JPH10270629A - Iron alloy material with excellent resin adhesion - Google Patents

Abstract

(57) [Problem] To provide an iron alloy material containing 35 to 45% by weight of Ni which gives good adhesion to a resin. An iron alloy material having a roughened surface that has been dull-rolled during final cold rolling or temper rolling, or an iron alloy material that has a roughened surface that has been etched by an acid solution, and is the electron beam shown in FIG. 10 by 3D roughness analyzer
The arithmetic average roughness is 0.0
5 to 0.8 μm and alternative surface area of 1.005 to 1.0
8 is an iron alloy material. These have an appropriate anchor effect and surface area, and have excellent bondability with a resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron alloy material containing 35 to 45% by weight of Ni and having excellent adhesion to resins such as epoxy resins, phenol resins and polyimides. The present invention relates to an iron alloy material suitable for being used as.

[0002]

2. Description of the Related Art In many industrial products, a portion where a metal and a resin are joined constitutes a part or the whole of the product. For example, a package for storing a semiconductor IC or the like includes a metal lead frame and a sealing material. As a metal lead frame, an iron-nickel alloy is a main material. That is, in recent years, high integration has progressed in the field of ICs such as microprocessors, and for example, in lead frames, multi-pin products with 200 pins or more are becoming mainstream,
These multi-pin materials are "42 alloy" from the viewpoint of strength.
The main material is an Fe-Ni-based alloy containing about 42% Ni. Ceramics have been used as the encapsulating material in the past, but currently low-cost resins (epoxy resin, etc.) are predominant. Further, a metal plate called a heat spreader may be used inside the semiconductor package, and the periphery of the metal plate is sealed with a resin. In an electronic circuit board, a metal foil is bonded to a glass cloth base material containing an epoxy resin, a phenol resin, or the like. In addition, the low thermal expansion coefficient “36”
Fe-Ni alloys called "alloys" are used in many electric and electronic fields.

In such products in which the iron alloy material and the resin are bonded together, resin adhesion is often a problem. As an example, FIG. 1 shows that the semiconductor chip 2 is bonded on the die pad 3 of the lead frame L made of 42 alloy, the semiconductor chip is connected to the lead 4 of the lead frame by the bonding wire 5, and these are integrated. 1 shows a semiconductor package manufactured by sealing with a resin mold 1 made of a thermosetting resin. In a semiconductor package using such a resin, as shown in FIG. 1, when the adhesiveness between the lead frame and the resin is insufficient, the resin is likely to peel off or crack in the package. There's a problem. Explaining this concretely, the moisture absorbed inside the resin reaches the interface between the lead frame die pad and the resin, and the moisture accumulated at the interface expands due to the heat generated by the semiconductor, and this expanding force causes the resin to expand. Is a phenomenon of peeling from the lead frame die pad or cracking of the resin. The semiconductor inside the package may be damaged due to this crack, and therefore the occurrence of crack must be prevented as much as possible. As in the above example, in the conventional technique, there may be a problem caused by poor adhesion between a metal material such as an iron-nickel alloy and a resin.

[0004] In order to improve the poor adhesion, a method of roughening the surface so as to obtain an anchor effect is generally adopted, but sufficient reliability has not yet been obtained.

[0005]

In view of the large number of types of industrial products in which the joint portion between the iron alloy material and the resin constitutes a part or the whole of the product, the present invention has general versatility. It is an object of the present invention to provide an iron alloy material containing 35 to 45% by weight of Ni that provides sufficient adhesion to a resin.

[0006]

To solve the above-mentioned problems, the present inventor conducted research and found that the surface of an iron alloy (iron-nickel) material was rolled by a dull roll or etched by an acidic solution to a specific area. It has been found that by forming a roughened surface having the following profile, good resin adhesion can be obtained. In that case, not only the arithmetic mean roughness (Ra) of the surface of the iron alloy material, but also the surface area substitution value, which is an index of the net area of the portion where the iron alloy material and the resin are joined, is set to be in an appropriate range. It has been found that excellent resin adhesion can be obtained. It was also found that it is preferable to perform the measurement with the plated material surface obtained by enlarging the surface 1000 times by an electron beam three-dimensional roughness analyzer as a reference.

