WO2017192003A1 - Solder ball, manufacturing method therefor, and electronic parts using same - Google Patents

Abstract

A solder ball, a manufacturing method therefor, and electronic parts comprising the same are disclosed in the present specification. More specifically, disclosed is a solder ball which is applicable in all technical fields which are based on solder ball bonding, and especially may be used in semiconductor packages using solder balls as basic contacts in the electronics industry. The solder ball maintains the shape of a core comprising a metal having a low melting point even during reflow, and has stable bonding reliability with a substrate.

Description

Solder ball, manufacturing method thereof and electronic component using the same

Disclosed herein is a solder ball used in a semiconductor package, a method of manufacturing the same, and an electronic component including the same. More specifically, a solder ball is disclosed that can be applied to all technical fields based on solder ball bonding, and that can be used in semiconductor packages based on connection of solder balls in the electronic industry.

Recently, the package used for semiconductor chips is getting smaller due to the lighter and shorter and higher functionality of electronic devices such as mobile phones and electronic components, and the next-generation high-density package is a chip size package as the mounting density increases. A ball grid array implementation is used. In addition, packages are being stacked in order to process more information, and accordingly, the weight of the chip is increasing.

In general, solder balls are used to electrically connect the chip and the substrate. In the case of the high-density fine pitch, the solder balls are submerged by the weight of the chips and bridged to the opposite solder balls. ) Phenomenon occurs. Accordingly, Cu cored solder ball (CCSB) is being applied to withstand the weight of the chip and maintain the height of the solder ball while preventing the bridge phenomenon. However, since the core of the CCSB is a high melting point material (about 1000 DEG C or more), it is difficult to manufacture.

In order to overcome this problem, there is a method of using a material having a higher melting point (about 400 ° C. or lower) than the SAC (Sn, Ag, Cu) alloy and the SAC alloy instead of the Cu core. However, when the SAC alloy is used as the core, there is a problem in that the shape of the SAC core melts at the reflow temperature (normally, the peak temperature is about 260 ° C.). When the SAC core phase changes from a solid phase to a liquid phase, a volume change occurs. A change of about 3 to 5% occurs.

In one aspect, an object of the present specification is to provide a solder ball, which maintains the shape of a core including a metal having a low melting point even during reflow and has stable bonding reliability with a substrate.

In another aspect, the present disclosure aims to provide a solder ball that can prevent the occurrence of bonding defects when applied to the manufacture of electronic components, semiconductor packages and electronic products.

In another aspect, an object of the present disclosure is to provide a method of manufacturing the solder ball.

In another aspect, an object of the present disclosure is to provide an electronic component including the solder ball.

In addition, the present invention is a core containing a metal having a first melting point; And a first metal layer formed on an outer surface of the core and including a metal having a second melting point higher than the first melting point, wherein the thickness (B, μm) of the first metal layer is a particle size (A, It provides a solder ball that satisfies the following formula (1).

[Equation 1]

(Where 50 ≤ A ≤ 600)

In addition, the first melting point of the core metal is 300 ° C. or less, or 300 to 600 ° C., and the second melting point of the first metal layer metal provides a solder ball of 400 to 4000 ° C.

Further, the metal having the first melting point of 300 ° C. or less may include tin (Sn); Or an alloy including any one or more metals selected from the group consisting of Ag, Cu, Ni, Zn, Al, and Sb and Sn in the remainder;

In addition, the metal having the first melting point of 300 to 600 ℃ provides a solder ball of Bi-X or Cu-X (X is Sn, Cu, or Zn).

In addition, the first metal layer metal provides a solder ball including nickel.

It also provides a solder ball having a use for a substrate surface-treated with Ni / Au.

In addition, the first metal layer provides a solder ball occupies 0.5 to 20% by volume of the total solder ball volume.

In addition, the solder ball is provided on the outer surface of the first metal layer, and provides a solder ball further comprising a second metal layer containing tin or tin alloy.

In addition, the tin alloy provides at least one metal selected from the group consisting of Ag, Cu and Bi, and provides a solder ball consisting of the balance of tin.

In addition, the second metal layer provides a solder ball that occupies 20 to 80% by volume of the total solder ball volume.

