KR101549810B1 - Leader-free solder and semiconductor component comprising the same - Google Patents

Abstract

More particularly, the present invention relates to a lead-free solder and a semiconductor component including the lead-free solder. More particularly, the present invention relates to a lead-free solder comprising 0.5 to 1.0 wt% of copper (Cu) and 0.001 to 0.1 wt% of palladium (Pd) Sn) and a semiconductor component containing the same. The present invention has the effect of obtaining a lead-free solder which is not only environmentally friendly but also excellent in high-temperature stability and excellent in wettability and thus useful for automotive semiconductor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lead-free solder and a semiconductor component including the lead-

The present invention relates to a lead-free solder and a semiconductor component including the lead-free solder, and more particularly to a lead-free solder which is not only environmentally friendly but also excellent in high temperature stability and excellent in wettability, .

BACKGROUND ART [0002] A printed circuit board (PCB) is widely used in household appliances such as televisions, mobile phones, and computers, but recently it has been widely used in automobiles. Lead (Sn) - lead (Pb) alloy products have been widely used as solders in household electrical appliances. Lead has been used as a component to determine the wettability, strength and mechanical properties of alloys. The melting point can be lowered to 183 DEG C, thereby preventing thermal damage occurring during the soldering process of electronic parts and semiconductor processes.

Meanwhile, tin (Sn) - silver (Ag) -copper (Cu) ternary lead-free solder alloys have been proposed due to the strict regulations regarding lead-related environmental problems. However, they are vulnerable to oxidation and have spreadability and wettability The workability is poor and the resistance against impact is weak. Also, it is not suitable for the high temperature environment of 130 ° C or higher like the automobile engine room, and silver (Ag) is included and the price is high.

U.S. Patent No. 7,682,468 U.S. Patent No. 7,488,445

A first object of the present invention is to provide a lead-free solder which is excellent in high-temperature stability and is excellent in wettability and thus can be used for automotive semiconductor.

A second object of the present invention is to provide a solder paste which is excellent in high-temperature stability and is excellent in wettability and thus can be used in automotive semiconductors.

A third object of the present invention is to provide a semiconductor component which is excellent in high-temperature stability and is excellent in wettability and thus can be used for an automotive semiconductor.

In order to achieve the first technical object of the present invention, there is provided a lead-free solder comprising 0.5 wt% to 1.0 wt% of copper (Cu) and 0.001 wt% to 0.1 wt% of palladium (Pd) do.

The lead-free solder may further include 0.01 wt% to 0.5 wt% of chromium (Cr). Optionally, the lead-free solder may further comprise from 0.001% to 0.2% by weight of calcium (Ca).

In particular, the lead-free solder may be a non-silver based material not containing silver. Further, the elongation of the lead-free solder may be about 20% to about 30%.

In order to achieve the second technical object, the present invention provides a method for manufacturing a lead-free solder, which comprises 5 parts by weight to 25 parts by weight of flux, 100 parts by weight of lead-free solder, 0.5 to 1.0% by weight of copper (Cu) And 100 parts by weight of lead-free solder containing 0.001 wt% to 0.1 wt% of lead (Pd) and the balance tin (Sn).

According to a third aspect of the present invention, there is provided a plasma display panel comprising: a substrate having a plurality of first terminals formed therein; A semiconductor device mounted on the substrate and having a plurality of second terminals corresponding to the plurality of first terminals; And solder bumps connecting the corresponding first terminals and the second terminals respectively, wherein the solder bumps comprise 0.5 wt% to 1.0 wt% of copper (Cu) and 0.001 wt% to 0.1 wt% of palladium (Pd) , And the remainder is tin (Sn).

The present invention has the effect of obtaining a lead-free solder which is not only environmentally friendly but also excellent in high-temperature stability and excellent in wettability and thus useful for automotive semiconductor.

1 shows a semiconductor component according to an embodiment of the present invention.
FIGS. 2A to 2D are cross-sectional photographs showing the results of testing the wettability of lead-free solder prepared according to Comparative Examples 1, 1, 2, and 4, respectively.

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.

In the examples of the present invention, the weight% (wt%) is a percentage of the weight of the total alloy in terms of the weight of the total alloy.

The lead-free solder according to an embodiment of the present invention may include copper (Cu) and palladium (Pd) with tin (Sn) as a main component. More specifically, the lead-free solder according to one embodiment of the present invention may include about 0.5 wt% to about 1.0 wt% copper and about 0.001 wt% to about 0.1 wt% palladium, with the remainder being tin.

Herein, the term "main component" means that the component is a component having more than 50% by weight of the entire alloy. In addition, the lead-free solder according to the embodiments of the present invention may contain trace amounts of impurity elements.

Copper can affect the tensile strength of the solder. If the content of copper is too low, it may be difficult to increase the tensile strength of the solder as desired. If the content of copper is too high, the solder may harden and breakage of the tissue may easily occur.

In addition, copper can affect the high temperature stability of the solder. If the content of copper is too low, it may be thermally fragile and damaged at high temperatures. If the content of copper is too large, dross may occur and soldering may become difficult.

