Package for moulded carriers of integrated circuits

Abstract: A flexible connection means (16) is provided for connecting a plurality of moulded carriers (14) together, each of which supports an integrated circuit (10) which has been previously bonded to electrical leads of a TAB tape. The flexible connection means (16) flexibly and sequentially connects the carriers (14) together, so as to form a flexible and continuous chain of the carriers (14) which can be folded to superimpose the carriers (14) upon one another in a stacked formation in a package. The flexible connection means is preferably a flexible, electrically-conductive tape which is continuously provided on parallel ends, or edges (18), of each carrier (14), so as to link the carriers (14) together. The package permits continuous feeding of the carriers (14) into subsequent test and assembly machines utilized to attach the integrated circuits (10) to a printed circuit board.

Description: This invention generally relates to the packaging of integrated circuits prior to mounting on a printed circuit board as specified in the preamble of claim 1, for example as disclosed in US-A-4,562,924. More specifically, this invention relates to the packaging of moulded carriers used for testing and transporting of these integrated circuits during assembly of a printed circuit incorporating the integrated circuit. Many methods are known for forming the electrical interconnections between an integrated circuit and the supporting substrate. Tape automated bonding (TAB) is one commonly-known method for forming these electrical interconnections. A TAB tape is provided which is made up of many identical electrical lead configurations sequentially patterned along the tape. The electrical lead pattern comprises many individual long, slender leads attached to, and extending radially inwards from, a perimeter of the TAB tape material. The integrated circuit is provided within the centre of the TAB tape and gang-bonded to each of the electrical leads. After bonding between the integrated circuit and electrical leads is complete, the integrated circuit is excised from the TAB tape. The integrated circuit is subsequently mounted on an appropriate printed substrate, if this has not already been done, and accordingly bonded to the substrate. The integrity of the individual integrated circuit assemblies must be maintained throughout processing, but particularly during the period after the integrated circuit has been bonded to the electrical leads but not yet excised from the TAB tape. During this period, the TAB tape, integrated circuit and patterned slender electrical leads must be maintained in a substantially planar manner to ensure the integrity of the assembly for subsequent attachment of the integrated circuit to an appropriate substrate. Therefore, generally, a carrier ring or other device which fits around the perimeter of the TAB tape to retain the integrated circuit and electrical leads is utilized. The carrier is typically formed from a moulded plastics or other material which is relatively inexpensive, yet durable. After moulding, the carrier assembly having the integrated circuit and leads is fed into an assembly machine which then excises the integrated circuit and leads from the carrier and mounts the integrated circuit onto an appropriate printed circuit. During assembly and transport, these carrier assemblies are generally stacked vertically or horizontally and individually fed into the assembly machine. However, this method results in several disadvantages. Firstly, complex packaging and feed systems are required to handle the individual carrier units, since the individual units are not amenable to use with conventional tape and reel packaging methods. Secondly, it is expensive to package each unit individually. Lastly, there is added waste and bulk as a result of the individual packaging for each unit. It is desirable therefore to provide a means for packaging these carrier assemblies which is amenable to the automatic feed handling systems used to attach the integrated circuit within the carrier unit to a printed circuit board, wherein the carrier assemblies would be provided in a continuous manner. It is also desirable that the method for packaging be simplistic in design and relatively inexpensive. Lastly, it is desirable that the packaging method not generate undue waste. A package for carriers of integrated circuits according to the present invention is characterised by the features specified in the characterising portion of claim 1 and a method for packaging carriers of integrated circuits according to the present invention is characterised by the features as specified in the characterising portion of claim 6. It is an object of the present invention to provide means for packaging a plurality of carrier assemblies, each having an integrated circuit which has been bonded to the electrical leads within a lead frame. It is a further object of this invention that such packaging means provide a flexible and continuous chain of these carrier assemblies. In accordance with a preferred embodiment of this invention, these and other objects and advantages are accomplished as follows. A package has been prepared for moulded carriers, each supporting an integrated circuit which has been previously bonded to the electrical leads of a TAB tape. The packaging means used flexibly and sequentially connects a plurality of the carriers together, so as to form a flexible and continuous chain of the carriers. The packaging means preferably comprises a flexible conductive tape which is continuously provided on parallel ends, or edges, and on the top and bottom surface of each carrier, so as to link the carriers together. An inventive feature of this invention is that the flexible chain of carriers permits the carriers to be fed continuously into subsequent test and assembly machines utilized to attach the integrated circuit to a printed circuit board. In addition, the cost