[0007] Based on these findings, the present invention provides: (1) 35-45 wt% Ni, the balance consisting of Fe and unavoidable impurities, and using a dull roll during final cold rolling or temper rolling. An arithmetic average roughness (Ra) of 0.1 is based on a surface of a rolled iron alloy material having a roughened surface, which is obtained by enlarging the surface by 1000 times using an electron beam three-dimensional roughness analyzer. 0.05 to 0.8 μm, and (surface area of sample obtained from measurement) /
A surface area alternative value defined as (length x width of measurement range) is in the range of 1.005 to 1.08, and an iron alloy material excellent in bondability to a resin, and (2) 35 to An iron alloy material containing 45% by weight of Ni, the balance of Fe and unavoidable impurities, and having a roughened surface etched by an acid solution after final cold rolling. Based on the surface obtained by enlarging the surface 1000 times by the device, the arithmetic mean roughness (Ra) is in the range of 0.05 to 0.8 μm, and (the surface area of the sample obtained from the measurement) / Surface area alternative value defined as (length x width of measurement range) is 1.00
An iron alloy material having excellent bondability with a resin, which is characterized by being in the range of 5 to 1.08.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A roughened surface formed by a specific method selected for the purpose of improving the adhesion between an iron alloy material and a resin is a surface obtained by using a three-dimensional surface roughness analyzer. It is a feature of the present invention that the roughness and the surface area substitution value are set in the optimum range, and the iron alloy material is provided with the surface characteristics having an appropriate anchoring effect and surface area. By using this material, a stronger resin and Can be obtained.

The iron alloy material of the present invention is an iron alloy containing 35 to 45% by weight of Ni, and the balance being Fe and inevitable impurities, and includes general metal materials such as amber and 42 alloy. These materials have low coefficients of thermal expansion,
Widely used for semiconductor packages. Such Fe
As for the -Ni alloy material, a Fe-Ni-based alloy melt obtained by melting pure iron and pure nickel by a vacuum melting method may be formed into an ingot or may be continuously cast. The ingot thus obtained can be forged or rolled without causing hot brittleness, and can be made into a material for electronic parts having a desired thickness by repeating annealing and cold rolling. In addition, strain relief annealing or shape correction may be performed after the final cold rolling.

In the present invention, the surface roughness and the surface area substitution value are defined. These values are obtained by using a three-dimensional surface roughness analyzer manufactured by Elionix Inc. and measuring the roughened surface at a magnification of 1000 times. doing. This is because it was determined to be optimal from the viewpoint of measurement reliability and convenience.

The three-dimensional surface roughness analyzer scans the surface of a sample with an electronic probe at high speed and reliably catches the fine surface shape.
It is possible to display a three-dimensional image on the RT, and also to display the surface area, Ra,
Rz, Rmax, etc., the number of peaks, particle size, contour lines, area ratio, and the like can be displayed in a graph or the like. The calculation of the surface area is
It is calculated as the sum of the areas of triangles having three sampling points as vertices in the fine surface shape image. This calculation is performed by the computer inside the measuring machine.

Arithmetic average roughness of the roughened surface (JIS B06)
01, hereinafter referred to as Ra) is an arithmetic mean value of the center line average roughness in each portion randomly extracted from the target surface.

The surface area alternative is given by the following equation:

## EQU00003 ## (Surface area of sample obtained from measurement) / (length * width of measurement range) Alternative surface area is the number of times the surface area of the uneven surface that actually contacts the resin is larger than the area of the flat surface without unevenness. And is proportional to the net area of the portion where the iron alloy material and the resin are joined. In order to improve the resin adhesiveness, not only the above-mentioned anchor effect but also the surface area of the resin joint is important. For example, when comparing the resin adhesion between a metal material having a large Ra and a metal material having a small Ra, the adhesion of the former is not necessarily good, and the surface of the latter is finely roughened, and the surface area substitute value is not so good. If larger, the latter may be better. That is, it is important to properly control the surface roughness of the material and the surface area substitution value.

FIG. 3 shows a roughened surface of a Fe-42% Ni material rolled on a dull roll, which will be described later in connection with the embodiment.
It is a bird's-eye view of the surface unevenness of 0 time. Here, the X axis of 120 microns and the Y axis of 90 microns are selected as the vertical and horizontal directions of the measurement range, and the actual fine contour is displayed three-dimensionally. The height of the bump-like irregularities is represented in color according to the height-color display on the left side. In this case, the surface area substitute value is a value obtained by dividing the actual surface area of the sample obtained by the measurement by the three-dimensional surface roughness analyzer by 120 microns × 90 microns.

