JP3280815B2 - Wire bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire bonding method in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art As is well known, individual semiconductor chips separated from a wafer through a dicing process are fixed on an island of a lead frame in a bonding process, and thereafter, wire bonding is performed.

Hereinafter, a conventional wire bonding method will be described with reference to FIG. FIG. 3 is a sectional view of a main part in the bonding step. In FIG. 3, reference numeral 1 denotes a semiconductor chip fixed on the island 3 of the lead frame 2, and reference numeral 4 denotes a plurality of lead pins formed on the lead frame 2. Reference numeral 5 denotes an adhesive tape member for bonding and connecting a plurality of lead pins 4 in advance so that individual positions do not shift, and 6 denotes a lead pin 4 corresponding to a terminal of the semiconductor chip 1.
And a lead wire for connecting

[0004] Reference numeral 7 denotes a stage which moves up and down in the vertical direction of the bonding apparatus.
And a frame holder that moves up and down similarly. The stage 7 supports the lead frame 2 from below at the time of wire bonding, and the frame presser 8 presses the plurality of lead pins 4 at once from above.

[0005] In the bonding step, connection between the terminals of the semiconductor chip 1 and the corresponding lead pins 4 by the lead wires 6 is performed as follows. That is, first, the lead frame 2 is moved so that the semiconductor chip 1 fixed on the island 3 comes to a predetermined position. Subsequently, the stage 7 of the bonding apparatus is moved upward to support the lead frame 2, and the frame retainer 8 is moved downward so that the plurality of lead pins 4 are attached to the distal end side of the position where the tape members 5 are adhered by the retainer 9. Hold down in parts.

Next, in a state where the plurality of lead pins 4 are collectively pressed by the frame presser 8, a lead wire 6 is stretched over a tip portion of the lead pin 4 and a terminal of the semiconductor chip 1 in a predetermined loop shape. And join them together. Then, after joining the corresponding terminals of the semiconductor chip 1 and the lead pins 4 with the lead wires 6, the stage 7 is moved downward, and the frame holder 8 is moved upward.

[0007] Thereafter, the lead frame 2 is moved again, and the above process is repeated, so that the next semiconductor chip 1 is subjected to wire bonding.

In such a conventional technique, when joining the lead wires 6, the lead pins 4 do not move unnecessarily due to flapping or the like, and the plurality of lead pins 4 do not contact with the joining tool. At a predetermined distance from the front end of the frame holder 8 is directly pressed by the holding portion 9 of the frame holder 8, and the tape member 5 is bonded to the outside of the position to be pressed at once. However, in order to directly press the plurality of lead pins 4 uniformly with the direct frame press 8, the press surface of the press section 9 needs to have high flatness.

That is, when the lead pin 4 is partially deformed or cannot be pressed uniformly because the flatness of the pressing surface of the pressing portion 9 is not good, the lead pin 4 having a small pressing force is generated. The lead pin 4
In this case, defective bonding may occur, or the loop shape drawn by the lead wire 6 may be disturbed.

In particular, in a lead frame having a depressed structure in which the island for fixing the semiconductor chip 1 is lower than the surface on which the lead pins are formed, the size of the stage of the bonding apparatus for supporting the island during bonding corresponding to the depressed structure. A small dimensional difference occurs between the shape and the shape. Due to such a dimensional difference, a repulsive force is generated on the lead pin when pressed by the frame presser 8, and the pressing force by the frame presser 8 is reduced to cause a bonding failure or the like to cause a bonding failure.

Therefore, when installing the frame presser 8 prior to performing the wire bonding, it is necessary to make sufficient adjustments to obtain highly accurate flatness, and the adjustment work also requires skill and time. And it was very time-consuming. Strict control of the flatness was required on a daily basis so that good bonding was always obtained.

In a recent situation where a semiconductor device has a narrow pitch and a large number of pins due to high integration and high functionality, it is more difficult to press all the lead pins at once by the frame presser 8 uniformly. There is a possibility that a bonding failure may be caused and it becomes more difficult to improve the yield in the bonding step.

[0013]

As described above, a plurality of lead pins of a lead frame are collectively and directly held by a frame holder in a bonding step, and lead wires are bonded to the semiconductor chip and the lead pins. A high-precision flatness is required, and if it cannot be obtained, it causes bonding failure such as bonding failure, and if it is attempted to obtain a high-precision flatness, installation adjustment is very troublesome. Was. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wire bonding method that can reduce bonding defects such as bonding defects and that does not require installation adjustment.

