JPH0212863B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a gold wire for bonding a semiconductor device, that is, a spool winding form of gold wire used for connecting a chip electrode and an external lead portion of a semiconductor device. <Conventional Background> Generally, gold wire for bonding is made of an alloy mainly made of gold (Au), to which silver (Ag), iron (Fe), etc. are added, and is drawn to a diameter of 25 to 50 μm. Most of the conventional spool winding configurations are single-layered, in which such gold wire is wound in an aligned manner around the spool, and the length of the gold wire is generally 50 to 100 m. However, with the recent development of high-speed automatic bonding machines, the bonding speed is faster and the amount of gold wire used has increased. The replacement frequency becomes faster, which causes a decline in workability and productivity of bonding work.
It is desirable to increase the length of the spool winding. In order to increase the length of the gold wire in the conventional single-layer spool winding mentioned above, it is possible to increase the diameter of the spool and/or increase the length of the winding surface, but there is a need to install the spool in a predetermined bonding machine. Therefore, it is not desirable to change the spool shape. Therefore, in order to use a commonly used spool and increase the length of the gold wire to 500 to 1000 m, it is required that the wire be wound in a multilayered form with two or more layers. <Problems to be Solved by the Invention> In view of the above-mentioned conventional circumstances, when the spool winding form is multilayered with two or more layers, the gold wire for bonding must be an ultra-fine wire with a wire diameter of about 25 to 50 μm, and the tensile strength Since the spool is extremely small, simply winding the spool in multiple layers in the conventional manner would cause the following problems. In other words, in the conventional single-layer aligned winding method, for example, when winding gold wire with a wire diameter of 30 μm onto a spool with a diameter of 2 inches (50.8φmm), the pitch l is set to 300 μm.
(gap between adjacent wires l' = 0), but if it is wound in multiple layers, the first and second layer windings will inevitably have a cross-winding configuration, but the cross-winding The angle θ is 0.0216 degrees, and since the intersecting angle θ and the pitch l are extremely small, the windings are difficult to unravel, causing wire breakage during bonding work. In addition, the gold wire for bonding is soft and the parts where the wires intersect are easily deformed by a small force, the wires are easy to stick to each other, and scratches are easily generated.
Pitch l, intersection angle θ, and gap like a normal pincushion
In a closely-spaced cross-wound configuration with a small l′, the windings are too wedged and difficult to unravel, and the folded portions are bent, causing wire breakage, reducing workability, and even if wires do not break, scratches may occur, resulting in bonding Even if the pitch l, the crossing angle θ, and the gap l' are set large, the problem cannot be solved if they are too large. Accordingly, the present invention prevents wire breakage or scratches due to excessive winding by obtaining an appropriate state of engagement between the windings, and also prevents the windings from falling off, thereby facilitating bonding work. It is an object of the present invention to provide a spool winding wire that can improve the workability of the wire and maintain the reliability of the gold wire. <Means for Solving the Problems> The means taken by the present invention to solve the above problems is to spool a single gold bonding wire with a wire diameter of 25 to 50μ onto a spool with a diameter of 2 inches (50.8φmm). In the winding configuration in which the wire is wound at a predetermined pitch l to form a multilayer structure, the pitch l is 2 to 8 mm, and the crossing angle between the forward winding and the return winding is 1 degree 20 minutes to 5 degrees 15 minutes. Cross at θ and reciprocate with the n-th winding on each side (n-1)
Minimum 0.1mm between the second winding and maximum (l-0.1)
This is because a gap of mm was provided. <Function> If the pitch l is less than 2 mm, it will be difficult to unravel during bonding, causing snags and causing wire breakage, and if it exceeds 8 mm, it will cause wire breakage again and cause the winding to fall off. If the crossing angle θ is less than 1 degree and 20 minutes, it will cause wire breakage during bonding, and if it exceeds 5 degrees and 15 minutes, it will cause the winding to fall off, deform, and cause scratches. If the gap l' is less than 1 mm, and exceeds (l-0.1) mm, it may cause wire breakage, deformation of the winding, or scratches during bonding. Therefore, the pitch l should be 2 to 8 mm, and the intersection angle θ should be 1 degree.
20 minutes to 5 degrees 15 minutes, gap l' is minimum 0.1 mm, maximum (l-
0.1) mm. <Example> To explain an example of the present invention with reference to the drawings, the first example is as follows.
The figure shows a spool winding in which bonding gold wire B is wound around spool A. After fixing one end of the gold wire B to the spool A, the spool is rotated at a constant speed while the spool is axially moved, or the wire feeding end is reciprocated along the axial direction of the spool. caught up in
The gold wire that is wound when feeding one side of the spool or gold wire is shown as an outgoing winding 10, and the gold wire that is wound when feeding the other side is shown as a returning winding 20. That is, one of the gold wires B is traversed with the rotation of the spool A, and is wound up by repeating reciprocating motion, but on the forward side, the winding 11 advances by a pitch l in one rotation of the spool A, and for each pitch l traverses to the other end of the spool A, then on the return side, the winding 21 also returns to the winding start end side at the pitch l, and on the next forward side, the winding 21 returns to the position with a gap l', that is, the winding indicated by 12. The wire is traversed from the wire again at pitch l, and thereafter wound in the same manner, and the winding 11 on the forward side and the winding wire 21 on the backward side intersect at an intersection angle θ (FIG. 2). The pitch l and crossing angle θ of the windings 10 and 20 are set by the rotational speed of the spool A and the feeding speed of the spool or gold wire. In order to explain the winding state of the windings 10 and 20, one pitch of the first layer is shown enlarged in FIG. In FIG. 2, the windings 10 are shown as follows: 11 is the first outgoing winding, 12, 13...17 are the second and third outgoing windings, respectively.
times...This is the seventh outgoing winding, and the winding 20 is the 2nd
1 is the first return winding, and 22, 23, . . . 27 are the second, third, ... seventh return windings, respectively. The above windings 11, 21, 12, 22...17, 27
The crossing portions X... are formed at two locations in one pitch, and the crossing portions sequentially move in the circumferential direction as shown in the figure. By continuing the above-mentioned involvement,
The windings 10 and 20 are stacked on top of each other in two, three, etc. layers, and the second layer has the winding 20 on top of the winding 10.
However, the windings 10 and 20 are sequentially and alternately stacked so that the windings 10 are arranged on the winding 20 (first
figure). The phase of the windings 10 and 20 is shifted for each winding, and a gap l' is provided between the n-th and (n-1)th windings. The above-mentioned gap l' can be formed by adjusting the turn-back timing at the feeding end of the spool A or the gold wire B, or by adjusting the opening ratio where the pitch l of the winding wire and the total width L of the winding wire are not an integral multiple, for example, the pitch l is 4 mm. , L
It is automatically formed by setting it to 23.5mm. The gap l' is formed not only in the first layer but also in the second and subsequent layers. Note that the stacked state of the multilayer structure may be either a state in which the overall width of the winding is constant, or a state in which the winding width is reduced as the upper layer is stacked in bales, but the latter is preferable because the folded end This is preferable because it can better prevent the material from falling off. Fig. 1 shows a stacked structure in which the windings 10 and 20 have a constant overall width L from the first layer to the top layer, whereas Fig. 3 shows a stacked structure in which the overall width L of the windings is reduced for each upper layer. Shows the stacking form. Also in the winding form shown in FIG. 3, the windings 10, 20
are the gaps between the n-th and (n-1)th times, respectively.
l′ is formed in the same way, but the windings 11,
Each intersection X of 21, 12, 22... moves in the circumferential direction and the axial direction, that is, in a spiral shape. The above-mentioned windings 10 and 20 can be appropriately engaged due to their pitch l, crossing state, and gap l', but the pitch l, crossing angle θ,
If the gap l′ is too large, it will easily come undone, and if it is too small, the biting will be too strong and it will be difficult to come undone. That is, the pitch l of the windings 10 and 20, the crossing angle θ,
The set value of the gap l' is an important factor in the engagement state of the windings. Therefore, experimental data for various values of pitch l, crossing angle θ, and gap l' are shown below. Note that the experimental data used a commonly used 2-inch diameter spool, and the gold wire used had a diameter of 30μ, but it has a diameter of 25 to 50μ.
A similar trend was observed within the range of .

