JP2007058870A - Method of manufacturing memory card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve attachment/detachment performance to a socket in a memory card. <P>SOLUTION: This invention is constituted of a wiring board 2, having a surface 2a and a reverse surface 2b mounted with a semiconductor chip 3, a bonding terminal 2c arranged on the surface 2a of the wiring board 2 and forming soft gold plating 2g on a surface 2f, an external connecting terminal 2d, arranged on the reverse surface 2b of the wiring board 2 and forming hard gold plating 2h on the surface 2f, a gold wire 4 for connecting the bonding terminal 2c to an electrode pad 3b of the semiconductor chip 3 and a cap 5 covering a resin sealing part 6 for sealing the semiconductor chip 3 and a plurality of gold wires 4. Metal plating of the surface 2f, of the external connecting terminal 2d of the memory card 1, is formed harder than or equal to metal plating of a surface 7b of a terminal 7a of the socket 7, and contact resistance between the external connecting terminal 2d of the memory card 1 and the terminal 7a of the socket 7 is reduced, and attaching-detaching performance of the memory card 1 to the socket 7 is improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique effective when applied to a method of manufacturing a semiconductor memory card (hereinafter simply referred to as a memory card).

Various memory card technologies are described (for example, see Non-Patent Document 1).
Nikkei Business Publications, September 21, 1998, “NE Nikkei Electronics September 21 issue”, pages 148-155

  Memory cards such as multimedia cards (US SanDisk) and SD (Security Device) cards (Panasonic, Toshiba, SanDisk) are external storage devices that store information in their internal semiconductor memory chips. is there. In this memory card, since the information is directly and electrically accessed to the nonvolatile memory formed in the semiconductor memory chip, since there is no mechanical control, writing compared to other external storage devices, The reading time is fast and the storage medium can be exchanged.

  In addition, because of its small size and light weight, it is mainly used as an auxiliary storage device for devices that require portability such as portable personal computers, mobile phones, and digital cameras.

  In the multimedia card, the semiconductor memory chip is mounted on a thin wiring board and is electrically connected to the terminals of the wiring board by wire bonding, and the semiconductor memory chip and the plurality of wires are made of a resin mold, a cap, or the like. It is sealed by.

  The memory card having such a structure uses a double-sided wiring board, a wire bonding terminal is provided on one side of the wiring board, and a terminal for contacting the socket terminal on the opposite side. Is provided.

  Therefore, the wire bonding terminal provided on one surface of the wiring board has a soft gold plating (hereinafter referred to as gold plating) having a low hardness on the surface in order to improve the bonding property of the wire bonding with the gold wire. In this case, since both sides of the wiring board are plated at the same time, the gold soft plating is also formed on the surface of the terminal that contacts the terminal of the socket of the wiring board.

  However, in the memory card such as the multimedia card of the above-described technology, the memory card is inserted and used in a push-push type socket (a type in which the card pops out when the card is pushed again when taking out). When removing the memory card, it is difficult to remove the memory card.

  This is probably because the surface of the memory card terminal that contacts the terminal of the socket is soft and soft, so that the contact resistance is high and it is easily caught.

  If the memory card is continuously inserted and removed in a state where the contact resistance is high, the problem is that the surface plating is scraped to cause contact failure.

  Furthermore, in order to improve the detachability (removability) of the memory card, a process of applying a sealing material (lubricant) to the terminal portion of the memory card is added to the process after the card assembly. Problems such as a longer turn around time) and difficulty in confirming whether or not the sealing material is applied occur.

  An object of the present invention is to provide a technique capable of improving the detachability of a memory card.

  Furthermore, another object of the present invention is to provide a technique capable of shortening the assembly process of the memory card.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  That is, the present invention includes a step of preparing a wiring board having a front surface and a back surface, a step of forming a copper foil on the front surface and the back surface of the wiring substrate, a step of forming nickel plating on the copper foil, the nickel plating Forming a first gold plating on the first gold plating on the back surface of the wiring board; forming a second gold plating having a hardness higher than that of the first gold plating on the surface of the wiring board; Forming a bonding terminal having the copper foil, nickel plating and first gold plating, and having the copper foil, nickel plating, first gold plating and second gold plating on the back surface of the wiring board. A step of forming a terminal, a step of mounting a semiconductor chip having an electrode pad on the surface of the wiring substrate, and a first gold plating of the electrode pad and the bonding terminal. A step of electrically connecting I, on the surface of the wiring substrate, the step of forming the semiconductor chip, a resin sealing portion of the wire and the bonding terminal for sealing, and has a.

