JP3146487B2 - IC memory card - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC memory card incorporating a large number of memory LSI chips.

2. Description of the Related Art An IC memory card is widely used as a portable information storage device incorporating a memory LSI such as a RAM and a ROM. In recent years, with the expansion of its use, an IC memory card having a large storage capacity, that is, a large capacity has been demanded. In such a large-capacity IC memory card, a large number of memory LSIs must be densely mounted on a printed wiring board having a fixed area.

By the way, as a high-density mounting method of memory LSI,
It has been considered effective that a method of bonding conductor leads to electrodes of a bare chip of a memory LSI by a so-called film carrier method and mounting the memory LSI chips on a printed wiring board in a plane is effective. Hereinafter, a structure of a conventional IC memory card in which a large number of memory LSIs are mounted on a printed wiring board by a film carrier method will be described with reference to the drawings.

FIG. 5 is a sectional view showing a conventional IC memory card.
In FIG. 5, reference numeral 31 denotes a case in which a printed wiring board 32 is housed. Conductive wiring 33 is formed on the printed wiring board 32. 34 and 34 'are memory LSI chips and printed wiring boards
32 are arranged in a plane. One end 37a of a conductor lead 37 is joined to the electrode 35 of the memory LSI chip 34 via a metal projection 36 by a film carrier method. The other end 37b of the conductor lead 37 is joined to the conductor wiring 33 of the printed wiring board 32. Since the bare chip is used, the area occupied by the memory LSI chip on the printed wiring board is relatively small.

However, in the above-described conventional configuration, since the memory LSI chips are arranged in a plane on the printed wiring board, the area occupied by the memory LSI chips increases as the number of memory LSI chips increases. Therefore, the number of memory LSI chips that can be mounted on a printed wiring board having a fixed area is naturally limited. In addition, when the number of memory LSI chips increases, the distance between the conductor leads bonded to the electrodes of the memory LSI chip and the length of the conductor wiring on the printed wiring board that electrically connects the conductor leads increases the wiring space. There has been a problem that the cost of the plate increases and the signal transmission speed also decreases.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and a memory LS
The mounting density of I is dramatically increased, and a large number of memory LSI chips are mounted on a printed wiring board with a fixed area to achieve a large capacity.

Another object of the present invention is to provide an IC memory card capable of realizing high-speed signal transmission by reducing wiring space, and to prevent deformation and misalignment of the other end of the conductor lead during the assembly process, An object of the present invention is to realize a low-cost IC memory card by facilitating the joining between conductor leads of electrodes and conductor wiring.

Means for Solving the Problems In order to achieve this object, an IC memory card of the present invention has a structure in which a memory LSI chip having an electrode to which one end of a conductor lead is joined is laminated on a printed wiring board, and the memory LSI chip The conductor lead joined to the non-common electrode is branched into the number of stacks, and the other ends of all the branched conductor leads are connected with the other end of the conductor lead joined to the non-conductive electrode by an insulating film, The conductor lead of the common electrode and all the conductor leads of the branched non-common electrode are overlapped and joined to the conductor wiring of the printed wiring board, and the conductor lead of the branched non-common electrode is required for each lamination level. One conductive lead is joined to the corresponding conductive wiring different from the other, and the other unnecessary conductive leads are partially cut so that they are not electrically connected to the conductive wiring. It has a corresponding conductor wiring and electrically connected to each only conductor leads of one non-common electrode required for each stack rank.

