KR20170033132A - Composition of solder alloy improving missing rate and method of manufacturing the same - Google Patents

Abstract

The present invention relates to solder alloy composition with an improved missing rate and a manufacturing method thereof. A solder ball comprises: 0 to 4.0 wt% of silver (Ag); 0.1 to 1.2 wt% of copper (Cu); 0.001 to 0.1 wt% of nickel (Ni); 0.0005 wt% or less of lead (Pb); 0.002 wt% or less of bismuth (Bi); 0.005 to 0.01 wt% of germanium (Ge); 0.002 to 0.005 wt% of phosphorus (P); and the remainder consisting of tin (Sn). Therefore, the tin-based solder ball having a 200 ppm (0.02%) or less of missing rate is provided when performing an attaching process on a printed circuit board.

Description

[0001] The present invention relates to a solder alloy composition and a method for manufacturing the solder alloy,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a solder alloy composition for improving solderability and a method for manufacturing the same.

In recent years, packages have become smaller as more and more devices such as mobile phones and electronic parts become more sophisticated and sophisticated. Particularly, in portable products, a fine pitch of a printed circuit board (PCB) and a miniaturization of a solder ball are prominent. Also, as the thickness of the PCB becomes thinner, warpage phenomenon occurs a lot. Therefore, during the reflow process, which is a process of attaching the solder ball on the printed circuit board, a phenomenon in which the solder ball does not stick on the PCB, a large amount of missing is generated, and workability is greatly reduced. Therefore, as the solder ball becomes smaller, it is necessary to improve the missing rate and the workability deterioration, which are more likely to occur at a fine pitch.

Solder balls, which transfer electrical signals by connecting a semiconductor chip and a substrate in a semiconductor packaging process, are formed of a metal alloy, which has high conductivity and is easily alloyed by a thermal process. In general, Sn-Ag-Cu alloys are used for reflow solder. Sn-Ag-Cu alloys have problems of oxidation and have problems such as wettability, heat resistance, durability strength needs to be improved.

The tin-based solder ball disclosed in the prior art (Laid-Open Publication No. 2013-0017626) is composed of Ag, Cu, Ni, Bi, Sn and unavoidable impurities. Which causes a missing ball to be generated.

Disclosure of Invention Technical Problem [8] The present invention aims to solve problems such as missing of a solder ball, deterioration in workability and reduction in durability.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the workability in the process of adhering a printed circuit board by controlling the content of impurity elements in the solder alloy.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

The present invention relates to a solder ball comprising at least one of silver (Ag), copper (Cu) and nickel (Ni) (Pb) and bismuth (Bi) are contained in an amount of not more than 5 ppm and not more than 20 ppm, and germanium (Ge) is used, And phosphorus (P), and further provides a solder ball having a missing rate of 200 ppm or less when the adhering process is performed on the printed circuit board.

Also, the germanium (Ge) is contained at 50 to 100 ppm, and the phosphorus (P) is provided at 20 to 50 ppm.

Also, when the solder ball contains both germanium (Ge) and phosphorus (P), the total content of germanium (Ge) and phosphorus (P) is 100 ppm or less.

The solder ball preferably contains 0 to 4.0 wt% of silver (Ag), 0.1 to 1.2 wt% of copper (Cu), 0 to 0.1 wt% of nickel (Ni) Lt; / RTI > solder balls.

Also, the solder ball includes 3.0 wt% of silver (Ag), 0.5 wt% of copper (Sn 3.0Ag 0.5Cu), 3.0 wt% of silver (Ag) and 0.2 wt% of copper (Sn 3.0Ag 0.2Cu), silver (Ag) of 1.2wt%, copper (Cu) of 0.5wt% and nickel (Ni) of 0.05wt% (Sn 1.2Ag 0.5Cu 0.05Ni) (Sn 1.0Ag 0.5Cu), silver (Ag) 2.5 wt% and copper (Cu) 0.5 wt% (Sn 2.5Ag 0.5Cu) or 1.0 wt% , 2.3 wt% of silver (Ag), 0.8 wt% of copper (Sn 2.3Ag 0.8Cu), 2.3 wt% of silver, 0.8 wt% of copper, (Sn 2.3Ag 0.8Cu 0.08Ni) or 4.0 wt% of silver (Ag) and 0.5 wt% of copper (Sn 4.0Ag 0.5Cu) or 0.7 wt% of copper (Cu) % (Sn 0.7Cu).

The present invention also provides a process for preparing purified tin comprising less than 1 ppm of an impurity metal containing lead (Pb) and bismuth (Bi); A second step of charging the purified tin and at least one kind of metal into a reaction furnace; And a third step of controlling the conditions including the pressure, temperature and time of the reaction furnace to produce an alloy.

In the second step, the purified tin is mixed with the purified tin in the group consisting of Ag, Cu, Ni, Pb, Bi, Ge, and P And weighing the selected at least one kind of metal at a weight ratio and charging the resultant mixture into a reaction furnace.

In the second step, when the lead (Pb) and the bismuth (Bi) are charged, the lead (Pb) is contained in an amount of 5 ppm or less and the bismuth (Bi) Wherein the solder alloy is formed on the substrate.

In the second step, when the germanium (Ge) or the phosphorus (P) is charged, the germanium (Ge) is contained in an amount of 50 to 100 ppm, and the phosphorus (P) And then charging it into the reaction furnace.

