JP4168077B2 - Copper alloy sheet for electrical and electronic parts with excellent oxide film adhesion - Google Patents

Description

  The present invention relates to a Cu—Fe—P-based copper alloy plate having high strength and improved oxide film adhesion in order to cope with problems of package cracking and peeling. The copper alloy plate of the present invention is suitable as a material for a lead frame for a semiconductor device. In addition to the lead frame for a semiconductor device, other semiconductor components, electrical / electronic component materials such as a printed wiring board, switch parts, bus bars, It is suitably used for various electrical and electronic parts such as mechanical parts such as terminals and connectors. However, in the following description, as a typical application example, the description will be focused on the case where it is used for a lead frame which is a semiconductor component.

  As a copper alloy for a semiconductor lead frame, a Cu—Fe—P based copper alloy containing Fe and P has been generally used. Examples of these Cu-Fe-P-based copper alloys include, for example, a copper alloy containing Fe: 0.05 to 0.15% and P: 0.025 to 0.040% (C19210 alloy), Fe: 2 An example is a copper alloy (CDA194 alloy) containing 0.1 to 2.6%, P: 0.015 to 0.15%, and Zn: 0.05 to 0.20%. These Cu-Fe-P-based copper alloys are excellent in strength, conductivity and thermal conductivity among copper alloys when an intermetallic compound such as Fe or Fe-P is precipitated in the copper matrix. Therefore, it is widely used as an international standard alloy.

  In recent years, along with the increase in capacity, size, and functionality of semiconductor devices used in electronic devices, lead frames used in semiconductor devices have become smaller in cross-sectional area, resulting in greater strength, conductivity, and thermal conductivity. Is required. Accordingly, copper alloy plates used for lead frames used in these semiconductor devices are required to have higher strength and thermal conductivity.

  On the other hand, plastic packages for semiconductor devices have become mainstream because packages in which a semiconductor chip is sealed with a thermosetting resin are excellent in economy and mass productivity. These packages are becoming thinner with the recent demand for miniaturization of electronic components.

  In assembling these packages, the semiconductor chip is heat bonded to the lead frame using an Ag paste or the like, or soldered or brazed via a plated layer of Au, Ag, or the like. Then, after resin sealing is performed and the resin sealing is performed, an outer lead is generally subjected to exterior plating by electroplating.

  The biggest problem related to the reliability of these packages is the problem of package cracks and peeling that occur during surface mounting. When the semiconductor package is assembled and the adhesion between the resin and the die pad (portion where the semiconductor chip of the lead frame is placed) is low, the package is peeled off due to thermal stress during the subsequent heat treatment.

  On the other hand, since the mold resin absorbs moisture from the atmosphere after the semiconductor package is assembled, moisture is vaporized in the subsequent heating in surface mounting. Is applied and acts as an internal pressure. This internal pressure causes the package to swell, or the resin cannot withstand the internal pressure and causes cracks. When cracks occur in a package after surface mounting, moisture and impurities enter and corrode the chip, which impairs the function as a semiconductor. In addition, the appearance of the package swells and the product value is lost. Such a problem of package cracking and peeling has become remarkable in recent years with the progress of thinning of the package.

  Here, the problem of package cracks and peeling is caused by poor adhesion between the resin and the die pad, but the oxide film of the lead frame base material has the greatest influence on the adhesion between the resin and the die pad. is there. The lead frame base material is subjected to various heating processes in order to manufacture plates and lead frames. For this reason, an oxide film having a thickness of several tens to several hundreds nm is formed on the surface of the base material before plating with Ag or the like. Since the copper alloy and the resin are in contact with each other through the oxide film on the surface of the die pad, the separation of the oxide film from the lead frame base material leads to the separation of the resin and the die pad, and the lead frame base material. The adhesion of the resin to the resin is significantly reduced.

  Therefore, the problem of package cracking and peeling depends on the adhesion of the oxide film to the lead frame base material. For this reason, the strengthened Cu-Fe-P copper alloy plate as a lead frame base material is required to have high adhesion of an oxide film formed on the surface through various heating processes. The

Until now, not much countermeasures have been proposed for such problems. However, Patent Document 1 proposes improving the oxide film adhesion by controlling the crystal orientation of the copper alloy electrode surface layer. That is, in Patent Document 1, in the crystal orientation of the extreme surface evaluated by the XRD thin film method of the lead frame base copper alloy, the {100} peak intensity ratio with respect to the {111} peak intensity is set to 0.04 or less. It has been proposed to improve film adhesion. In addition, in this patent document 1, although all lead frame base material copper alloys are included, Cu-Fe-P-type copper alloys which are illustrated substantially are Cu- having a large Fe content of 2.4% or more. Only Fe-P-based copper alloys.
JP 2001-244400 A

  However, the technique of Patent Document 1 does not reach a high level of oxide film adhesion intended in the present invention.

