprises forming th lead pack 11 with its bumped, plated and spaced leads an placing the lead pack 11 within the window 13 with th outwardly extending ends of the leads connecting to th transport tape leads. The transport tape 12 include sprocket holes 14 which are used to index the tape as i moves in the direction of the arrow 16 to first present th windows for reception of a lead pack 11 then to advance t a station where a semiconductor chip is bonded to th inwardly extending ends of the lead pack leads then to testing station. The lead pack and chip move to stations where upper and lower housing portions are applied. Each of the operations can be followed by a testing step using the tape test pads to assure that the packaging operation has not altered the electrical properties or relationship between the lead pack and integrated circuit chip. The packaged chip then moves to a burn in station, if such is required, and then to an excise station where the leads are severed from the transport tape and the leads bent to form attachment feet for the packaged semiconductor integrated circuit. The packaged circuit can then be mounted on a printed circuit board or in other electrical circuits. The lead pack lead support frame includes upper and lower frame portions adhered to one another to embed the leads. Referring to Figure 1A the lower frame portion is formed from an insulating material 16 which includes sprocket openings 17 and is moved sequentially through processing stations. For example, the tape may be a polyimide, acry¬ lic, polycarbonate, polyester, epoxy or other thermally responsive insulating and adhesive material. A frame 18 is formed by first forming windows 19 in the tape. Figure 2A, and thereafter excising the central portion 21 to form the frame 18. The upper frame portion 22 is formed from a similar insulating material 23 of the same type as the tape 16. The tape 23 includes sprocket openings 24 for index¬ ing. Referring to Figure 3A, the tape is perforated to form windows 26 and 27 and then the central portion 28 is excised to leave a frame having an inner frame portion 29 to mate with the lower frame portion 18 and an outer por¬ tion 30 which is adapted to engage and support the ends of the leads as will be presently described. The thin metal leads for the lead pack are formed from a thin metal tape (Figure 1A) , such as a copper tape, 3 which includes sprocket holes 32 for indexing the tape a it passes various stations. An enlarged portion of th tape 31 is shown in Figure 4. The tape is first punched. -7- perforated or etched to form a plurality of windows 33 a indexing holes 35 diagonally across from one another wi one hole being round, as shown, and the other (not show being a rectangular slot. The windows 33 define thereb tween elongated leads 34 which have a narrow end 36. T enlarged sectional view of Figure 5 shows the beam lead This first step is schematically illustrated at 38, Figu 1A. The tape is then advanced and indexed to a seco station 39 where the perforated foil is presented to forming die which forms bumps, or dimples, in the narr end 36 of the leads. As shown in Figure 6, the die co prises a lower die portion 41 which receives the leads a a forming punch 42 which deforms the leads into the low die to form dimples which are spaced from the sides of t lead. The perforated punched tape is then moved to station 43 where the leads are plated with gold, tin other material 44 (Fig. 7) . The tape is then advanced station 46 where it is heated. At the next stage 47 t lower thermal adhesive frame 18 is applied. Referring Figures 8 and 9, the frame 18 is positioned to allow t portions 36 of the beam leads 34 to project beyond t frame 18. Referring to Figure 12, the lead frame 18 i brought into registry with the beam leads 34 with a vacu chuck 48. The heated beam leads 34 and frame 18 a pressed towards one another by moving the vacuum chuck 4 downwardly to bring the thermal adhesive into contact wit the beam leads and to further advance and press the fram 18 until it is flush with the lower surface 48 of the bea leads. The successive steps just described are shown i Figures 12B-12F. The foil tape is then advanced to the next station 51 wher the upper lead pack frame 22 is registered with the lowe lead pack frame. Figures 10-11, and is pressed downwardl as indicated by the arrow 52, Figure 11. This adheres th two frames together and imbeds the beam leads 34 betwee them. The lead support 29 is shown engaging the leads at location spaced from the frame. Next, the metal foil is removed from the center 56, Figur 13, to leave the beam lead ends 36 cantilevered inwardl from the lead frame formed by the upper and lower lea frame portions 18 and 28 with the dimpled region space from the end of the lead as shown in Figure 14. The nex step 57, Figure 1A and Figure 15, is to apply an electric ally conductive thermal adhesive 58 to the lower side o the outwardly extending lead portions 34 and thereafte severing the leads from the foil tape, step 