Operation With this configuration, the area occupied by the memory LSI chips is greatly reduced, so that a large number of memory LSI chips can be mounted on a printed wiring board with a limited area to achieve a large capacity. Since the conductor lead of the common electrode between them is directly joined, the wiring space is reduced and the speed of signal transmission can be increased.In addition, the other end of the conductor lead is connected with an insulating film, and the other end of the conductor lead is connected. In addition to reducing the deformation and displacement of the ends, the conductor leads of the non-common electrode are branched, and unnecessary portions are cut off. As a result, the assembling process is facilitated, and a low-cost and highly reliable IC memory card can be realized.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of an IC memory card according to an embodiment of the present invention, FIG.
FIG. 3 is a block diagram of the electric circuit, and FIG. 4 is a perspective view showing the same laminated state. 1 to 4, reference numeral 1 denotes a case in which the printed wiring board 2 is housed. The printed wiring board 2 includes a memory circuit section 3, a control circuit section 4, and an external interface circuit section 5. The memory circuit unit 3 includes a plurality of memory LSI chips 6,
A large number of stacked memory LSI chips 6 are mounted on the printed wiring board 2. Control circuit section 4
Is constituted by a decoder IC 7 and the like, and performs chip selection by an address signal, backup control by power supply switching and the like. The external interface circuit unit 5 includes a connection connector 8 and the like. The connection connector 8 is connected to a connection unit (not shown) attached to another device or apparatus, and supplies power to the printed wiring board 2. Supply and give signals. 9
Is a battery for backing up the memory circuit unit 3, which uses a button type lithium battery and is housed in the case 1. The battery 9 supplies backup power when no power is supplied to the memory circuit unit 3 from the connection connector 8.

Next, the stacked state of the memory LSI chip 6 will be described. The memory LSI chip 6 is stacked on another memory LSI chip 6 'in a direction in which the respective electrode arrangements are the same. Reference numeral 10 denotes a common electrode of the memory LSI chip 6 and a metal projection 1
One end 12a of the conductor lead 12 is joined via 1.
Reference numeral 13 denotes a non-common electrode of the memory LSI chip 6, to which one end 15a of the conductor lead 15 is joined via a metal projection 14. The conductor lead 15 is formed from branched conductor leads 16 and 17. The other ends 16b and 17b of the conductor leads 16 and 17 are connected to the insulating film 1 together with the other ends 12b of the conductor leads connected to the common electrode 10.
Linked by eight. The above configuration is the same for the memory LSI chip 6 '. Reference numerals 19 and 19 'denote insulating materials made of resin or the like, which serve to protect the electrode 10, one end 12a of the conductor lead, and the like.

Next, the state of electrical connection of the conductor leads 12 and the like to the printed wiring board 2 will be described. The conductor leads 12, 12 '
Since they are connected to the common electrodes 10, 10 'of the memory LSI chips 6, 6', they are connected to the same conductor wiring 20 of the printed wiring board 2. On the other hand, the conductor lead 1 connected to the non-common electrodes 13, 13 '
5, 15 'cannot be connected to the same conductor wiring.
For this reason, the conductor leads 16, 17 obtained by branching the conductor lead 15 are
Among them, the conductor lead 17 is connected to the conductor wiring 22, and the conductor lead 16 is partially cut except for the other end 16b.
Conductor leads 16 'and 17' are obtained by branching conductor lead 15 '.
Of these, the conductor lead 16 'is connected to the conductor wiring 21, and the conductor lead 17' is partially cut off, leaving the other end 17'b. That is, the non-common electrode 13 includes the conductor wiring 22 and the non-common electrode 1.
3 'are electrically connected to the other conductor wirings 21, respectively.

Next, the joining state of the other end portion 12b of the conductor lead will be described. The other ends 12b and 12b 'of the conductor leads are overlapped and soldered to the conductor wiring 20. The other ends 16b and 16b 'of the conductor leads are superimposed on the conductor wiring 21, and the other ends 17 and 17' of the conductor leads are also superimposed on the conductor wiring 22.
, Respectively. Such a solder joint can be easily performed by a simple-shaped heat tool (not shown) because the heights of the other ends 12b, 16b, and 17b of the conductor leads from the surface of the printed wiring board 2 are the same. Can be performed collectively. Further, the other ends 12b, 16b,
17b are connected by the insulating film 18, so that when soldering to the conductor wiring 20 or the like, there is no danger that they will contact each other due to deformation or displacement. The other end 12b ', 16 of the conductor lead
The same applies to b 'and 17'b.