associated with this means of packaging, instead of conventional individual packaging units, is relatively inexpensive. Further, this means for packaging generates lesser amounts of waste. Other objects and advantages of this invention will be better appreciated from a detailed description thereof, which follows. The invention and how it may be performed are hereinafter particularly described with reference to the accompanying drawing, which is a perspective view of a packaging means for use with a carrier of an integrated circuit in accordance with a preferred embodiment of the present invention. A package is provided for testing and transporting moulded carriers, each of which supports an integrated circuit which has been previously bonded to the electrical leads of a TAB tape. The package provides a flexible and continuous chain of the carriers, which permits the carriers to be fed continuously into subsequent test and assembly machines utilized to attach the integrated circuit to a printed circuit board. As shown in the accompanying drawing an integrated circuit 10 is bonded to electrical leads 12. The electrical leads 12 are integral with and provided by a TAB tape. The integrated circuit 10 and electrical leads 12 are maintained in a substantially planar manner by a moulded carrier 14 in the form of an annular ring. The moulded carrier 14 is formed from a moulded plastics material after the integrated circuit 10 has been bonded to the electrical leads 12. The carrier 14 may be formed from any material which is durable, electrically dielectric and relatively inexpensive, such as a plastics material. The individual carriers 14 are connected to one another by means of a flexible tape 16 which is provided on parallel ends 18, or the edges, of each carrier 14. The flexible tape 16 is also provided on the top and bottom surface of the carrier 14 along the edges 18. The tape 16 adheres to the surface of the carrier 14 where it is provided. The carriers 14 are spaced a predetermined distance apart from each other, so that a gap 20 exists between each carrier 14. The size of the gap 20 is determined by the requirements of the subsequent processing machines and tolerances. Theoretically, the gap 20 could be quite large, however, for practical purposes it is desirable that the gap 20 be one to two times the thickness of the carrier 14. With a gap 20 of this preferred dimension, the chain of carriers 14 is still flexible, yet is not unduly cumbersome. If the gap 20 is too large, the flexible tape 16 may become entangled or tear, whilst if the gap 20 is too small, there may not be enough flexibility between the carriers 14, which may hinder subsequent processing of the carriers 14 and integrated circuits 10. As shown in the accompanying drawing, the flexible tape 16 links an indefinite number of carriers 14 together. At the gap 20, the flexible tape 16 forms a flexible link 22 between carriers 14. The link 22 is formed by the oppositely disposed tapes 16 provided on the top and bottom surfaces of the carrier 14 along the edges 18 of the carrier 14. The flexible links 22 permit the carriers 14 and integrated circuits 10 to fold over one another or to be hinged to one another in a manner similar to a chain. This allows the carriers 14 to be transported, stored and dispensed from a protective container having the carriers 14 layered within the container, similar to the manner in which continuously-fed ammunition is stored. The carriers 14 may then be continuously fed, instead of individually fed, into an assembly machine, such as a trim and form machine. In practice, after assembly or test at a particular machine, the integrated circuit 10 would be excised from the carrier 14. The carrier 14 having the flexible tape 16 could then be discarded. It is preferred that the tape 16 be formed from a material which does not deteriorate with age, does not cause damage to the integrated circuit and other components through out-gassing, does not generate an electrostatic discharge, and protects the components from electrostatic discharge generated elsewhere by being electrically conductive or at least conductive to static electricity. A preferred material for the flexible tape is a metallized polyester with an acrylic adhesive backing. The preferred metal is aluminium or nickel, although a conductive PVC or polystyrene may also be used on an acrylic adhesive. It is preferred that the acrylic adhesive be pressure-sensitive for ease in applying the tape to the carriers, however, it is foreseeable that the adhesive may be heat-sensitive and applied by exposing it to an appropriate temperature. It is also foreseeable that the tape 16 could be provided only at the gap 20 region. Therefore, it would not need to run the entire length of the edges of the carrier 14. The tape 16 would be provided on the carrier 14 near the gap 20 in an amount sufficient to ensure good adherence between the tape 16 and carrier 14. This variation would consume less amounts of the tape 16, however, it may prove more difficult to produce than the continuously-provided tape 16 shown in the figure. Advantages of this method for packaging the carriers 14 are many. The packaging permits the carriers 14 to be fed continuously into subsequent assembly machines utilized to attach the integrated circuit to a printed circuit board. In addition, the costs associated with this means of packaging, instead of conventional individual packaging units, are relatively inexpensive. Also, a high packing density of the carriers 14 is obtained and less refuse is generated. While the invention has been described in terms of a preferred embodiment using TAB tape technology, it is apparent that other forms could be adopted by one skilled in the art, such as the use of a different tape material or such as the use of integrated circuits which have been previously wire-bonded to an electrical lead frame. Accordingly, the scope of the invention is to be limited only by the following claims.