  That is, first, as described above, the substantial Fe content of the Cu—Fe—P-based copper alloy in Patent Document 1 is more than 2.4 mass% at least. In this regard, the technique of Patent Document 1 may be effective for improving the oxide film adhesion of a Cu—Fe—P copper alloy having a large Fe content. In fact, in Patent Document 1, the adhesion of the oxide film of the Cu—Fe—P-based copper alloy of Example 1 in which the Fe content is 2.41% is up to 633 K (360 ° C.) at the separation limit temperature of the oxide film. It has improved.

  However, when the Fe content exceeds 2.4% by mass, another problem arises in that not only material properties such as conductivity but also productivity such as castability is significantly reduced. Actually, in Patent Document 1, the tensile strength of the Cu—Fe—P copper alloy of Example 1 is relatively high at 530 MPa, but the conductivity is as low as 63% IACS.

  On the other hand, in order to forcibly increase the electrical conductivity, for example, if the amount of precipitation of the above-mentioned precipitated particles is increased, there is a problem that, on the contrary, growth and coarsening of the precipitated particles are caused and strength and heat resistance are lowered. . In other words, the technique of Patent Document 1 cannot combine the high strength required for the Cu—Fe—P-based copper alloy and the oxide film adhesion.

  Therefore, even if the technique of Patent Document 1 is applied as it is to a Cu-Fe-P-based copper alloy whose strength has been increased by a composition in which the Fe content is substantially reduced to 0.5% or less, it has been described above. The oxide film adhesion required for lead frames cannot be obtained.

  The present invention has been made to solve such problems, and its purpose is to achieve high strength and excellent oxidation even with a composition in which the Fe content is substantially reduced to 0.5% or less. The object is to provide a Cu-Fe-P-based copper alloy plate that achieves both film adhesion.

The gist of the copper alloy plate for electrical and electronic parts of the present invention for achieving this object is, in mass%, Fe: 0.01 to 0.50%, P: 0.01 to 0.15%, respectively. A field-emission scanning electron microscope in which the copper alloy plate made of the remaining Cu and unavoidable impurities and having an orientation difference between adjacent crystals within ± 15 ° is considered to belong to the same crystal plane. It has a texture in which the orientation distribution density of the Brass orientation measured by a crystal orientation analysis method using a backscattered electron diffraction image EBSP by FE-SEM is 37% or more, and the average crystal grain size is 6.0 μm or less. .

  In order to achieve high strength, the copper alloy plate of the present invention further contains 0.005 to 5.0% Sn by mass, or further improves the heat-resistant peelability of solder and Sn plating. % 0.005 to 3.0% Zn may be contained.

  The copper alloy sheet of the present invention preferably has a tensile strength of 500 MPa or more and a hardness of 150 Hv or more as a measure for increasing the strength. The electrical conductivity correlates with the strength of the plate, and the high electrical conductivity referred to in the present invention means that the electrical conductivity is relatively high for high strength.

  The copper alloy sheet of the present invention may further contain 0.0001 to 1.0% of one or more of Mn, Mg, and Ca in total by mass%.

  The copper alloy sheet of the present invention is further in mass%, and one or more of Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, and Pt are added in a total amount of 0.001 to 1.0. % May be contained.

  The copper alloy sheet of the present invention is further in mass%, and 0.001 to 1.0% in total of one or more of Mn, Mg, and Ca, Zr, Ag, Cr, Cd, Be, Ti In addition, 0.001 to 1.0% in total of one or more of Co, Ni, Au, and Pt, respectively, and the total content of these elements as 1.0% or less, It may be contained.

  The copper alloy plate of the present invention further includes Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As. , Sb, Bi, Te, B, misch metal content is preferably 0.1% by mass or less in total of these elements.

  The copper alloy plate of the present invention can be applied to various electric and electronic parts, but is particularly preferably used for a semiconductor lead frame which is a semiconductor part.

  In the case of a normal copper alloy sheet, the texture called Cube orientation, Goss orientation, Brass orientation (hereinafter also referred to as B orientation), Copper orientation (hereinafter also referred to as Cu orientation), S orientation, etc. as shown below. And there are crystal planes corresponding to them.

  The formation of these textures differs depending on the processing and heat treatment methods even in the case of the same crystal system. In the case of the texture of the plate material by rolling, the rolling surface and the rolling direction are represented, the rolling surface is represented by {ABC}, and the rolling direction is represented by <DEF>. Based on this expression, each direction is expressed as follows.

