KR101905942B1 - Bonding wire - Google Patents

Abstract

The bonding wire has good bonding properties to the Ni / Pd / Au coated electrode (a) or the Au coated electrode (a), has excellent thermal shock resistance, and is less expensive than gold bonding wire. At least one element selected from the group consisting of Pd and Au in a total amount of not less than 1.0 wt% and not more than 4.0 wt% selected from Ca, Y, La, Sm, and Ce as a bonding wire (W) And the balance of Ag and unavoidable impurities, and having a tensile strength at room temperature of 18 to 32 kgf / mm ² and a tensile strength at 250 캜 Is 14 kgf / mm ² or more. With this configuration, in the evaluation of the continuous bonding property, the thermal cycle test, the evaluation of the chip damage directly under the first bonding portion, the evaluation of the electrical resistance, the wire flow during resin sealing, and the sulfidation resistance of the wire , There is no practical problem.

Description

[0001] BONDING WIRE [0002]

The present invention relates to a nickel-palladium-gold (Ni) film on a semiconductor device in a semiconductor package such as a power IC, an LSI, a transistor, a ball grid array package (BGA), a quad flat non lead package (QFN) / Pd / Au) coated electrode or an Au coated electrode, and a conductor wire of a circuit board such as a lead frame, a ceramic board, and a printed board by a ball bonding method.

1, a package substrate 3 is provided on a wiring board 1 with a solder ball 2 therebetween, and the package substrate 3 is provided with a die A semiconductor element (chip) 5 is provided through a bonding material 4 and the semiconductor element 5 is sealed with a sealing material 6. [ Electrical connection between the electrode a of the semiconductor element 5 and the conductor wiring (terminal) c of the package substrate 3 in this semiconductor package is performed according to the ball bonding method described above.

2, the LED 13 is provided on the case heat sink 11 through the die bonding material 12, and the LED 13 is mounted on the phosphor body e (see FIG. 2) And the LED 13 is sealed with the encapsulant 14 in which the LEDs 13 are mixed. The electrical connection between the electrode a of the LED 13 and the conductor wiring (terminal) c of the case electrode 15 in this package is performed according to the ball bonding method in the same manner as the semiconductor package such as the BGA. In the figure, reference numeral 16 denotes a resin case body.

3 (a) to 3 (h) are typical, and the wire W is inserted into the capillary 10a shown in the same figure (a) The clamp 10b is opened and the capillary 10a descends toward the electrode a on the integrated circuit element from the state where the free air ball (FAB) b is formed. At this time, the ball (FAB) b is captured in the capillary 10a.

When the molten ball b contacts the target electrode a (the capillary 10a reaches the electrode a), the capillary 10a grips the molten ball b to apply heat, load, and ultrasonic waves to the molten ball b , So that the molten ball b is pressed (pressed ball b ') and solid-phase bonded to the electrode a, and a first bond is formed and bonded to the electrode a (1st joint, Fig. 3 (b)).

After the first bond is formed, the capillary 10a is lifted up to a predetermined height (Fig. (C)), and then moved to just above the conductor wiring c (Figs. At this time, in order to form a stable loop, there is a case where the capillary 10a is made to perform a special movement to put a "habit" on the wire W (refer to the solid line in the dashed line in the same drawing (d)).

The capillary 10a immediately above the conductor wire c drops toward the conductor wire c and presses the wire W onto the conductor wire (second target) c (Figs. (E) to (f)). At the same time, heat, load, and ultrasonic waves are applied to the pressed portion to deform the wire W, thereby forming a stitch bond for bonding the wire W to the conductor wiring c and a tail bond for securing the tail in the next step 2nd joint, the same drawing (f)).

After the two bonds are formed, the capillary 10a is lifted while leaving the wire W to secure a certain length of tail at the tip of the capillary 10a, and then the clamp 10b is closed And pulls the wire W from the portion of the tail bond (FIG. 7 (g)).

