Semiconductor chip installing tape, semiconductor device and a method for fabricating thereof

Abstract

A semiconductor chip mounting tape on which external connecting terminals are formed in accordance with a layout pattern has post portions which are to be connected to a semiconductor chip and external connecting terminals. Post portoins are formed on the first surface of an insulation tape used as a base of the semiconductor chip mounting tape. External connecting terminals are formed on the second surface of the insulation tape. The post portions and the external connecting terminals are integrally formed by same solder balls via through holes formed in the insulation tape.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a semiconductor chip package such as a ball (or bump) grid array (BGA) package, a semiconductor chip mounting tape particularly, and also to a semiconductor device, and fabricating methods.

[0003] 2. Description of Related Art

[0004] In BGA packages, circuit patterns are formed on both sides of a substrate (or a tape) and a semiconductor chip is mounted on the surface of the substrate.

[0005] For the electrical connection of the semiconductor chip mounted on the substrate, pads formed on the semiconductor chip and leads formed on the surface of the substrate are electrically connected by wire bonds (or bumps in the case of a flip chip system) and a connecting portion is protected by a resin seal formed by a method such as molding, potting, or the like.

[0006] Solder balls serving as external connecting terminals are formed on the circuit pattern on the back side of the substrate in accordance with a predetermined layout pattern.

[0007] The solder ball is temporarily fixed to a predetermined position by a ball mounter by using a flux, thereafter, reflowed through a furnace, and fixedly bonded onto the substrate, thereby forming the external connecting terminal.

[0008] With regard to the external connecting terminals, the diameter of the ball is reduced due to demands for miniaturization of the package and use of multi-pins, and the adoption of a narrower pitch of terminals is also occurring.

[0009] FIG. 1 is a cross sectional view showing a state where a solder balls are held by vacuum at a vacuum plate of the conventional ball mounter. The mounting of solder balls 1 by the ball mounter is performed by using the vacuum plate 2.

[0010] Vacuum holes 4 having tapered portions 3 are formed in the vacuum plate 2 in accordance with the layout pattern of the pads on the back side of the substrate, thereby holding the solder balls 1 by vacuum evacuating by an apparatus (not shown).

[0011] The solder balls 1 are subsequently deposited on the substrate by a method whereby a flux 5 is transferred to the solder balls 1 and the solder balls 1 are temporarily fixed onto the pads of the substrate by an adhering force of the flux 5.

[0012] However, a problem occurs in that the diameter of the solder ball 1 decreases and the flux 5 transferred to the solder ball 1 is deposited to the tapered portion 3 of the vacuum plate 2. As a result, separation of the solder balls 1 from the vacuum plate 2 is disturbed or hindered by the flux, and the solder ball 1 cannot be deposited surely onto the pad of the substrate.

[0013] When, on the other hand, the solder balls 1 have a reduced diameter, the transfer amount of the flux to the solder ball 1 decreases, so that fouling such as an oxide film on the pad of the substrate cannot be sufficiently removed by the flux. This will result in degrading of the fusing state of the solder at the time of the reflow process. Thus, there also is a problem that the solder ball 1 drops because the solder is insufficiently fused.

OBJECTS AND SUMMARY OF THE INVENTION

[0014] To solve the above problems, according to the invention, post portions to be connected to semiconductor chips are formed on a first surface of a tape having an insulation characteristic, which will be referred to as insulation tape, external connecting terminals are formed on a second surface of the insulation tape, and the post portions and the external connecting terminals are integrally formed by solder balls piercing through holes formed in the insulation tape.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a cross sectional view showing solder balls held by vacuum in a conventional arrangement;

[0016] FIGS. 2 and 3 are diagrams showing a semiconductor chip mounting tape according to the invention, in which FIG. 2 is a plan view and FIG. 3 is a cross sectional view;

[0017] FIG. 4 is an enlarged cross sectional view of a part of the semiconductor chip mounting tape shown in FIGS. 2 and 3;

[0018] FIG. 5 is a plan view showing a state where through holes are formed in an insulation tape;

[0019] FIG. 6 is a plan view showing a state where the insulation tape is plated;

[0020] FIG. 7 is an enlarged cross section of a part of the plated insulation tape; and

[0021] FIG. 8 is a cross sectional view showing a semiconductor device according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] FIGS. 2 and 3 are diagrams showing a semiconductor chip mounting tape according to the invention. FIG. 2 is a plan view and FIG. 3 is a cross sectional view. These diagrams are shown in a state where the back side of the semiconductor chip mounting tape faces upward.

