KR102482396B1 - Lead frame material and its manufacturing method and semiconductor package - Google Patents

Abstract

A roughening comprising a conductive substrate (1) and at least one roughened layer (2) formed of projections (4) of a plurality of coarsened particles on at least one side of the conductive substrate (1), either directly or through an intermediate layer. A film (3) is provided, and the projection (4) has a maximum width when measured in a cross section in the thickness direction of the roughened film (3), which is located on the side of the conductive substrate (1) from a position where the maximum width is measured. A lead frame material (10) having a shape that is 1 to 5 times larger than the minimum width when measured from the lower part.

Description

Lead frame material and its manufacturing method and semiconductor package

The present invention relates to a lead frame material suitable for use in a resin-encapsulated semiconductor device formed by electrically connecting a semiconductor element and a lead frame having a surface treatment layer to each other and sealing them with a mold resin, a manufacturing method thereof, and a semiconductor package. .

This type of resin-encapsulated semiconductor device has a structure in which a semiconductor element and a lead frame electrically connected to each other by a wire or the like are sealed with a mold resin. Such a resin-encapsulated semiconductor device is generally manufactured by subjecting a lead frame to surface treatment such as exterior plating and forming a surface film with, for example, a Sn alloy such as a Sn-Pb alloy or a Sn-Bi alloy.

Therefore, in recent years, in order to simplify the assembly process and reduce the cost, during mounting by soldering to the printed board on the surface of the lead frame in advance, plating with specifications that enhance wettability with solder (eg Ni/Pd/Au) A lead frame (Pre-Plated Frame) is starting to be adopted (see Patent Document 1, for example).

On the other hand, in order to improve the adhesion between the lead frame and the mold resin in a resin-encapsulated semiconductor device, a technique for roughening the plating surface of the lead frame has been proposed (see Patent Document 2, for example).

The technique of roughening the plating surface is by roughening the surface by roughening the lead frame, (1) the mold resin enters the unevenness of the roughened plating film and forms a strong mechanical bond (anchor effect), (2) the mold It is expected to improve chemical bonding as the contact area between the resin and the plating surface is improved.

By roughening the surface of the lead frame, the adhesion of the mold resin to the lead frame is improved, and as a result of suppressing separation between the lead frame and the mold resin, the reliability of the resin-encapsulated semiconductor device can be improved.

Patent Document 1: Japanese Patent Laid-Open No. 4-115558 Patent Document 2: Patent Publication No. 6-029439

By roughening the surface of the lead frame, the adhesion of the mold resin to the lead frame can certainly be improved compared to conventional resin-encapsulated semiconductor devices. However, in recent years, the required level for reliability has become more stringent than before, and high-temperature, high-humidity durability tests, for example, high-temperature, high-humidity tests under severe conditions in which the temperature is 85 ° C and the humidity is 85% for 168 hours. Even so, it is necessary to pass the acceptance criterion of reliability. On the other hand, in the conventional configuration in which the surface of the lead frame is merely roughened, as in Patent Document 1, a gap is formed between the resin and the lead frame, and the acceptance criteria for reliability may not be passed. This is a resin-encapsulated semiconductor device, and as packages such as QFN (Quad Flat Non-Leaded Package) type and SOP (Small Outline Package) type are widely used in recent years, the level of demand for resin adhesion to the lead frame has become higher. You might think it's because As described above, in the resin-encapsulated semiconductor device, the adhesiveness of the resin to the lead frame has been required to be maintained even under the severe conditions as described above, and thus further improvement is required.

An object of the present invention is to provide a lead frame material suitable for forming a lead frame surface capable of maintaining good resin adhesion even when subjected to a high temperature, high humidity test under the above-mentioned severe conditions, a manufacturing method thereof, and a semiconductor package having high reliability. do.

The present inventors studied to solve the above problems, and considered that the cross-sectional shape of the projections of the roughened particles constituting the roughened layer of the roughened film formed on the conductive substrate greatly affects the resin adhesion, and formed on the surface of the lead frame material. It was investigated whether good adhesion caused by the so-called anchor effect, which occurs when resin is filled and formed on the uneven surface (especially the concave portion) caused by a protrusion, can be maintained even when a high temperature and high humidity test is performed under the above severe conditions. .