In the second step, when the germanium (Ge) and the phosphorus (P) are both charged, they are weighed in a weight ratio so that the total content of germanium (Ge) and phosphorus (P) Wherein the solder alloy is produced by a method comprising the steps of:

The third step includes a first heating step of raising the temperature of the reactor to a first temperature and then maintaining the reactor at a second temperature higher than the first temperature and a second heating step of maintaining the reactor at a second temperature higher than the first temperature, Which is a step of manufacturing a solder alloy.

The first step is a step of preparing the purified tin by vacuum refining to remove impurity metal by supplying steam of 99.9% to 99.99% purity in a vacuum furnace.

The first step is a step of passing molten tin having a purity of 99.9% to 99.99% through a filter having a thickness of 1 to 2 mm with a hole of 2 to 7 m under a pressure of 3 to 4 bar to remove impurity metal, Which is a step of preparing a solder alloy.

(Ag), 0.1 to 1.2 wt% of copper (Cu), 0 to 0.1 wt% of nickel (Ni) and 0 to 0.1 wt% of lead (Pb), which are prepared by the solder alloy manufacturing method of the present invention, (Sn) containing 0.005 wt% or less of bismuth (Bi), 0.002 wt% or less of bismuth (Bi), 0.005 to 0.01 wt% of germanium (Ge) and 0.002 to 0.005 wt% of phosphorus (P) Alloy.

A melting step of charging the solder alloy manufactured by the solder alloy manufacturing method of the present invention into a molten metal and melting the molten solder at 230 to 250 ° C; An injection step of supplying the master alloy to the molten alloy and maintaining the temperature at 250 to 280 DEG C; A heating step of induction heating the alloy into which the master alloy is introduced; And a ball forming step of passing the induction heated alloy through an orifice hole.

According to the present invention, it is possible to control the content of a specific impurity metal by injecting an impurity metal through a solder alloy manufacturing process after purifying the impurity metal content in the tin to 1 ppm or less, (Reduced) solder balls can be provided, and overall workability such as a process of adhering a printed circuit board can be improved.

1 is a flowchart of a tin refining method through vacuum refining according to the present invention.
Fig. 2 is a view showing the preparation of tin to be applied to the present invention. Fig.
3 is a view showing an example of a vacuum furnace applicable to the present invention.
4 is a diagram showing the structure of a filter device used for filtering annotations.
Figure 5 is a perspective view of a filter used to filter annotations.
6 is a top plan view of the filter used to filter the tin.
Figure 7 is a cross-sectional view of a filter used to filter annotations.
8 is an oxide film analysis graph of an alloy made using a filtering tin according to an embodiment of the present invention.

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is defined solely by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise stated.

Throughout this specification and claims, the word "comprise", "comprises", "comprising" means including a stated article, step or group of articles, and steps, , Step, or group of objects, or a group of steps.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. Any feature that is specifically or advantageously indicated as being advantageous may be combined with any other feature or feature that is indicated as being preferred or advantageous. Hereinafter, embodiments of the present invention and effects thereof will be described with reference to the accompanying drawings.

<Method of manufacturing solder alloy for sewing>

Sewing improved solder alloys according to one embodiment of the present invention are made using refined tin. The purified tin uses tin having a concentration of impurities including Pb and Bi remaining in the tin of less than 1 ppm. Tablet tin may be refined through vacuum refining, or refined tin may be used through filtration.

In more detail, a method of manufacturing a solder alloy according to an embodiment of the present invention includes a first step (S100) of preparing tabular tin, a second step (S200) of charging tabular tin and at least one kind of metal into a reaction furnace, And a third step (S300) of preparing an alloy by adjusting reaction conditions including pressure, temperature and time of the reaction furnace.

In a first step S100 according to an embodiment of the present invention, 3N (99.9%) or 4N (99.99%) tin is refined through vacuum refining or purified through filtration have. A method of refining tin through vacuum refining and a method of refining tin through filtering will be described later.

The first step S100 is a step of preparing refined tin containing less than 1 ppm of an impurity metal including lead (Pb) and bismuth (Bi).

The second step S200 according to an embodiment of the present invention is a step of charging the purified tin and at least one kind of metal into the reaction furnace. The purified tin prepared through the first step S100, the silver (Ag) At least one or more kinds selected from the group consisting of copper (Cu), nickel (Ni), lead (Pb), bismuth (Bi), germanium (Ge), phosphorus (P), iron (Fe) and antimony And the metal is weighed at a weight ratio and charged into the reactor.

The reaction furnace is preferably a high frequency vacuum induction furnace. In the case of producing an alloy in a high-frequency vacuum induction furnace, the unnecessary reaction of tin to form tin oxide (SnO ₂ ) by reacting with oxygen is suppressed, so that the content of other elements is less changed and the segregation rate can be reduced. Further, the agitating force due to the electrical vortex in the high-frequency vacuum induction furnace is superior to the mechanical agitating force of the conventional method using the electric furnace, and work is performed in an inert atmosphere instead of working in the atmosphere.

In the case where silver (Ag), copper (Cu) and nickel (Ni) are charged in the second step (S200), 0 to 4.0 wt% of silver (Ag) By weight, and 0 to 0.1% by weight of nickel (Ni). It is necessary to separately charge silver (Ag), copper (Cu) and nickel (Ni) in the second step in the case where tabular tin contains silver (Ag), copper (Cu) and nickel none.