The present invention also provides a method of forming a core comprising: (1) forming a core comprising a metal having a first melting point; And (2) forming a first metal layer on the outer surface of the core, the first metal layer including a metal having a second melting point higher than the first melting point, wherein step (2) uses electroless plating or electroplating. It provides a method of manufacturing a solder ball to the thickness (B, μm) of the first metal layer to have a thickness satisfying the following formula 1 with respect to the particle diameter (A, μm) of the core.

[Equation 1]

(Where 50 ≤ A ≤ 600)

In addition, after the step (2), (3) provides a method for manufacturing a solder ball further comprising the step of forming a second metal layer containing tin or tin alloy on the outer surface of the first metal layer.

In another aspect, the present invention provides an electronic component comprising the solder ball.

In one aspect, the technique disclosed herein maintains the shape of the core even upon reflow by providing a solder ball comprising a first metal layer comprising a metal having a high melting point on the outer surface of the core comprising a metal having a low melting point And there is an effect of providing a solder ball that can have a stable bonding reliability with the substrate.

In another aspect, the technology disclosed herein has the effect of providing a solder ball that can prevent the occurrence of bonding defects when applied to the manufacture of electronic components, semiconductor packages and electronic products.

In another aspect, the technique disclosed herein has the effect of providing a method of manufacturing the solder ball.

In another aspect, the technology disclosed herein has the effect of providing an electronic component including the solder ball.

1 is a cross-sectional structure of a solder ball according to an embodiment of the present disclosure.

FIG. 2 is a result of a comparative example in which a void form occurs in a core because the resistance of the first metal layer is small with respect to a volume change of the core during a reflow process in an exemplary embodiment of the present specification.

Figure 3 shows one solder ball having (a) a core having a melting point of 300 ° C. or lower, (b) a core having a melting point of 300 ° C. to 600 ° C., (c) a core having a melting point of 800 ° C. or higher, and (d) a SAC alloy. The resistance of the first metal layer to the volume change of the core during the reflow process is large enough to result in the embodiment assembled in a normal shape without a void (void) in the core.

4 is a result of a comparative example in which a bridge phenomenon occurs due to solder splash after reflow in an experimental example of the present specification.

FIG. 5 shows the results of (a) an example in which no copper consumption phenomenon occurred and a comparative example in which (b) copper consumption occurred after reflow in an experimental example of the present specification.

6 is a result of comparing the fracture surface of the (a) conventional solder ball and (b) the new solder ball according to the present specification.

7 is a result of measuring the bond strength according to an experimental example of the present specification.

8 is a drop impact test results according to an experimental example of the present specification.

Hereinafter, the present invention will be described in detail.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof described on the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and are not construed in ideal or excessively formal meanings unless expressly defined herein. Do not.

Solder ball

1 is a cross-sectional structure of a solder ball according to an embodiment of the present disclosure.

Solder ball according to the present specification is a core including a metal having a low melting point (low-melting point); And a first metal layer formed on an outer surface of the core and including a metal having a high-melting point.

Accordingly, the solder ball according to the present specification has excellent thermal and electrical properties, and the core maintains a normal shape without generating voids even after reflow, and also ensures reliability between ball pitches and increases core height. There is a sustained effect.

Meanwhile, in order to realize such an effect, the relationship between the core particle diameter and the thickness of the first metal layer, the volume of the first metal layer in the solder ball, or the thickness of the first metal layer is important.

The solder ball may include a core including a metal having a first melting point; And a first metal layer formed on an outer surface of the core and including a metal having a second melting point higher than the first melting point.

In an exemplary embodiment, the first melting point of the core metal may be 700 ° C. or less. Specifically, the first melting point of the core metal may be 670 ° C or less, 640 ° C or less, 600 ° C or less, 550 ° C or less, 500 ° C or less, 450 ° C or less, 400 ° C or less, 350 ° C or less, or 300 ° C or less. More specifically, 150 to 700 ° C, or 150 to 670 ° C, or 150 to 640 ° C, or 150 to 600 ° C, or 150 to 550 ° C, or 150 to 500 ° C, or 150 to 450 ° C, or 150 to 400 ° C Or 150 to 350 ° C, or 150 to 300 ° C.

In an exemplary embodiment, the first melting point of the core metal may be 300 ° C. or less or 300 to 600 ° C., and the second melting point of the first metal layer metal may be 400 to 4,000 ° C.