Cube orientation {001} <100>
Goss direction {011} <100>
Rotated-Goss orientation {011} <011>
Brass direction (B direction) {011} <211>
Copper orientation (Cu orientation) {112} <111>
(Or D direction {4 4 11} <11 11 8>)
S orientation {123} <634>
B / G direction {011} <511>
B / S orientation {168} <211>
P direction {011} <111>

  Here, the B orientation, the Cu orientation, and the S orientation exist in a fiber texture (β-fiber) that continuously changes between the orientations.

  As described above, the texture of a normal copper alloy sheet is composed of a large number of orientation factors. However, when these constituent ratios change, the plastic anisotropy of the sheet changes, and properties such as workability and formability change. Changes.

  Patent Document 1 described above improves the oxide film adhesion particularly by setting the {100} peak intensity ratio to the {111} peak intensity to 0.04 or less in this texture. However, even if the orientation distribution density of the Cube orientation and Goss orientation is increased with respect to the Copper orientation (Cu orientation), the Fe content targeted by the present invention is reduced to 0.5% or less. In the copper alloy plate having the Cu—Fe—P based composition, the strength cannot be increased and the adhesion of the oxide film cannot be improved. For this reason, in the copper alloy plate which has this Cu-Fe-P type | system | group composition with little content of Fe, it is impossible to make high strength and the outstanding heat resistance compatible.

  In contrast, in the present invention, the orientation distribution density of the Brass azimuth (110 plane) is increased (increased) to form a texture having the same azimuth as much as possible, so that Cu-Fe- having a low Fe content is obtained. A copper alloy sheet having a P-based composition achieves both high strength and excellent heat resistance.

  That is, in the copper alloy sheet having a Cu-Fe-P composition with a low Fe content, the orientation distribution density of the Brass orientation (B orientation) is particularly large in the adhesion of the oxide film in the texture. Affect. As the orientation distribution density in the B direction is larger, the rolling texture is developed, the strength is increased, and the adhesion of the oxide film is improved.

  In the following, the significance and embodiments of each requirement in the Cu—Fe—P based copper alloy sheet of the present invention for satisfying the required characteristics, such as for semiconductor lead frames, will be specifically described.

(Measurement of orientation distribution density in B direction)
The measurement of the orientation distribution density of the Brass orientation (B orientation) of the Cu—Fe—P-based copper alloy plate in the present invention is performed using a field emission scanning electron microscope FESEM (Field Emission Scanning Electron Microscope). Measured by crystal orientation analysis method using electronBackscatter Diffraction Pattern.

  In defining the texture of the Brass orientation of the plate in the present invention, the measurement by the crystal orientation analysis method using the above EBSP is specified in order to improve the adhesion of the oxide film. This is because the structure (texture structure) in a more microscopic area is affected. In the crystal orientation analysis method using EBSP, the texture of this micro region can be quantified.

  On the other hand, in the X-ray diffraction (X-ray diffraction intensity, etc.) generally used for texture definition or measurement, the structure in a relatively macro area (compared to the crystal orientation analysis method using the EBSP) ( Texture). For this reason, it is not possible to accurately measure the microstructure (texture structure) of the above-mentioned micro area of the plate for improving the adhesion of the oxide film.

  Actually, the present inventors measured and compared them. According to the results of comparison, the orientation distribution density value of the B orientation measured by the crystal orientation analysis method using EBSP and the orientation distribution of the B orientation measured by X-ray diffraction. The density value is greatly different from each other even on the same plate. For this reason, in a comparison between a plurality of plates having different orientation distribution densities in the B orientation, the overall group tendency (rough tendency) in which the orientation distribution density in the B orientation is extremely large or extremely small is measured. Although the methods are the same, the order of the orientation distribution density values of the measured B orientations of the respective plates is greatly different between the two measurement methods. Therefore, as a result, there is no compatibility (correlation) between the measurement methods.

  In other words, this fact also indicates that the texture of the microscopic region of the plate has an influence on the adhesion of the oxide film, and the crystal orientation analysis using the above EBSP for the brass orientational texture of this microscopic region. The significance of the present invention defined by the measurement by the method can be understood.

(Directional distribution density measurement method of B direction)
This crystal orientation analysis method analyzes the crystal orientation based on a backscattered electron diffraction pattern (Kikuchi pattern) generated when an electron beam is obliquely applied to the sample surface. This method is also known as a high resolution crystal orientation analysis method (FESEM / EBSP method) for crystal orientation analysis of diamond thin films, copper alloys, and the like. Examples in which the crystal orientation analysis of a copper alloy is performed by this method as in the present invention are also disclosed in JP-A-2005-29857, JP-A-2005-139501, and the like.