Preferably 3.0 wt% of silver (Ag) and 0.5 wt% of copper (Sn 3.0Ag 0.5Cu) or 3.0 wt% of silver (Ag) and 0.2 wt% of copper (Sn) 3.0Ag 0.2Cu), or silver (Ag) of 1.2wt%, copper (Cu) of 0.5wt% and nickel (Ni) of 0.05wt% (Sn 1.2Ag 0.5Cu 0.05Ni) (Sn 1.0Ag 0.5Cu), silver (Ag) 2.5 wt%, copper (Cu) 0.5 wt% (Sn 2.5Ag 0.5Cu), or silver (Ag) of 2.3 wt%, copper (Cu) of 0.8 wt% (Sn 2.3Ag 0.8Cu), silver (Ag) of 2.3 wt%, copper (Cu) of 0.8 wt%, nickel (Sn 2.3Ag 0.8Cu 0.08Ni) or 4.0 wt% of silver (Ag), 0.5 wt% of copper (Sn 4.0Ag 0.5Cu) or 0.7 wt% of copper (Cu) (Sn 0.7 Cu).

When lead (Pb) and bismuth (Bi) are charged for improving the missing rate, lead (Pb) is contained in an amount of not more than 5 ppm and bismuth (Bi) is not more than 20 ppm And weighing them in a weight ratio so as to be charged into the reactor. (Pb) and bismuth (Bi) contained in the solder alloy are separately charged in the second step by using purified tin in which lead (Pb) and bismuth (Bi) Bi) can be controlled and controlled.

In addition, when at least one of germanium (Ge) or phosphorus (P) is charged for the prevention of oxidation as well as improvement of the missing rate, germanium (Ge) is contained in an amount of 50 to 100 ppm And weighing the mixture in a weight ratio so that the mixture is charged into a reactor and phosphorus (P) is weighed at a weight ratio of 20 to 50 ppm and charged into the reactor.

When the content of germanium (Ge) is less than 50 ppm or when the content of phosphorus (P) is less than 20 ppm, the solder ball is discolored to yellow to interfere with soldering, thereby increasing the sewing rate. When the content of P exceeds 100 ppm or the content of phosphorus (P) is added in excess of 50 ppm, the thickness of Ge-O oxide and P ₂ O ₅ oxide increases, thereby interfering with soldering, You can see in the example.

In addition, when iron (Fe) and antimony (Sb) are charged, they can be weighed in a weight ratio so that iron (Fe) and antimony (Sb) It was confirmed that the contents of iron (Fe) and antimony (Sb) did not affect the improvement of the machining rate of the solder balls.

In a third step S300 according to an embodiment of the present invention, the reaction conditions including the pressure, temperature, and time of the reactor are adjusted to produce an alloy. For example, the third step S300 includes a first temperature raising step of raising and maintaining the reactor to a first temperature and a second raising temperature step of raising and maintaining the reactor to a second temperature higher than the first temperature To produce an alloy.

In the third step S300, the reactor is maintained at a degree of vacuum of 2.0 × 10 ^-2 torr to 6.0 × 10 ^-2 torr for 10 to 20 minutes before the first heating step, purging the reactor with an inert gas, And a pre-treatment step of holding the atmosphere for 10 to 20 minutes. When the degree of vacuum is lowered to 10 ^-1 torr, oxygen reacts with tin to form a large amount of tin oxide, so that the degree of vacuum is preferable. Through purging, the alloy in the reaction chamber is neutralized with an inert gas which does not cause a chemical or physical reaction And the purging pressure is preferably 750 to 760 torr.

The first temperature of the first heating step is 700 to 800 캜, and the temperature is raised for 10 to 20 minutes until the first temperature is reached, and is maintained for 10 to 20 minutes when the first temperature is reached.

The second temperature of the second heating step is 1000 to 1100 DEG C, and the temperature is raised for 10 to 20 minutes until the second temperature is reached, and is held for 60 to 70 minutes when the second temperature is reached. The reason why the holding time is from 60 minutes to 70 minutes is to homogenize alloy elements having different specific gravity such as Ag, Cu, Ni, Pb, Bi, Fe, and Sb.

The solder alloy according to the present invention is characterized in that it contains 0 to 4.0 wt% of silver (Ag), 0.1 to 1.2 wt% of copper (Cu), 0 to 0.1 wt% of nickel (Ni), 0.0005 wt% of lead (Pb) The solder alloy containing 0.002 wt% or less of bismuth (Bi) and containing the remainder tin (Sn) can be produced. When at least one of germanium (Ge) and phosphorus (P) is contained, germanium (Ge) is contained in an amount of 0.005 to 0.01 wt% and phosphorus (P) is contained in an amount of 0.002 to 0.005 wt%. Also, when both germanium (Ge) and phosphorus (P) are included, the total content of germanium (Ge) and phosphorus (P) is not more than 100 ppm.