In an exemplary embodiment, the metal having the first melting point of 300 ° C. or less may include tin (Sn); Or an alloy including any one or more metals selected from the group consisting of Ag, Cu, Ni, Zn, Al, and Sb and the balance Sn. For example, the core metal may be Sn, Sn—Ag—Cu alloy, Sn—Cu alloy, Sn—Sb alloy, Sn—Ag alloy, Sn—Zn alloy, Sn—Al alloy, or Sn—Ni alloy).

In an exemplary embodiment, the metal having the first melting point of 300 to 600 ° C. may be Bi-X or Cu-X. X is included 5 wt% or less, preferably 1 wt% or less as Sn, Cu or Zn.

In an exemplary embodiment, the core may have a particle diameter of 50 to 600 ㎛. Preferably the core has a particle size of 100 to 500 ㎛.

In an exemplary embodiment, the first metal layer metal may include nickel or copper.

In an exemplary embodiment, when the first metal layer metal is nickel (Ni), the first metal layer may have a use purpose for a substrate surface-treated with Ni / Au. At this time, the thickness (B, μm) of the first metal layer satisfies the following formula 1 with respect to the particle diameter (A, μm) of the core.

[Equation 1]

(Where 50 ≤ A ≤ 600)

In the case of having a first metal layer including nickel that satisfies Equation 1, the core is in a normal shape without a void form because the resistance of the first metal layer is large enough to change the volume of the core during reflow of the solder ball. It can represent an assembled form.

In addition, the first metal layer may occupy 0.5 to 20% by volume with respect to the total volume of the solder ball. Specifically, the first metal layer is at least 0.5% by volume, at least 1% by volume, at least 2% by volume, at least 3% by volume, at least 4% by volume, or at least 5% by volume with respect to the total volume of the solder ball. Up to 18% by volume, up to 16% by volume, up to 14% by volume, up to 12% by volume, or up to 10% by volume. In another aspect, the first metal layer may have a thickness of 1 to 20 μm. Preferably it has a thickness of 1 to 10 ㎛.

According to the experimental example to be described later, in order to maintain the shape of the core during reflow and have a bonding reliability, it can be seen that the volume or the thickness of the first metal layer occupying the first metal layer including nickel in the solder ball acts as an important factor. During reflow, if the first metal layer does not have sufficient resistance to volume change of the core, i.e. if the volume occupied by the first metal layer in the solder ball or the thickness of the first metal layer is thin, the first metal layer is broken and the core protrudes out to be void. There is a problem that a (void) form occurs.

In an exemplary embodiment, when the first metal layer metal is copper (Cu), it may have a use purpose for a substrate surface-treated with an organic solderability preservative (Cu-OSP). In this case, the first metal layer may occupy 1 to 60% by volume with respect to the total volume of the solder ball. Specifically, the first metal layer is at least 1% by volume, at least 3% by volume, at least 5% by volume, at least 7% by volume, at least 9% by volume, or at least 10% by volume relative to the total volume of the solder ball. Up to 55% by volume, up to 50% by volume, up to 45% by volume, up to 40% by volume, up to 35% by volume, or up to 30% by volume. In another aspect, the first metal layer may have a thickness of 2 to 20 ㎛. Preferably it has a thickness of 2 to 10 ㎛.

When using a solder ball including a first metal layer made of a metal containing nickel on a substrate treated with Cu-OSP, solder reflow, Cu consumption, and bridge phenomenon after reflow May cause a defect.

For example, Cu and Sn present in the second metal layer of the solder ball react with the pad during the reflow to form a bonding layer called Cu ₆ Sn ₅ , and the Cu content of the second metal layer is insufficient. As a result, copper consumption occurs. In addition, as copper consumption occurs, soldering occurs due to the influence of highly reactive Cu, which causes a bridge between the voids of the second metal layer and the second metal layer.

Therefore, for the substrate treated with Cu-OSP, by using a solder ball including a first metal layer made of a metal containing copper, the Cu content of the copper layer is supplied to the bonding layer formed by reacting with the pad. It can play a role of preventing the copper consumption of the pad. Moreover, since the supply amount of Cu is enough, the reactivity of Cu can be delayed and the soldering phenomenon can also be prevented.

In an exemplary embodiment, the solder ball may further include a second metal layer formed on an outer surface of the first metal layer and including tin or a tin alloy.

