KR101563884B1 - Core solder ball, method for manufacturing the same, and electronic part including the same - Google Patents

Abstract

The present invention relates to a core solder ball, a method of manufacturing the core solder ball, and an electronic component including the core solder ball. The core solder ball includes an multilayer solder layer and an outermost layer capable of preventing oxidation of the core solder ball. And an electronic component including the same.

Description

Technical Field [0001] The present invention relates to a core solder ball, a method of manufacturing the core solder ball, and an electronic part including the core solder ball, a method for manufacturing the same,

The present invention relates to a core solder ball, a method of manufacturing the core solder ball, and an electronic component including the core solder ball. The core solder ball includes an multilayer solder layer and an outermost layer capable of preventing oxidation of the core solder ball. And an electronic component including the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection means used in a semiconductor device, and more particularly to a solder ball used for electrical connection between a semiconductor chip and an external mounting means.

At present, electronic parts on which a semiconductor or the like is mounted on a substrate are manufactured using a package called a ball grid array (BGA) or a chip size package (CSP). In such an electronic component, solder balls are used for bonding the terminals. Such bonding of the terminals using the solder balls is generally used when bonding the terminals at intervals of several hundred microns, so that a high degree of dimensional accuracy is required. In addition, when the soldering is performed poorly at the time of bonding the terminals, defects in the package, which are extremely expensive compared to the soldering cost, occur. Therefore, high reliability is also required when bonding the terminals by solder balls.

In order to achieve high dimensional accuracy and reliability at terminal bonding, it is important to control the composition of the solder balls, solder bonding conditions, and the surface condition of the solder balls. Among the above requirements, the degree of oxidation on the surface of the solder ball must be low in relation to the surface condition of the solder ball. In manufacturing a package using a solder ball, a solder ball is mounted on a predetermined position on a BGA substrate, and then a solder ball is melted by a heating device to form a bump. At this time, when the surface of the solder ball is oxidized, the wettability of the solder ball at the time of melting is lowered, so that the solder ball is not completely attached to the terminals on the substrate, so that the bonding strength is insufficient.

Further, in addition to the case where the above-described oxide film is formed, when a film of dirt or organic matter is formed on the surface of the solder ball, the bonding strength becomes insufficient as described above. The lack of bonding strength of such a solder appears because of poor soldering, which further causes a package failure.

Oxidation of the solder ball surface is referred to as " blackening " because the surface of the solder ball after oxidation appears black. A method of suppressing the oxidation of the surface of the solder ball by coating the surface of the solder ball with another material different from the solder ball has been studied in order to solve the problem of lowering the bonding strength of the solder due to the blackening described above. Examples of the coating material of the solder ball include lubricants such as an aliphatic hydrocarbon-based lubricant, a higher aliphatic alcohol-higher fatty acid-based lubricant, a fatty acid amide-based lubricant, a metal soap lubricant and a fatty acid ester lubricant 2000-288771); (For example, Au, Sn, etc.) corrosion inhibitor (for example, see Japanese Patent Application Laid-Open No. 08-164496).

Japanese Patent Application Laid-Open No. 2000-288711 Japanese Patent Laid-Open No. 08-164496

It is an object of the present invention to provide a core solder ball of a new structure capable of suppressing surface oxidation and improving soldering characteristics and bonding strength.

The present invention also aims to provide a method of manufacturing a core solder ball according to the present invention.

The present invention also aims to provide an electronic component for mounting a core solder ball according to the present invention.

The present invention has been made to solve the above problems

core;

A metal layer formed on a surface of the core;

A solder layer formed on a surface of the metal layer; And

And an outermost layer formed on a surface of the solder layer,

The solder layer

A first solder layer including an Sn-Ag-based alloy formed on a surface of the metal layer;

A second solder layer including a Sn-Cu-based alloy formed on a surface of the first solder layer;

A third solder layer including an Sn-Ag based alloy formed on a surface of the second solder layer; And

A fourth solder layer including a Sn-Cu-based alloy formed on the surface of the third solder layer; / RTI >

The outermost layer has a composition of? G ⁰ (Standard Gibbs free energy) value of Sn is less than Sn.