59, Figure 1A, to provide a lead pack comprising a frame with inwardl cantilevered lead portions 36 and outwardly extending lea portions 34 with an adhesive 58 on the underside of th outer end of the lead and a lead support and separator 2 as shown in Figure 16. As previously described and in accordance with the inven tion, a reusable transport tape 12 is used to transport th lead pack 11 and associated integrated circuit chip fo processing. Referring to Figure 1A, the transport tape 1 includes a plurality of spaced windows 13 which are indexe by sprocket holes 14. The enlarged view of a portion 17-1 of the tape is shown in Figure 17. The tape includes plurality of test pads 61 connected by leads or lines 62 t lead ends 63 which extend to and are adjacent the edge o the window 13. If the transport tape is of electrical in sulating material such as mylar or polyamide, then the pad 61, leads 62, and ends 63 are formed by photoetching metal film carried by the tape. In the preferred embodi ment, the tape is a stainless steel tape. The tape surfac is provided with a nonconductive adhesive layer to which metal film is applied and photo etched to define the leads In accordance with the invention, the lead pack is place in the window 13, Figures 18 and 19, with the leads 3 overlapping the transport leads 63 and the conductiv thermal adhesive 58 therebetween and the assembly heated t thereby form electrical contact between the ends of th leads 34 and the ends 63 of leads 62 connected to test pad 61. The insertion of the lead pack in the window and con nection of the leads to transport leads is schematicall illustrated by the station 71. The lead pack is accuratel located and oriented by engaging the locating holes 35 i the lead frame tab 65. The next station 72 is where th cantilevered inner ends 36 of the lead pack leads ar bonded to the bonding pads of an associated chip 73 Figures 20 and 21. It is noted that the lower lead fram portion 18 serves to guard against shorting of the lead 3 to the edge 75 of the semiconductor wafer 73. The end 3 of the lead may be bonded to the die by thermal compressio bonding, thermosonic bonding or ultrasonic bonding, or b other suitable bonding techniques with either single poin or gang bonding tools. The bonded assembly is then advanc ed to the next station 74 where electrical contact is mad to the test pads to electrically test semiconductor inte grated circuit 73 attached to the inner leads 36. If th circuit 73 is satisfactorily bonded and tested as bein operable, the circuit can be packaged by molding a housin on the circuit using the frame as the mold dam, station 76 Alternatively, the packaging can comprise a lower preforme packaged body 77, attached by thermal compression bondin as illustrated in Figures 22 and 23. The lower housing 7 is placed over the semiconductor die 73 and is presse against lower frame portion 18 while thermal energy i applied to melt the adhesive interface and to provide seal. Alternatively, the adhesive may adhere solely b pressure. The arrows 78 indicate pressure applied t provide a bonding force for the thermal adhesive bond t take place at the interface 79. At the next station, 81, the upper housing body 82 is applied by thermal compressio and/or adhesive bonding. This is illustrated in Figures 24 and 25. The pressure is schematically illustrated by th arrows 83. The tab 65 and hole and slot 35 are used in th foregoing steps to maintain alignment of the housing wit respect to the leads by identifying the center and angular ity of the lead pattern. This same tab 65 and hole an slot 35 are used to locate the lead pack on the transport tape and again in the excise and lead form die assembly and again in application to the printed wiring board as an accurate placement means in match-up with a mating lead pattern or forming die, each adaptation being described hereafter. In the next station, 86, the encapsulation can be tested for seal and mechanical integrity followed b burn-in of the device at station 87, if desired. Final electric testing is performed at station 88 marking an coding the device package at station 89. At station 91 th package is excised by cutting the leads 34 adjacent th leads 63 as shown in Figure 26. This step is also accu rately located by the hole and slot 35. Thereafter, th extending lead portions are bent as shown in Figure 27 t form feet 92, with the leads supported and spaced from on another by the frame 29. In Figure 28, a packaged devic 95, formed in accordance with the present invention, i shown attached to a printed wiring board 96. The hole an slot 35 in tab 65 can be used for orientation. The trans port tape lead ends 63 can be cleaned to remove the elec tronically conductive adhesive and severed lead ends s that the transport and test tape can be reused. Th cleaning station is illustrated at 97. Thus, there has been provided a novel lead pack having plurality of spaced, dimpled leads particularly useful fo use with a novel reusable transport and test tape.