More preferably, 3.0 wt% of silver (Ag) and 0.5 wt% of copper (Sn 3.0Ag 0.5Cu) or 3.0 wt% of silver (Ag) and 0.2 wt% of copper (Cu) Sn 3.0Ag 0.2Cu), or silver (Ag) of 1.2wt%, copper (Cu) of 0.5wt% and nickel (Ni) of 0.05wt% (Sn 1.2Ag 0.5Cu 0.05Ni) (Sn 1.0Ag 0.5Cu), silver (Ag) 2.5 wt% and copper (Cu) 0.5 wt% (Sn 2.5Ag 0.5Cu) or 1.0 wt% (Ag) of 2.3 wt%, copper (Cu) of 0.8 wt% (Sn 2.3Ag 0.8Cu), silver (Ag) of 2.3 wt%, copper (Cu) of 0.8 wt%, nickel (Sn 2.3Ag 0.8Cu 0.08Ni) or 4.0 wt% of silver (Ag) and 0.5 wt% of copper (Sn 4.0Ag 0.5Cu) or 0.7 wt% of copper (Cu) (Sn 0.7Cu), the tin-based solder alloy containing lead (Pb) in an amount of 0.0005 wt% or less and bismuth (Bi) in an amount of 0.002 wt% or less.

<Manufacturing Method of Solder Ball Using Solder Alloy>

A method of manufacturing a solder ball according to an embodiment of the present invention includes a fourth step S400 of charging a solder alloy manufactured by a solder alloy manufacturing method and melting the solder alloy, (S500) of maintaining the master alloy, a sixth step (S600) of induction heating the alloy to which the master alloy is introduced, and a seventh step (S700) of passing the alloy through the orifice hole.

In a fourth step (S400) according to an embodiment of the present invention, the manufactured solder alloy is charged into a molten metal and melted at 230 to 250 ° C.

In a fifth step S500 according to an embodiment of the present invention, the master alloy is introduced into the molten alloy and the temperature is maintained at 250 to 280 ° C. The reason for injecting the master alloy in the fifth step S500 is that an alloy (Sn-Ge master alloy) containing a large amount of the additive element (Sn) is made separately as a melting agent and added to a molten metal as a base of the alloy to be diluted As a method, it is intended to uniformly add a predetermined amount of an alloying element to be added when preparing a desired alloy. Since the melting point (938 DEG C) of Ge alone is high, the melting point can be lowered by producing the master alloy. The master alloy includes tin (Sn) and germanium (Ge), preferably, but not limited to, 0.1 to 5 parts by weight of germanium relative to 100 parts by weight of tin.

The sixth step S600 according to an embodiment of the present invention is a step of induction heating the alloy into which the master alloy is introduced. The sixth step S600 is a method of converting electrical energy into thermal energy by electromagnetic induction and using the Joule's heat generated when a secondary current induced by electromagnetic induction flows into the material to be heated. In this case, the material to be heated is an alloy produced through the fifth step.

In a seventh step S700 according to an embodiment of the present invention, an induction-heated alloy is passed through an orifice hole to form a solder ball. The size of the solder ball formed in the seventh step (S700) can be controlled by the frequency and the pressure. A solder ball having an average diameter of 100 to 500 mu m is manufactured at an orifice hole having a diameter of 70 to 120 mu m at a frequency of 7 to 15 KHz and a pressure of 1000 to 2000 mbar.

The method of manufacturing a solder ball according to the present invention is characterized in that it comprises the steps of: 0 to 4.0 wt% of silver, 0.1 to 1.2 wt% of copper, 0 to 0.1 wt% of nickel, and 0.0005 wt% of lead And 0.002 wt% or less of bismuth (Bi), and having an average particle size of 100 to 500 탆 including tin (Sn) as the remainder. It is also possible to produce a solder ball containing at least one of germanium (Ge) and phosphorus (P). When germanium (Ge) is included, 0.005 to 0.01 wt% 0.005 wt%, and when both germanium (Ge) and phosphorus (P) are included, a solder ball having a total content of 0.01 wt% or less can be produced while satisfying the content within the above range.

That is, the solder ball of the present invention is a solder ball comprising at least one of silver (Ag), copper (Cu), and nickel (Ni) (Pb) and bismuth (Bi) content by using refined tin to 1ppm or less.

In addition, the solder ball according to the present invention includes lead (Pb) of 5 ppm or less and bismuth (Bi) of 20 ppm or less and is solder ball having a missing rate of 200 ppm (0.02% Increase in the number of times of rework, and cost reduction effect.

Further, the solder ball further includes germanium (Ge) and phosphorus (P), as the case may be, to provide a solder ball having an excellent machining rate improvement and oxidation prevention effect.

&Lt; Preparation of Tablet Tin >

(1) Purification of tin by vacuum refining

A method (S110) for purifying tin through vacuum refining according to an embodiment of the present invention is a method for removing impurities such as lead and bismuth from tin by using a difference in vapor pressure of elements. Can be removed to ppb levels below the ppm level.

A method (S110) for purifying tin through vacuum refining according to an embodiment of the present invention is to remove impurity metal by supplying high-temperature steam in a vacuum furnace to tin having a purity of 99.9% to 99.99%.

More specifically, a step of preparing general tin containing an impurity metal (S1101), a step of storing the prepared tin in a crucible and putting it in a vacuum furnace (S1105), and a step of vaporizing the vapor in the vacuum furnace, (S1106). &Lt; / RTI &gt;

Preferably, the step of washing the prepared tin through hydrochloric acid (S1102) as a pretreatment step between steps (S1101) and (S1105), washing the washed tin through any one of acetone, ethanol and distilled water And then drying (S1103).