Fig. 1 schematically shows the structure of a core solder ball according to the present invention. As shown in FIG. 1, a core solder ball according to the present invention includes a core 1; A metal layer (2) formed on the surface of the core; A solder layer 3 formed on the surface of the metal layer; And an outermost layer (4) formed on the surface of the solder layer.

In the core solder ball according to the present invention, the above-mentioned? G ⁰ Is a metal selected from the group consisting of Ge, In, Al, Ni, and Pd. The? G ⁰ The value of Sn is smaller than the metal in the former temperature range than the Sn contained in the solder layer and the fourth △ G ⁰ The oxide is generated prior to Sn, so that further oxidation can be prevented.

In the core solder ball according to the present invention, the core is pure Cu or at least 95% by weight of Cu.

In the core solder ball according to the present invention, the core is an alloy of Cu and one metal selected from the group consisting of Zn, Sn, P, Ni, and Au.

In the core solder ball according to the present invention, the metal layer may be one or two or more selected from the group consisting of gold, silver, nickel, zinc, tin, aluminum, chromium, and antimony.

In the core solder ball according to the present invention, the metal layer has a thickness of 0.1 to 5 占 퐉.

In the core solder ball according to the present invention, the metal layer is a plurality of layers of two or more layers.

In the core solder ball according to the present invention, the solder layer has a thickness of 5 to 50 mu m.

In the core solder ball according to the present invention, the thickness of the outermost layer is 0.001 to 1 占 퐉.

The present invention also relates to

Preparing a core;

Forming a metal layer on the surface of the core through electroless or electrolytic plating;

Sequentially forming a first solder layer to a fourth solder layer on the surface of the metal layer through electroless plating or electrolytic plating; And

Forming an outermost layer on the surface of the fourth solder layer through one of PECVD (Plasma Enhanced Chemical Vapor Deposition), ALD (Atomic Layer Deposition), electroless plating, and electrolytic plating; A method of manufacturing a core solder ball according to the present invention is provided.

In the method of manufacturing a core solder ball according to the present invention, the outermost layer may be formed by any one of PECVD (Plasma Enhanced Chemical Vapor Deposition), ALD (Atomic Layer Deposition), electroless plating, and electrolytic plating .

Plasma-enhanced chemical vapor deposition (PECVD) is a method of depositing a thin film by forming a plasma state by applying an electric field to a mixed gas in a reactor. The thin film can be deposited at a low temperature. Atomic Layer Deposition (ALD) is a nanoscale thin film deposition technique using chemical adsorption and desorption of a monolayer, which is applied to the chamber in pulsed form to form a surface saturation ) Chemical adsorption and desorption by reaction, it is possible to deposit thin film at low temperature.

The present invention also provides an electronic component including a solder bump formed using the core solder ball according to the present invention.

The core solder ball according to the present invention further comprises a plurality of solder layers and an outermost layer for preventing further oxidation to the outer periphery of the solder layer, thereby making it possible to produce oxidation and heat resistant solder balls, And bonding properties are improved.

1 shows a structure of a core solder ball according to the present invention.
FIG. 2 shows a result of a multi-reflow test on the core solder balls manufactured in one embodiment of the present invention and a comparative example.
FIGS. 3 and 4 show results of a multi-reflow test on the core solder balls manufactured according to one embodiment of the present invention and a comparative example, and then the appearance of the core solder balls was observed.
FIG. 5 shows the results of a comparison of surface oxidation degrees after performing a multi-reflow test five times on core solder balls manufactured in one embodiment of the present invention and a comparative example.
FIGS. 6 and 7 show the results of a comparison of the surface oxidation degree after a multi-reflow test on the core solder balls manufactured in one embodiment and the comparative example of the present invention.
FIG. 8 shows high temperature storage test results of the core solder balls manufactured in one embodiment and the comparative example of the present invention.
FIGS. 9 to 11 show Auger electron spectroscopy (AES) analysis results of the core solder balls prepared in one embodiment of the present invention and a comparative example.

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples.

< Example > Core Solder  Manufacture of balls

The copper core melts the copper through heating and has an average diameter of 180 mu m through the orifice in the molten melt.

