KR20160103922A - Solder ball for fluxless bonding, method of manufacturing the same, and method of forming a solder bump - Google Patents

Solder ball for fluxless bonding, method of manufacturing the same, and method of forming a solder bump Download PDF

Info

Publication number
KR20160103922A
KR20160103922A KR1020160013531A KR20160013531A KR20160103922A KR 20160103922 A KR20160103922 A KR 20160103922A KR 1020160013531 A KR1020160013531 A KR 1020160013531A KR 20160013531 A KR20160013531 A KR 20160013531A KR 20160103922 A KR20160103922 A KR 20160103922A
Authority
KR
South Korea
Prior art keywords
metal layer
solder
core
solder ball
temperature
Prior art date
Application number
KR1020160013531A
Other languages
Korean (ko)
Other versions
KR101811992B1 (en
Inventor
손재열
문정탁
송재헌
이영우
김응재
맹익주
유찬구
김휘중
Original Assignee
엠케이전자 주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 엠케이전자 주식회사 filed Critical 엠케이전자 주식회사
Priority to US15/050,708 priority Critical patent/US20160244891A1/en
Priority to TW105105336A priority patent/TW201633480A/en
Priority to JP2016033528A priority patent/JP2016155173A/en
Publication of KR20160103922A publication Critical patent/KR20160103922A/en
Application granted granted Critical
Publication of KR101811992B1 publication Critical patent/KR101811992B1/en

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
    • B23K35/0244—Powders, particles or spheres; Preforms made therefrom
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering, brazing
    • B23K35/0233—Sheets, foils
    • B23K35/0238—Sheets, foils layered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0255—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in welding
    • B23K35/0261—Rods, electrodes, wires
    • B23K35/0283—Rods, electrodes, wires multi-cored; multiple
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
    • B23K35/24—Selection of soldering or welding materials proper
    • B23K35/26—Selection of soldering or welding materials proper with the principal constituent melting at less than 400 degrees C
    • B23K35/262—Sn as the principal constituent
    • B23K2201/36—

Abstract

The present invention relates to a solder ball for fluxless bonding, a method of manufacturing the same, and a method of forming a solder bump and, more specifically, provides a solder ball for fluxless bonding comprising: a solder core; a first metal layer on a surface of the solder core; and a second metal layer on the first metal layer. The first metal layer comprises at least one of nickel (Ni), silver (Ag), zinc (Zn), tin (Sn), chromium (Cr), antimony (Sb), platinum (Pt), palladium (Pd), aluminum (Al), or an alloy thereof. The second metal layer comprises gold (Au). As the above solder ball for fluxless bonding is in use, a solder bump having high reliability may be formed via a relatively short, low costs, and a simple process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder ball for fluxless bonding, a method for manufacturing the same, and a method for forming a solder bump.

The present invention relates to a solder ball for fluxless bonding, a method of manufacturing the solder ball, and a solder bump forming method. More specifically, the present invention relates to a solder ball for fluxless bonding, A solder ball, a method of manufacturing the same, and a method of forming a solder bump.

In order to bond the solder balls through the reflow process, it is necessary to use a flux to remove the natural oxide film on the solder ball surface. However, even after the cleaning process using the flux, it was not completely removed, which was a cause of lowering the reliability of the semiconductor device due to corrosion. Further, since the flux is expensive, it causes a rise in the unit cost of the semiconductor element.

Furthermore, pick-up equipment that places the solder balls on the substrate has a tool for dotting the flux, which is a cause of equipment downtime due to a periodic cleaning problem.

A first object of the present invention is to provide a solder ball capable of forming a reliable solder bump in a shorter time and at a lower cost through a simpler process.

A second object of the present invention is to provide a solder ball manufacturing method capable of forming a reliable solder bump in a shorter time and at a lower cost through a simpler process.

A third object of the present invention is to provide a method of forming a solder bump using the solder ball.

In order to achieve the first technical object of the present invention, A first metal layer on the surface of the solder core; And a second metal layer on the first metal layer, wherein the first metal layer comprises at least one of nickel (Ni), silver (Ag), zinc (Zn), tin (Sn), chromium (Cr), antimony (Sb) Pt, Pd, Al, or an alloy thereof, and the second metal layer is gold (Au).

At this time, the sum of the thicknesses of the first metal layer and the second metal layer may be 0.01 탆 or more and less than 1 탆. The thickness of the second metal layer may be 0.005 탆 or more and 0.9 탆 or less. The melting point of the solder core may be 180 ° C to 250 ° C.

In some embodiments, the solder ball for fluxless bonding may further include a core ball for support inside the solder core. At this time, the support core ball may be a material which is not melted at a temperature of 300 ° C or lower.

Another aspect of the present invention relates to a solder core; And an antioxidant metal layer on the surface of the solder core, wherein the antioxidant metal layer is a gold (Au) layer having a thickness of not less than 0.01 mu m and less than 1 mu m.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: providing a solder core; Forming a first metal layer on the solder core; And forming a second metal layer on the first metal layer. The first metal layer may include at least one selected from the group consisting of Ni, Ag, Zn, Sn, Cr, Sb, Pt, Pd, , Or an alloy thereof, and the second metal layer may be gold (Au).