The capillary 10a stops when the capillary 10a rises to a required height and discharges (sparks) by applying a high voltage to the tip portion of the wire W secured at the tip of the capillary 10a with the discharge rod g, The wire W is melted with the heat, and the melted wire material becomes a melting ball b which is spherical near the surface due to the surface tension (FIG.

The above operation completes one cycle. Thereafter, the connection is made according to the ball bonding method between the electrode a and the conductor wiring c by the same operation.

As the material of the bonding wire (wire) W used in the ball bonding method, 4N (purity: 99.99 wt% or more) to 2N of gold is used. The reason why the gold balls are used in such a manner is that the shape of the gold balls b becomes an accurate sphere and that the hardness of the gold balls b formed is appropriate and that the chip 5 is not damaged by the load at the time of bonding and ultrasonic waves, Since bonding can be performed, reliability is high.

On the other hand, in a semiconductor package such as a BGA, since the gold bonding wire W is expensive, replacement with an inexpensive copper (Cu) bonding wire is also performed. In addition, a Pd surface-coated copper bonding wire has been developed which is improved in productivity by improving the second bonding property, which is a problem in copper bonding wires, by coating palladium (Pd) or the like on the surface of the copper bonding wire One). Also, silver (Ag) bonding wires have been developed and used in some cases (see Patent Documents 2, 3 and 4 below).

Japanese Patent Application Laid-Open No. 2007-123597 Japanese Unexamined Patent Publication No. 57-194232 Japanese Patent Laid-Open Publication No. 58-6948 Japanese Patent Application Laid-Open No. 11-288962

The gold bonding wire is expensive. The copper bonding wire, which is a substitute thereof, is inexpensive, but the FAB is harder than the gold bonding wire, and if the chip of the electrode a is weak, the risk of chip damage is increased. In addition, the 2nd bonding property is worse than the gold bonding wire, and there is a problem in the continuous bonding property.

The Pd surface-coated copper bonding wire has a good 2nd bonding property and a good continuous bonding property as compared with the copper bonding wire. However, since the FAB is harder than the copper bonding wire, there is a problem of chip damage.

Conventionally, an Al alloy (Al-Si-Cu, etc.) pad has been used for the electrode a of a semiconductor package such as a BGA. However, a pad having a high temperature reliability, for example, The electrode a coated with Ni / Pd / Au (nickel / palladium / gold) is being studied. In addition, it is also necessary to reduce the damage to the vulnerable chip 5.

The Pd surface-coated copper bonding wire is difficult to bond to the Ni / Pd / Au coated electrode a. When the copper bonding wire is bonded under the condition that the chip 5 is not damaged, , There is a problem that sufficient bonding can not be performed.

In the conventional LED package, the LED 13 of the electrode a coated with Au is used, and a gold bonding wire is used for connection to the electrode a. Inexpensive bonding wires are also required for the LED 13 because cost can not be reduced in the combination using this gold. However, the copper bonding wire has difficulty in continuous bonding, and since the FAB is hardened on the Pd surface-coated copper bonding wire, chip damage may occur. In addition, when the copper bonding wire or the Pd surface-coated copper bonding wire is used, since the reflectivity of the bonding wire itself is low, the wire portion becomes a shadow, and depending on the type of the LED 13, In some cases.

Further, in the conventional silver bonding wire, nitrogen (N ₂ ) gas is blown in forming the balls b, and it is generally discharged in an inert atmosphere. On the other hand, in Patent Documents 2 and 3, by adding Al (aluminum) or Mg (manganese) to Ag (silver), N ₂ It is described that a ball b having a good shape can be obtained even when discharged in air without blowing gas.

In recent years, however, in the semiconductor package of the BGA, since the electrode a is made smaller and the distance between the electrodes a is also close to each other, it is necessary to obtain a more stable spherical ball b, , Common N ₂ It is preferable to discharge gas by blowing gas. This N ₂ When the gas is blown and discharged, oxygen can be prevented from entering from the surroundings. However, when the tip of the wire melts, Al or Mg removes oxygen from the silver oxide on the wire surface to generate Al ₂ O ₃ or MgO. At this time, if Al or Mg is contained in a large amount, the Al ₂ O ₃ or MgO is generated on the surface of the ball b in large quantities, and hard Al ₂ O ₃ or MgO damages the electrode a when bonded to the electrode a there is a problem.