The lead-free solder according to one embodiment of the present invention may contain from about 0.6% to about 0.8% copper by weight. The lead-free solder according to one embodiment of the present invention may contain about 0.7 wt% copper.

The lead-free solder according to one embodiment of the present invention may contain about 0.005 wt% to about 0.05 wt% of palladium. The lead-free solder according to one embodiment of the present invention may contain about 0.005 wt% to about 0.05 wt% of palladium. The lead-free solder according to one embodiment of the present invention may contain about 0.01 wt% palladium.

Palladium can affect the tensile strength of the solder. If the palladium content is too low, it may be difficult to increase the tensile strength of the solder as desired. It may also be difficult to reduce the dissolution of the electrode by the solder. If the content of palladium is too high, the solder may harden and breakage of the tissue may occur easily. Also, if the content of palladium is too large, it may be economically disadvantageous.

The lead-free solder of the present invention may contain substantially no silver (Ag). Here, it is meant that the lead-free solder does not contain "substantially" silver and may contain a small amount of silver as an inevitable impurity.

The lead-free solder of the present invention is cheaper than conventional tin (Sn) -silver (Cu) -based lead-free solder containing silver because it contains substantially no silver.

The lead-free solder according to one embodiment of the present invention may contain from about 0.01 wt% to about 0.5 wt% chromium (Cr). The lead-free solder according to one embodiment of the present invention may contain about 0.1 wt.% To about 0.3 wt.% Chromium. The lead-free solder according to one embodiment of the present invention may contain about 0.2 weight percent chromium.

Chromium can improve the mechanical strength of the solder. Chromium can also affect the wettability of the solder. If the chromium content is too low, it may be difficult to increase the mechanical strength and wettability of the solder as desired. It may also be difficult to reduce the dissolution of the electrode by the solder. If the chromium content is too high, it can be economically disadvantageous.

The lead-free solder according to one embodiment of the present invention may contain about 0.001 wt% to about 0.2 wt% calcium (Ca). The lead-free solder according to an embodiment of the present invention may contain about 0.10 wt% to about 0.18 wt% calcium. The lead-free solder according to one embodiment of the present invention may contain about 0.15 wt% calcium.

Calcium can affect the mechanical strength of the solder. If the calcium content is too low, it may be difficult to increase the mechanical strength of the solder as desired. If the calcium content is too high, the wettability may deteriorate.

The lead-free solder may have an elongation of about 20% to about 30%. If the elongation percentage of the lead-free solder is too low, the brittleness may become excessive, and it may become vulnerable to an external impact. If the elongation percentage of the lead-free solder is too high, the tensile strength may be insufficient.

Another aspect of the invention provides a solder paste. The solder paste may include about 5 to about 25 parts by weight of flux relative to 100 parts by weight of lead-free solder.

The flux may be, for example, an RMA type paste flux and may be liquid at room temperature. However, the flux is not limited thereto.

The lead-free solder may be any of the lead-free solders described above. Therefore, redundant description thereof will be omitted below.

The mixture of the lead-free solder and the flux may form a paste phase at room temperature.

In addition, the lead-free solder may be provided in the form of a solder bar or a solder ball.

Another aspect of the present invention provides a semiconductor component. 1 shows a semiconductor component 100 according to an embodiment of the present invention.

Referring to FIG. 1, a substrate 110 on which a plurality of first terminals 112 are formed is provided. The substrate 110 may be, for example, a printed circuit board (PCB) or a flexible printed circuit board (FPCB).

The plurality of first terminals 112 may be a bump pad to which a bump can be coupled, and may have a structure in which a single metal layer or a plurality of metals are stacked. The first terminals 112 may be made of copper (Cu), aluminum (Al), nickel (Ni), or an alloy of two or more thereof, but the present invention is not limited thereto.

A semiconductor device 120 having a plurality of second terminals 122 corresponding to the plurality of first terminals 112 may be mounted on the substrate 110. The second terminals 122 may be formed of any suitable material such as, for example, a flash memory, a phase change RAM (PRAM), a resistive RAM (RRAM), a ferroelectric RAM (FeRAM) (magnetic RAM, MRAM), and the like. The flash memory may be, for example, a NAND flash memory. The semiconductor device 120 may be a semiconductor chip or a stack of semiconductor chips. In addition, the semiconductor device 120 may be a semiconductor chip itself, or may be a semiconductor package in which a semiconductor chip is mounted on a package substrate and the semiconductor chip is sealed by an encapsulating material.

A plurality of the first terminals 112 and a plurality of the second terminals 122 corresponding to the first terminals 112 may be connected by the solder bumps 130. At this time, the solder bump 130 may have a composition as mentioned above.

When the substrate 110 and the semiconductor device 120 are connected by the solder bump 130 as described above, since they do not contain lead, they are not only environmentally friendly but also excellent in high temperature stability and excellent in wettability, have.

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.