In addition, the manufacturing method may further include treating the surface of the solder core with an acid before forming the first metal layer. The sum of the thicknesses of the first metal layer and the second metal layer may be 0.01 탆 or more and less than 1 탆.

The step of forming the first metal layer and the step of forming the second metal layer may be performed by electroplating or electroless plating.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: providing a substrate having a bonding pad; Providing a solder ball for fluxless bonding on the bonding pad; And reflowing the solder ball for fluxless joining. Here, the fluxless solder ball may include a solder core; A first metal layer on the surface of the solder core; And a second metal layer on the first metal layer. The first metal layer may include at least one selected from the group consisting of Ni, Ag, Zn, Sn, Cr, Sb, Pt, Pd, ), Or an alloy thereof, and the second metal layer is gold (Au).

In particular, in the solder bump forming method, the step of applying a flux for removing the native oxide film on the solder ball may not be included. Further, the reflowing may be performed at a temperature of 180 ° C to 300 ° C for about 1 second to about 1 minute. Also, the reflowing step may not have a pre-heating period.

Further, the reflowing step includes raising the temperature of the solder ball from the room temperature to the reflow temperature. At this time, the temperature of the solder ball may increase linearly with time from the room temperature to the reflow temperature or increase with a convex shape profile.

By using the solder ball for fluxless bonding according to the present invention, a reliable solder bump can be formed through a simpler process at a lower cost in a shorter time.

1 is a cross-sectional side view conceptually illustrating a solder ball for fluxless bonding according to an embodiment of the present invention.
2 is a side cross-sectional view illustrating a solder ball for fluxless bonding according to another embodiment of the present invention.
3 is a flowchart illustrating a method of manufacturing a solder ball for fluxless bonding in accordance with an embodiment of the present invention.
4 is a flowchart illustrating a method of forming a solder bump according to an embodiment of the present invention.
5A and 5B are side cross-sectional views sequentially illustrating a method of forming a solder bump according to an embodiment of the present invention.
FIG. 6 is a view showing a reflow temperature profile when using the solder ball for fluxless bonding according to an embodiment of the present invention and a reflow temperature profile when using the solder ball according to the related art.
FIGS. 7A and 7B are images showing the shape of the solder balls of Example 1, Comparative Example 1 and Comparative Example 2 during the dwell time and after cooling in the reflow process. FIG.
FIG. 8 is a plan view of a solder ball placed on a bonding pad according to an embodiment of the present invention, in which the solder ball normally seats as a solder bump after reflowing.
Figure 9 is a side schematic view showing preferred and undesirable exemplary profiles of reflowed solder balls.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, embodiments of the inventive concept may be modified in various other forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. Embodiments of the inventive concept are desirably construed as providing a more complete understanding of the inventive concept to those skilled in the art. The same reference numerals denote the same elements at all times. Further, various elements and regions in the drawings are schematically drawn. Accordingly, the inventive concept is not limited by the relative size or spacing depicted in the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and conversely, the second component may be referred to as a first component.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the inventive concept. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the expressions "comprising" or "having ", etc. are intended to specify the presence of stated features, integers, steps, operations, elements, parts, or combinations thereof, It is to be understood that the invention does not preclude the presence or addition of one or more other features, integers, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept belongs, including technical terms and scientific terms. In addition, commonly used, predefined terms are to be interpreted as having a meaning consistent with what they mean in the context of the relevant art, and unless otherwise expressly defined, have an overly formal meaning It will be understood that it will not be interpreted.

If certain embodiments are otherwise feasible, the particular process sequence may be performed differently from the sequence described. For example, two processes that are described in succession may be performed substantially concurrently, or may be performed in the reverse order to that described.

In the accompanying drawings, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Accordingly, embodiments of the present invention should not be construed as limited to any particular shape of the regions shown herein, but should include variations in shape resulting from, for example, manufacturing processes. All terms "and / or" as used herein encompass each and every one or more combinations of the recited elements. In addition, the term "substrate" as used herein can mean a substrate itself, or a laminated structure including a substrate and a predetermined layer or film formed on the surface thereof. Further, in the present specification, the term "surface of a substrate" may mean an exposed surface of the substrate itself, or an outer surface such as a predetermined layer or a film formed on the substrate.

"Principal component" means that, based on atomic%, the component accounts for the largest atomic percentage of the constituent materials of the total material.

The present invention provides a solder ball for fluxless joining comprising a first metal layer and a second metal layer sequentially on a solder core. The term "for fluxless bonding" means that when the substrate, the semiconductor device, the substrate and the substrate, or the semiconductor device and the semiconductor device are physically connected using the solder ball, the natural oxide film existing on the surface of the conductor is removed This means that it is not necessary to apply a flux for the flux.