According to a first aspect of the present invention, an iron alloy material is rolled using dull rolls at the time of final cold rolling or temper rolling, and is manufactured as a strip having a predetermined Ra and a surface area substitution value. The dull roll is a type of rolling roll, and is a roll having fine irregularities formed on its surface.
The dull roll used in the rolling mill has its surface processed and adjusted by shot blasting, electric discharge machining, or a grinding wheel. The reason for rolling with a dull roll is that the copper or copper alloy of the present invention can be manufactured inexpensively and with good reproducibility.
In this case, the arithmetic average roughness (Ra) of the roughened surface of the iron alloy material rolled by the dull roll is specified in the range of 0.05 to 0.8 μm. This Ra is a value obtained by enlarging the surface 1000 times with an electron beam three-dimensional roughness analyzer. R
When a is in the above range, the metal material bites into the resin (anchor effect), and good adhesion is obtained. Ra
Is less than 0.05 μm, the anchor effect is insufficient, and the effect of improving the resin adhesion cannot be expected. Again 0.8
When the thickness exceeds μm, the effect of improving the resin adhesion is saturated, while the manufacturing cost of the dull roll for manufacturing this metal strip becomes high, which is uneconomical. The surface area alternative value, which is another condition for defining the surface properties, is in the range of 1.005 to 1.08. This value is also obtained by multiplying the surface magnification by 10 with an electron beam three-dimensional roughness analyzer.
It is a value obtained by enlarging the image at 00 times. For materials having a surface area replacement value of less than 1.005, the area of the joint is not sufficient, while those having a surface area replacement value of more than 1.08,
While the effect of improving the resin adhesion is saturated, the manufacturing cost is increased, which is uneconomical.

According to a second aspect of the present invention, the iron alloy material is etched by dipping in an acid solution containing nitric acid, iron chloride, or the like after usual final rolling or temper rolling, to obtain a predetermined Ra. And a strip having a surface area alternative value. In this case, as before, Ra of the roughened surface of the iron alloy material was 0.05 to 0.8 μm based on the surface obtained by enlarging the surface 1000 times by the electron beam three-dimensional roughness analyzer.
Then, the alternative surface area value is set in the range of 1.005 to 1.08. The reason for setting these ranges is the same as the reason described for the roughened surface obtained by rolling with a dull roll.
Although the etching process is higher in cost than the dull roll process, a surface having fine irregularities can be obtained, so that the effect of improving the resin adhesion is greater.

[0017]

EXAMPLES Examples and comparative examples of the present invention are shown below.
Vacuum melting method using pure iron and pure nickel as raw materials, Fe-
42% Ni and Fe-36% Ni molten metal was cast to obtain an ingot. Next, forging, scale removal, hot rolling, and scale removal were performed, and cold rolling and annealing were repeated to obtain 0.1%.
A 5 mm thick alloy strip was produced. In the process of manufacturing Fe-42% Ni strip and Fe-36% Ni strip, the following treatment was performed at the time of final rolling or after the final rolling. [Treatment A] Final rolling is performed by using a rolling roll having a surface made uneven by a shot blasting method (a method in which hard particles are blown to a metal to roughen the surface). At this time, samples having different surface shapes are prepared using several types of rolls prepared by changing the pressure at which particles are sprayed. [Treatment B] After the final rolling, ferric chloride solution (45 ° C.)
The metal strip is dipped in and etched. At this time, the etching time is changed to prepare samples having different surface shapes.

The surface roughness (Ra) and the surface area substitute value are obtained by a three-dimensional roughness analyzer ERA-800 manufactured by Elionix Inc.
Using 0, the surface was measured at 1000 times magnification. As shown in FIG. 2, the evaluation of the adhesiveness with the resin was performed by contact-curing an epoxy resin columnar body having a joint area of 50 mm ^{2 on} the surface of the test strips of various metal strips and then curing the test strip and the columnar cylinder. The body was gradually pulled in the opposite direction, and the tensile strength until the interfaces were shear-peeled was obtained. Specifically, FIG.
The procedure in (d) was followed. That is, on a rectangular test piece (60 mm length × 25 mm width × 0.25 mm thickness) to be used for the test, a Teflon (trade name of polytetrafluoroethylene manufactured by Du Pont) having a 50 mm ² area hole (thickness) was used. (3 mm) is placed so that the hole is located in the center near one end of the test piece, and epoxy resin is poured into the hole.
After curing for a time (a), a shearing test piece having an epoxy resin cylinder having a cross-sectional area of 50 mm ² was formed on the test piece (b), and then a tensile tool with a hole that fits tightly into the cylinder was prepared. Put the test piece on the test piece so that the hole fits into the molded resin cylinder (c), and then use a tensile tester at room temperature at a pulling speed of 5 mm / min. As shown in (d). Thus, the shear strength of the mold resin on the test piece was measured.