  The effects obtained by the representative ones of the inventions disclosed by the present application will be briefly described as follows.

  In a memory card, the contact resistance between both terminals can be reduced by making the hardness of the metal plating on the surface of the terminal engaged with the socket equal to or higher than the hardness of the metal plating on the surface of the socket terminal. The memory card can be pulled out smoothly and easily even when it is pulled out from the socket. Thereby, the detachability of the memory card can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

(Embodiment)
1 is a plan view showing the structure of a memory card as an example of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a bottom view showing the structure of the memory card shown in FIG. 1, and FIG. 3 is a memory card shown in FIG. FIG. 4 is a bottom view showing an example of the structure of the wiring board shown in FIG. 3, and FIG. 5 is an example of a cross-sectional structure taken along the line AA of FIG. FIG. 6 is an enlarged partial cross-sectional view showing an example of a cross-sectional structure taken along line BB in FIG. 4, and FIG. 7 is an example of the structure after wire bonding in the assembly of the memory card shown in FIG. 8 is a plan view showing an example of the structure of a socket that engages with the memory card shown in FIG. 1, FIG. 9 is a bottom view showing an example of the structure of the socket shown in FIG. 8, and FIG. When the memory card shown in Fig. 8 is inserted into the socket shown in Fig. FIG. 11 is a bottom view showing an example of the structure of the memory card inserted state shown in FIG. 10, and FIG. 12 is an enlarged partial cross section showing an example of a cross section taken along line CC in FIG. FIG.

  The semiconductor device of this embodiment shown in FIGS. 1 and 2 is a multimedia card (US SanDisk Corporation) that can be used as an external storage device of a small electronic device such as a mobile phone or a digital camera. A memory card 1 called an SD card (Panasonic, Toshiba, SanDisk) or the like.

  The memory card 1 is made of a small thin plate having a planar rectangular shape, and its thickness is, for example, about 1.4 mm.

  The configuration of the memory card 1 will be described. A wiring board 2 having a front surface 2a, which is a first main surface on which a semiconductor chip 3 is mounted, and a back surface 2b, which is a second main surface on the opposite side, and the wiring substrate 2 A bonding terminal (first terminal portion) 2c provided on the front surface 2a and having a soft gold plating 2g as a first gold plating formed on the front surface 2f; and a back surface 2b of the wiring board 2, and An external connection terminal (second terminal portion) 2d having a hard gold plating 2h as the second gold plating formed on the surface 2f, a soft gold plating 2g of the bonding terminal 2c, and the semiconductor chip 3 shown in FIG. It consists of a gold wire (wire) 4 that connects the electrode pad (surface electrode) 3b, and a cap 5 that covers the resin sealing portion 6 that seals the semiconductor chip 3 and the plurality of gold wires 4.

  Furthermore, in the memory card 1 of the present embodiment, the hardness of the hard gold plating 2h of the external connection terminal 2d on the back surface 2b is the surface 7b of the terminal 7a of the socket 7 that contacts the external connection terminal 2d shown in FIG. It is the same as or higher than metal plating and higher than 2 g of soft gold plating.

  That is, the metal plating of the surface 2f of the external connection terminal 2d on the back surface 2b of the memory card 1 is made harder than or equivalent to the metal plating of the surface 7b of the terminal 7a of the socket 7 into which the memory card 1 is inserted. The contact resistance between the external connection terminal 2d and the terminal 7a of the socket 7 that is electrically connected to the external connection terminal 2d is reduced, and the memory card 1 is attachable to and removable from the socket 7 (removability). Is to improve.

  Therefore, in the present embodiment, the case where the surface 7b of the terminal 7a of the socket 7 is the hard gold plating 2h will be described.

  In addition, the hard gold plating 2h is generally employed in, for example, a terminal portion such as a module substrate or a main substrate of a personal computer, and has high reliability. The hardness of the hard gold plating 2h is, for example, a Vickers hardness of 180 to 200 (Hv) and a gold purity of 99.8 to 99.9%.