Likewise, Patent Document 4 discloses that Ca (calcium), Sr (strontium), Y (yttrium), La (lanthanum), Ce (cerium), Eu (europium), Be (beryllium) (Germanium), indium (indium), and tin (tin) are added. However, when these elements are added in a large amount, there is a problem that the hardness of the ball b increases and the electrode a is damaged.

Patent Document 4 discloses that Pt (platinum), Pd, Cu, Ru (ruthenium), Os (osmium), Rh (rhodium), Ir (iridium) and Au are added in order to improve the bonding reliability of the wires have. However, when a large amount of such an element is added, the electrical resistance of the wire itself increases, and the performance as the bonding wire W is deteriorated. That is, as described above, in the semiconductor package such as the BGA, the electrode a is smaller and the distance between the electrodes a is made closer to each other. Therefore, it is required to reduce the size of the first junction. For this purpose, it is necessary to reduce the diameter of the bonding wire. However, if the electrical resistance of the wire increases, there is a problem that the diameter of the wire can not be reduced. In the LED 13, the operating current is increased to raise the luminance. However, when the electrical resistance of the wire is high, there is a problem of heat generation and a defect that reduces the life of the sealing resin occurs.

In recent years, standards for evaluating the reliability of semiconductor packages have become more difficult, especially for vehicle applications, and the demand for thermal shock resistance, which is repeatedly maintained at a low temperature and a high temperature, has been increasing.

When the semiconductor package stacked using the above silver wire is subjected to a more precise heat cycle test, the wire may be broken due to the bending of the substrate or the expansion and contraction of the resin.

In addition, when the gold bonding wire and the Ni / Pd / Au covered electrode a or the Au covered electrode a are bonded to each other, a high thermal shock resistance can be obtained, but the material cost becomes high.

An object of the present invention is to provide a bonding wire which is good in bonding property to the Ni / Pd / Au coated electrode a or the Au coated electrode a under the above-described actual state, has excellent thermal shock resistance, and is cheaper than the gold bonding wire.

In order to achieve the above object, the present invention provides a bonding wire for connecting a Ni / Pd / Au covered electrode of a semiconductor element or a conductor wire of an Au coated electrode and a circuit wiring substrate by a ball bonding method, At least one element selected from the group consisting of Ca and rare earth elements in a total amount of not less than 20 ppm by weight and not more than 500 ppm by weight, inevitably consists of impurities, the tensile strength at room temperature of the wire (W) and less than 18kgf / mm ² at least 32kgf / mm ^2, preferably at most 18kgf / mm ² at least 25kgf / mm ^2, the wire 250 ℃ (furnace) from the tensile strength at a high temperature tensile test, a tensile test was conducted to 14kgf / mm ^2, more preferably at least 15kgf / mm ^2. At this time, in the high-temperature tensile test at 250 占 폚, it is preferable that the wire is heated at 250 占 폚 for 20 seconds and then at 250 占 폚.

The bonding wire mainly composed of Ag is inexpensive as compared with a bonding wire mainly composed of Au.

Incidentally, the bonding wire mainly composed of Ag has high corrosion resistance at the joint portion with the Ni / Pd / Au coated electrode or the Au coated electrode, but the joint portion with the Al electrode has low corrosion resistance.

Pd, and Au is added to obtain corrosion resistance and good electrical characteristics. If at least one element selected from Pd and Au is less than 1.0% by weight, the sulfidization resistance of the wire becomes a problem. In the presence of a substance (such as hydrogen sulfide) promoting sulfuration in the atmosphere or in the encapsulating resin, By the generation of silver sulfide, the reliability of the connection part deteriorates.