1 is a side cross-sectional view conceptually showing a solder ball 100 for fluxless bonding according to an embodiment of the present invention.

Referring to FIG. 1, the fluxless solder ball 100 may include a first metal layer 110 on a solder core 130 and a second metal layer 120 on the first metal layer 110.

The solder core 130 may be any of a tin (Sn) -nickel (Ni) alloy, a tin (Sn) A Sn-Bi alloy, a Sn-Bi alloy, a Sn-Ag alloy, a Sn-Bi alloy, a Sn-Cu alloy, a Sn-Zn alloy, a Sn- Sn-Ag-Cu-Bi alloy, Sn-Zn-Bi alloy, Sn-Ag-Cu-Sb alloy, Sn-Ag- Au-indium (In) alloy, Zn-Al alloy, Au-germanium (Ge) -Sn alloy, Bi-Sb alloy and the like. In some embodiments, the solder core 130 may be a tin-based tin-based solder core.

The melting point of the solder core 130 may be about 180 ° C to about 250 ° C. When the melting temperature of the solder core 130 is not constant, the molten state can be maintained in a temperature range of about 180 ° C to about 300 ° C.

The solder core 130 may have a diameter D1 of about 100 [mu] m to about 800 [mu] m. In some embodiments, the diameter D1 of the solder core 130 may be, for example, from about 100 [mu] m to about 500 [mu] m. In some embodiments, the diameter D1 of the solder core 130 may be, for example, from about 200 [mu] m to about 400 [mu] m.

A first metal layer 110 may be provided on the solder core 130. The first metal layer 110 may be formed directly on the solder core 130 or may be formed on the solder core 130 through another material layer. The first metal layer 110 may be formed of at least one selected from the group consisting of Ni, Ag, Zn, Sn, Cr, Sb, Pt, Pd), and aluminum (Al).

The thickness of the first metal layer 110 may be, for example, about 0.002 μm to about 0.1 μm.

If the thickness of the first metal layer 110 is too small, a portion of the surface of the solder core 130 may be partially exposed. The first metal layer 110 may function to attach a second metal layer 120, which will be described later, to the surface of the solder core 130 well. Therefore, when the surface of the solder core 130 is exposed to the outside of the first metal layer 110, the second metal layer 120 may not adhere well to the solder core 130.

On the other hand, if the first metal layer 110 is too thick, dissolution of the first metal layer 110 and the second metal layer 120 and the solder core 130 during reflow may occur incompletely .

A second metal layer 120 may be provided on the first metal layer 110. The second metal layer 120 may be formed directly on the first metal layer 110. The second metal layer 120 may be gold (Au) or palladium (Pd). The second metal layer 120 may be a metal different from the first metal layer 110. The second metal layer 120 may be gold (Au). However, the present invention is not limited thereto.

The thickness of the second metal layer 120 may be about 0.005 μm to about 0.9 μm.

If the thickness of the second metal layer 120 is too small, there may be a portion where the surfaces of the solder core 130 and / or the surface of the first metal layer 110 are exposed. The second metal layer 120 may function as an oxidation-preventing metal layer for preventing the solder core 130 and the first metal layer 110 from being naturally oxidized due to oxygen or the like in the atmosphere. Therefore, when the surface of the solder core 130 and / or the first metal layer 110 is exposed to the outside of the second metal layer 120, the surface is discolored and the bonding strength with the pad is reduced due to the natural oxide film Can occur.

On the contrary, if the thickness of the second metal layer 120 is too large, the first and second metal layers 110 and 120 and the solder core 130, which occur during reflow, may be incompletely melted.

The sum of the thickness of the first metal layer 110 and the thickness of the second metal layer 120 may be about 0.01 탆 or more and less than about 1 탆. If the sum of the thicknesses of the first metal layer 110 and the second metal layer 120 is less than 0.01 mu m, the effect of eliminating the need for flux during application of the solder ball 100 may be insufficient. If the sum of the thicknesses of the first metal layer 110 and the second metal layer 120 is 1 탆 or more, the solder ball 100 may be weakly bonded or not bonded to the conductive pad.

In some embodiments, the first metal layer 110 may be omitted and only the second metal layer 120 may be present. In this case, the second metal layer 120 may have a thickness of about 0.01 μm or more and less than about 1 μm.

2 is a side cross-sectional view showing a solder ball 200 for fluxless bonding according to another embodiment of the present invention.

Referring to FIG. 2, the fluxless solder ball 200 may include a first metal layer 210 and a second metal layer 220 on the solder core 230 in order. Further, the solder core 230 may further include a core ball 240 for support.

The support core ball 240 may be made of a general metal or an organic material, and may be an organic / organic composite material or an organic / inorganic composite material. The material of the support core ball 240 is not particularly limited and may be a material which is not melted at a temperature of 300 ° C or lower.