<DSC analysis>

5 mg of samples having compositions as shown in Table 1 below were prepared and subjected to DSC analysis in a nitrogen atmosphere. The temperature was raised at a rate of about 5 ° C per minute per minute.

[Table 1]

As a result, as shown in Table 1, it can be seen that the undercooling temperature is almost constant irrespective of whether or not palladium, chromium, and / or calcium is added. Therefore, even if the composition of the present invention is used, it can be understood that a conventional reflow process can be used without any additional setting process.

In addition, as shown in Table 1 above, it can be seen that the high temperature stability is comparatively excellent in that the onset temperature at the time of heating is about 230 캜.

<Wettability Analysis>

The wettability was evaluated by reflowing the copper substrate with a solder ball having a diameter of 500 mu m at a temperature of 250 DEG C for 90 seconds and measuring the contact angle. As the flux, an RMA type flux was used, and the results are shown in FIGS. 2A to 2D. Fig. 2B is a result of Example 1, Fig. 2C is a result of Example 2, and Fig. 2D is a result of Example 4. The results are summarized in Table 2 below. Respectively.

[Table 2]

As shown in Table 2 above, the contact angles of Examples 1, 2 and 4 were significantly improved compared to Comparative Example 1, and the wettability was greatly improved.

<Tensile Strength>

The test pieces having the compositions of Examples 1 to 4 and Comparative Example 1 were made into No. 13A according to the KS standard, and then crosshead speeds corresponding to about 2% / min of the gage distances were measured using a tensile tester (Model: TO-102D) Tensile test was carried out. The maximum strength obtained here was evaluated by the tensile strength of the alloy, which is summarized in Table 3.

[Table 3]

As shown in Table 3, it can be seen that the tensile strength of Examples 1 to 4 is significantly improved as compared with Comparative Example 1.

&Lt; Preparation of solder paste >

Powders having the compositions of Examples 1 to 4 and Comparative Example 1 were prepared by using a vacuum gas atomizer, and then powdered with a sieve to a type 4 (type 4) having a diameter of approximately 20 to 38 탆, &Lt; / RTI &gt; At this time, the melting temperature was 550 ° C and argon (Ar) gas was used as the gas.

Then, 12 parts by weight of flux for RMA type paste was added to 100 parts by weight of the powder, and the mixture was mixed at a speed of 1000 rpm for 3 minutes and 30 seconds using a paste mixer to prepare a solder paste.

&Lt; Preparation of solder bar and solder ball &

Alloy solder bars having compositions of Examples 1 to 4 and Comparative Example 1 were prepared by using an alloy device for vacuum degassing, and the process temperature at this time was 500 ° C. In order to manufacture the alloy solder bar, a bubbling process and a vacuum degassing process were performed, followed by boiling.

Also, a solder ball having a diameter of 0.3 mm was manufactured using the alloy solder bar manufactured.

<Elongation Measurement>

The tensile strength and elongation were measured while changing the content of palladium as shown in Table 4 below. Since the measurement of the tensile strength is as described above, the detailed description is omitted here.

Elongation was measured using an Instron universal testing machine (3300 Testing Machine) according to ASTM E8.

[Table 4]

As shown in Table 4, when the content of palladium exceeds 0.1 wt% to 0.12 wt% (Comparative Example 2), the elongation becomes only 17%. When the elongation percentage is less than 20%, the brittleness is excessively high, which may be vulnerable to external impact.

In addition, it can be seen that the tensile strength of Comparative Example 1, which does not include palladium, is insufficient, and that when the palladium is contained in an amount of about 0.001% by weight (Example 6), it has a relatively excellent tensile strength.

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 present invention can be usefully used in the semiconductor industry and the automobile industry.

100: semiconductor component 110: substrate
112: first terminal 120: semiconductor device
122: second terminal 130: solder bump

Claims (8)

(Cu), 0.001 wt% to 0.2 wt% of calcium (Ca), and 0.001 wt% to 0.1 wt% of palladium (Pd), the balance being tin (Sn)
Lead-free solder that is non-silver based (Ag free). The method according to claim 1,
Further comprising 0.01 wt% to 0.5 wt% of chromium (Cr). delete delete delete The method according to claim 1,
Wherein the lead-free solder has an elongation of 20% to 30%. The flux is contained in an amount of 5 to 25 parts by weight with respect to 100 parts by weight of the lead-free solder,
Wherein 100 parts by weight of the lead-free solder is 100 parts by weight of the lead-free solder having the composition according to claim 1 or 2. A substrate on which a plurality of first terminals are formed;
A semiconductor device mounted on the substrate and having a plurality of second terminals corresponding to the plurality of first terminals; And
A solder bump connecting the corresponding first terminals and the second terminals to each other;
Lt; / RTI &gt;
Wherein the solder bump comprises 0.5 to 1.0% by weight of copper (Cu), 0.001 to 0.2% by weight of calcium (Ca) and 0.001 to 0.1% by weight of palladium (Pd) ego,
The solder bump is a non-Ag based non-silver based semiconductor component that does not include silver (Ag).

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