As described above, according to the present embodiment, the memory LSI chip 6,
By laminating 6 ', a large number of memory LSI chips 6 can be mounted on the printed wiring board 2 having a fixed area, so that a large-capacity IC memory card can be realized, and the conductor leads 12 connected to the common electrodes 10, 10' can be realized. 12 'is superimposed on conductor wiring 20
Since it is joined to the wiring, the wiring space can be reduced and the speed of signal transmission can be increased, and further, the other ends 12b,
16b and the like are connected by an insulating film 18 and the non-common electrode 1
Unnecessary portions such as the conductor leads 16 and 16 'connected to 3, 13' are cut off, and the other ends 16b and 16'b etc. are overlapped and joined to the conductor wiring 21 and so on. The process is easy, and a low-cost and highly reliable IC memory card can be realized.

Advantageous Effects of the Invention The present invention stacks a memory LSI chip having electrodes to which one end of a conductor lead is joined on a printed wiring board, and branches the conductor leads joined to the non-common electrodes of the memory LSI chip by the number of layers. The other end of each of the branched conductor leads is connected to the other end of the conductor lead joined to the common electrode by an insulating film, and the conductor lead of the common electrode and all the conductor leads of the branched non-common electrode are connected. Are superimposed on each other and joined to the conductor wiring of the printed wiring board, and the conductor leads of the non-common electrode that are branched are different from the conductors corresponding to one conductor lead required for each lamination level. Unnecessary other conductive leads joined to the wiring and branched are partially cut so that they are not electrically connected to the conductive wiring, and one non-common electrode conductive lead required for each stacking level Only the corresponding conductor wiring is electrically connected. Therefore, according to the present invention, a large number of memory LSI chips can be mounted on a printed wiring board having a fixed area, so that a large-capacity IC memory card can be realized.
A memory card can be realized, and the other ends of the conductor leads are connected by an insulating film, and the conductor leads joined to the non-common electrode as well as the common electrode are overlapped and joined to the conductor wiring. Connection between the other end of the wire and the conductor wiring is easy, and low cost and high reliability
It has an excellent effect that an IC memory card can be realized.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of an IC memory card according to an embodiment of the present invention, FIG.
FIG. 4 is a block diagram of the electric circuit, FIG. 4 is a partial perspective view showing the same laminated state, and FIG. 5 is a partial sectional view of a conventional IC memory card. 2 ... Printed wiring board, 6 ... Memory LSI chip, 10 ...
... common electrode, 13 ... non-common electrode, 12, 15, 16, 17 ... conductor lead, 12a, 15a ... one end of conductor lead, 12b, 16b, 17b
…… The other end of the conductor lead, 18 …… Insulating film, 20,21,
22 ... Conductor wiring.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-217296 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 25/04 H01L 25/10

Claims (1)

(57) [Claims] 1. A printed circuit board comprising a plurality of memory LSI chips having electrodes to which one ends of conductive leads are bonded, and the conductive leads bonded to the non-common electrodes of the memory LSI chips are divided by the number of layers. The other ends of all of the branched conductor leads are connected with the other ends of the conductor leads joined to the common electrode of the memory LSI chip by an insulating film, and the conductor leads of the common electrode are branched. All the conductor leads of the non-common electrode are overlapped and joined to the conductor wiring of the printed wiring board, and the conductor lead of the branched non-common electrode has one conductor lead required for each lamination level. Each of the other unnecessary conductor leads which are joined to the corresponding conductor wiring different from the corresponding others and which is branched and unnecessary is partially cut, and the necessary one conductor lead is required for each stacking floor.
An IC memory card wherein only the conductor leads of the non-common electrode are electrically connected to the corresponding conductor wiring.