  On the other hand, the soft gold plating 2g is much softer than the hard gold plating 2h and can be connected to the gold wire 4 for wire bonding, and the hardness thereof is, for example, about Vickers hardness 100 (Hv). The gold purity is 99.99% or more.

  In the memory card 1, since the semiconductor chip 3 is electrically connected by wire bonding using the gold wire 4, the surface 2f of the bonding terminal 2c on the surface 2a side on which the semiconductor chip 3 is mounted. Must be 2 g of soft gold plating connectable to the gold wire 4.

  Here, the respective compositions of the bonding terminal 2c on the front surface 2a shown in FIG. 3 provided on the wiring board 2 of the memory card 1 and the external connection terminal 2d on the back surface 2b shown in FIG. 4 will be described. As shown, the bonding terminal 2c has a three-layer structure, and in order from the substrate 2k side, the lowermost layer is Cu foil (including Cu plating) 2i, the intermediate layer is Ni plating 2j, and the uppermost layer is soft gold plating 2g. It has become.

  Since the uppermost layer is 2 g of soft gold plating, wire bonding with the gold wire 4 is possible.

  As shown in FIG. 6, the external connection terminal 2d has a lowermost layer of Cu foil (including Cu plating) 2i, a first intermediate layer of Ni plating 2j, a second intermediate layer of soft gold plating 2g, and an uppermost layer. Is hard gold plating 2h.

  Since the uppermost layer is the hard gold plating 2h, it is the same as the hard gold plating 2h on the surface 7b of the terminal 7a of the socket 7. Therefore, the external connection terminal 2d of the memory card 1 and the socket 7 electrically connected thereto are used. The contact resistance with the terminal 7a can be reduced.

  The thickness of each plating on the front and back surfaces is, for example, about 20 μm for Cu foil 2i, about 8 μm for Ni plating 2j, 0.1 to 0.8 μm for soft gold plating, and 0.1 to 0.8 for hard gold plating 2h. Although it is about 0.8 μm, these numerical values are merely examples, and are not limited to these numerical values.

  Further, for example, a flash memory (EEPROM (Electrically Erasable Programmable Read Only Memory)) is formed on the semiconductor chip 3 mounted on the memory card 1 of the present embodiment, and as shown in FIG. It is mounted on the chip mounting portion 2e on the surface 2a of the wiring board 2 with the surface (element forming surface) 3a facing upward.

  The wiring substrate 2 is, for example, a thin glass-filled epoxy substrate, and an insulating solder resist 21 as shown in FIG. 12 is formed on the base material 2k shown in FIGS. .

  Further, the socket 7 into which the memory card 1 is inserted (engaged) has an opening 7c for inserting and removing the memory card 1, as shown in FIGS. Further, a terminal 7a that contacts the external connection terminal 2d of the memory card 1 is provided inside, and the surface 7b of the terminal 7a is a hard gold plating 2h.

  The socket 7 shown in FIGS. 8 and 9 is a push-push type socket 7, and when the inserted memory card 1 is taken out, the memory card 1 pops out when the card is pushed again.

  10 to 12 are views showing a state in which the memory card 1 is inserted into the socket 7, and the external connection terminal 2d of the memory card 1 and the terminal 7a of the socket 7 are in contact and electrically connected. It is in the state.

  Next, a method for manufacturing the memory card 1 of the present embodiment will be described.

  First, as shown in FIG. 5, the hard gold on the surface 7b of the terminal 7a of the socket 7 which has the bonding terminal 2c formed on the surface 2f with the soft gold plating 2g on the surface on the semiconductor chip mounting side. The wiring board 2 shown in FIG. 3 and FIG. 4 having the external connection terminal 2d formed on the surface 2f as shown in FIG. 6 is prepared by the same hard gold plating 2h as the plating 2h.

  In addition, in the terminal 2c for bonding on the front surface 2a of the wiring board 2 and the terminal 2d for external connection on the back surface 2b, the Cu foil 2i, the Ni plating 2j, and the soft gold plating 2g are sequentially formed from the base 2k side. About the same plating of front and back, you may form in the same process, and may form in a separate process.