Then, the inventors of the present invention found that the lower portion of the protrusion forming the roughened layer of the roughened film formed on the conductive substrate is located on the conductive substrate side than the measurement position of the maximum width when the maximum width is measured in the cross section in the thickness direction of the roughened film. By controlling the shape to have a shape that is 1 to 5 times larger than the minimum width measured in , shearing of the resin, which is likely to occur when stress is concentrated due to expansion or contraction of the resin, particularly in the location of the minimum width of the protrusions of the roughened particles. It was found that the peeling phenomenon due to can be effectively suppressed. As a result, good adhesion due to the anchor effect can be maximized by the roughened layer, and furthermore, by controlling the protrusions forming the roughened layer to the above shape, durability tests of high temperature and high humidity that could not be endured conventionally, such as temperature It was found that good resin adhesion to the lead frame could be maintained even when a high-temperature, high-humidity test was conducted under the severe conditions of being left for 168 hours in an environment of 85°C and 85% humidity.

That is, the gist of the present invention is as follows.

(1) a roughened film comprising a conductive substrate and at least one roughened layer formed of projections of a plurality of coarsened particles directly or via an intermediate layer on at least one surface of the conductive substrate;

The protrusion has a shape in which the maximum width when measured in the cross section of the roughened film in the thickness direction is 1 to 5 times greater than the minimum width when measured at a lower portion located on the conductive substrate side from the measurement position of the maximum width. A lead frame material having

(2) The lead frame material according to (1) above, wherein the conductive substrate is copper, copper alloy, iron, iron alloy, aluminum or aluminum alloy.

(3) The roughened layer is made of copper, copper alloy, nickel, nickel alloy, palladium, palladium alloy, silver, silver alloy, tin, tin alloy, zinc, zinc alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, iridium and The lead frame material according to (1) or (2) above, comprising a metal or alloy selected from the group of iridium alloys.

(4) further comprising a surface coating comprising at least one surface coating layer on at least a part of the surface of the roughened coating, wherein the surface coating layer is made of palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, The lead frame material according to any one of (1) to (3) above, comprising a metal or alloy selected from the group of platinum, platinum alloy, iridium, iridium alloy, gold, gold alloy, silver and silver alloy.

(5) The lead frame material according to (4), wherein the intermediate layer is nickel, a nickel alloy, cobalt, a cobalt alloy, copper or a copper alloy.

(6) forming a roughened film comprising at least one roughened layer formed of projections of a plurality of roughened particles by electroplating directly or through an intermediate layer on at least one side of the conductive substrate; The protrusion has a shape in which the maximum width when measured in the cross section of the roughened film in the thickness direction is 1 to 5 times greater than the minimum width when measured at a lower portion located on the conductive substrate side from the measurement position of the maximum width. A method for producing a lead frame material having a.

(7) A semiconductor package comprising the lead frame material according to any one of (1) to (5) above.

The lead frame material of the present invention includes a conductive substrate and a roughened film comprising at least one roughened layer formed of projections of a plurality of roughened particles directly or through an intermediate layer on at least one surface of the conductive substrate, The projection has a shape in which the maximum width when measured in the cross section of the roughened film in the thickness direction is 1 to 5 times larger than the minimum width when measured at a lower portion located on the conductive substrate side from the measurement position of the maximum width. By having, even when a high-temperature, high-humidity durability test is performed, for example, a high-temperature, high-humidity test under severe conditions in which a temperature of 85 ° C. and a humidity of 85% are left for 168 hours, the good resin adhesion to the lead frame is maintained with little deterioration. Therefore, a semiconductor package constructed using this lead frame material can realize high reliability.

1 is a schematic cross-sectional view of a representative lead frame material according to the present invention.
2 is a diagram for explaining a method for calculating the specific surface area of a roughened layer.
Fig. 3 is a diagram for explaining the maximum width Wmax and the minimum width Wmin of the protrusions constituting one roughened layer.
4 is a schematic cross-sectional view of another lead frame material according to the present invention.
5 is a view for explaining the maximum width Wmax and the minimum width Wmin of the protrusions constituting the two-layer roughened layer.