For example, the core ball 240 for supporting the organic material may be a core ball 240 made of a plastic material, and the core ball 240 made of plastic may be formed of epoxy, melamine-formaldehyde, benzoguanamine - plastic cores comprising thermosetting resins such as formaldehyde, divinylbenzene, divinyl ether, oligo or polydiacrylates, alkylene bisacrylamide resins, polyvinyl chloride, polyethylene, polystyrene, nylon, A plastic core including the same thermoplastic resin, an elastic core such as natural rubber and synthetic rubber, and the like. And a plastic core formed of a resin mixed with a thermosetting resin and a thermoplastic resin.

Meanwhile, the plastic core ball 240 may be formed using a polymer synthesis method. As an example, it may be formed to have a diameter of about 20 탆 to about 300 탆 by a synthesis method such as suspension, emulsification, dispersion polymerization and the like.

The support core ball 240 made of a metal may be made of, for example, pure Cu or an alloy of Cu.

3 is a flowchart illustrating a method of manufacturing a solder ball for fluxless bonding in accordance with an embodiment of the present invention.

Referring to FIG. 3, a solder core 130 is provided (S1). Since the solder core 130 has been described in detail with reference to FIGS. 1 and 2, a detailed description thereof will be omitted.

When the solder core 130 is stored in a standby state, a natural oxide film may be formed on the surface. Since the natural oxide film may interfere with plating, deposition and bonding of other metal materials, the natural oxide film is removed through acid treatment (S2).

The acid may be, for example, hydrofluoric acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or a combination thereof, although the present invention is limited thereto It is not.

Next, a first metal layer 110 is formed on the solder core 130 (S3). The first metal layer 110 may be formed by plating, deposition, or the like. In some embodiments, the first metal layer 110 may be formed by performing an electroplating or electroless plating process.

A brightener may be used to improve the roughness of the surface of the first metal layer 110 when the first metal layer 110 is formed. That is, by using a luster material, a first metal layer 110 having a more smooth surface can be obtained. The luster material includes, for example, an oxygen-containing organic compound such as a polyether compound such as polyethylene glycol; Nitrogen-containing organic compounds such as tertiary amine compounds and quaternary ammonium compounds; And / or a sulfur-containing organic compound having a sulfonate group, and the like.

However, since the smoothness of the first metal layer 110 obtained using the polishing material may adversely affect the adhesion between the first metal layer 110 and the second metal layer 120, The use of a luster material may be omitted.

1 and 2, the first metal layer 110 may be formed of a metal such as nickel (Ni), silver (Ag), zinc (Zn), tin (Sn), chromium (Cr) May be a metal such as antimony (Sb), platinum (Pt), palladium (Pd), aluminum (Al), and may have a thickness of, for example, from about 0.002 μm to about 0.1 μm.

Next, a second metal layer 120 is formed on the first metal layer 110 (S4). The second metal layer 120 may be formed by plating, vapor deposition, or the like. In some embodiments, the second metal layer 120 may be formed by performing an electroplating or electroless plating process. The second metal layer 120 may be gold (Au) or palladium (Pd), and may have a thickness of, for example, about 0.005 μm to about 0.9 μm. In some embodiments, when only the second metal layer 120 is formed without forming the first metal layer 110, the second metal layer 120 may be formed to have a thickness of 0.01 탆 or more and less than 1 탆 .

After the formation of the second metal layer 120 is completed, a cleaning and drying process can be performed.

4 is a flowchart illustrating a method of forming a solder bump according to an embodiment of the present invention. 5A and 5B are side cross-sectional views sequentially illustrating a method of forming a solder bump according to an embodiment of the present invention.

Referring to Figs. 4 and 5A, a substrate 101 having bonding pads 105 is provided (SP1).

The substrate 101 may be a package substrate or a semiconductor substrate. Furthermore, the substrate 101 may be a glass substrate.

When the substrate 101 is a semiconductor substrate, the substrate 101 may include at least one of a III-V material and a IV material. The III-V material may be a binary, ternary, or quaternary compound comprising at least one Group III element and at least one Group V element. The III-V material may be a compound containing at least one element of In, Ga and Al as a group III element and at least one element of As, P and Sb as a group V element. For example, the Group III-V material can be selected from InP, In z Ga 1-z As (0 ≤ z ≤ 1), and Al z Ga 1-z As ( 0 ≤ z ≤ 1). The binary compound may be, for example, InP, GaAs, InAs, InSb or GaSb. The ternary compound may be any one of InGaP, InGaAs, AlInAs, InGaSb, GaAsSb and GaAsP. The Group IV material may be Si and / or Ge. However, the III-V material and the IV material usable for forming the thin film according to the technical idea of the present invention are not limited to those illustrated above.

When the substrate 101 is a package substrate, the substrate 101 may be a printed circuit board (PCB), a ceramic substrate, or an interposer. The printed circuit board may be a flexible printed circuit board (FPCB) or a rigid printed circuit board (PCB).