Table 1 shows the evaluation results. The iron alloy material shown in the examples of the present invention has good adhesion to the resin and exhibits consistent resin adhesion (shear tensile strength). Comparative Example 1 is an example of Fe-42% Ni which was not treated. In Comparative Examples 2 and 3, both the arithmetic average roughness (Ra) and the surface area substitution value of the surfaces obtained in the treatments A and B were out of the predetermined ranges, and the resin adhesion (shear tensile strength) was lowered. doing. From the above results, it is understood that the iron alloy materials shown in the examples of the present invention have excellent resin adhesion.

[0020]

[Table 1]

FIG. 3 is a bird's-eye view of the surface unevenness of the dull rolled material of Example 2 at a magnification of 1000 times observed by a three-dimensional surface roughness analyzer, as mentioned above. FIG. 4 is a bird's-eye view of the surface unevenness at a magnification of 1000 times of the surface of the acid solution etching material of Example 4 observed by a three-dimensional surface roughness analyzer. FIG. 5 shows the untreated Fe-42 of Comparative Example 1 observed by the same three-dimensional surface roughness analyzer.
It is a bird's-eye view of the surface unevenness of the% Ni material at a magnification of 1000.
As is clear from the comparison between FIGS. 3 and 4 and FIG. 5, many bumpy irregularities are formed on the surface of the material of the present invention. In FIG. 4 etched with an acid solution, a surface having finer irregularities obtained by dull roll rolling than in FIG. 3 is obtained.

[0022]

EFFECTS OF THE INVENTION The iron alloy material of the present invention, which has excellent resin adhesion, has good adhesion to the resin, and as a result, the reliability of semiconductor packages and the like can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a situation in which a crack or peeling has occurred in a semiconductor package sealed by a resin mold.

FIGS. 2A to 2D are perspective views sequentially showing steps of a test method for evaluating the adhesion between a plating material and a resin.

FIG. 3 is an image photograph showing the surface irregularities on the surface of a rolled rolled material of the Fe-42% Ni alloy of Example 2 observed by a three-dimensional surface roughness analyzer (magnification: 1000).

FIG. 4 is an image photograph showing the surface irregularities of the surface of the Fe-42% Ni alloy acid solution etching material of Example 4 observed by a three-dimensional surface roughness analyzer (magnification: 1000 times).

FIG. 5 is an image photograph of the untreated Fe-42% Ni alloy surface of Comparative Example 1 observed by a three-dimensional surface roughness analyzer (magnification: 1000 times).

[Explanation of symbols]

 L Lead frame 1 Resin mold 2 Semiconductor chip 3 Die pad 4 Lead 5 Bonding wire

Claims (2)

[Claims] 1. An iron alloy material containing 35 to 45% by weight of Ni, the balance consisting of Fe and unavoidable impurities, and having a roughened surface rolled using a dull roll during final cold rolling or temper rolling. In addition, based on the surface obtained by enlarging the surface 1000 times by the electron beam three-dimensional roughness analyzer, the arithmetic average roughness (Ra) is 0.05 to 0.8 μm.
m and a surface area alternative value defined as: (surface area of sample obtained from measurement) / (length × width of measurement range) is 1.005 to 1.08.
It is an iron alloy material having excellent bondability with resin, which is characterized by 2. An iron alloy material comprising 35-45% by weight Ni, the balance consisting of Fe and unavoidable impurities, and having a roughened surface etched by an acidic solution after final cold rolling, The arithmetic average roughness (Ra) is in the range of 0.05 to 0.8 μm based on the surface obtained by enlarging the surface 1000 times by the electron beam three-dimensional roughness analyzer, and The surface area alternative value defined as (surface area of sample obtained from measurement) / (length × width of measurement range) is 1.005 to 1.08.
It is an iron alloy material having excellent bondability with resin, which is characterized by