The prepared copper core was subjected to a general electroless plating process after a pretreatment process to form a nickel plating layer (metal layer) having a thickness of about 1 mu m. Thereafter, a first solder layer composed of Sn-3.0Ag-based alloy solder having a thickness of about 18 탆 and a Sn-0.7Cu-based alloy solder is formed on the copper core in which the nickel plating layer is formed by performing the barrel electroplating process A second solder layer, a third solder layer composed of an Sn-3.0Ag-based alloy solder, and a fourth solder layer composed of an Sn-0.7Cu-based alloy solder are successively formed by electrolytic plating, The Ge layer was formed by PECVD (plasma-enhanced chemical vapor deposition).

PECVD was performed by using Tetrakisethylmethylamido Germanium (Ge {N (CH ₃ ) C ₂ H ₅ } as a Ge source, N ₂ as a dilute gas, Ar as an inert gas as a purge gas and He as a carrier gas. Dilute gas was injected at a constant temperature by a line heater at the source. The deposition temperature was 200 ° C, the bubbler temperature was 30 ° C, and the gas line temperature was 60 ° C. The MFC was controlled and supplied with N ₂ 60 sccm, Ar 100 sccm, and He 150 sccm. The experiment was carried out at a ratio of Precursor + H / Ar: H / Ar + Ar (1: 3 + 200 cycles.

The solder balls of Examples 1 to 5 were manufactured as follows while varying the thickness of Ge as the outermost layer and the kind of metal used as the outermost layer. As a comparative example, SAC 305 (Sn: Bal., Ag: 3 wt%, Cu: 0.5 wt%) was used in the case where an outermost layer was not formed.

core Metal layer
(thickness) Solder layer
(thickness) Outermost layer
(thickness) Example 1 Cu Ni
(1 um) Sn / Ag / Cu
(18um) Ge
(0.1 um ↓) Example 2 Cu Ni
(1 um) Sn / Ag / Cu
(18um) Ge
(0.1 mu m) Example 3 Cu Ni
(1 um) Sn / Ag / Cu
(18um) Ge
(1um ↑) Example 4 Cu Ni
(1 um) Sn / Ag / Cu
(18um) In
(0.1 um ↓) Example 5 Cu Ni
(1 um) Sn / Ag / Cu
(18um) Ni
(0.1 um ↓) Comparative Example 1 SAC 305 Comparative Example 2 Cu Ni
(1 um) Sn / Ag
(18um) X Comparative Example 3 Cu Ni
(1 um) Sn / Ag / Cu
(18um) X

< Experimental Example > multi reflow test

Table 2 shows the result of a multi reflow test on the core solder balls prepared in Examples and Comparative Examples. FIG. 2 shows a result of a multi reflow test of the core solder balls prepared in Example 1 and Comparative Example 3. FIG. As shown in FIG. 2 and Table 2, it can be seen that the wrinkle phenomenon is alleviated in the case of the solder ball including the outermost layer produced by the present invention.

Oxidation Wrinkle MRT1 MRT3 MRT5 MRT1 MRT3 MRT5 Example 1 0 0 0 0 0 0 Example 2 3 5 9 0 2 3 Example 3 No soldering Example 4 0 One 3 0 0 0 Example 5 0 5 12 0 3 5 Comparative Example 1 0 0 0 0 0 0 Comparative Example 2 37 70 90 0.3 9 7 Comparative Example 3 31 72 83 0.25 10 3

< Experimental Example > multi reflow test  Appearance after

The core solder balls prepared in Example 1 and Comparative Example 3 were subjected to a multi-reflow test, and the external appearance was observed. The results are shown in FIG. 3 and FIG. 3, wrinkle phenomenon does not occur at the outer surface of the core solder ball formed with Ge outermost layer according to the embodiment of the present invention. In contrast, in the comparative example of FIG. 4, wrinkle phenomenon .