  Analysis procedure by this crystal orientation analysis method, first, the measurement region of the material to be measured is usually divided into hexagonal regions, etc., and for each divided region, from the reflected electrons of the electron beam incident on the sample surface, A Kikuchi pattern (B orientation mapping) is obtained. At this time, if the electron beam is scanned two-dimensionally on the sample surface and the crystal orientation is measured at every predetermined pitch, the orientation distribution on the sample surface can be measured.

  Next, the obtained Kikuchi pattern is analyzed to know the crystal orientation at the electron beam incident position. That is, the obtained Kikuchi pattern is compared with data of a known crystal structure, and the crystal orientation at the measurement point is obtained. Similarly, the crystal orientation of the measurement point adjacent to the measurement point is obtained, and those whose crystal orientation difference is within ± 15 ° (deviation within ± 15 ° from the crystal plane) are located on the same crystal plane. Shall belong. Further, when the orientation difference between both crystals exceeds ± 15 °, the interval (such as the side where both hexagons are in contact) is defined as the grain boundary. In this way, the distribution of grain boundaries on the sample surface is obtained.

  More specifically, a specimen for observing the structure is collected from the manufactured copper alloy plate, subjected to mechanical polishing and buffing, and then subjected to electrolytic polishing to adjust the surface. For the specimen obtained in this way, for example, using FESEM manufactured by JEOL Ltd. and EBSP measurement / analysis system OIM (Orientation Imaging Macrograph) manufactured by TSL, analysis software of the system (software name “OIM Analysis”) ) Is used to determine whether each crystal grain has an orientation density of the target Brass orientation (within 15 ° from the ideal orientation), and the Brass orientation density in the measurement visual field is obtained.

  This measurement visual field range is a minute (micro) region of about 500 μm × 500 μm, and is a very minute region even compared to the measurement range of X-ray diffraction. Therefore, as described above, the azimuth density measurement in the structure of the microscopic region of the plate that affects the adhesion of the oxide film can be performed in more detail and with higher accuracy than the azimuth density measurement by X-ray diffraction. it can.

  Since these orientation distributions change in the plate thickness direction, it is preferable to obtain them by taking an average for some points in the plate thickness direction. However, a copper alloy plate used for a semiconductor material such as a lead frame is a thin plate having a thickness of about 0.1 to 0.4 mm. Therefore, even a value measured with the plate thickness can be evaluated.

(Significance of orientation distribution density)
In the present invention, as described above, the development of the rolling texture is specified in order to achieve both high strength of the Cu-Fe-P-based copper alloy sheet with low Fe content and excellent adhesion of the oxide film. Adjust the direction.

For this purpose, in the present invention, the orientation distribution density of the Brass azimuth (B azimuth) is increased (increased), and the texture is 37% or more as measured by the crystal orientation analysis method using FESEM / EBSP described above. To do. However, as a premise, in the present invention, those whose orientation differences between adjacent crystals are within ± 15 ° (deviation within ± 15 ° from the crystal plane) are regarded as belonging to the same crystal plane.

  In a copper alloy plate having a Cu-Fe-P composition with a low Fe content (0.5% or less), the orientation distribution density of the B orientation greatly affects the adhesion of the oxide film. As the orientation distribution density in the B direction is larger, the rolling texture is developed, the strength is increased, and the adhesion of the oxide film is improved.

On the other hand, when the orientation distribution density of the Brass orientation (B orientation) is less than 37% , the rolling texture of the Cu—Fe—P based copper alloy sheet having a low Fe content does not develop, and the strength decreases. The adhesion of the oxide film is not improved.

(Average crystal grain size)
In the present invention, as a precondition for controlling the texture and exerting the effect of the texture itself, the average crystal grain size in the copper alloy sheet structure is the crystal orientation using the above-mentioned FESEM / EBSP. The measured value by the analysis method is 6.0 μm or less. By reducing the average crystal grain size to 6.0 μm or less, the adhesion of the oxide film is improved, and the control to the texture and the effect of improving the adhesion of the texture of the texture itself are exhibited. It becomes easy. On the other hand, when the average crystal grain size is larger than 6.0 μm, it becomes difficult to control the texture and to exert the effect of the texture itself.

  This average crystal grain size can be measured in the orientation distribution density measurement of the B orientation by the crystal orientation analysis method using FESEM / EBSP as described above.

(Component composition of copper alloy sheet)
In the present invention, for semiconductor lead frames and the like, a high strength with a tensile strength of 500 MPa or more, a hardness of 150 Hv or more, and an electrical conductivity of 50% IACS or more and excellent oxide film adhesion are achieved. For this reason, as a Cu-Fe-P-based copper alloy plate, in mass%, the Fe content is in the range of 0.01 to 0.50%, and the P content is 0.01 to 0.15%. It is set as the basic composition which consists of remainder Cu and an inevitable impurity made into the range.