On the other hand, if an amount exceeding 4.0 wt% is added, the electrical resistance of the wire becomes too high, so that it becomes difficult to reduce the diameter of the wire.

Ca and a rare earth element are added to improve wire strength and heat resistance, but when it is less than 20 ppm by weight, the heat resistance of the wire is lowered, resulting in practical problems. In addition, if it is added in an amount exceeding 500 ppm by weight, the hardness of the ball b becomes high, and the electrode a is damaged at the time of the first bonding. Therefore, the total addition amount of at least one element selected from Ca and rare earth elements is 20 wt ppm or more and 500 wt ppm or less. More preferably, it is 20 ppm by weight or more and 100 ppm by weight or less, and if it is within this range, the heat resistance of the wire is high and the degree of damage of the electrode a at the time of the first bonding can be suppressed to be lower. Here, Ca is the most preferable because rare earth elements are difficult to obtain.

The wire diameter of the wire W is arbitrary as long as it can be used as a bonding wire, but is set to be, for example, 12 占 퐉 or more and 50.8 占 퐉 or less. If the thickness is less than 50.8 占 퐉, the molten ball b can be made smaller. If it is less than 12 占 퐉, it is difficult for the operator to penetrate the wire W into the capillary 10a before bonding, There is a fear that sufficient tension can not be applied to the wire, and loop control becomes difficult.

For example, Pd in an Ag of 99.99 wt% or more in purity, 1.0 to 4.0 wt% of at least one element selected from Au, Ca, a rare earth element selected from rare earth elements 20 to 500 ppm by weight in total of one or more kinds of elements are added, rods of the above chemical composition having a large line diameter are prepared by a continuous casting method, and the rods are sequentially passed through the dies up to a line diameter of 50.8 탆 or less, Draw wire by wire diameter. Thereafter, the wire W is subjected to a crude heat treatment (refining heat treatment).

In the crude-phase heat treatment, the wire W wound on the reel is drawn to a predetermined wire diameter, and the wire W is rewound to travel in a tubular heat treatment furnace, and is wound on a take-up reel to perform continuous heat treatment. Among the tubular heat treatment furnaces, N ₂ Gas or gas mixed with N ₂ and a trace amount of hydrogen is flowed. The furnace temperature is 350 ° C or higher and 600 ° C or lower, and the wire traveling speed is 30-90m / min. At this time, for example, when the furnace length is 50 cm and the wire traveling speed is 30 to 90 m / min, the crude heat treatment time is 0.33 to 1 second.

The "room temperature tensile strength" of the bonding wire W represents a value obtained by tensile test of a sample having a length of 100 mm at room temperature of 15 to 25 ° C and dividing the fracture load of the wire W by the cross sectional area.

The " high-temperature tensile strength " of the bonding wire W shows a value obtained by heating a sample having a length of 100 mm in a furnace at 250 DEG C, and then tensile testing in a furnace at 250 DEG C and dividing the fracture load of the wire W by the cross-

Here, if the tensile strength at room temperature is less than 18 kgf / mm < ^{2 &} gt ;, the wire strength is insufficient and a wire flow is generated in which the wire loop deforms due to the resin flowing in the resin sealing after wire bonding. On the other hand, if it exceeds 32 kgf / mm ² , the 2nd bonding property is deteriorated, which causes a machine stop. More preferably, the second bonding property is 25 kgf / mm ² or less, and stable production is possible even at a low temperature setting such as a stage temperature of 150 ° C.

In addition, the high temperature tensile strength is 14kgf / mm ² or less, a resin, only the life problems with when exposing the bag after the product to heat cycle tests occur, more preferably at 15kgf / mm ² or more. If you obtain a higher heat cycle characteristics .

The reason why the furnace temperature is 350 ° C. or more and 600 ° C. or less and the wire traveling speed is 30 to 90 m / min in the crude heat treatment is that the Pd and Au are 1.0 to 1.0 μm, The tensile strength at room temperature was 18 to 32 kgf / mm ² , and the tensile strength at high temperature was 14 kgf / mm ² or more in wire W having a chemical composition such as 4.0 wt%.