When the substrate 101 is a printed circuit board, the substrate 101 may include a substrate base, and bonding pads 105 formed on at least one side of the top and bottom surfaces. The bonding pads 105 may be exposed by a solder resist layer covering the upper and lower surfaces of the substrate base. The substrate base may be made of at least one material selected from phenol resin, epoxy resin, and polyimide. For example, the substrate base can be made of FR4, tetrafunctional epoxy, polyphenylene ether, epoxy / polyphenylene oxide, bismaleimide triazine (BT) A thermometer, a cyanate ester, a polyimide, and a liquid crystal polymer. The term " thermostable material " The bonding pad 105 may be made of Ni / Au, Cu-OSP bare copper, ENIG, and ENEPIG. Internal wirings electrically connected to the bonding pads 105 may be formed on the substrate base. The internal wiring may be formed in the substrate base, but not limited thereto, and may be formed on the upper surface and / or the lower surface of the substrate base and covered with the solder resist layer. The bonding pad 105 may be a portion exposed by the solder resist layer of each of the patterned circuit wirings after the Cu foil is applied to the top and bottom surfaces of the substrate base.

When the substrate 101 is an interposer, the substrate base may be formed from, for example, a silicon wafer.

Subsequently, a solder ball 100 for fluxless bonding is provided on the bonding pad 105 (SP2). Since the solder ball 100 for fluxless bonding has been described with reference to FIG. 1, a detailed description thereof will be omitted. In FIG. 5A, the solder ball 100 for fluxless bonding shown in FIG. 1 is disposed, but the solder ball 200 for fluxless bonding in FIG. 2 may be disposed.

Referring to FIGS. 4 and 5B, the solder ball 100 may be reflowed (SP3).

The temperature of the solder ball 100 and / or the temperature of the space in which the reflow progresses are raised to reflow the solder ball 100. When the temperature of the solder ball 100 exceeds the reflow temperature of the solder core 130, the shape of the solder ball 100 may be deformed to become the solder bump 100a. After the solder ball 100 is sufficiently reflowed, the temperature can be lowered to harden the solder bump 100a.

The reflowing may be performed by heating the solder ball 100 at a temperature ranging from about 180 DEG C to about 300 DEG C for about 1 second to about 1 minute.

When the solder bumps are formed on the bonding pads using the fluxless solder balls 100 and 200, a flux application step for removing the native oxide film on the solder ball surface is unnecessary and not performed.

When the temperature of the solder ball 100 is raised for reflow, the solder core starts melting at a temperature of about 218 DEG C in the case of a solder ball having a melting point, e.g., a SAC305 composition, and the metal layer of the first and second metal layers Are mutually melted and intermixed with the solder core.

Whereby the solder balls can be favorably bonded to the bonding pads 105. More specifically, the flowable solder ball comes into contact with the entire upper surface of the bonding pad 105 while having wettability with the bonding pad 105. In addition, the free surface side forms a solder bump 100a in a rounded shape in order to minimize its surface energy.

FIG. 6 is a view showing a reflow temperature profile when using the solder balls 100 and 200 for fluxless bonding according to an embodiment of the present invention and a reflow temperature profile when using a solder ball according to the related art, respectively.

6, it is necessary to reflow the solder ball 100 according to the temperature profile of the path OABCDO "by using the solder ball according to the related art. However, when the solder ball 100, 200 for fluxless soldering according to the embodiments of the present invention is used It may be sufficient to just reflow along the temperature profile of O'-BCDO.

More specifically, using a solder ball according to the prior art, a step of providing a flux to remove it is required prior to the reflow step because a natural oxide film is formed on the surface, and in the reflow step, Pre-heating time for activation is required.

That is, the temperature of the solder ball is increased to the pre-heating temperature (OA), and the temperature is maintained during the pre-heating time (AB). During the pre-heating time (AB), the flux present on the surface of the solder ball is activated to remove the native oxide film. After the natural oxide film is sufficiently removed, the temperature of the solder ball can be raised to a temperature higher than the reflow temperature Trf (BC). The reflow temperature Trf may be the lowest temperature at which reflow of the solder ball can occur. Therefore, the solder ball may have fluidity at the reflow temperature (Trf) or higher.

During the reflow time during which the temperature of the solder ball is maintained above the reflow temperature Trf, the solder ball may be reflowed. When the heating of the solder ball is stopped (point of time D) in consideration of the difference between the temperature of the solder ball and the reflow temperature Trf and the cooling rate, the reflowed solder bump is gradually cooled and the reflow temperature Trf And hardened.

In the case of using the solder balls 100 and 200 for fluxless bonding according to the embodiments of the present invention, it is not necessary to use an expensive flux because a pre-heating time is unnecessary and the temperature is raised to a temperature higher than the reflow temperature Trf It may be enough to make it.

More specifically, at time O ', the temperature of the solder ball is raised from the room temperature. The solder ball can then be reflowed (CD) for a period of time (O'C) after raising the temperature of the solder ball above the reflow temperature (Trf). In some embodiments, the temperature of the solder ball may increase linearly with time from room temperature to reflow temperature. Although the temperature profile shown in Fig. 6 is shown linearly increasing the temperature in the O'C section to raise the temperature of the solder balls, in some embodiments, the temperature can rise with a convexly shaped temperature profile have. Here, the convex shape of a certain temperature profile means that the temperature profile between the two points on the profile is located above the straight line when the two points are connected by a straight line.