  With respect to this basic composition, one or two of Zn and Sn may be further contained within the following range. Further, other selectively added elements and impurity elements are allowed to be contained within a range that does not impair these characteristics. In addition, the display% of content of an alloy element and an impurity element all means the mass%.

(Fe)
Fe is a main element that precipitates as Fe or an Fe-based intermetallic compound and improves the strength and heat resistance of the copper alloy. When the Fe content is less than 0.01%, depending on the production conditions, the amount of the precipitated particles generated is small and the improvement in conductivity is satisfied, but the contribution to the improvement in strength is insufficient, and the strength and heat resistance are insufficient. To do. On the other hand, if the Fe content exceeds 0.50%, the electrical conductivity and Ag plating properties are lowered as in the conventional technique described above. Therefore, if the amount of precipitation of the precipitated particles is increased in order to forcibly increase the conductivity, conversely, growth and coarsening of the precipitated particles are caused. For this reason, strength and heat resistance are reduced. Therefore, the Fe content is set to a relatively low range of 0.01 to 0.50%.

(P)
P is a main element that has a deoxidizing action and forms a compound with Fe to improve the strength and heat resistance of the copper alloy. When the P content is less than 0.01%, depending on the production conditions, precipitation of the compound is insufficient, so that desired strength and heat resistance cannot be obtained. On the other hand, when the P content exceeds 0.15%, not only the conductivity is lowered, but also the heat resistance, hot workability, and press punching properties are lowered. Therefore, the P content is in the range of 0.01 to 0.15%.

(Zn)
Zn improves the heat-resistant peelability of copper alloy solder and Sn plating required for lead frames and the like. If the Zn content is less than 0.005%, the desired effect cannot be obtained. On the other hand, if it exceeds 3.0%, not only the solder wettability is lowered, but also the heat resistance and the conductivity are greatly lowered. Therefore, the Zn content in the case of selective inclusion is 0.005 to 3 depending on the balance between the electrical conductivity required for the application and the heat resistance peelability of the solder and Sn plating (in consideration of the balance). Select from a range of 0%.

(Sn)
Sn contributes to improving the strength of the copper alloy. When the Sn content is less than 0.001%, it does not contribute to high strength. On the other hand, when the Sn content is increased, the effect is saturated, and conversely, the conductivity is lowered. Accordingly, the Sn content in the case of selective inclusion is in the range of 0.001 to 5.0% depending on the balance between strength (hardness) and conductivity required for the application (in consideration of the balance). It is supposed to be selected and contained.

(Mn, Mg, Ca content)
Since Mn, Mg and Ca contribute to the improvement of hot workability of the copper alloy, they are selectively contained when these effects are required. When the content of one or more of Mn, Mg, and Ca is less than 0.0001% in total, a desired effect cannot be obtained. On the other hand, if the total content exceeds 1.0%, coarse crystallized substances and oxides are generated, and not only the strength and heat resistance are lowered, but also the conductivity is severely lowered. Therefore, the content of these elements is selectively contained in the range of 0.0001 to 1.0% in total.

(Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au, Pt amount)
Since these components have an effect of improving the strength of the copper alloy, they are selectively contained when these effects are required. When the content of one or more of these components is less than 0.001% in total, the desired effect cannot be obtained. On the other hand, if the total content exceeds 1.0%, coarse crystallized substances and oxides are generated, which not only lowers the strength and heat resistance, but also causes a significant decrease in conductivity, which is not preferable. Therefore, the content of these elements is selectively contained in the range of 0.001 to 1.0% in total. In addition, when these components are contained with the said Mn, Mg, and Ca, the total content of these contained elements shall be 1.0% or less.

(Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B , Misch metal amount)
These components are impurity elements, and when the total content of these elements exceeds 0.1%, coarse crystallized products and oxides are formed, and the strength and heat resistance are lowered. Therefore, the total content of these elements is preferably 0.1% or less.

(Production conditions)
Next, preferable manufacturing conditions for making the copper alloy sheet structure the structure defined in the present invention will be described below. The copper alloy sheet of the present invention is not required to greatly change the normal manufacturing process itself, except for preferable conditions such as final low temperature annealing conditions, in order to make the texture defined in the present invention controlled by the above texture. Can be manufactured in the same process.

  That is, first, a molten copper alloy adjusted to the preferred component composition is cast. Then, after chamfering the ingot, it is heated or homogenized and then hot-rolled, and the hot-rolled plate is water-cooled. This hot rolling may be performed under normal conditions.

  After that, the first cold rolling, which is said to be intermediate, is annealed, washed, and then finished (final) cold rolled and low-temperature annealed (final annealing, final annealing) to obtain a copper alloy sheet having a product thickness. . These annealing and cold rolling may be repeated. For example, in the case of a copper alloy plate used for a semiconductor material such as a lead frame, the product plate thickness is about 0.1 to 0.4 mm.