In one exemplary embodiment, the metal that can be alloyed with Sn, for example Ag. Metals, such as Cu and Bi, are used, It is used as an alloy metal in the technical field to which this invention belongs, It can be used without a restriction. For example, the tin alloy may be a Sn—Ag—Cu alloy, a Sn—Cu alloy, a Sn—Ag alloy, or a Sn—Bi alloy.

In an exemplary embodiment, the second metal layer may occupy 20 to 80% by volume with respect to the total volume of the solder ball. Specifically, the second metal layer is at least 20% by volume, at least 25% by volume, at least 30% by volume, at least 35% by volume, at least 40% by volume, at least 45% by volume, or at least 50% by volume relative to the total solder ball volume. It may also comprise up to 80% by volume, up to 75% by volume, up to 70% by volume, up to 65% by volume, up to 60% by volume, up to 55% by volume, or up to 50% by volume. In another aspect, the second metal layer may have a thickness of 2 to 40 μm. Preferably it may have a thickness of 10 to 20 ㎛.

Manufacturing method of solder ball

Solder balls, (1) forming a core comprising a metal having a first melting point; And (2) forming a first metal layer on the outer surface of the core including a metal having a second melting point higher than the first melting point.

In an exemplary embodiment, in the step (1), the core may be manufactured to a desired diameter through a predetermined orifice hole using a vibrator in a heated state after melting the core metal material by induction heating through a high temperature high frequency induction furnace. have. At this time, the desired size can be produced in various ways depending on the orifice diameter, it is possible to adjust the frequency and pressure.

In an exemplary embodiment, in the step (2), the first metal layer may be formed by a widely known electroless plating or electroplating method.

In the step (2), when the first metal layer including nickel is formed, the metal core is pickled, and then a palladium seed (Pd seed) is attached to the etched surface with a palladium (Pd) solution. It may include the step of activating and charging the stirred electroless plating solution. The electroless plating can be continuously stirred until all reactions are completed to form the first metal layer. Although there is a large difference depending on the loading amount and the concentration and amount of the electroless plating solution, the first metal layer may be formed by sufficiently reacting for about 1 to 2 hours after the reaction is started.

The first metal layer is pickled metal core, and then the D.I. The core washed with water is charged into the electrolytic plating solution, and the electroplating may be performed using a metal, for example nickel or a metal to be plated, as an anode. At this time, the non-conductor is plated on the cathode. The thickness of the plating layer may control the time of the applied current to implement the desired thickness of the first metal layer. In the step (2), the thickness (B, μm) of the first metal layer is increased by using electroless plating or electroplating. The first metal layer is formed to have a thickness satisfying the following formula 1 with respect to the particle diameter (A, μm) of the core.

[Equation 1]

(Where 50 ≤ A ≤ 600)

Step (2) is to form a first metal layer containing copper, by mixing a dummy ball and a core having one composition or more than one composition inside the mesh barrel of the barrel plating apparatus Electroplating may be performed using an alkaline plating solution containing a CN group. The thickness of the plating layer may implement a desired thickness of the first metal layer by controlling the amount of current required for electroplating and the plating time.

In an exemplary embodiment, in order to increase the adhesion of the core during electroplating, the rpm may be initially maintained at a low speed and the rpm may be gradually increased after the plating is performed to some extent.

In an exemplary embodiment, the organic matter or impurities on the surface may be removed as much as possible in the pre-plating step to increase the plating adhesion between the core of the plated body and the first metal layer metal such as Cu. To remove this, pure water of about 50 ℃ can be used, and it is more effective when used together with Sony. In addition, the temperature of the plating bath can be maintained between 55 ~ 60 ℃ in order to increase the plating adhesion.

In an exemplary embodiment, after the step (2), (3) may further comprise the step of forming a second metal layer containing tin or tin alloy on the outer surface of the first metal layer.

In an exemplary embodiment, step (3) may be performed by a plating method which is generally well known. The solder layer, which is the second metal layer, is a plating layer formed by electrolyzing a metal containing Sn on the surface of the metal core on which the first metal layer is formed. After washing with water, for example, Sn or Sn-Ag may be hung on the Anode and the subject may be plated on the Cathode. At this time, the temperature of the plating liquid may be maintained at 20 ~ 30 ℃. The current density of the electroplating is 0.5 ~ 1.2 A / dm to achieve a desired plating thickness by plating for 2 to 4 hours.