[0023] A plurality of external connecting terminals 12 are arranged on the back side (second surface) of a film-like insulation tape 11 made of, for example, polyimide in accordance with a layout pattern which has been predetermined for a plurality of semiconductor chips.

[0024] A plurality of post portions 13 to be electrically connected to bonding pads formed on the semiconductor chips by wire bonds are formed on the surface (first surface) of the insulation tape 11.

[0025] The external connecting terminal 12 and post portion 13 are integrally formed by the same solder ball via a through hole formed in the insulation tape 11.

[0026] FIG. 4 is an enlarged cross sectional view of a part of the semiconductor chip mounting tape shown in FIGS. 2 and 3. The diagram is shown in a state where the second surface of the insulation tape 11 faces upward.

[0027] Through holes 14 are formed in the insulation tape 11 and plating 15 is performed to opening portions of the through holes, namely, wall portions of the through holes 14 and hole peripheral portions on both sides of the insulation tape 11.

[0028] The external connecting terminals 12 are formed on the second surface of the insulation tape 11 and the post portions 13 are formed on the first surface in a manner such that the external connecting terminals 12 and the post portions 13 are integrally formed by the same solder balls 16 exposed to both sides of the insulation tape 11 via the through holes 14.

[0029] The solder ball 16 is fixed to the insulation tape 11 through the plating 15 by ref lowing.

[0030] According to the semiconductor chip mounting tape by the invention as mentioned above, since the solder balls 16 are embedded into the through holes 14 and the external connecting terminals 12 and post portions 13 are formed, the external connecting terminals 12 can be positively formed on the insulation tape 11.

[0031] FIGS. 5 to 7 are diagrams for explaining a manufacturing method of the semiconductor chip mounting tape shown in FIGS. 2 to 4. FIG. 5 is a plan view showing an insulation tape in which through holes are formed. FIG. 6 is a plan view showing a plated insulation tape. FIG. 7 is an enlarged cross sectional view of a part of the plated insulation tape.

[0032] In FIG. 5, the circular through holes 14 slightly smaller than the diameter of the solder balls are formed in the prepared insulation tape 11 in accordance with a predetermined layout pattern of the external connecting terminals.

[0033] In FIGS. 6 and 7, the plating 15 is performed to the opening portions of the through holes 14. Specifically, the wall portions of the through holes 14 and hole peripheral portions on both sides of the insulation tape 11 is performed by electrolyte-free plating or the like.

[0034] Subsequently, flux is deposited onto the second surface of the insulation tape 11, for example, the lower surface of FIG. 7 by dipping. The method of depositing the flux is not limited to the dipping method but the flux can be also deposited by any of such methods as transferring and coating.

[0035] The second surface of the insulation tape 11 on which the flux is deposited is set so as to face upward and the solder balls 16 are mounted to the through holes 14 by a ball mounter as shown in FIG. 4.

[0036] By allowing the tape to pass through a reflow furnace, the solder balls 16 are reflowed, thereby fixedly bonding the solder balls 16 onto the insulation tape 11 through the plating 15 as shown in FIG. 4.

[0037] The external connecting terminals 12 are, consequently, formed to the second surface of the insulation tape 11 and, at the same time, a part of each of the solder balls 16 is exposed to the first surface of the insulation tape 11 via the through hole 14 as shown in FIG. 4, thereby forming the post portion 13.

[0038] In the manufacturing method of the semiconductor chip installing tape according to the invention as mentioned above, since the flux is not directly transferred to the solder balls 16, no flux is deposited to the vacuum plate and the solder balls 16 can be positively mounted to the insulation tape 11.

[0039] Since the flux is sufficiently deposited to the plated portions of the insulation tape 11 by dipping or the like, the solder balls 16 do not drop due to the non-fused state of the soldering.

[0040] Further, since the external connecting terminal 12 and post portion 13 are simultaneously formed from the same solder ball 16, the manufacturing time can be shortened. Differing from the conventional substrate, it is possible to omit the copper foil sticking step for the circuit pattern, the wiring step of wiring the post portions and external terminals of the substrate, the soldering resist coating step of protecting the circuit pattern, and the like.

[0041] FIG. 8 is a cross sectional view showing a semiconductor device according to the invention and shows a BGA package using a semiconductor chip mounting tape with external connecting terminals according to the invention.