  In addition, you may perform the solution treatment of a copper alloy plate, and the quenching process by water cooling before primary cold rolling. At this time, the solution treatment temperature is selected from a range of 750 to 1000 ° C., for example.

(Final cold rolling)
Final cold rolling is also according to conventional methods. However, in order to improve heat resistance with little reduction in strength during heat treatment (strain relief annealing) after stamping on the lead frame, increase the rolling speed in the final cold rolling or roll in the final cold rolling. It is preferable to increase the hardness (shear hardness). That is, a means such as increasing the rolling speed in the final cold rolling to 200 m / min or higher, or increasing the roll hardness (shear hardness) in the final cold rolling to 60 Hs or higher is selected and used. Or they are preferably used in combination.

  Further, in order to improve the press punchability in the stamping process, the amount of strain introduced in the final cold rolling is increased. That is, in the final cold rolling, the roll diameter is a small diameter roll of less than 80 mmφ, the minimum reduction rate (cold rolling ratio, processing rate) per pass is 20% or more, or roll length (roll width) It is preferable to select and use a means such as setting the thickness to 500 mm or more, or use in combination.

  The number of final cold rolling passes is preferably 3 to 4 times as usual, avoiding too few or too many passes. Also, the rolling reduction per pass need not exceed 50%, and each rolling reduction per pass takes into account the original plate thickness, the final plate thickness after cold rolling, the number of passes, and this maximum rolling reduction. It is determined.

(Final annealing)
In the present invention, it is preferable that the final annealing at a low temperature is performed in a continuous heat treatment furnace after the final cold rolling. The final annealing condition in this continuous heat treatment furnace is preferably a low temperature condition of 0.2 to 300 minutes at 100 to 400 ° C. In the manufacturing method of the copper alloy plate used for a normal lead frame, since the strength is lowered, the final annealing is not performed after the final cold rolling except for annealing for removing strain (about 350 ° C. × 20 seconds). However, in the present invention, this strength reduction is suppressed by the cold rolling conditions and by lowering the final annealing. And press punching property improves by performing final annealing at low temperature.

  Under conditions where the annealing temperature is lower than 100 ° C, the annealing time is less than 0.2 minutes, or the conditions where this annealing is not performed, the structure and properties of the copper alloy sheet are almost the same as those after the final cold rolling. It is likely that it will not change. Conversely, if annealing is performed at a temperature exceeding 400 ° C. or annealing time exceeding 300 minutes, recrystallization occurs, rearrangement of dislocations and recovery phenomenon occur excessively, and precipitates also become coarse. For this reason, there is a high possibility that the press punchability and the strength are lowered.

(Texture in final annealing, control of average grain size)
In addition, by performing this final annealing in a continuous heat treatment furnace, the texture and average crystal grain size specified in the present invention can be obtained, the strength can be increased, and the adhesion of the oxide film can be improved. . That is, in a continuous heat treatment furnace, it is possible to control the tension applied to the plate at the time of threading and the threading speed, and thereby the rolling texture in which the orientation distribution density of the Brass orientation (B orientation) is 37% or more. Can be developed. Moreover, the average crystal grain size can be refined to 6.0 μm or less. In a continuous heat treatment furnace, the tension applied to the plate and the plate passing speed during plate passing greatly affect the orientation distribution density and average crystal grain size of the Brass orientation (B direction).

In order to obtain a texture and an average crystal grain size specified in the present invention, a tension is applied in the range of 0.1 to 8 kgf / mm ² during the passing through in the final annealing by a continuous heat treatment furnace, and The sheet passing speed is controlled in the range of 10 to 100 m / min. When either or both of the tension and the plate speed at the time of passing are out of this range, there is a high possibility that the texture and the average crystal grain size specified in the present invention cannot be obtained.

  Examples of the present invention will be described below. Copper alloy thin plates having various Brass orientation orientation distribution densities and average crystal grain diameters were produced by changing the tension and the plate-passing speed in the final annealing in a continuous heat treatment furnace. And the characteristics, such as tensile strength of each of these copper alloy thin plates, hardness, and electrical conductivity, and the adhesiveness (peeling temperature of an oxide film) of an oxide film were evaluated. These results are shown in Table 1.

  Specifically, after each copper alloy having the chemical composition shown in Table 1 was melted in a coreless furnace, it was ingoted by a semi-continuous casting method, and the ingot was 70 mm thick × 200 mm wide × 500 mm long. Got. Each ingot was chamfered on the surface and heated, and then hot rolled at a temperature of 950 ° C. to form a plate having a thickness of 16 mm, and rapidly cooled into water from a temperature of 750 ° C. or higher. Next, after removing the oxide scale, primary cold rolling (intermediate rolling) was performed. After the face is cut, final cold rolling is performed in which four passes of cold rolling are performed while intermediate annealing is performed, and then final annealing is performed at a furnace atmosphere temperature of 450 ° C. to obtain a thickness corresponding to the thinning of the lead frame. A 0.15 mm copper alloy plate was obtained.