【table】

[Table] Measure how many times it was hit before
(Note 2): Deformation is determined visually after the vibration test. The effects of the above experimental results are summarized in the table below.

[Table] ○ mark: Good effect × mark: Bad effect According to these experimental results, it was found that the values in the following range are optimal. In other words, when using gold wire B with a diameter of 25 to 50μ and a spool with a diameter of 2 inches, the pitch is
is 2 to 8 mm, the intersection angle θ is 1 degree 20 minutes to 5 degrees 15 minutes, and the gap l' is in the range of minimum 0.1 mm and maximum (l-0.1) mm. In this way, by setting the pitch l, crossing angle θ, and gap l' of the windings 10 and 20 to values within the above ranges, the winding can be made in the best way to prevent snagging, deformation, and scratches of the gold wire B. This results in an optimal winding engagement state. Incidentally, the pitch l does not need to be constant at all times, and may be varied within the range of 2 to 8 mm for each winding or for each layer. <Effects> As described above, the present invention winds a single gold wire for bonding onto a spool at a predetermined pitch, intersecting angle, and gap to form a multilayer structure, so the same spool is used compared to conventional single-layer winding. Even in this case, the length of the gold wire can be increased several times. Since the outgoing winding and the incoming winding intersect at a predetermined angle, the winding can be prevented from falling off.Moreover, the pitch l of the winding is 2 to 8 mm, and the nth winding on each reciprocating side Since a gap of minimum 0.1 mm and maximum (l-0.1) mm is interposed between the wire and the (n-1)th winding, the outgoing winding and the returning winding are Unlike the case where the yarns are arranged alternately for each book and in close contact with each other, a plurality of outgoing winding groups and incoming winding groups are arranged in one pitch, and there is a gap between each wire. An intervening winding configuration is obtained, so that the windings do not come into close contact with each other, and an appropriate state of engagement between the windings is obtained in which excessive digging is suppressed. Therefore, it is possible to provide a spool winding that does not cause unraveling or disconnection of the winding and that requires less frequent spool replacement, thereby improving the productivity of bonding work and achieving the intended purpose.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of the spool winding of the present invention, FIG. 2 is an enlarged view of the first pitch portion of the first layer, and FIG. 3 is an enlarged view of the main part of a modified example. In the figure, A is the spool, B is the gold wire, 10 is the forward winding, 20 is the return winding, l is the pitch, l' is the gap, θ
is the intersection angle.

Claims (1)

[Claims] 1. In a winding configuration in which a single gold wire for bonding with a wire diameter of 25 to 50μ is wound onto a spool with a diameter of 2 inches (50.8φmm) at a predetermined pitch l to form a multilayer structure, the pitch l is 2 ~8mm, the outgoing winding and the returning winding intersect at a crossing angle θ of 1 degree 20 minutes to 5 degrees 15 minutes, and the nth winding on each side (n-1)
Minimum 0.1mm between the second winding and maximum (l-0.1)
Spool winding of gold wire for bonding semiconductor devices with a gap of mm.