Next, the lead frame material according to the present invention will be described below, giving an example of a specific embodiment with reference to the drawings. 1 shows a schematic cross-section of a representative lead frame material according to the present invention, in which reference numeral 1 in FIG. 1 is a conductive substrate, 2 is a roughened layer, 3 is a roughened film, 4 is a projection, and 10 is a lead frame material. The lead frame material 10 of the present invention includes a conductive substrate 1 and a roughened film 3 containing at least one roughened layer 2.

(conductive gas)

The conductive substrate 1 may be any material having conductivity, and examples thereof include copper, copper alloys, iron, iron alloys, aluminum or aluminum alloys, and copper alloys, iron alloys, or aluminum alloys are preferable. . The lead frame material requires strength capable of withstanding deformation such as bending during bonding with a semiconductor element, and use of a copper alloy having a good balance between conductivity and strength is particularly preferable. Among them, examples of the copper alloy include "C14410 (Cu-0.15Sn, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC (registered trademark)-3)", "C19400 (Cu-Fe)", which are CDA (Copper Development Association) published alloys. Base alloy material, Cu-2.3Fe-0.03P-0.15Zn)”, “C18045 (Cu-0.3Cr-0.25Sn-0.2Zn, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC (registered trademark)-64T)”, “C50710 (Cu-2.0Sn-0.2Ni-0.05P), manufactured by Furukawa Denki Industrial Co., Ltd., trade name: MF202", "C70250 (Cu-3Ni-0.65Si-0.15Mg), manufactured by Furukawa Electric Industrial Co., Ltd., trade name: EFTEC (registered trademark)- 7025” and the like. In addition, the units of the numbers indicated immediately before each element are all "mass %". Like these copper alloys, a copper alloy having a tensile strength of 350 to 800 N/mm ² , preferably 500 to 800 N/mm ² , and a conductivity of 30 to 90% IACS, preferably 50 to 80% IACS, is prepared. It is preferable to use In addition, the above "% IACS" indicates the conductivity when the resistivity of 1.7241 × 10 ^-8 Ωm of the International Annealed Copper Standard is 100% IACS. For example, the conductivity of "50% IACS" is It means that it is 50% of the conductivity of standard interlocking. In addition, in the case of an iron alloy, 42 alloy (Fe-42 mass %Ni), stainless steel, etc. are mentioned, for example. The conductive base material 1 containing such an iron alloy does not have a very high conductivity, but does not require that much conductivity, and can be applied to the lead frame material 10 for the purpose of transmitting electrical signals. Furthermore, in the case of an aluminum alloy, Al-Mg type alloys, such as A5052, are mentioned, for example. Since the inside of a resin-encapsulated semiconductor device is easily filled with heat due to mold resin, it is important to dissipate heat from the inside along the conductive substrate. In the present invention, by forming a roughened film on the surface of the conductive substrate, compared to the case where the roughened film is not formed, the heat dissipation effect can be improved, and at the same time, the thickness of the conductive substrate can be reduced to 0.05 mm. If the thickness of the conductive substrate is less than 0.05 mm, sufficient heat dissipation cannot be achieved, and if the thickness of the conductive substrate is 2 mm or more, miniaturization of the semiconductor device cannot be achieved. For this reason, the thickness of the conductive substrate 1 is preferably 0.05 to 2 mm, more preferably 0.1 to 1 mm.

(harmonized coating)

The roughened film 3 is at least one layer of roughened layer 2 formed of projections 4 of a plurality of roughened particles directly or through an intermediate layer (not shown) on at least one surface of the conductive substrate 1. It consists of In addition, although the roughened film 3 should just be comprised from at least 1 layer of roughened layer 2, considering the complexity of a manufacturing process, etc., it is preferable to comprise from 1-3 layers of roughened layer 2. In the method of forming the roughened film 3, after forming the first roughened layer 2-1, one or more factors such as composition and formation conditions are different from that of the first roughened layer 2-1, the second roughened layer. Formation by so-called multiple roughening, in which (2-2) is laminated on the first roughened layer 2-1, is more preferable because the specific surface area can be effectively increased with a relatively thin film thickness (Fig. 4). Reference). Note that, in the present invention, the film thickness of the roughened film 3 is not measured locally, but at least a collimator diameter of 0.2 mm or more by a fluorescence X-ray method (for example, a film thickness measuring device such as SFT9400 (trade name) manufactured by SII). It is assumed that it is expressed as an average film thickness when measured at three arbitrary points. In addition, when the roughened film 3 is comprised from the some roughened layer 2, the total thickness of all layers shall be defined as the thickness of the roughened film 3. In addition, the film thickness of the roughened film 3 is not particularly limited, but the larger the film thickness, the larger the unevenness caused by roughening tends to be. Therefore, in order to enlarge the roughened shape, the lower limit of the film thickness of the roughened film 3 is preferably 0.2 μm or more, more preferably 0.5 μm or more, still more preferably 0.8 μm or more. On the other hand, when the film thickness of the roughened film 3 exceeds 3 µm, there is a possibility that the roughened film 3 is dropped during conveyance, that is, so-called "powdering" may increase. For this reason, the upper limit of the film thickness of the roughened film 3 is preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less.