[0014]

According to a wire bonding method of the present invention, a predetermined pin of a semiconductor chip fixed on an island of a lead frame and a tip portion of a plurality of lead pins are collectively held by a frame retainer. In the wire bonding method in which the lead wires are joined and connected in a state where the lead pins are held down, a tape member is provided at a position separated by a predetermined distance from the tip of the lead pin so as to connect the lead pins together , and a frame is formed on the tape member. Push
The lead wire is joined to and connected to the lead pin in a state where the lead wire is pressed at a time, and a position separated by a predetermined distance from the tip of the lead pin is pressed when the lead wire is joined. Thereby, the tip portion of the lead pin is a position that does not show unnecessary movement, further, the tape member,
It is characterized by having polyimide resin as a base material and having adhesiveness on one side.

[0015]

According to the wire bonding method configured as described above, a plurality of lead pins are positioned at a predetermined distance from the tip.
To each other with a tape member, and furthermore,
The lead is pressed at once by the frame presser, and the lead wire is joined and connected to the tip of the lead pin under the pressed state, so it is sufficient to press the lead pin via a tape member and directly press the metal lead pin. Even if the presser surface of the frame presser does not have a high degree of flatness as in the case, the lead pins can be pressed securely and uniformly collectively, and the presser surface is not required to have a high degree of flatness. It is not necessary to spend much skill and time for adjusting the installation more than necessary even when attaching to a bonding apparatus. For this reason, even if the lead pins do not maintain the flatness , the lead pins can be reliably pressed, bonding defects such as bonding defects can be reduced, and installation adjustment is not troublesome.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic perspective view in a bonding step, and FIG. 2 is a sectional view of a main part.

In FIG. 1 and FIG. 2, reference numeral 11 denotes a semiconductor chip individually cut from a wafer, which is formed of, for example, a 42 alloy of Ni--Fe alloy and has a thickness of 0.1 mm.
It is fixed on the island 13 of the long strip-shaped lead frame 12 having a predetermined thickness in the range of 15 mm to 0.3 mm with a conductive adhesive. The islands 13 are provided at predetermined intervals on the lead frame 12, and are formed by punching or the like together with a plurality of lead pins 14 provided substantially radially around the islands.

The plurality of lead pins 14 provided around the island 13 are formed of a polyimide resin base material having a width of about 0.5 mm or more and a thickness of about 0.075 mm, and have an adhesive property on one side. By adhering the tape members 15 to each other, the individual members are connected so as not to shift. The bonding position of the tape member 15 is a position separated from the tip of each lead pin 14 by a predetermined distance in the range of 0.8 to 1.2 mm. It should be noted that this position is adjusted by pressing the lead pin 14.
Even if the tip part of this is processed, it does not move unnecessarily, such as flapping.

Further, the terminals of the semiconductor chip 11 and the corresponding lead pins 14 are connected by lead wires 16 such as gold wires. The bonding of the lead wires 16 to the terminals of the semiconductor chip 11 and the lead pins 14 is performed by wire bonding performed using a bonding apparatus 17 described below.

The bonding apparatus 17 includes a stage 19 that moves back and forth in the vertical direction Z ₁ has a rectangular horizontal support surface 18
When, a frame retainer 21 fixed to the mount 20 to advance and retreat likewise vertically Z ₂ above the horizontal support surface 18 of the stage 19. Further, between the stage 19 and the frame holder 21, the semiconductor chip 11 is
3 while supporting the lead frame 12 horizontally, and holding the lead frame 12 such that the island 13 stops immediately below the frame retainer 21 in the longitudinal direction Y.
Is provided.

The frame retainer 21 has a rectangular opening 23 formed at the center thereof so that the tips of the semiconductor chip 11 and the lead pins 14 on the island 13 stopped right below can be seen from above, and the lower surface is further formed on the lower surface. A rectangular ring-shaped pressing portion 24 protruding along the edge of the rectangular opening 23 is provided, and a lower pressing surface 25 is a flat surface. The shape of the pressing surface 25 of the pressing portion 24 is substantially equal to the upper surface of the tape member 15 adhered to a predetermined position at the tip of the lead pin 14. Although not shown, the bonding apparatus 17 is provided with a bonding tool and the like for bonding the lead wires 16.

Then, such a bonding apparatus 17
Accordingly, wire bonding for joining the lead wires 16 to the terminals of the semiconductor chip 11 and the lead pins 14 is performed as follows. That is, first, the lead frame 12 supported by the support base 22 is moved so that the semiconductor chip 11 fixed on the island 13 is located immediately below the square opening 23 of the frame holder 21.

[0023] Subsequently, the stage moves back and forth in the vertical direction Z _{1 1}
9 is moved upward to contact and support the lead frame 12 and the lower surface of its island 13. Furthermore, the lower pressing surface 25 of the pressing portion 24 is pressed against the upper surface of the tape member 15 by moving the frame retainer 21 which also moved in the vertical direction Z ₂ downward, the tape member 1 a plurality of lead pins 14
5 is pressed all at once.