The time at which the solder ball stays at a temperature higher than the reflow temperature is called a dwell time. That is, the time indicated by the reflow time in FIG. 6 may be referred to as a dwell time. The solder ball may reflow during the dwell time to form the solder bump 100a (see FIG. 5B).

Comparing the solder balls according to the prior art and the fluxless solder balls according to the embodiments of the present invention, the solder balls according to the prior art require a time of OO "for reflow, while the flux ball according to the embodiments of the present invention, The solder ball for bonding may be sufficient only for the time of O'O ". Since the time OO 'required for activation of the flux reaches about 1/3 to about 1/2 of the total time OO required for reflow, using the solder ball for fluxless bonding according to the embodiment of the present invention allows a considerable time It is possible to save energy and maintain high productivity, and it is also possible to save energy consumed in pre-heating, thereby contributing to reduction of production cost.

Further, in the case of using flux, a cleaning process for removing flux after completion of reflow is separately required. Even if the cleaning process is performed, a small amount of flux may remain, which may cause product corrosion.

On the other hand, when the solder ball for fluxless bonding according to the embodiments of the present invention is used, the cleaning process for removing the flux can be omitted and the problem caused by the flux residue can be prevented.

Hereinafter, the constitution and effects of the present invention will be described in more detail with reference to specific examples and comparative examples. However, these examples are merely intended to clarify the present invention and are not intended to limit the scope of the present invention.

A first metal layer and a second metal layer were formed on a tin lead free solder ball surface having a diameter of 250 탆 of 3% Ag and 0.5% Cu as shown in Table 1 below. In the case where there is no corresponding metal layer for the first metal layer and the second metal layer, X is indicated.

The bonding performance test for the Ni / Au pad finish was then performed. In order to perform the bonding performance test, solder balls were provided on the Ni / Au pad fishy without flux application, and reflow was performed at 240 ° C for 30 seconds.

<Table 1>

Figure pat00001

As a result of the bonding performance test, it was found that the solder core itself (Comparative Example 1) in which neither the first metal layer nor the second metal layer was present as shown in Table 1 was inapplicable without flux application. It was also found that solder balls having no second metal layer of gold on their surfaces were not able to be bonded (Comparative Examples 3 and 4), or that bonding was weak due to instability even when bonding occurred (Comparative Example 5).

In the case where only the second metal layer (gold) is present without the first metal layer, it has been shown that the joining is performed well in a predetermined thickness range (Examples 12 to 14), but when the thickness is excessively thick or thin, (Comparative Examples 6 and 7). This is presumed to be due to the fact that if the thickness of the second metal layer is excessively thin, the antioxidant effect is insufficient and if it is excessively thick, the dissolution of the solder core and the second metal layer during reflow becomes weak.

Further, when the sum of the thicknesses of the first metal layer and the second metal layer is excessively large (Comparative Examples 2, 8, and 9), bonding with the bonding pad was found to be impossible. This is presumably because the thicknesses of the first metal layer and the second metal layer are excessively thick and the first metal layer and the second metal layer not sufficiently melted together with the solder core in the reflow time.

FIGS. 7A and 7B are images showing the shape of the solder balls of Example 1, Comparative Example 1 and Comparative Example 2 during the dwell time and after cooling in the reflow process. FIG. 7B is a view of the solder balls of FIG.

In the case of Example 1, it was found that the solder ball was appropriately bonded to the bonding pad while being subjected to the reflow process, thereby deviating from the original sphere. In the case of Comparative Example 1 and Comparative Example 2, it was observed that the original spherical shape was kept almost unchanged, and the unbonded state was observed.

Also, the solder balls of Examples 1 to 11 and Comparative Examples 1 to 9 were subjected to a high temperature discoloration experiment to observe discoloration after being left at high temperature (125 DEG C) for 48 hours in atmospheric conditions. The discoloration was judged by observing the initial illuminance value and the illuminance value after 48 hours. The roughness value was measured using a roughness meter. When the roughness value after the leaving was changed from 0 to 2 in the initial roughness value, it was judged that there was substantially no discoloration ("X"). It was judged that there was slight discoloration ("DELTA") when the illuminance value was changed from 3 to 9, and that the discoloration was severe ("O ") when the illuminance value was changed by 10 or more.

As shown in Table 1, a slight discoloration was observed in the solder ball of Comparative Example 1 in which no metal layer was formed on the surface, and a considerable discoloration was observed in the solder ball of Comparative Example 3 in which a metal layer of nickel was formed on the surface. This discoloration is due to oxidation, and it can be seen that the metal layer of nickel is more susceptible to oxidation than the solder core under normal atmospheric conditions.