[harmonized layer]

The roughened layer 2 is formed of projections 4 of a plurality of roughened particles. Although various methods such as wet plating and dry plating can be used as a method for forming the roughened layer 2, it is particularly preferable to form the roughened layer 2 by electroplating from the viewpoint of being easy and inexpensive to form. The roughened layer 2 is made of, for example, copper, copper alloy, nickel, nickel alloy, palladium, palladium alloy, silver, silver alloy, tin, tin alloy, zinc, zinc alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, It preferably includes a metal or alloy selected from the group of iridium and iridium alloys. The roughened layer 2 is copper, copper alloy, nickel or nickel from the viewpoint of improving the adhesion to the surface film, particularly when a later-described surface film (not shown) is further formed on the roughened film 3. It is more preferable to include an alloy. Examples of copper alloys include copper-tin alloys, copper-zinc alloys, and nickel alloys such as nickel-zinc alloys and nickel-tin alloys.

And, the main feature of the configuration of the present invention is to optimize the cross-sectional shape of the projections 4 of the roughened particles constituting the roughened layer 2, more specifically, as shown in FIG. 3, the projections The maximum width Wmax when water 4 is measured in the cross section in the thickness direction of the roughened film 3 is the minimum width Wmin when measured at the lower portion located on the conductive base 1 side from the Wmax measurement position of the maximum width described above. It is to control to have a shape that is 1 to 5 times larger than that.

As a result of diligent research by the present inventors, this is because if the roughened layer is formed with the same surface roughness, the shear strength (bonding strength) of the resin in the shear test is high, and good resin adhesion can be obtained, but at high temperature After a high-humidity durability test, for example, a high-temperature and high-humidity test under severe conditions of leaving it for 168 hours in an environment of 85 ° C. and 85% humidity, the roughened layer having the same surface roughness significantly decreased in shear strength and had good resin adhesion. It turns out that there is something that can't be maintained. As a result of further investigation on this point, it was found that the cross-sectional shape of the projections of the roughened particles forming the roughened layer was greatly affected, and in particular, the stress due to thermal expansion and contraction of the resin at the minimum width of the projections was reduced. It was found that the concentration was reduced and the adhesion was lowered.

For this reason, when the present inventors conducted a further detailed examination, the ratio of the maximum width to the minimum width of the projections of the roughened particles forming the roughened layer of the roughened film was set to 1 to 5, that is, the projections were separated from the cross section in the thickness direction of the roughened film. Roughening with the same degree of surface roughness by controlling the maximum width at the time of measurement to have a shape that is 1 to 5 times larger than the minimum width at the time of measurement at the lower part located on the conductive substrate side from the measurement position of the maximum width. Even in the layer, the shear strength (bonding strength) of the resin hardly decreases even after a durability test at high temperature and high humidity, for example, a high temperature and high humidity test under severe conditions in which it is left for 168 hours in an environment of 85 ° C. and 85% humidity. It discovered that resin adhesiveness could be maintained.