Since the present invention is mainly made of Ag as described above, the present invention can be made inexpensively as compared with a bonding wire mainly made of Au. Further, by adding an appropriate amount of Pd, Au, Ca and rare earth elements, And the bonding property with the Ni / Pd / Au covered electrode or the Au electrode can be good.

1 is a schematic view of a semiconductor package.
2 is a schematic view of an LED package.
Fig. 3 is an explanatory view of the ball bonding method, and Figs. 3 (a) to 3 (h) are views thereof.

A silver alloy having the chemical composition shown in Table 1 was cast using high purity Ag having a purity of 99.99 wt% or more (4N) to prepare a wire rod of 8 mm in diameter. The wire rod was drawn into a silver alloy wire having a predetermined final wire diameter (12 to 50 mu m phi) and subjected to continuous annealing at various heating temperatures and heating times in a nitrogen atmosphere. The crude hydrothermal treatment by the continuous annealing was conducted at a furnace length of 50 cm at a furnace temperature of 350 ° C or higher and 600 ° C or lower and a wire traveling speed of 30 to 90 m / min. In addition, quantification of chemical components was carried out by ICP-OES (high frequency inductively coupled plasma emission spectroscopy).

Each of the continuously-annealed wires W was subjected to a tensile test at a room temperature of 15 to 25 캜 to measure a tensile strength at room temperature (kgf / mm ² ). In the tensile test, a wire W having a sample length of 100 mm was drawn at a rate of 10 m / min, and a fracture load at the time of fracture was measured, and the fracture load / cross-sectional area was calculated. In Table 1, the normal temperature tensile strength is defined as " room temperature fracture load ".

For the tensile strength at 250 ° C, the wire W was heated in a furnace at 250 ° C for 20 seconds and pulled at a tensile speed of 10 m / min while maintaining the temperature at 250 ° C to measure the fracture load at break , And the fracture load / cross-sectional area was calculated. In Table 1, the tensile strength thereof is defined as " high temperature fracture load ".

The following tests were carried out on each of these examples and comparative examples.

"Evaluation Items"

For each wire W, connection was made by the ball bonding method shown in Fig. 3 with an automatic wire bonder. That is, the FAB (ball b) is formed at the tip of the wire W by the arc discharge by the discharge rod, and the FAB (ball b) is formed on the Ni / Pd / Au coated electrode a or the Au coated electrode a on the semiconductor elements And the other end of the wire was bonded to the lead terminal (conductor wiring) c (see FIGS. 1 and 2). At the time of fabricating the FAB, arc discharge was performed while flowing nitrogen (N ₂ ) gas to the tip of the wire W. An Ag-coated 42% Ni-Fe alloy was used for the lead terminal c.

Table 2 shows the continuous bonding property in the bonding sample used for evaluation, the thermal cycle test, the chip damage of the first bonding portion, the electrical resistance, the wire flow at the time of resin sealing, These evaluation methods and the like are as follows.

"Assessment Methods"

(1) "Continuous Bonding Property"

"A" when no machine stop occurred, "B" when one machine stop occurred, and "D" when two or more machine stops occurred, by performing 10,000 continuous bonding with the bonding machine. At this time, when the temperature of the stage was lowered, it was performed at two levels of 175 ° C (± 5 ° C) and 150 ° C (± 5 ° C) in that continuous bonding became difficult.