Next, in a state where the plurality of lead pins 14 are collectively pressed by the frame presser 21, the lead wire 16 is connected to the tip of the lead pin 14 and the terminal of the semiconductor chip 11 in the rectangular opening 23 by a predetermined amount. Bonding is performed using a bonding tool so as to be drawn in a loop shape. Then, after joining the terminals of the corresponding semiconductor chip 11 and the lead pins 14 with the lead wires 16, the stage 19 is moved downward and the frame retainer 21 is moved upward.

After that, the lead frame 12 is moved again in the Y direction, and is stopped so that the next semiconductor chip 11 is located immediately below the square opening 23 of the frame holder 21.
Then, the above process is repeated, and the next semiconductor chip 11 is subjected to wire bonding.

In the above configuration, the stage 1
9 and the frame presser 21, the pressing surface 25 of the presser 24
Is pressed against the upper surface of the tape member 15, and the plurality of lead pins 14 are pressed at once through the tape member 15. In such a state, the pressing surface 2 of the pressing portion 24
5 is for pressing the lead pin 14 while pressing the tape member 15 made of polyimide resin, and is not for directly pressing the lead pin 14 made of metal, so that the pressing surface 25 does not realize flatness with high accuracy. Thus, the lead pin 14 can be uniformly and reliably pressed.

In addition, since the lead wire 16 is pressed in a state in which the lead pin 14 is pressed uniformly and securely and the pressing force is small but no object is generated, the leading end portion of the lead pin 14 is There is no unnecessary movement such as fluttering. And the square opening 2
Since a sufficient distance is provided between the edge of the lead wire 3 and the joint portion of the lead pin 16 with the lead wire 16, the bonding tool does not hit the frame retainer 21. As a result, there is no danger that the bonding of the lead wire 16 at the leading end portion of the lead pin 14 will be poor, or the loop shape drawn by the lead wire 16 will not be disturbed.

Further, since the flatness of the pressing surface 25 of the pressing portion 24 does not need to be higher than necessary, even when the frame presser 21 is fixed to the mounting base 20 and installed, the required range can be maintained within the required range. The adjustment work for obtaining the flatness of the precision is unnecessary. Also, daily flatness management does not have to be particularly strict. Further, the switching of the product type can be completed within a short time.

Similarly, even in the case of a lead frame having a depressed structure, the lead pins 14 can be pressed uniformly and reliably, resulting in poor bonding of the lead wires 16 and disturbance of the loop shape drawn by the lead wires 16. There is no danger of occurrence of bonding failure. Furthermore, even in a semiconductor device with a narrow pitch and a large number of pins, a large number of lead pins can be uniformly pressed on the upper surface of the tape member by the frame press at the same time, thereby improving the yield in the bonding process without causing bonding failure. Can be done.

[0030]

As is apparent from the above description, according to the present invention, a plurality of lead pins are arranged at a position separated from the tip by a predetermined distance.
Connected with a tape member, and
The lead pin does not maintain the flatness because the lead wire is pressed and pressed together and the lead wire is joined and connected to the tip of the lead pin under the pressed state.
Together may reduce the bond of bonding failure such as it is possible to suppress surely poor, the effects of such troublesome to miss is obtained to the installation adjustment.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a bonding step according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part in a bonding step according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part in a bonding step according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Semiconductor chip 12 ... Lead frame 13 ... Island 14 ... Lead pin 15 ... Tape member 16 ... Lead wire 17 ... Bonding apparatus 19 ... Stage 21 ... Frame holding 24 ... Holding part 25 ... Holding surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-298055 (JP, A) JP-A-61-88536 (JP, A) JP-A-63-87731 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21/60

Claims (3)

(57) [Claims] 1. A lead wire is joined and connected between a predetermined terminal of a semiconductor chip fixed on an island of a lead frame and tip portions of a plurality of lead pins while the lead pins are collectively held down by a frame holder. In the wire bonding method, a tape member is provided at a position separated by a predetermined distance from the tip of the lead pin so as to connect the lead pins together, and the tape member is placed on the tape member.
Wherein in a state of being pressed together by the frame holding Ridopi
A wire bonding method , wherein the lead wire is bonded to and connected to the lead wire. 2. The wire according to claim 1, wherein the position separated from the tip of the lead pin by a predetermined distance is a position where the tip of the lead pin does not show unnecessary movement by being pressed at the time of joining the lead wire. Bonding method. 3. The wire bonding method according to claim 1, wherein the tape member is made of a polyimide resin as a base material and has adhesiveness on one side.