More preferably, the method further includes a step (S1104) of washing the crucible, which is provided inside the vacuum furnace and accommodates tin, with hydrochloric acid and then drying the crucible.

Further, after the step S1106, the step (S1107) of cooling the tin in which the impurities have been removed by cooling the vacuum furnace (S1107), and the step (S1108) of removing the contaminant particles further by washing the tin with the nitrogen gas .

It is preferable that the annotations in step S1101 are prepared in the form of a granule through granulation, a thin plate through rolling, or a wide plate through casting so as to obtain a large surface area relative to the volume. The tin is preferably a tin-based alloy containing silver or copper.

FIG. 1 is a flowchart showing a method of refining tin by vacuum refining according to the present invention. FIG. 2 is a view showing a preparation of tin used in the present invention, and FIG. As shown in FIG.

As shown in FIGS. 1 and 2, in the tin refining method through vacuum refining according to an embodiment of the present invention, a raw material tin 201 having a purity of 99.9% to 99.99% is first prepared (S1101). At this time, the tin (201) is made into a granular form through a granulation method to obtain a large surface area relative to a volume, a thin plate is formed through rolling, or a large plate is formed through casting. In this specification, tin, which is a raw material of the solder, is exemplified. However, the tin may contain, for example, 1.0 to 3.0 wt% (Wt%) of Ag or 0.4 to 0.8 wt% (Wt%) may be used.

Next, as a pretreatment step, the tin 201 prepared in the step (S1101) is immersed in a washing tank containing dilute hydrochloric acid solution (7 to 12%) (S1102).

The washed tin 201 is then immersed and washed in a washing tank containing acetone (205 or ethanol) or distilled water (207) through step (S1102), and then the washed tin (201) And dried (S1103).

3, the crucible 310, which is provided inside the vacuum furnace 300 and accommodates the tin 201, is washed with hydrochloric acid and dried with nitrogen gas (S1104). At this time, the crucible 310 may be a container made of quartz or alumina plate. Among them, it is preferable to use a container made of a high-purity quartz plate to prevent impurities from being mixed into the tin.

Here, the vacuum furnace 300 can use a vacuum furnace generally known in the art, or an electric furnace in a box shape or other types, as long as it can remove impurities such as lead and bismuth from tin. As shown in FIG. 3, the vacuum furnace 300 according to one embodiment of the present invention includes graphite inner walls 303 formed on inner and lower surfaces of a U-shaped support frame 301 A vacuum outlet 305 is formed through a part of the bottom surface of the graphite inner wall 303 and the bottom surface of the support frame 301 and a plurality And a crucible 310 mounted on an upper portion of the supporter 307 to receive the tin 201. The upper end of the crucible 310 is connected to a water inlet A diffusion pump 312 which is a vacuum pump that sprays or diffuses steam at a high speed in order to obtain a high vacuum, and a diffusion pump 312 that facilitates obtaining a vacuum, And a rotary pump 314 that performs a rotary motion. A pressure gauge 316 for measuring the internal pressure of the vacuum furnace and a thermocouple 318 for measuring the internal temperature of the vacuum furnace are provided inside the vacuum furnace 300. The temperature of the inside of the vacuum furnace 300 , A controller (not shown) for setting the pressure and the time.

After the pre-processing of steps S1102 to S1104, the tin 201 is mounted on the crucible 310 and placed in the vacuum furnace 300 (S1105).

Next, impurities such as lead, bismuth, antimony, and arsenic are removed from the tin in the vacuum furnace 300 (S1106) according to predetermined conditions of temperature, pressure, and time.

That is, the tin refining method through vacuum refining according to the present invention can separate impurities such as lead, bismuth and antimony from tin through distillation at the same temperature.

Specifically, tin has a low melting point and a high boiling point, and the impurities such as lead, bismuth, and antimony contained in the tin have a low boiling point and a high vapor pressure at the same temperature as tin, It is possible to remove the impurities having.

Subsequently, after the step S1106, the vacuum furnace 300 is cooled to remove the vacuum-refined tin, and the tin from which the impurities have been removed is cooled (S1107).

After removing the impurities from the vacuum furnace 300, the tin is washed with nitrogen gas to remove carbon and other contaminant particles (S1108).

(2) Purification of tin by filtering

A method (S120) for purifying tin by filtering according to an embodiment of the present invention comprises filtering a molten tin having a purity of 99.9% to 99.99% with a 1 to 2 mm thick filter having a hole of 2 to 7 탆 at a pressure of 3 to 4 bar It is possible to remove the impurity metal by 1 ppm or less as a method of removing the impurity metal by passing the impurity metal.

More specifically, the step of melting the tin at a purity of from 99.9% to 99.99% at 250 to 350 ° C (S1201), passing the molten tin through a filter device having a filter of 2 to 7 μm holes at a pressure of 3 to 4 bar, And purification step S1202.

Since the melting point of tin is 232 deg. C at the step (S1201), the melting operation is not smooth at 250 deg. C or lower, and the filtering effect is insufficient because the oxidation of tin due to high temperature is high at 350 deg. Preferably, the tin is melted at 290 to 310 占 폚.