(2) "Heat cycle test"

After the bonding, the semiconductor sample with the resin encapsulation was evaluated using a commercially available thermal cycle testing apparatus. The temperature history was set to -40 ° C / 30 minutes to 125 ° C / 30 minutes as one cycle, and the test was performed for 1000 cycles. After the test, electrical measurement was carried out and conductivity was evaluated. The number of wires evaluated is 500. When the defect rate is 0, it is "A" in that the resistance against the thermal cycle is high, "B" when the defect rate is 1% or less, Quot; D "

(3) "Evaluation of Chip Damage Immediately After 1st Bonding"

The 1st junction and the electrode film were dissolved in aqua regia and cracks of the semiconductor elements 5 and 13 were observed with an optical microscope and a scanning electron microscope (SEM). "A" when 1 minute or less of small pits less than 3 ㎛ can not be seen by observing 100 joints, and "2" or more cracks of 3 탆 or more are recognized. D " when five or more cracks of 3 占 퐉 or more were recognized.

(4) "electric resistance"

The electrical resistance at room temperature was measured using a four terminal method. &Quot; A " when the average of the intrinsic resistivity of the three samples is 4.0 mu OMEGA .cm or less, and " D "

(5) " Evaluation of wire flow during resin sealing "

Wire length: A bonding sample of 5 mm was encapsulated with an epoxy resin, and then the maximum wire flow rate was measured by an X-ray non-destructive observation apparatus. Twenty measurements were made, and the ratio of the average value divided by the wire length of 5 mm was defined as the wire flow rate. When the wire flow rate is less than 7%, "A" is considered. When the wire flow rate is 7% or more, it is considered that there is a practical problem, and the evaluation is "D".

(6) "Sulfur resistance of wire"

The 5% ammonium sulphide solution in the vessel was heated to 60 DEG C, and the wire sample was allowed to stand in a vaporized environment. After 5 minutes, the surface analysis was measured by Auger spectroscopy (AES). In the Auger spectroscopy, sputtering was performed in a depth direction with Ar ions for a unit time, and the sulfur concentration was measured every time, and the thickness of the sulfided layer was measured until the concentration became 1/2 of the sulfur concentration in the outermost layer. For the conversion of thickness, a general SiO ₂ conversion was used. Here, if the thickness of the sulfided layer is 200 Å or less, "A" is considered. If the thickness exceeds 200 Å, there is a practical problem, and the evaluation is "D".

"Overall evaluation"

In each evaluation, "A" is "A", "B" is a mixture of "A" and "B", and "D" is one of "D".

When the total amount of at least one element selected from Ca, Y, Sm, La, and Ce exceeds 500 ppm by weight in Tables 1 and 2, the formation of precipitates on the FAB surface is observed from Comparative Examples 8 and 10, "Damage of the chip at the 1st joint" becomes "D" because the chip damage occurs at the joint, and "D" is set in the overall evaluation. On the other hand, when the total of these elements is less than 20% by weight, the heat resistance is lowered from Comparative Examples 5, 6, and 9, and the result is "D" in the heat cycle test and "D" in the comprehensive evaluation.

When the total of Pd and Au is less than 1.0% by weight, from Comparative Example 1, "D" in the wire sulfide resistance is more than 4.0% by weight, and in Comparative Examples 8 to 10, "D "And" D "in the overall evaluation.

In addition, when the tensile strength (room temperature fracture load) at room temperature was less than 18 kgf / mm < ^{2 &} gt ;, Comparative Examples 1, 4 and 7 gave "D" in the evaluation of wire flow during resin sealing, Respectively. On the other hand, if it exceeds 32 kgf / mm ² , the second bonding property deteriorates from Comparative Examples 8 to 10, so that the continuous bonding property becomes "D" and "D" in the comprehensive evaluation.

Further, when the tensile strength (high-temperature fracture load) in the tensile test conducted at 250 캜 was less than 14 kgf / mm ² , the resistance to thermal cycles was low in Comparative Examples 2, 3, 5, 6 and 9 , &Quot; D " in the thermal cycle test, and " D " in the overall evaluation.