The fact that the maximum width of the projection is 1 times the minimum width indicates that the maximum width and the minimum width are the same, and examples of the shape of the projection include a substantially cylindrical shape or a prismatic shape. On the other hand, if the maximum width of the projections exceeds 5 times the minimum width, the concentration of stress due to expansion or contraction of the resin increases at the minimum width of the projections forming the roughened layer, so the anchor effect cannot be effectively exhibited. It becomes easy to fracture in the location of the minimum width of a projection. For this reason, the maximum width of the projection is 1 to 5 times the minimum width. In addition, the mold resin not only exhibits an anchor effect, but also improves the shear strength with respect to the lead frame material by making it difficult for the resin to break at the minimum portion of the projections forming the roughened layer, and also improves the shear strength in the vertical direction. When it is necessary to further improve the tensile strength of the protrusion, the ratio of the maximum width to the minimum width of the protrusion is preferably 1.1 to 4.9 times, more preferably 1.2 to 4.8 times, and even more preferably 1.5 to 4.0 times. It is preferable, and it is most preferable to make it 1.5 to 3.0 times. Further, the shape of the surface of the projection may be sharp, pointed, round, or smooth, and the ratio of the maximum width to the minimum width of the projection is important.

<About the definition of the maximum width and minimum width of projections>

The maximum and minimum widths of the projections in the present invention are obtained by processing a lead frame material having a roughened layer by, for example, a method such as Focused Ion Beam (FIB) or mechanical polishing to prepare a vertical cross-section sample, and then Cross-sectional observation of the roughened layer of the cross-section sample is performed using an optical microscope or a scanning electron microscope, and a line segment is moved in parallel from the surface of the conductive substrate toward the surface of the roughened layer, and a plurality of projections forming the roughened layer are observed. The width of each projection is measured to determine the maximum value (maximum width) Wmax and minimum value (minimum width) Wmin. More specifically, as shown in FIG. 3, a perpendicular line is drawn from the conductive base 1 in the direction of the roughened layer, and a line parallel to the base (parallel line) is scanned from the apex in the direction toward the conductive base 1 The width showing the maximum value of the projections 4 at the time of making the maximum width is Wmax as the maximum width, and the minimum value of the projections 4 when a parallel line is again scanned from the position of the maximum width Wmax in the direction toward the conductive substrate 1 is The indicated width is determined as Wmin as the minimum width. And in this invention, it is necessary that the value of the ratio Wmax/Wmin is 1-5. In addition, the minimum width Wmin of the projection 4 is the lower part located on the conductive base 1 side from the measurement position of the largest width Wmax of the projection 4 when measured in the cross section in the thickness direction of the roughened film 3. It means the minimum width Wmin when measured in This is based on the finding that the shear strength depends on the width of the lower portion (base end portion) of the projection 4 located on the side of the conductive substrate 1 in the shear test. In addition, the projections 4 are observed at various positions of the roughened layer 2 in order to observe an arbitrary cross section. This is because the roughened layer 2 is generally formed basically three-dimensionally, so as the roughened layer 2 for measuring the maximum width Wmax and the minimum width Wmin of the protrusion 4, one roughened layer 2 ) or, as shown in FIG. 5, even if it is two or more roughened layers (for example, two roughened layers 2-1 and 2-2 in FIG. 5), the maximum width Wmax of the projection 4 is further and the case where the measurement of the minimum width Wmin is possible is taken as a measurement target, and other than that, for example, a case where the roughened layer has two or more layers and the outermost contour of the roughened film 3 is not clear, or it is not clear from the conductive substrate 1. In the case of the roughened layer 2, etc., which are visible, it is a roughened layer that cannot be said to be a target of measurement in the present invention. According to these methods, the maximum width Wmax and the minimum width Wmin of each of the 10 projections 4 present in one roughened layer 2 are measured in an arbitrary cross section, and the ratio Wmax/ of the maximum width Wmax to the minimum width Wmin is measured. Wmin is calculated, and the lead frame material 10 having the roughened layer 2 whose average value of their ratio is 1 to 5 times is defined as the lead frame material of the present invention.

<About the minimum width of projections and the distance between projections>

The size of the minimum width Wmin of the projections 4 constituting the roughened layer 2 in the present invention is not particularly regulated, but if the minimum width Wmin is too small, the resin is formed on the projections of the roughened layer 2. It tends to become difficult to flow in the gap between the water 4, 4, and on the other hand, if the minimum width Wmin is too large, the effect of increasing the shear strength tends to be small. For this reason, the minimum width Wmin of the protrusion 4 is preferably in the range of 0.2 μm to 3 μm on average, and more preferably in the range of 0.5 μm to 1 μm. Further, the distance between the projections 4 and 4 is not particularly limited, but the average distance between the vertices of the projections 4 and 4 is preferably in the range of 0.2 to 20 μm, and in the range of 0.5 μm to 10 μm. more desirable

<About the specific surface area of the roughened layer>

The lead frame material 10 of the present invention first has a roughened layer 2 on a conductive substrate (hereinafter, simply referred to as "substrate") 1. It is preferable that this roughened layer 2 has a specific surface area of 110% or more. This is because the anchor effect cannot be sufficiently obtained when the specific surface area is less than 110%. In addition, the upper limit of the specific surface area is not particularly regulated, but if the specific surface area is too large, the unevenness of the roughening becomes too large and the roughened layer easily falls off, so the specific surface area is preferably set to 500% or less.