  The rolling speed of the final cold rolling was 300 m / min, the roll hardness (shear hardness) was 90 Hs, the roll diameter used was 60 mmφ, and the minimum rolling reduction per pass was 10%.

Table 1 shows the respective tensions (kgf / mm ² ) and the passing speeds (m / min) at the time of threading in the final annealing in the continuous heat treatment furnace.

  In each of the copper alloys shown in Table 1, the remaining composition excluding the described element amount is Cu, and other impurity elements are Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, The contents of C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B, and misch metal are those elements including those shown in Table 1. The total amount was 0.1% by mass or less.

  Further, when one or more of Mn, Mg, and Ca are included, the total amount is in the range of 0.0001 to 1.0 mass%, and Zr, Ag, Cr, Cd, Be, Ti, Co, In the case of one or more of Ni, Au, and Pt, the total amount is in the range of 0.001 to 1.0% by mass, and the total amount of these elements is also 1.0% by mass or less. did.

  With respect to the copper alloy plate obtained as described above, in each example, a sample was cut out from the copper alloy plate, and the texture, tensile strength, hardness, electrical conductivity, adhesion of the oxide film, etc. of each sample The characteristics were evaluated. These results are shown in Table 1, respectively.

(Measurement of texture)
A specimen for observing the structure was collected from the obtained copper alloy plate, subjected to mechanical polishing and buffing, and then subjected to electrolytic polishing to adjust the surface. About each obtained test piece, the measurement by the above-mentioned method measured the orientation distribution density of the Brass azimuth | direction (B azimuth | direction) in the 500 micrometer x 500 micrometer area | region at the space | interval of 1 micrometer.

  As described above, measurement and analysis were performed using FESEM manufactured by JEOL Ltd., EBSP measurement / analysis system manufactured by TSL, and analysis software of the same system.

(Hardness measurement)
A 10 × 10 mm test piece was cut out from the copper alloy plate obtained as described above, and a load of 0.5 kg was applied using a micro Vickers hardness meter (trade name “micro hardness meter”) manufactured by Matsuzawa Seiki Co., Ltd. The hardness was measured at four points, and the hardness was an average value thereof.

(Conductivity measurement)
The electrical conductivity of the copper alloy sheet sample was calculated by an average cross-sectional area method by processing a strip-shaped test piece having a width of 10 mm and a length of 300 mm by milling, measuring the electric resistance with a double bridge type resistance measuring device.

(Oxide film adhesion)
The oxide film adhesion of each test material was evaluated by a tape peeling test at the limit temperature at which the oxide film peels off. In the tape peeling test, a 10 × 30 mm test piece is cut out from the copper alloy plate obtained as described above, heated at a predetermined temperature in the atmosphere for 5 minutes, and then a commercially available tape is formed on the surface of the test piece on which the oxide film is formed. (Product name: Sumitomo 3M Mending Tape) was applied and peeled off. At this time, when the heating temperature was changed in increments of 10 ° C., the lowest temperature at which the oxide film was peeled was obtained, and this was defined as the oxide film peeling temperature.

As is apparent from Table 1, the inventive example , which is a copper alloy within the composition of the present invention, is manufactured under conditions in which the tension and the plate speed in the final plate annealing in the continuous annealing furnace are favorable. For this reason, the invention example has a texture in which the orientation distribution density of the Brass orientation is 37% or more according to the measurement method, and the average crystal grain size can be refined to 6.0 μm or less.

As a result, the inventive examples have excellent oxide film adhesion with a high strength such as a tensile strength of 500 MPa or more and a hardness of 150 Hv or more, and an oxide film peeling temperature of 370 ° C. or more. Therefore, the invention example has high adhesiveness between the resin and the die pad when assembling the semiconductor package as a semiconductor base material, and the reliability of the package is high. However, the oxide film peeling temperatures of Reference Examples 6 to 8 that are outside the scope of the present invention are 350 to 360 ° C.

On the other hand, Comparative Examples 15 to 17 are copper alloys within the composition of the present invention, but either or both of the tension and the feeding speed at the time of threading in the final annealing by the continuous heat treatment furnace. , Deviating from the preferred conditions. For this reason, in Comparative Examples 15 to 17, the orientation distribution density of the Brass orientation by the measurement method is less than 37% , and the average crystal grain size is also coarsened exceeding 6.0 μm. As a result, the strength level is low, the oxide film peeling temperature is 330 ° C. or lower, and the oxide film adhesion is extremely inferior.