[0042] A semiconductor chip 17 is mounted on the surface of a semiconductor chip mounting tape in which the post portions 13 are formed on the first surface of the insulation tape 11 by solder balls 16 and the external connecting terminals 12 are formed on the second surface by the same solder balls 16. The semiconductor chip 17 is fixed with an adhesive 18.

[0043] Pads 19 formed on the semiconductor chip 17 and the post portions 13 are wire-bonded by bonding wires 20 such as gold wires or the like respectively, thereby resin-sealing the wire-bonded portions and the semiconductor chip 17 by a resin 21. The wire-bonded portions of the post portions 13 and a joint interface between the semiconductor chip 17 and insulation tape 11 are, therefore, protected by the resin-sealing.

[0044] Although the semiconductor device of the BGA package is attached onto an installing substrate (not shown) by reflowing the solder balls 16, in this instance, even if the solder is fused, since the wire-bonded portions are resin-sealed, there is no fear such that the wires 20 are peeled off from the post portions 13.

[0045] As mentioned above, in the second embodiment according to the invention, the BGA package with the external connecting terminals in which the diameter of the solder balls is small and a pitch is narrow can be realized by using the semiconductor chip mounting tape according to the invention.

[0046] Since the semiconductor chip mounting tape is thinner than that of the conventional substrate, a package which is thinner by an amount corresponding to the thin tape can be formed.

[0047] Subsequently, a manufacturing method of the semiconductor device according to the invention will now be described. First, the semiconductor chip mounting tape according to the invention is prepared. The semiconductor chip mounting tape is constructed so as to have a length such that a plurality of semiconductor chips can be installed simultaneously.

[0048] As shown in FIG. 8, the first surface of the insulation tape 11 formed with the post portions 13 is set so as to face upward, and the semiconductor chip 17 is die-bonded at a predetermined position on the first surface. The semiconductor chip 17 is fixed onto the insulation tape 11 by the adhesive 18.

[0049] Subsequently, the pads 19 formed on the semiconductor chip 17 and the post portions 13 are electrically connected by the wire-bonding method by using the wires 20.

[0050] After that, the wire-bonded portions and the semiconductor chip 17 are resin-sealed with the resin 21.

[0051] Since the manufacturing process is executed on the semiconductor chip mounting tape and a plurality of semiconductor devices are manufactured, the semiconductor chip mounting tape is cut and the BGA package is segmented, thereby completing the manufacturing method.

[0052] According to the method of fabricating the semiconductor device of the invention as mentioned above, since the manufacturing step of the semiconductor chip mounting tape is remarkably shortened, the manufacturing time of the semiconductor device can be also reduced.

[0053] According to the invention as mentioned above, since the post portions and external connecting terminals which are connected to the semiconductor chip via the through holes formed in the insulation tape are integrally formed, the external connecting terminals can be certainly formed to the insulation tape.

Claims

1. A semiconductor chip mounting tape on which external connecting terminals are formed in accordance with a layout pattern, comprising: an insulation tape having through holes; post portions which are to be connected to a semiconductor chip, said post portions formed on a first surface of an insulation tape; and external connecting terminals formed on a second surface of said insulation tape, wherein said post portions and said external connecting terminals are integrally formed via said through holes of said insulation tape.

2. A method for fabricating a semiconductor chip mounting tape, comprising the steps of: forming through holes which are slightly smaller than a diameter of solder balls in an insulation tape in accordance with a layout pattern of external connecting terminals; performing plating to opening portions of said through holes; depositing a flux onto a second surface of said insulation tape; depositing solder balls to said through holes by setting the second surface of said insulation tape so as to face upward; and reflowing said solder balls, forming the external connecting terminals onto the second surface of said insulation tape, and at the same time, forming post portions which are to be connected to a semiconductor chip on a first surface of said insulation tape.

3. A semiconductor device according to claim 1, wherein a semiconductor chip is mounted on said semiconductor chip mounting tape according to claim 1, said semiconductor chip having pads for electrical connection, said pads and said post portions bonded with wires, and wire-bonded portions and said semiconductor chip are sealed with a resin.

4. A method for fabricating a semiconductor device according to claim 1, comprising the steps of: preparing said semiconductor chip mounting tape according to claim 1; die-bonding a semiconductor chip onto said semiconductor chip mounting tape; bonding pads on said semiconductor chip and said post portions by wires; sealing said wire-bonded portions and said semiconductor chip by a resin; and segmenting said resin-sealed package.