Electronic parts

Solder balls according to the present specification can be used for electronic components. The solder ball according to the present disclosure is not limited to the semiconductor package use but may be used for various purposes in the electronic component. In addition, the semiconductor package according to the present disclosure may be applied to a package on package (PoP) in which a top package is stacked on a bottom package in a stacked type in which a plurality of integrated circuits are mounted on one substrate.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples.

Example

(1) Preparation of a solder ball having a first metal layer containing nickel

Solder balls according to Comparative Examples and Examples described in Tables 1 to 5 were prepared by the following methods and their performances were compared.

First, the core metal material was melted by induction heating through a high temperature high frequency induction furnace, and then vibrated at a high speed of 1 Khz or more using a vibrator in a heated state, and a core was manufactured to a desired diameter through a predetermined orifice hole.

Thereafter, a first metal layer was formed on an outer surface of the manufactured core. Specifically, the metal core is pickled, and then palladium seed (Pd seed) is attached to the etched surface with palladium (Pd) solution, activated with dilute sulfuric acid solution and charged in a bath-less electrolytic plating solution until all reactions are completed. Stirring was continued. Electroplating pickles the prepared cores and then the D.I. A core washed with water was charged into an electrolytic plating solution, and plating was performed using nickel or a metal to be plated as an anode as an anode. At this time, the non-conductor was plated on the cathode. The thickness of the plating layer was implemented by adjusting the time of the applied current to achieve the desired plating thickness.

In the forming of the second metal layer, the core on which the first metal layer is formed is pickled. After washing with water, for example, Sn or Sn-Ag was hung on the Anode, and the subject was plated on the Cathode. At this time, the temperature of the plating liquid was maintained at 20 ~ 30 ℃. The current density of the electroplating is 0.5 ~ 1.2 A / dm at 2-4 hours to achieve the desired plating thickness.

	Comparative Example 1	Comparative Example 2	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6	Example 7	Example 8	Example 9
Core (SAC) + first metal layer (Ni) diameter μm	100	100	100	100	100	100	100	100	100	100	100
Second metal layer (SAC) ㎛	20	20	20	20	20	20	20	20	20	20	20
Final cored ball size㎛	140	140	140	140	140	140	140	140	140	140	140
First metal layer (Ni) thickness μm	0	0.5	One	2	3	4	5	6	7	8	9
Core volume	523	533.179	517.185	486.162	456.406	427.889	400.586	374.469	349.513	325.691	302.977
void occurrence	o	o	x	x	x	x	x	x	x	x	x

As shown in Table 1, Comparative Example 1 is a solder ball that does not include the first metal layer, that is, pure SAC Core, compared with the core volume of Comparative Example 1 (4/3 × π × 50 ³ = 523) According to the thickness of the first metal layer (Ni), the core volume of the cores of Comparative Examples 2 and Examples 1 to 9 was expanded by 5%. In order to compare with the pure SAC core (Comparative Example 1) 5% expanded volume value for the core volume when the total diameter of the core and the first metal layer of Comparative Examples 2 and Examples 1 to 9 is 100 was calculated.

Since the volume value 533.179 of the comparative example 2 is larger than the volume value 523 of the comparative example 1, the first metal layer collapses after the reflow to generate voids, and the volume values of Examples 1 to 9 Since V is smaller than the volume value of Comparative Example 1, since the resistance of the first metal layer is sufficient and does not collapse, voids do not occur even after reflow. The same concept is applied to Tables 2 to 5 below, and the thickness of the first metal layer also varies according to the size of the core.

	Comparative Example 3	Comparative Example 4	Example 10	Example 11	Example 12	Example 13	Example 14	Example 15	Example 16	Example 17
Core (SAC) + first metal layer (Ni) diameter μm	200	200	200	200	200	200	200	200	200	200
Second metal layer (SAC) ㎛	20	20	20	20	20	20	20	20	20	20
Final cored ball size㎛	240	240	240	240	240	240	240	240	240	240
First metal layer (Ni) thickness μm	0	One	2	3	4	5	6	7	8	9
ball volume	4187	4265.43	4137.48	4012.11	3889.3	3769.02	3651.25	3535.95	3423.11	3312.7
void occurrence	o	o	x	x	x	x	x	x	x	x

5% expanded to core volume when the total diameters of the core and the first metal layer of Comparative Example 4 and Examples 10 to 17 were 200 for comparison with a pure SAC core (Comparative Example 3) as shown in Table 2 above. Volume values were calculated.