The copper alloy of Comparative Example 18 has an Fe content of 0.007%, which is lower than the lower limit of 0.01%. On the other hand, the tension at the time of threading and the threading speed in final annealing by a continuous heat treatment furnace are manufactured within preferable conditions. Therefore, having a texture that is 39% of the orientation distribution density of Brass orientation, although able to refine the average grain size below 6.0 .mu.m, a low intensity level.

In the copper alloy of Comparative Example 19, the Fe content is 0.58%, which is out of the upper limit of 0.50 %. On the other hand, the tension at the time of threading and the threading speed in final annealing by a continuous heat treatment furnace are manufactured within preferable conditions. Therefore, having a texture that is 40% of the orientation distribution density of Brass orientation, although able to refine the average grain size below 6.0 .mu.m, the conductivity is significantly low.

The copper alloy of Comparative Example 20 has a P content of 0.008%, which is slightly lower than the lower limit of 0.01%. On the other hand, the tension at the time of threading and the threading speed in final annealing by a continuous heat treatment furnace are manufactured within preferable conditions. Therefore, having a texture that is 40% of the orientation distribution density of Brass orientation, although able to refine the average grain size below 6.0 .mu.m, a low intensity level.

In the copper alloy of Comparative Example 21, since the P content was 0.16%, which was higher than the upper limit of 0.15%, cracks occurred at the end of the plate during hot rolling. On the other hand, the tension at the time of threading and the threading speed in final annealing by a continuous heat treatment furnace are manufactured within preferable conditions. Therefore, having a texture that is 40% of the orientation distribution density of Brass orientation, although able to refine the average grain size below 6.0 .mu.m, the conductivity is significantly low.

  From the above results, the component composition of the copper alloy sheet of the present invention, the critical significance of the texture definition, and the preferred structure for obtaining such a structure, in order to improve the heat resistance after increasing the strength. The significance of manufacturing conditions is supported.

  As described above, according to the present invention, it is possible to provide a Cu—Fe—P-based copper alloy plate that is excellent in oxide film adhesion and has both of these characteristics (combined) while having high strength. Can do. As a result, it is possible to provide a semiconductor base material having high adhesion between the resin and the die pad during assembly of the semiconductor package and high package reliability. Therefore, for electrical and electronic parts that are reduced in size and weight, in addition to lead frames for semiconductor devices, lead frames, connectors, terminals, switches, relays, etc. have increased strength and oxide film adhesion = package reliability. Can be applied to applications that require.

Claims (9)

It is a copper alloy plate containing Fe: 0.01 to 0.50% and P: 0.01 to 0.15%, respectively, and the balance being Cu and inevitable impurities, and each of the adjacent crystals. Measurements were made by a crystal orientation analysis method using a backscattered electron diffraction image EBSP by a field emission scanning electron microscope FE-SEM, assuming that those with an orientation difference within ± 15 ° belong to the same crystal plane. A copper alloy plate for electrical and electronic parts having excellent texture adhesion, characterized by having a texture in which the orientation distribution density of the Brass orientation is 37% or more and having an average crystal grain size of 6.0 μm or less.   The copper alloy plate according to claim 1, wherein the copper alloy plate further contains Sn: 0.005 to 5.0% by mass.   The copper alloy plate according to claim 1 or 2, wherein the copper alloy plate further contains Zn: 0.005 to 3.0% by mass.   The copper alloy plate according to any one of claims 1 to 3, wherein the copper alloy plate has a tensile strength of 500 MPa or more and a hardness of 150 Hv or more.   5. The copper alloy sheet according to claim 1, further comprising 0.0001 to 1.0% of one or more of Mn, Mg, and Ca in total by mass%. Copper alloy plate for electrical and electronic parts.   6. The copper alloy sheet according to claim 1, further comprising 0.001 to 1.0% in total of one or more of Zr, Ag, Ti, and Ni in mass%. A copper alloy plate for electrical and electronic parts as described in 1.   The copper alloy plate is further, by mass%, one or more of Mn, Mg, and Ca in a total of 0.0001 to 1.0%, and one of Zr, Ag, Ti, and Ni, or The total content of these elements is 0.001% or less while containing two or more kinds in total of 0.001 to 1.0%, respectively. Copper alloy plate for electrical and electronic parts.   The copper alloy plate is Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, The copper alloy plate for electrical and electronic parts according to any one of claims 1 to 7, wherein the content of Bi, Te, B, and Misch metal is 0.1% by mass or less in total of these elements.   The copper alloy plate for electrical and electronic parts according to claim 1, wherein the copper alloy plate is for a semiconductor lead frame.