  Thereafter, the semiconductor chip 3 is mounted on the chip mounting portion 2e on the surface 2a where the bonding terminals 2c of the wiring board 2 are provided.

  Further, as shown in FIGS. 7 and 12, the electrode pads 3 b of the semiconductor chip 3 and the bonding terminals 2 c on the surface 2 a of the wiring substrate 2 are electrically connected by wire bonding using a gold wire 4.

  Thereafter, the plurality of gold wires 4 and the semiconductor chip 3 connected by wire bonding are sealed with a resin mold to form a resin sealing portion 6, and the resin sealing portion 6 is covered with a cap 5.

  The cap 5 is fixed with, for example, an adhesive.

  Thereby, the memory card 1 which is a card-type semiconductor device as shown in FIGS. 1 and 2 can be assembled.

  In the memory card 1 and the manufacturing method thereof according to the present embodiment, the hardness of the metal plating of the surface 2f of the external connection terminal 2d that engages with the socket 7 of the memory card 1 is set to the metal plating hardness of the surface 7b of the terminal 7a of the socket 7. By making it equal to the hardness, the contact resistance between the external connection terminal 2d of the memory card 1 and the terminal 7a of the socket 7 can be lowered, and when the memory card 1 is pulled out from the socket 7, it can be pulled out smoothly and easily. be able to.

  Thereby, the detachability of the memory card 1 can be improved.

  In addition, since the contact resistance between the memory card 1 and the socket 7 is reduced, metal plating can be reduced and the occurrence of contact failure can be prevented.

  Furthermore, the connection reliability with the socket 7 of the memory card 1 can be improved.

  Further, since the contact resistance between the memory card 1 and the socket 7 can be reduced, the sealing material (lubricant) application step in the assembly of the memory card 1 can be eliminated.

  Thereby, the assembly process of the memory card 1 can be shortened, and TAT (time required until the product is completely finished) can be shortened.

  Further, since the sealing material is not applied, it is not necessary to inspect the appearance of whether or not the sealing material is applied. Therefore, the inspection work of the memory card 1 can be simplified.

  Also, instead of checking for the presence or absence of the sealing material, by performing an inspection by measuring the plating thickness of the bonding terminal 2c and the external connection terminal 2d of the wiring board 2, the wiring board is shipped from the board manufacturer and the semiconductor manufacturer. Since the plating thickness can be measured and inspected twice at the time of delivery of the wiring board at, it is possible to reduce the flow of the defective wiring board 2 to the assembly process.

  That is, the defective potential in the assembly process of the memory card 1 can be reduced, and the manufacturing cost can be reduced.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments of the invention. However, the present invention is not limited to the embodiments of the invention, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  For example, in the above embodiment, the case where the front surface 2f of the external connection terminal 2d on the back surface 2b of the memory card 1 is the hard gold plating 2h has been described, but the hardness is higher than that of the gold instead of the hard gold plating 2h. High palladium (Pd) plating may be used.

  That is, the metal plating of the surface 2f of the external connection terminal 2d of the memory card 1 is not the hard gold plating 2h if the hardness is equal to or higher than the metal plating of the surface 7b of the terminal 7a of the socket 7. Other metal plating such as palladium (Pd) plating may be used.

  Further, instead of the hard gold plating 2h, first, palladium (Pd) plating may be formed, and a soft gold plating 2g having a thickness of 0.05 μm or less may be formed thereon, in which case the external connection terminal 2d The hardness can be equivalent to the hardness of palladium (Pd) plating, and can be gold plating in appearance.

  Note that the metal plating on the surface 2f of the bonding terminal 2c of the memory card 1 must be metal plating with good connection to the wire by wire bonding, and the wire is the gold wire 4 as in the above embodiment. In some cases, it is preferable to employ 2 g of soft gold plating.

  In the above embodiment, the case where the present invention is applied to the memory card 1 incorporating the flash memory (EEPROM) has been described. However, the present invention is not limited to this. For example, SRAM (Static Random Access Memory), FRAM (Ferroelectric Random) The present invention can also be applied to a memory card 1 incorporating another memory circuit such as an access memory (MRAM) or a magnetic random access memory (MRAM).