Since the volume value 44265.43 of Comparative Example 4 is larger than that of Comparative Example 3, the first metal layer collapses to cause voids after reflow, and thus the volume values of Examples 10 to 17. Since V is smaller than the volume value of Comparative Example 3, since the resistance of the first metal layer is sufficient and does not collapse, voids do not occur even after reflow.

	Comparative Example 5	Comparative Example 6	Comparative Example 7	Example 18	Example 19	Example 20	Example 21	Example 22	Example 23	Example 24
Core (SAC) + first metal layer (Ni) diameter μm	300	300	300	300	300	300	300	300	300	300
Second metal layer (SAC) ㎛	30	30	30	30	30	30	30	30	30	30
Final cored ball size㎛	360	360	360	360	360	360	360	360	360	360
First metal layer (Ni) thickness μm	0	One	2	3	4	5	6	7	8	9
ball volume	14137	14549.1	14258.1	13971.1	13687.9	13408.6	13133.0	12861.3	12593.4	12329.2
void occurrence	o	o	o	x	x	x	x	x	x	x

5% of the core volume when the total diameters of the core and the first metal layer of Comparative Examples 6 and 7, Examples 18 to 24 are 300 for comparison with pure SAC cores (Comparative Example 5) as shown in Table 3 above. The expanded volume value was calculated.

Since the volume values of Comparative Examples 6 and 7 are larger than the volume values 14130 of Comparative Example 5, the first metal layer collapses after the reflow to cause voids, and the volume values of Examples 18 to 24 are Since it is smaller than the volume value of Comparative Example 5, the resistance of the first metal layer is sufficient and does not collapse, so that voids do not occur even after reflow.

	Comparative Example 8	Comparative Example 9	Comparative Example 10	Comparative Example 11	Example 25	Example 26	Example 27	Example 28	Example 29	Example 30
Core (SAC) + first metal layer (Ni) diameter μm	400	400	400	400	400	400	400	400	400	400
Second metal layer (SAC) ㎛	30	30	30	30	30	30	30	30	30	30
Final cored ball size㎛	460	460	460	460	460	460	460	460	460	460
First metal layer (Ni) thickness μm	0	One	2	3	4	5	6	7	8	9
ball volume	33493	34643.1	34123.5	33609.1	33099.8	32595.8	32096.9	31603.1	31114.4	30630.8
void occurrence	o	o	o	o	x	x	x	x	x	x

5% of the core volume when the total diameters of the cores and the first metal layers of Comparative Examples 9-11 and 25-25 are 400 in order to compare with pure SAC cores (Comparative Example 8) as shown in Table 4 above. The expanded volume value was calculated.

Since the volume values of Comparative Examples 9 to 11 are larger than those of Comparative Example 8, the first metal layer collapses to cause voids after reflow, and the volume values of Examples 25 to 30 are Since it is smaller than the volume value of Comparative Example 8, the resistance of the first metal layer is sufficient and does not collapse, so that voids do not occur even after reflow.

	Comparative Example 12	Comparative Example 13	Comparative Example 14	Comparative Example 15	Comparative Example 16	Example 31	Example 32	Example 33	Example 34	Example 35
Core (SAC) + first metal layer (Ni) diameter μm	500	500	500	500	500	500	500	500	500	500
Second metal layer (SAC) ㎛	40	40	40	40	40	40	40	40	40	40
Final cored ball size㎛	580	580	580	580	580	580	580	580	580	580
First metal layer (Ni) thickness μm	0	One	2	3	4	5	6	7	8	9
ball volume	65417	67866.5	67052.2	66244.3	65443	64648.1	63859.7	63077.8	62302.3	61533.1
void occurrence	o	o	o	o	o	x	x	x	x	x

5% of the core volume when the total diameters of the cores and the first metal layer of Comparative Examples 13 to 16 and Examples 31 to 35 were 500 for comparison with the pure SAC core (Comparative Example 12) as shown in Table 5 above. The expanded volume value was calculated.

Since the volume values of Comparative Examples 13 to 16 are larger than those of Comparative Example 12, the first metal layer collapses to generate voids after reflow, and the volume values of Examples 31 to 35 are Since it is smaller than the volume value of Comparative Example 12, since the resistance of the first metal layer is sufficient and does not collapse, voids do not occur even after reflow.