The filter unit used in step S1202 has the structure as shown in FIG. 4 and includes an injection unit 21 into which molten tin is injected, an outflow unit 22 through which the filtered tin flows out, a filter 10, a spring 30 And a main body 40 surrounding the main body 40. The molten tin is injected through the injection part 21 under a pressure of 3 to 4 bar, and through the cylindrical filter 10, impure molten tin is obtained through the outflow part 22.

The filter 10 has a cylindrical structure with a height of 2 cm and a thickness of 1 to 2 mm as shown in the perspective view of FIG. 5 and the plan view of FIG. 6, with the lower end closed, as shown in the cross-sectional perspective view of FIG.

The material of the filter is ferritic stainless steel or austenitic stainless steel. The stainless steel may further include at least one of molybdenum, nickel, and chromium. For example, when molybdenum is contained in an amount of 6% or less, it has an effect of being able to withstand cracks and stress, and when it contains 13% or more of chromium, it has an effect of giving high oxidation resistance. When the content of nickel is less than 10%, it has an effect of maintaining the austenite structure from the melting point to the low temperature. The size of the filter hole is 2 to 7 μm, and when it is less than 2 μm, the workability is deteriorated.

Also, if the pressure is less than 3 bar and greater than 4 bar, there is no filtering effect.

After the tin filtering, impurities such as Pb, Fe, Bi, Al, Zn are removed and the concentration of each impurity becomes 1 ppm or less. As shown in FIG. 8, the filtered tin has a lower concentration of oxygen than that of unfiltered tin and has a relatively high concentration of Sn, Ag, Cu and the like, and minimizes the Mushy region. When the liquid phase changes to a solid phase, the liquid phase and the solid phase are simultaneously present. When the liquid phase changes into a solid phase, impurities such as Pb and Fe are present, and the respective elements exist as one phase. By creating sites and increasing the time to solidify, the machine area will increase. When the solder balls are bonded, a fast reaction must occur. In the case where the machice area is large, the reaction time is long and the bonding reaction is slowed, so that the machice area should be minimized.

&Lt; Examples and Experimental Examples >

(1) Evaluation of sewing rate

The solder ball's machining rate evaluation method was calculated as follows.

The rate at which missing was generated as a whole was calculated by dividing the number of missed bumps by the number of bumps and units multiplied by the number of bumps present per unit.

The Missing rate was evaluated by using a solder ball of size 250um according to the embodiment of the present invention. The printed circuit board (PCB) having SR open of 0.23 mm, pitch of 0.4 mm, ) &Lt; / RTI &gt; The size of the solder balls was 250 μm.

1) Evaluation of sewing rate according to impurity content (1st evaluation)

Sewing ratio evaluation was performed according to the Pb, Bi, Fe, and Sb contents of the solder balls prepared according to the present invention. According to the solder alloy manufacturing method of the present invention, the solder alloy was prepared by adjusting the Pb content to 300 ppm, the Bi content to 50 ppm, the Fe content to 200 ppm, and the Sb to 20 ppm. The solder alloy according to the present invention , And the results are shown in Table 1. &lt; tb &gt; &lt; TABLE &gt;

Pb (ppm) Bi (ppm) Fe (ppm) Sb (ppm) Missing rate (ppm) 1-1 300 0 0 0 3200 1-2 0 0 0 20 100 1-3 0 0 30 20 150 1-4 300 0 0 20 3250 1-5 300 50 0 20 3800 1-6 0 50 0 20 1350 1-7 300 50 30 20 4000 1-8 300 0 30 20 3400 1-9 300 50 30 0 3700 1-10 0 50 30 20 1500 1-11 0 50 30 0 1450 1-12 0 0 0 0 0 1-13 300 0 30 0 3200 1-14 300 50 0 0 3900 1-15 0 50 0 0 1300 1-16 0 0 30 0 100

As a result of the first evaluation, it can be understood that the greatest factors influencing the sewing rate are Pb and Bi, and Fe and Sb have no great influence on the sewing rate. Based on the results of the first evaluation, the relation between the sewing rate and the Pb and Bi contents can be expressed by a regression equation as shown in the following equation (1).

[Formula 1]

(Bi-25) / 25 * 251 + (Pb-150) / 150 * (Bi-25) / 25 * -181.25

2) Evaluation of sewing rate according to impurity content (secondary evaluation)

Sewing ratio evaluation was performed according to the Pb and Bi contents of the solder balls prepared by the present invention. According to the solder alloy manufacturing method according to the present invention, the Pb content is controlled to 0 to 300 ppm and the Bi content to 0 to 50 ppm to prepare a solder alloy. According to the solder ball manufacturing method according to the present invention, The results are shown in Table 2.

Pb (ppm) Bi (ppm) Missing rate (ppm) 2-1 300 50 3900 2-2 300 0 3200 2-3 0 50 1300 2-4 200 0 2400 2-5 100 0 1200 2-6 50 0 600 2-7 30 0 450 2-8 20 0 300 2-9 10 0 220 2-10 0 40 800 2-11 0 30 400 2-12 5 0 130 2-13 2 0 50 2-14 0 20 120 2-15 0 10 80 2-16 0 5 30 2-17 5 20 180 2-18 2 5 85

As a result of the secondary evaluation, it can be seen that solder balls (2-12 to 2-18) prepared to contain not more than 5 ppm of Pb and not more than 20 ppm of Bi are suitable for controlling the process at a sewing rate of 200 ppm or less.