< Experimental Example > Surface oxidation degree comparison

The core solder balls were manufactured in the same manner as in Example 1 except that the metal components of the outermost layers were different from each other. The core solder balls thus prepared and the core solder balls prepared in the above Comparative Example were subjected to a multi reflow test five times, The results are shown in FIG. 5, and the surface oxidation states of Examples 1 and 4 and Comparative Example 3 according to the number of multi reflow tests are shown in FIG. FIG. 7 shows the thicknesses of oxide films formed in Example 1 and Comparative Example 3 after the multi-reflow test was performed three times.

As shown in FIGS. 5 and 6, when the outermost layer contains Ge or In, surface oxidation hardly occurs even after the multi-reflow test is performed five times. In contrast, when the outermost layer is not included or Sb is included in the outermost layer It can be confirmed that surface oxidation occurs. In particular, in FIG. 6, it can be clearly seen that blackening phenomenon occurs in which the oxidation progresses on the surface of the core solder ball of the comparative example to discolor the surface color.

< Experimental Example > High Temperature Storage ( HTS ) analysis

The core solder balls prepared in Example 1 and Comparative Example 3 were subjected to a high temperature storage test at 150 ° C. for 96 hours and 250 hours. The results are shown in FIG. 8, The results of Auger electron spectroscopy (AES) analysis of the core solder balls after that are shown in Figs. 9 to 11.

As shown in FIG. 8, in the case of the present invention including the outermost Ge layer, blackening phenomenon does not appear even after 250 hours, whereas in the comparative example not including the Ge outermost layer, blackening phenomenon appears remarkably.

9 to 11, in the case of Example 1 before heat treatment, the oxide film was formed to a thickness of 7.5 nm on the surface, and the oxide film was 8.5 nm thick even after heat treatment at 150 ° C. for 96 hours. On the other hand, in the case of Comparative Example 3, it can be confirmed that an oxide film having a thickness of 14 nm was formed after the heat treatment, and that the core solder ball of the present invention is excellent in high temperature storage characteristics.

Claims (11)

core;
A metal layer formed on a surface of the core;
A solder layer formed on a surface of the metal layer; And
And an outermost layer formed on a surface of the solder layer,
The solder layer
A first solder layer including an Sn-Ag-based alloy formed on a surface of the metal layer;
A second solder layer including a Sn-Cu-based alloy formed on a surface of the first solder layer;
A third solder layer including an Sn-Ag based alloy formed on a surface of the second solder layer; And
A fourth solder layer including a Sn-Cu-based alloy formed on the surface of the third solder layer; / RTI &gt;
The outermost layer has a composition of? G ⁰ Of Sn is less than &lt; RTI ID = 0.0 &gt; Sn. &Lt; / RTI &gt;
The method according to claim 1,
The? G ⁰ Wherein the metal having a smaller value of Sn is at least one selected from the group consisting of Ge, In, Al, Ni, and Pd.
The method according to claim 1,
Wherein the core is pure Cu or at least 95 wt% Cu.
The method according to claim 1,
Wherein the core is an alloy of Cu and one metal selected from the group consisting of Zn, Sn, P, Ni, and Au.
The method according to claim 1,
Wherein the metal layer is one or two or more selected from the group consisting of gold, silver, nickel, zinc, tin, aluminum, chromium, and antimony.
The method according to claim 1,
Wherein the metal layer has a thickness of 0.1 to 5 占 퐉.
The method according to claim 1,
Wherein the metal layer is a plurality of layers of two or more layers.
The method according to claim 1,
Wherein the solder layer has a thickness of 5 to 50 占 퐉.
The method according to claim 1,
Wherein the outermost layer has a thickness of 0.001 to 1 占 퐉.
A core solder ball having a core, a metal layer formed on a surface of the core, a solder layer formed on a surface of the metal layer, and an outermost layer formed on a surface of the solder layer,
Forming a metal layer on the surface of the core through electroless or electrolytic plating;
Sequentially forming a first solder layer to a fourth solder layer on the surface of the metal layer through electroless plating or electrolytic plating; And
Forming an outermost layer on the surface of the fourth solder layer by any one of plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), electroless plating, and electrolytic plating; A method for manufacturing a core solder ball as set forth in claim 1.
An electronic component comprising a solder bump formed using the core solder ball of claim 1.

Images