On the contrary, in each of Examples 1 to 10, the total of Pd and Au is 1.0 to 4.0% by weight, the total of at least one element selected from Ca, Y, Sm, La and Ce is 20 ppm by weight or more, 500 comprising by weight ppm or less, in that the tensile strength at a tensile test to the test in a tensile strength at room temperature for ^{18 ~ 32kgf / mm 2, 250} ℃ more than 14kgf / mm ^2, a continuous bonding property, the heat cycle test, A " or " B " was obtained in evaluation of chip damage immediately under the first joint, electrical resistance, evaluation of wire flow at the time of resin sealing, and resistance to wire sulfidation, And it can be seen that there is no practical problem.

Examples 1 to 3, 5 to 7, and 9, and Comparative Examples 1 to 3 and 6, respectively, each of which contains at least one element selected from Ca, Y, Sm, La, and Ce, , 7, and 9, it becomes "A" in the evaluation of the chip damage directly under the 1st joint portion, and it can be understood that it has high reliability. In addition, if the tensile strength at room temperature for 18 ~ 25kgf / mm ^2, Examples 1, 2, 5 to 7 and Comparative Examples 2, 3, 5, "A" in the continuous bonding evaluation in from 6, 150 ℃ And it is understood that good workability at a low stage temperature can be obtained. In addition, if the tensile strength of from 15kgf / mm ² or more to 250 ℃, Examples 2, 4, 5, 7, 9, 10 and Comparative Examples 1, 7 and 8, "A" in from 10, the heat cycle test Respectively.

In view of the above, a total of at least 1.0 weight% and at most 4.0 weight% of at least one element selected from Pd and Au, at least 20 weight ppm and not more than 500 weight ppm of Ca and at least one element selected from rare- And the remainder is made of Ag and inevitable impurities. The wire W has a tensile strength at room temperature of 18 to 32 kgf / mm ² , the wire is heated in a furnace at 250 ° C for 20 seconds, A tensile strength of 14 kgf / mm < ^{2 >} or more in the tensile test of the wire, the continuous bonding property, the heat cycle test, the evaluation of the chip damage immediately under the first joint, the evaluation of the wire flow at the time of resin sealing, In the evaluation, there is no problem in practical use, and if the content of Ca and at least one element selected from the rare earth elements is 20 ppm by weight or more and 100 ppm by weight or less, Standing and to have a high reliability are the "A", if the tensile strength at room temperature for 18 ~ 25kgf / mm ^2, is the "A" in the continuous bondability evaluation at 150 ℃, which can obtain a good workability When the tensile strength at 250 DEG C is 15 kgf / mm < ^{2 >} or more, resistance to heat cycles is high.

3, 15 circuit wiring board
5 Semiconductor device
13 LEDs
W bonding wire
a electrode of a semiconductor element (LED)
b Molten ball
b 'squeeze ball
c Circuit Wiring Conductor wiring (lead terminal)

Claims (4)

Bonding for connecting the Ni / Pd / Au coated electrode (a) or the Au coated electrode (a) of the semiconductor elements 5 and 13 and the conductor wiring (c) of the circuit wiring substrates 3 and 15 according to the ball bonding method As the wire (W) for use,
Pd, and Au in a total amount of 1.0 wt% or more and 4.0 wt% or less; Ca, Y, and Ce, or two or more elements selected from the group consisting of Ca, Y, Sm, La, and Ce in a total amount of 20 ppm by weight or more and 500 ppm by weight or less ; ≪ / RTI &
The remainder being composed of Ag and inevitable impurities,
The tensile strength at the room temperature of the wire (W) is 18 to 32 kgf / mm ² , the tensile strength in the tensile test in which the wire is heated in the furnace at 250 ° C., ² or more. The method according to claim 1,
A content of at least one element selected from the group consisting of Ca, Y and Ce of the wire (W) or two or more elements selected from the group consisting of Ca, Y, Sm, La and Ce is 20 ppm by weight Or more and 100 weight ppm or less. The method according to claim 1 or 2,
Wherein the wire (W) has a tensile strength at room temperature of 18 to 25 kgf / mm ² . The method according to claim 1 or 2,
Wherein the wire (W) has a tensile strength of at least 15 kgf / mm ² at 250 캜.

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