Claims: -11- CLAIMS : 1. A lead pack comprising: a lead support frame of insulating polymer material; a plurality of spaced leads imbedded in and completel surrounded by said material carried solely by said frame each of said leads having one end extending inwardly o said frame toward one another to a common area for connec tion to the bonding pads of an associated semiconducto device and extending outwardly of said frame for connectio to an associated circuit. 2. A lead pack as in Claim 1 including an additional oute insulating frame member engaging the outwardly extendin ends of said spaced leads adjacent to the frame and space from the ends to maintain them in line and in space relationship. 3. A lead pack as in Claim 1 in which said leads are thi flat metal conductors. 4. A lead pack as in claim 3 including at least one aper tured orientation tab extending outwardly of said frame. 5. A lead pack as in Claim 3 in which the ends of th inwardly extending leads include a die-formed bump o dimple. 6. A lead pack as in Claim 5 wherein said die-formed bum is spaced inwardly from the end and sides of the inwardl extending lead end. 7. A lead pack as in Claim 5 in which the outwardl extending end of the lead is bent to offset the end fro the lead axis. 8. A lead pack as in any one of the foregoing claims i which the leads are plated with a solderable and/or protec tive coating. 9. A reusable lead pack transport tape comprising: an elongated tape; windows for receiving a lead pack of the type havin outwardly extending leads spaced uniformly along said tape; a plurality of test pads carried by said tape outwardl of said window and insulated from one another; and a plurality of spaced leads insulated from one anothe and splayed outwardly from the edge of said window to th test pads for receiving the outwardly extending lead pac leads. 10. A reusable lead pack transport tape as in Claim 9 i which the transport tape is of insulating material with patterned thin metal foil forming the leads and test pad. 11. A reusable lead pack transport tape as in Claim 9 i which the tape comprises a metal tape with patterned thi metal leads and test pads carried on an insulating layer o one face of said metal tape. 12. A reusable lead pack transport tape as in Claim 9, 1 or 11 in which the elongated tape is provided with space sprocket holes along its edge to index the tape to proces sing stations. 13. A reusable lead pack transport tape and lead pac comprising: an elongated tape; a plurality of longitudinally spaced windows formed i said tape; a plurality of leads splayed outwardly from the edg of said window; a plurality of lead packs carried by said tape, eac of said lead packs including a frame and a plurality o -13- spaced frame leads, have one end extending inwardly of sai frame and a second end extending outwardly of said frame and means for detachably securing said outwardly extendin frame leads to the window end of the transport tape leads. 14. A reusable transport tape and lead pack as in Claim 1 including a semiconductor device disposed within said lea pack and having its bonding pads connected to the inwardl extending ends of said frame leads. 15. A semiconductor device assembly comprising: a lead pack including a lead support frame of insu lating polymer material and a plurality of spaced lead imbedded and supported in said frame and having one en extending inwardly of said frame and the other en extending outwardly therefrom; and a semiconductor device having its bonding pads bonde to the inwardly extending ends of said leads. 16. A semiconductor device assembly as in Claim 15 includ ing a housing enclosing said device and sealed to sai frame. 17. A semiconductor device assembly as in Claim 15 or 1 including a bar of insulating material engaging the out wardly extending leads adjacent to the frame and space from their ends to maintain the same in spaced relation ship. 18. A method of forming a lead pack comprising the step of: forming a plurality of elongated windows in a conduc tive foil, such as copper, to define therebetween fla spaced leads; supplying a frame member of electrical insulatin material to each side of said foil spaced from the inne end of said leads to imbed and support the leads; and excising the foil adjacent the two ends of the leads to form a lead pack comprising a frame of electrical insu¬ lating material supporting a plurality of spaced leads extending inwardly and outwardly from said frame. 19. A method of forming a lead pack as in Claim 18 including the additional step of forming bonding bumps o dimples on the inwardly extending ends of said leads prio to excising. 20. A method of forming a lead pack as in Claim 18 or 1 including the additional step of plating said inwardl extending leads. 21. A tape automated bonding, packaging, and testin process for semiconductor devices comprising the steps of: forming a lead pack of the type having spaced lead extending inwardly and outwardly from a frame of electric ally insulating material; attaching the outer end of the leads of the lea pack to spaced splayed conductors carried by transport tap and extending between ends which receives the lead pack an test pads; and bonding the inner ends of the lead pack leads to th contact pads of a semiconductor device. 22. A tape automated bonding, packaging and testing pro cess as in Claim 21 including the step of housing sai semiconductor in a housing which seals to the fram material. 23. A tape automated bonding process as in Claim 22 in cluding the additional steps of removing the ends of sai leads which are fixed to the tape transport for receptio of a new lead pack.

Inventors: CAIN EARL S, CAIN, EARL, S.
Applicants: TRIBOTECH
Application year: 1989
Main classification: H01L29
IPC codes: H01L21, H01L23