As a result, if the first metal layer containing nickel does not have sufficient resistance to volume change of the core during reflow, that is, if the volume occupied by the first metal layer in the solder ball or the thickness of the first metal layer is thin, the first metal layer is It broke and the core protruded outward to generate a void form (see FIG. 2). On the other hand, when the resistance of the first metal layer is large enough to change the volume of the core during the reflow of the solder ball, the core is assembled into a normal shape without a void shape (see FIG. 3). Accordingly, in order to maintain the shape of the core during reflow and to have the bonding reliability, it was confirmed that the volume occupied by the first metal layer or the thickness of the first metal layer acts as an important factor.

(2) Manufacture of solder balls with a first metal layer containing copper

Solder balls according to Comparative Examples and Examples described in Tables 6 to 8 were prepared by the following method and their performances were compared.

The core and the second metal layer of the solder ball having the first metal layer containing copper were carried out in the same manner as in (1) the manufacturing method of the solder ball having the first metal layer containing nickel, and the first metal layer was a barrel plating apparatus. A dummy ball and a core having one composition or more than one composition were mixed in a mesh barrel of an electroplating using an alkaline plating solution containing a CN group. Plating thickness was controlled by adjusting the amount of current and plating time required for electroplating.

In addition, in order to increase the plating adhesion between the core of the plated body and the Cu, organic substances or impurities on the surface were removed as much as possible in the pre-Cu plating step. In order to remove this, the Sony was used together with pure water of about 50 ℃. In addition, the temperature of the plating bath was maintained between 55 ~ 60 ℃ in order to increase the adhesion of the plating, the rpm was initially maintained at a low speed to increase the adhesion of the core, and the rpm was gradually increased after a certain degree of plating.

On the other hand, Cu thickness of Cu pad used for evaluation in this Example is 10 micrometers. Cu is added to the core of the comparative examples and examples shown in Table 7 5% or less, Sn is added to the core of the comparative examples and examples of Table 8 5% or less.

	Comparative Example 17	Comparative Example 18	Example 36	Example 337	Example 38	Example 39	Example 40	Example 41
Core	SAC	SAC	SAC	SAC	SAC	SAC	SAC	SAC
Core size ㎛	180	180	180	180	160	160	140	140
Copper layer μm	0.5	One	2	5	10	20	25	30
Second metal layer (SAC) thickness μm	19.5	19	18	15	20	10	15	10
Yield% after reflow	8.46%	30.44%	86.12%	93.24%	98.70%	98.91%	92.68%	91.22%
Solder paste rating	One	One	3	4	5	5	4	4
Copper consumption μm	10.00	8.42	2.96	1.92	1.44	1.16	1.02	1.04
void occurrence	o	o	x	x	x	x	x	x
Solder 튐	One	One	3	4	5	5	4	4

	Comparative Example 19	Comparative Example 20	Example 42	Example 43	Example 44	Example 45	Example 46	Example 47
Core	Bi-x	Bi-x	Bi-x	Bi-x	Bi-x	Bi-x	Bi-x	Bi-x
Core size ㎛	180	180	180	180	160	160	140	140
Copper layer μm	0.5	One	2	5	10	20	25	30
Second metal layer (SAC) thickness μm	19.5	19	18	15	20	10	15	10
Yield% after reflow	5.42%	28.46%	88.24%	91.18%	98.96%	93.54%	92.48%	90.88%
Solder paste rating	One	One	3	4	5	4	4	4
Copper consumption μm	10.00	8.38	2.98	1.96	1.48	1.12	1.08	1.06
void occurrence	o	o	x	x	x	x	x	x
Solder 튐	One	One	3	4	5	5	5	4

	Comparative Example 21	Comparative Example 22	Example 48	Example 49	Example 50	Example 51	Example 52	Example 53
Core	Cu-X	Cu-X	Cu-X	Cu-X	Cu-X	Cu-X	Cu-X	Cu-X
Core size ㎛	180	180	180	180	160	160	140	140
Copper layer μm	0.5	One	2	5	10	20	25	30
Second metal layer (SAC) thickness μm	19.5	19	18	15	20	10	15	10
Yield% after reflow	6.22%	22.68%	88.62%	94.22%	98.24%	97.88%	96.22%	92.64%
Solder paste rating	One	One	3	4	5	5	5	4
Copper consumption μm	10.00	8.52	2.94	1.98	1.46	1.18	1.06	1.08
void occurrence	o	o	x	x	x	x	x	x
Solder 튐	One	One	3	4	5	4	4	4