  Furthermore, the present invention can be applied to an IC (Integrated Circuit) card that does not have a memory circuit.

  The present invention is suitable for assembling a memory card.

It is a top view which shows the structure of the memory card which is an example of the semiconductor device of embodiment of this invention. It is a bottom view which shows the structure of the memory card shown in FIG. It is a top view which shows an example of the structure of the wiring board integrated in the memory card shown in FIG. It is a bottom view which shows an example of the structure of the wiring board shown in FIG. FIG. 4 is an enlarged partial cross-sectional view illustrating an example of a cross-sectional structure along the line AA in FIG. 3. FIG. 5 is an enlarged partial cross-sectional view illustrating an example of a cross-sectional structure along the line BB in FIG. 4. It is a top view which shows an example of the structure after completion | finish of wire bonding in the assembly of the memory card shown in FIG. It is a top view which shows an example of the structure of the socket engaged with the memory card shown in FIG. It is a bottom view which shows an example of the structure of the socket shown in FIG. It is a top view which shows an example of a structure at the time of inserting the memory card shown in FIG. 1 in the socket shown in FIG. It is a bottom view which shows an example of the structure of the memory card insertion state shown in FIG. It is an expanded partial sectional view which shows an example of the structure of the cross section along CC line of FIG.

Explanation of symbols

1 Memory card (semiconductor device)
2 Wiring board 2a Surface (first main surface)
2b Back surface (second main surface)
2c Bonding terminal (first terminal part)
2d External connection terminal (second terminal part)
2e Chip mounting part 2f Surface 2g Soft gold plating (first metal plating)
2h Hard gold plating (second metal plating)
2i Cu foil 2j Ni plating 2k Base material 2l Solder resist 3 Semiconductor chip 3a Main surface 3b Electrode pad (surface electrode)
4 Gold wire
5 Cap 6 Resin sealing part 7 Socket 7a Terminal 7b Surface 7c Opening part

Claims (9)

(A) preparing a wiring board having a front surface and a back surface;
(B) forming a copper foil on the front and back surfaces of the wiring board;
(C) forming a nickel plating on the copper foil;
(D) forming a first gold plating on the nickel plating;
(E) On the first gold plating on the back surface of the wiring board, by forming a second gold plating whose hardness is higher than that of the first gold plating, the copper foil, nickel plating and Forming a bonding terminal having a first gold plating, and forming an external connection terminal having the copper foil, nickel plating, first gold plating and second gold plating on the back surface of the wiring board;
(F) mounting a semiconductor chip having electrode pads on the surface of the wiring board;
(G) electrically connecting the electrode pad and the first gold plating of the bonding terminal by a wire;
(H) forming a resin sealing portion for sealing the semiconductor chip, the wire and the bonding terminal on the surface of the wiring board;
A method for manufacturing a memory card, comprising: The method of manufacturing a memory card according to claim 1, further comprising:
(I) A step of forming a cap that covers the surface of the wiring board and the resin sealing portion after the step (h),
A method for manufacturing a memory card, comprising: In the manufacturing method of the memory card according to claim 1 or 2,
The method of manufacturing a memory card, wherein the gold purity of the first gold plating is higher than the gold purity of the second gold plating. In the manufacturing method of the memory card of Claim 3,
The gold purity of the first gold plating is 99.99% or more, and the gold purity of the second gold plating is in the range of 99.8 to 99.9%. . In the manufacturing method of the memory card according to claim 1, 2, 3, or 4,
The Vickers hardness of the first gold plating is about 100 (Hv), and the Vickers hardness of the second gold plating is in the range of 180 to 200 (Hv). In the manufacturing method of the memory card according to claim 1, 2, 3, 4 or 5,
The method of manufacturing a memory card, wherein the wire is a gold wire. In the manufacturing method of the memory card according to claim 1, 2, 3, 4, 5 or 6,
A method of manufacturing a memory card, wherein the semiconductor chip includes a memory circuit. In the manufacturing method of the memory card according to claim 7,
A method of manufacturing a memory card, wherein the memory circuit constitutes a flash memory.   9. The method of manufacturing a memory card according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the external connection terminal is a terminal for connecting to a connection terminal of a card connector for mounting a memory card. A method for manufacturing a memory card.

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