Further, the solder balls of Examples 1 to 11 and Comparative Examples 1 to 9 were subjected to a high temperature and high humidity discoloration experiment to observe discoloration after standing at high temperature (125 ° C) under high humidity (85%) condition for 48 hours. The measurement method and the determination method of the illuminance value were performed in the same manner as the high temperature discoloration experiment.

As shown in Table 1, in the high-temperature and high-humidity conditions, the solder core (Comparative Example 1) also showed significant discoloration. Particularly, referring to specific experimental data, the solder balls of Comparative Example 1 were more discolored than the solder balls of Comparative Example 3. Specifically, the solder ball of Comparative Example 1 had an initial roughness value of 75, but after being left for 48 hours, it was reduced to 43. The solder ball of Comparative Example 3 had an initial roughness value of 75, but dropped to 51 after being left for 48 hours. Thus, the solder core of Comparative Example 1 in which no metal layer was formed was found to be particularly vulnerable to high humidity conditions.

FIG. 8 is a plan view of a solder ball placed on a bonding pad according to an embodiment of the present invention, in which the solder ball normally seats as a solder bump after reflowing. Figure 9 is a side schematic view showing preferred and undesirable exemplary profiles of reflowed solder balls.

Referring to FIG. 8 (a), the solder balls of Example 1 were arranged on a bonding pad having a width larger than a proper width with respect to the size of the solder ball, and then reflowed. As a result, as shown in FIG. 8 (b), all the wettability was properly covered to cover the entire bonding pad.

9, when the wettability of the solder ball is insufficient, the solder bump 100c covering only a part of the upper surface of the bonding pad 305 may be formed by performing reflow on the bonding pad 305 having a relatively larger size than the solder ball . On the other hand, when the wettability of the solder ball is sufficient, the solder bump 100b that covers the entire upper surface of the bonding pad 305 by reflow is obtained even on the relatively large-sized bonding pad 305 as compared with the solder ball.

Referring to FIG. 8 (b) again, solder balls according to embodiments of the present invention have adequate wettability in that solder bumps are formed covering the whole of a relatively large bonding pad area after reflow. have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. The present invention may be modified in various ways. Therefore, modifications of the embodiments of the present invention will not depart from the scope of the present invention.

The solder balls 100 and 100 are solder bumps. The solder bumps 101 and the solder bumps 101 are electrically connected to the solder bumps 101 through the solder bumps 101 and the solder bumps 101, respectively.

Claims (16)

Solder core;
A first metal layer on the surface of the solder core; And
A second metal layer on the first metal layer;
/ RTI &gt;
The first metal layer may include at least one of nickel, silver, zinc, tin, chromium, antimony, platinum, palladium, aluminum, Or an alloy thereof,
And the second metal layer is gold (Au). The method according to claim 1,
Wherein the sum of the thicknesses of the first metal layer and the second metal layer is 0.01 占 퐉 or more and less than 1 占 퐉. 3. The method of claim 2,
Wherein a thickness of the second metal layer is 0.005 탆 or more and 0.9 탆 or less. The method according to claim 1,
Wherein the melting point of the solder core is 180 ° C to 250 ° C. The method according to claim 1,
Wherein the solder ball for fluxless bonding further comprises a core ball for support inside the solder core. 6. The method of claim 5,
Wherein the support core ball is made of a material which is not melted at a temperature of 300 DEG C or less. Providing a solder core;
Forming a first metal layer on the solder core; And
Forming a second metal layer on the first metal layer;
Lt; / RTI &gt;
The first metal layer may include at least one of nickel, silver, zinc, tin, chromium, antimony, platinum, palladium, aluminum, Or an alloy thereof,
Wherein the second metal layer is gold (Au). 8. The method of claim 7,
Further comprising the step of treating the surface of the solder core with an acid prior to the step of forming the first metal layer. 8. The method of claim 7,
Wherein the sum of the thicknesses of the first metal layer and the second metal layer is 0.01 占 퐉 or more and less than 1 占 퐉. 8. The method of claim 7,
Wherein the step of forming the first metal layer and the step of forming the second metal layer are performed by electroplating or electroless plating. Providing a substrate having a bonding pad;
Providing a solder ball for fluxless bonding on the bonding pad; And
Reflowing the solder balls for fluxless bonding;
Lt; / RTI &gt;
The fluxless solder ball for solder joints,
Solder core;
A first metal layer on the surface of the solder core; And
A second metal layer on the first metal layer;
/ RTI &gt;
The first metal layer may include at least one of nickel, silver, zinc, tin, chromium, antimony, platinum, palladium, aluminum, Or an alloy thereof,
And the second metal layer is gold (Au). 12. The method of claim 11,
Wherein the step of applying a flux for removing the native oxide film on the solder ball is not included. 12. The method of claim 11,
Wherein the reflowing step is performed at a temperature of 200 캜 to 300 캜 for about 1 second to about 1 minute. 14. The method of claim 13,
Wherein a solder bump can be formed even if there is no pre-heating period in the reflow step. 14. The method of claim 13,
Wherein the reflowing step includes raising the temperature of the solder ball from the room temperature to the reflow temperature,
Wherein the temperature of the solder ball increases linearly with time from the room temperature to the reflow temperature or increases with a convex shape profile. Solder core; And
An anti-oxidation metal layer on the surface of the solder core;
/ RTI &gt;
Wherein the oxidation-preventing metal layer is a gold (Au) layer having a thickness of 0.01 mu m or more and less than 1 mu m.