Solder splash rating
5	Yield 95% or more
4	Yield 90% or more
3	Yield 85% or more
2	Yield 80% or more
One	Yield less than 80%

In addition, as shown in Tables 6 to 8, as a result of observing the soldering phenomenon and the copper consumption phenomenon according to the thickness of the copper layer which is the first metal layer, the yield of the copper layer is 85% or more and 70% or less than the copper consumption Cu pad. It was found that from 2 µm is appropriate, and when the thickness exceeds 20 µm, the expected effect is insufficient and the plating time is long. Accordingly, it was confirmed that the appropriate first metal layer had a thickness of 2 to 20 μm.

Reliability evaluation

Bonding strength was measured by mounting a new solder ball and a conventional general solder ball (see FIG. 6) manufactured according to the above example method on a PCB. Bond strength was measured according to JESD22-B117.

As a result, as shown in Figure 7, the new solder ball according to the present disclosure showed a stronger strength value in terms of bonding strength than the general solder ball, it was shown that there is no significant difference between the new solder ball.

In addition, a drop impact test was performed by mounting a new solder ball and a conventional general solder ball (see FIG. 6) manufactured according to the above-described method. Drop impact test was measured according to JESD22-B111 regulation.

As a result, as shown in Figure 8, the new solder ball according to the present specification was found to have a greater resistance to drop impact than the general solder ball, the crack path generated during the impact of the new solder ball has a longer crack path than the normal solder ball Seemed. For this reason, the new solder ball according to the present specification was found to have a large resistance to drop impact.

As described above, specific portions of the present specification have been described in detail, and for those skilled in the art, these specific techniques are merely preferred embodiments, and it is obvious that the scope of the present invention is not limited thereto. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (13)

1. A core comprising a metal having a first melting point; And

   A first metal layer formed on an outer surface of the core and including a metal having a second melting point higher than the first melting point,

   The thickness (B, μm) of the first metal layer is a solder ball that satisfies the following formula 1 with respect to the particle diameter (A, μm) of the core.

   [Equation 1]

   

   (Where 50 ≤ A ≤ 600)
2. The method of claim 1,

   The first melting point of the core metal is 300 ° C. or less, or 300 to 600 ° C.,

   The second melting point of the first metal layer metal is 400 to 4000 ℃ solder ball.
3. The method of claim 2,

   The metal having the first melting point of 300 ° C. or less,

   Tin (Sn); or

   Solder ball, which is an alloy containing any one or more metals selected from the group consisting of Ag, Cu, Ni, Zn, Al, and Sb and the balance Sn.
4. The method of claim 2,

   The metal having the first melting point of 300 to 600 ℃,

   Solder balls with Bi-X or Cu-X, where X is Sn, Cu, or Zn.
5. The method of claim 1,

   The first metal layer metal is a solder ball containing nickel.
6. The method of claim 5,

   Solder balls for use on substrates surfaced with Ni / Au.
7. The method of claim 6,

   The first metal layer is a solder ball occupies 0.5 to 20% by volume of the total solder ball volume.
8. The method of claim 1,

   The solder ball,

   Solder balls are formed on the outer surface of the first metal layer, further comprising a second metal layer containing tin or tin alloy.
9. The method of claim 8,

   The tin alloy is a solder ball containing any one or more metals selected from the group consisting of Ag, Cu and Bi and the balance of tin.
10. The method of claim 8,

    The second metal layer is a solder ball occupies 20 to 80% by volume with respect to the total volume of the solder ball.
11. (1) forming a core comprising a metal having a first melting point; And

    (2) forming a first metal layer on the outer surface of the core comprising a metal having a second melting point higher than the first melting point,

    In the step (2), the thickness (B, μm) of the first metal layer is formed to have a thickness satisfying the following formula 1 with respect to the particle size (A, μm) of the core using electroless plating or electroplating. Method for producing phosphorus solder ball.

    [Equation 1]

    

    (Where 50 ≤ A ≤ 600)
12. The method of claim 11,

    After the step (2),

    (3) The method of manufacturing a solder ball further comprising the step of forming a second metal layer containing tin or tin alloy on the outer surface of the first metal layer.
13. An electronic component comprising the solder ball according to any one of claims 1 to 10.

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