Claims: A package for carriers of integrated circuits comprising a plurality of integrated circuits (10), each of said integrated circuits (10) having a plurality of electrical leads (12) attached to and extending outwardly from said integrated circuit (10); a plurality of carriers (14), each of said carriers (14) retaining an individual integrated circuit (10); and a flexible connection means (16) for flexibly and sequentially connecting said carriers (14) to one another so as to form a flexible chain of said carriers (14), characterised in that each carrier (14) rigidly retains in a substantially planar direction all of said electrical leads (12) attached to and extending outwardly from said integrated circuit (10); and in that said flexible connection means (16) connects said carriers (14) to one another so that said connected carriers can be folded over one another in a stacked configuration. A package according to claim 1, wherein said flexible connection means comprises an adhesive tape (16). A package according to claim 1 or 2, wherein said flexible connection means (16) comprises an electrically conductive material. A package according to claim 1, wherein said flexible connection means comprises adhesive tape adhered to a sufficient region of at least two of said carriers for flexibly and sequentially connecting said carriers together to form said flexible chain of said carriers. A package according to claim 1, wherein each of said carriers (14) has at least two parallel edges (18); and said flexible connection means comprises adhesive tape (16) adhered to said parallel edges (18) of at least two of said carriers (14) for flexibly and sequentially connecting said carriers (14) together to form said flexible chain of said carriers (14). A method for packaging carriers of integrated circuits comprising the following steps: providing a plurality of integrated circuits (10), each having a plurality of electrical leads (12) attached to and extending outwardly from said integrated circuit (10); retaining said integrated circuits (10) in a substantially planar manner in a carrier (14); and connecting each of said carriers (14) to another of said carriers (14) by means of a flexible link (22), characterised in that all of said electrical leads of each integrated circuit are rigidly retained in a substantially planar direction in a respective carrier (14), each flexible link (22) is formed from a material (16) of sufficient thinness and flexibility to allow said link (22) to be doubled back on itself, and the spacing (20) of each connected carrier (14) from the adjacent connected carrier (14) is such that said carriers (14) are flexibly and sequentially connected to one another to form a chain in which said connected carriers (14) can be folded over one another in a stacked configuration to form a package. A method for packaging carriers of integrated circuits according to claim 6, wherein said flexible link (22) used in said connecting step comprises an adhesive tape (16). A method for packaging carriers of integrated circuits according to claim 6, wherein said flexible link (22) used in said connecting step comprises an electrically-conductive tape (16). A package according to claim 1, wherein each of said carriers (14) has top and bottom surfaces and each of said surfaces has first and second opposed edges; and said flexible connection means comprises first, second, third and fourth strips of adhesive tape (16), said first strip of adhesive tape (16) has a portion thereof adhered to a portion of the top surface near said first edge of each carrier (14) and a portion thereof extending across a gap (20) between adjacent carriers (14), said second strip of adhesive tape (16) has a portion thereof adhered to a portion of the bottom surface near said first edge of each carrier (14) and a portion thereof extending across said gap (20) between adjacent carriers (14), said first and second strips are secured together for a distance along said portions extending across said gap (20) between adjacent carriers (14) to form a first flexible link (22), said third strip of adhesive tape (16) has a portion thereof adhered to a portion of the top surface near said second edge of each carrier (14) and a portion thereof extending across said gap (20) between adjacent carriers (14), said fourth strip of adhesive tape (16) has a portion thereof adhered to a portion of the bottom surface near said second edge of each carrier (14) and a portion thereof extending across said gap (20) between adjacent carriers (14), and said third and fourth strips are secured together for a distance along said portions extending across said gap (20) between adjacent carriers (14) to form a second flexible link (22). A package according to claim 9, wherein said first, second, third and fourth strips of adhesive tape (16) are all electrically conductive. A package according to claim 9, wherein said adhesive tape (16) has adhesive on only one side thereof. A package according to claim 9, wherein said adhesive tape (16) has adhesive on only one side thereof, and has an electrically-conductive surface on the other side thereof. A package according to claim 9, wherein all of the carriers (14) are of substantially equal thickness, and said gap (20) between adjacent carriers (14) is equal to a distance slightly greater than twice the thickness of each carrier (14) so that said carriers (14), when folded over one another, are positioned in substantially superimposed positions, one upon another. A package according to claim 9, wherein said adhesive tape (16) comprises a metallized polyester tape having a backing of acrylic adhesive. A package according to claim 9, wherein said first, second, third and fourth strips of adhesive tape (16) are all formed from continuous lengths of adhesive tape (16) which extend along the lengths of the respective first and second opposed edges of each of said carriers (14) as well as across said gaps (20) between the adjacent carriers (14).

Inventors: KRUPPA VICTOR DAVID, KRUPPA, VICTOR DAVID
Applicants: DELCO ELECTRONICS CORP, DELCO ELECTRONICS CORPORATION
Application year: 1991
Main classification: H05K13
IPC codes: H01L21, H05K13