3) Evaluation of sewing rate according to impurity content (third evaluation)

The machining rate was evaluated according to the Ge and P contents of the solder balls manufactured by the present invention. According to the solder alloy manufacturing method of the present invention, the solder alloy was prepared by setting the Pb content to 5 ppm, the Bi content to 20 ppm, the Ge content to 30 to 150 ppm, and the P content to 10 to 80 ppm, The solder balls were manufactured according to the method of manufacturing the solder balls according to the present invention, and the solder balls were evaluated. The results are shown in Table 3.

Composition Pb (ppm) Bi (ppm) Ge (ppm) P (ppm) Missing rate (ppm) 3-1 SAC302 5 20 30 0 500 3-2 SAC302 5 20 50 0 180 3-3 SAC302 5 20 80 0 175 3-4 SAC302 5 20 100 0 180 3-5 SAC302 5 20 150 0 800 3-6 SAC302 5 20 0 10 600 3-7 SAC302 5 20 0 20 180 3-8 SAC302 5 20 0 50 190 3-9 SAC302 5 20 0 80 1200 3-10 SAC302 5 20 80 20 185 3-11 SAC302 5 20 100 20 350 3-12 SAC302 5 20 100 40 750 3-13 SAC302 5 20 80 50 500 3-14 SAC305 5 20 80 180 3-15 SAC105 5 20 80 185 3-16 SAC405 5 20 80 170 3-17 SAC2505 5 20 80 175 3-18 SAC205 5 20 30 180 3-19 SAC1205Ni 5 20 30 185 3-20 Sn 0.7 Cu 5 20 30 190

In order to manage the process with a sewing rate of 200 ppm or less as a result of the third evaluation, solder balls (3-2 to 3-4, 3-14 to 3-17) prepared to be contained in 50 to 100 ppm in the case of Ge, The solder balls 3-7 to 3-8, 3-18 to 3-20, which are prepared so as to be contained at 50 ppm, are suitable. In addition, when both Ge and P are included, it is understood that the solder balls (3-11 to 3-13) manufactured to contain 100 ppm or more of the solder ball (3-10) have.

4) Evaluation of the sewing rate according to the solder ball size

The machining rate was evaluated according to the size of the solder ball manufactured by the present invention. According to the method of manufacturing the solder alloy according to the present invention, the solder alloy was prepared by adjusting the Pb content to 5 ppm and the Bi content to 20 ppm. According to the solder ball manufacturing method according to the present invention, various sizes of solder balls were manufactured , And the results are shown in Table 4.

Ball size
(um) Pb (ppm) Bi (ppm) Missing rate
(ppm) 4-1 250 5 20 180 4-2 300 5 20 180 4-3 400 5 20 185 4-4 500 5 20 250 4-5 600 5 20 400 4-6 200 5 20 160 4-7 150 5 20 140 4-8 100 5 20 130

As a result, the Pb and Bi contents were controlled to 5 ppm and 20 ppm, respectively, and the soldering ball size was less than 500 袖 m.

5) Evaluation of sewing rate according to composition of tin, etc.

Evaluation of the unsuccess rate of the solder balls according to the present invention was carried out according to the compositions of tin and the like. According to the method for manufacturing a solder alloy according to the present invention, a composition of various tin, a Pb content, and a Bi content were adjusted to 5 ppm and 20 ppm, respectively, to prepare a solder alloy. Solder balls with various SAC compositions were prepared to evaluate the unsuccess rate. The results are shown in Table 4.

Composition Sn Ag
(wt%) Cu
(wt%) Ni
(wt%) Pb
(ppm) Bi
(ppm) Missing rate (ppm) 5-1 SAC302 remain 3.0 0.2 5 20 180 5-2 SAC305 remain 3.0 0.5 5 20 180 5-3 SAC105 remain 1.0 0.5 5 20 185 5-4 SAC405 remain 4.0 0.5 5 20 170 5-5 SAC2505 remain 2.5 0.5 5 20 175 5-6 SAC205 remain 2.0 0.5 5 20 180 5-7 SAC2308 remain 2.3 0.8 5 20 180 5-8 SAC2308Ni remain 2.3 0.8 0.08 5 20 185 5-9 SAC1205Ni remain 1.2 0.5 0.05 5 20 185 5-10 Sn 0.7 Cu remain 0.7 5 20 190

As a result of the evaluation, when the content of Pb and Bi is controlled to 5 ppm or less and 20 ppm or less, it is understood that the sewing rate is 200 ppm or less irrespective of the composition of SAC within the above range.

6) Evaluation of sewing rate according to PCB surface treatment

Using the solder balls manufactured according to the present invention, the machining rate was evaluated according to the surface treatment of the PCB. As shown in Table 6, the solder balls prepared by controlling the surface-treated PCB pads, Pb content to 5 ppm and Bi content to 20 ppm were evaluated and the results are shown in Table 5.

Pad finish Pb (ppm) Bi (ppm) Missing rate (ppm) 6-1 NiAu 5 20 180 6-2 Cu-OSP 5 20 175 6-3 ENIG 5 20 185 6-4 ENEPIG 5 20 180 6-5 Immersion Tin 5 20 190

As a result of the evaluation, when the contents of Pb and Bi are adjusted to 5 ppm and 20 ppm or less, respectively, it can be understood that the sewing rate is less than 200 ppm irrespective of the surface treatment of the PCB pad.