KR1020160013531A 2015-02-25 2016-02-03 Solder ball for fluxless bonding, method of manufacturing the same, and method of forming a solder bump KR101811992B1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US15/050,708 US20160244891A1 (en) 2015-02-25 2016-02-23 Solder ball for fluxless bonding, method of manufacturing the same, and method of forming solder bump
TW105105336A TW201633480A (en) 2015-02-25 2016-02-24 Solder ball for fluxless bonding, method of manufacturing the same, and method of forming solder bump
JP2016033528A JP2016155173A (en) 2015-02-25 2016-02-24 Solder ball for non-flux joining, production method of the same and solder bump formation method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR20150026734 2015-02-25
KR1020150026734 2015-02-25

Publications (2)

Publication Number Publication Date
KR20160103922A true KR20160103922A (en) 2016-09-02
KR101811992B1 KR101811992B1 (en) 2017-12-26

Family

ID=56943097

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020160013531A KR101811992B1 (en) 2015-02-25 2016-02-03 Solder ball for fluxless bonding, method of manufacturing the same, and method of forming a solder bump

Country Status (2)

Country Link
KR (1) KR101811992B1 (en)
TW (1) TW201633480A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3967443A1 (en) * 2020-09-10 2022-03-16 Senju Metal Industry Co., Ltd. Core material, electronic component and method for forming bump electrode

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6376266B1 (en) * 2017-10-24 2018-08-22 千住金属工業株式会社 Nuclear material, solder joint and bump electrode forming method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101049520B1 (en) * 2011-03-04 2011-07-15 덕산하이메탈(주) Core solder balls, method of manufacturing core solder balls and electronic parts using the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3967443A1 (en) * 2020-09-10 2022-03-16 Senju Metal Industry Co., Ltd. Core material, electronic component and method for forming bump electrode
US11495566B2 (en) 2020-09-10 2022-11-08 Senju Metal Industry Co., Ltd. Core material, electronic component and method for forming bump electrode

Also Published As

Publication number Publication date
TW201633480A (en) 2016-09-16
KR101811992B1 (en) 2017-12-26

Similar Documents

Publication Publication Date Title
JP2016155173A (en) Solder ball for non-flux joining, production method of the same and solder bump formation method
US20190088611A1 (en) &#34;Lead-Free Solder Ball&#34;
US8242378B2 (en) Soldering method and related device for improved resistance to brittle fracture with an intermetallic compound region coupling a solder mass to an Ni layer which has a low concentration of P, wherein the amount of P in the underlying Ni layer is controlled as a function of the expected volume of the solder mass
KR100722645B1 (en) Method for manufacturing printed circuit board for semi-conductor package and printed circuit board manufactured therefrom
US10090268B2 (en) Method of forming solder bump, and solder bump
US7812460B2 (en) Packaging substrate and method for fabricating the same
US8022530B2 (en) Package substrate having electrically connecting structure
US9078382B2 (en) Method of producing circuit board
KR101528030B1 (en) Stud bump structure and method for manufacturing the same
US20070172690A1 (en) Joining method, method of mounting semiconductor package using the same, and substrate-joining structure prepared by the joining method
KR101460914B1 (en) Semiconductor device
KR20120102803A (en) Lead-free solder joint structure and solder ball
US8486760B2 (en) Method of manufacturing substrate for flip chip and substrate for flip chip manufactured using the same
US20120175772A1 (en) Alternative surface finishes for flip-chip ball grid arrays
KR101811992B1 (en) Solder ball for fluxless bonding, method of manufacturing the same, and method of forming a solder bump
JP2004349487A (en) Conductive ball and method for forming electrode of electronic component, and electronic component and electronic equipment
US20170162555A1 (en) Solder composition and semiconductor package including the same
EP2820596B1 (en) Printed circuit board for memory card
JP4888096B2 (en) Semiconductor device, circuit wiring board, and manufacturing method of semiconductor device
KR20130142170A (en) Method for manufacturing sn alloy bump
KR102345867B1 (en) Methods of Forming Nuclear Materials, Electronic Components and Bump Electrodes
KR100743190B1 (en) Lead-free solder with low boiling point and method of producing same
JP2018181939A (en) Mounting structure of semiconductor component
JP2017120839A (en) Conductive bonding sheet and method for producing conductive bonding sheet
US20120280023A1 (en) Soldering method and related device for improved resistance to brittle fracture

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E701 Decision to grant or registration of patent right
GRNT Written decision to grant