The features, structures, effects, and the like illustrated in the above-described embodiments can be combined and modified in other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

Claims (15)

Wherein the solder ball comprises at least one selected from the group consisting of silver (Ag), copper (Cu), and nickel (Ni)
The solder ball is prepared by adjusting the content of lead (Pb) and bismuth (Bi) using purified tin purified to 1 ppm or less of lead (Pb) and bismuth (Bi)
The solder ball contains lead (Pb) in an amount of 5 ppm or less and bismuth (Bi) in an amount of 20 ppm or less,
The solder ball further includes at least one selected from the group consisting of germanium (Ge) and phosphorus (P)
Wherein the solder ball has a missing rate of 200 ppm or less when the solder ball is attached to the printed circuit board.
The method according to claim 1,
The germanium (Ge) is contained in an amount of 50 to 100 ppm,
Wherein the phosphorus (P) is contained in an amount of 20 to 50 ppm.
3. The method of claim 2,
When the solder ball contains both germanium (Ge) and phosphorus (P)
Wherein the total content of germanium (Ge) and phosphorus (P) is 100 ppm or less.
The method according to claim 1,
The solder ball,
0 to 4.0 wt% of silver (Ag)
0.1 to 1.2 wt% of copper (Cu)
0 to 0.1 wt% of nickel (Ni)
A solder ball having an average particle diameter of 100 to 500 mu m.
5. The method of claim 4,
The solder ball,
3.0 wt% of silver (Ag), 0.5 wt% of copper (Cu)
3.0 wt% of silver (Ag) and 0.2 wt% of copper (Cu)
, Silver (Ag) in an amount of 1.2 wt%, copper (Cu) in an amount of 0.5 wt%, and nickel (Ni) in an amount of 0.05 wt%
1.0 wt% of silver (Ag) and 0.5 wt% of copper (Cu)
2.5 wt% of silver (Ag) and 0.5 wt% of copper (Cu)
, Silver (Ag) in an amount of 2.3 wt% and copper (Cu) in an amount of 0.8 wt%
, Silver (Ag) in an amount of 2.3 wt%, copper (Cu) in an amount of 0.8 wt%, and nickel (Ni) in an amount of 0.08 wt%
4.0 wt% of silver (Ag) and 0.5 wt% of copper (Cu)
Solder balls containing 0.7 wt% of copper (Cu).
A first step of preparing tabular tin containing less than 1 ppm of an impurity metal containing lead (Pb) and bismuth (Bi);
A second step of charging the purified tin and at least one kind of metal into a reaction furnace; And
And a third step of controlling the conditions including the pressure, temperature and time of the reactor to produce an alloy.
The method according to claim 6,
The second step may be selected from the group consisting of silver tin and silver (Ag), copper (Cu), nickel (Ni), lead (Pb), bismuth (Bi), germanium (Ge) And at least one kind of metal is weighed at a weight ratio and charged into a reactor.
8. The method of claim 7,
In the second step, when the lead (Pb) and the bismuth (Bi) are charged,
Wherein the lead (Pb) is contained in an amount of not more than 5 ppm and the bismuth (Bi) is weighed in a weight ratio so as to be not more than 20 ppm.
8. The method of claim 7,
In the second step, when the germanium (Ge) or phosphorus (P) is charged,
The germanium (Ge) is contained in an amount of 50 to 100 ppm,
Wherein the phosphorus (P) is weighed at a weight ratio of 20 to 50 ppm and charged into the reactor.
10. The method of claim 9,
If the germanium (Ge) and phosphorus (P) are all charged,
And weighing the germanium (Ge) and phosphorus (P) in a weight ratio so that the total content of the germanium (Ge) and phosphorus (P) is 100 ppm or less.
11. The method of claim 10,
The third step includes a first heating step of raising the temperature of the reactor to a first temperature and then maintaining the reactor at a second temperature higher than the first temperature and a second heating step of maintaining the reactor at a second temperature higher than the first temperature, A method of manufacturing a solder alloy.
The method according to claim 6,
Wherein the first step is to prepare the purified tin through vacuum refining to remove impurity metal from the tin in a vacuum furnace in a purity of 99.9% to 99.99%.
The method according to claim 6,
The first step is to pass the refined tin through filtration to remove impurity metal by passing molten tin having a purity of 99.9% to 99.99% through a 1 to 2 mm thick filter having a 2 to 7 탆 pore under a pressure of 3 to 4 bar Preparing a solder alloy.
A solder alloy manufacturing method according to claim 7,
0 to 4.0 wt% of silver (Ag)
0.1 to 1.2 wt% of copper (Cu)
0 to 0.1 wt% nickel (Ni)
The lead (Pb) is 0.0005 wt% or less,
0.002 wt% or less of bismuth (Bi)
Germanium (Ge) in an amount of 0.005 to 0.01 wt%
0.002 to 0.005 wt% of phosphorus (P)
A solder alloy comprising tin (Sn) in the remainder.
A melting step of charging the solder alloy produced by the solder alloy manufacturing method of claim 6 into a molten metal and melting the molten solder at 230 to 250 ° C;
An injection step of supplying the master alloy to the molten alloy and maintaining the temperature at 250 to 280 DEG C;
A heating step of induction heating the alloy into which the master alloy is introduced; And
And a ball forming step of passing the induction-heated alloy through an orifice hole.

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