In addition, as a calculation method of the specific surface area, as the cross section of the lead frame material 10 is shown in Fig. 2, the line segment length of the outermost layer of the roughened film 3 (Fig. 2, the broken line A) is divided by the (straight line) length (thick solid line B in FIG. 2) of the surface of the conductive substrate 1, and the percentage of the ratio A/B is the specific surface area (%), for example It can measure using a measuring device (for example, manufactured by Bruker axs), such as a non-contact type interference microscope. In the present invention, the roughened layer may be formed in at least a part of the resin molded portion, and the roughened layer 2 may be partially formed as well as the entire surface treatment. Further, for example, the lead frame material 10 is preferably formed on at least 1/5 or more of the resin molded portion, and more preferably formed on 1/2 or more area, so that the effect of improving adhesion can be exhibited. It is most preferable that the roughening layer 2 is formed on the entire surface of the resin mold. As the shape of the partially provided roughened layer 2, it is possible to take various forms such as stripe shape, dot shape, and ring shape. Furthermore, in the case of a product having only one side of the resin mold, it is also possible to form the roughened layer 2 on only one side, for example.

(middle layer)

In addition, the lead frame material 10 of the present invention is an intermediate layer between the conductive substrate 1 and the roughened film 3, for example, to suppress diffusion of components constituting the conductive substrate 1 and to improve adhesion. may form The intermediate layer includes, for example, nickel, a nickel alloy, cobalt, a cobalt alloy, copper or a copper alloy.

(surface coating)

Further, the lead frame material 10 of the present invention preferably further includes a surface coating comprising at least one surface coating layer directly or via an intermediate layer on at least a part of the surface of the roughened coating film 3, The surface coating layer contains a metal or alloy selected from the group of palladium, palladium alloys, rhodium, rhodium alloys, ruthenium, ruthenium alloys, platinum, platinum alloys, iridium, iridium alloys, gold, gold alloys, silver and silver alloys. desirable.

[Surface coating layer]

As various alloys constituting the surface coating layer, for example, a palladium-silver alloy as a palladium alloy, a rhodium-palladium alloy as a rhodium alloy, a ruthenium-iridium alloy as a ruthenium alloy, a platinum-gold alloy as a platinum alloy, and a platinum-iridium alloy as an iridium alloy Examples of alloys and gold alloys include gold-silver alloys and silver alloys such as silver-tin alloys. Although one type of surface film may be sufficient, two or more layers are preferable. As a typical layer structure in the case where the surface coating layer constituting the surface coating is two or more layers, Pd/Au, Rh/Au, Pd/Ag/Au, Pd/Rh/Au, Ru in the order of lamination from the rough coating (3) side. /Pd/Au etc. are mentioned. Thus, by forming a surface film layer on the roughened film, while heat resistance is improved with respect to heat generation of the lead frame, the strength of the projections of the roughened particles forming the roughened layer of the roughened film is improved, and breakage of the projections is prevented. More anchor effect can be exerted. Further, from the viewpoint of improving the adhesion to the surface coating, it is more preferable that the surface coating layer is two layers of Pd/Au or two layers of Rh/Au to the two layers of copper and nickel in the roughened layer, and the layer configuration of the roughened layer is The lower roughened layer is copper, and the upper roughened layer is nickel. The layer composition of the surface coating layer is that the lower surface coating layer is Pd and the upper surface coating layer is two layers of Au, or the lower surface coating layer is Rh and the upper surface coating layer is Au. It is more preferable that it is the second layer of. If the film thickness of these surface coatings is too thick, there is a possibility that the surface irregularities of the roughened coating film 3 may be buried and the effect of the present invention described above may not be sufficiently exhibited, and the surface coating is mainly composed of noble metal materials. There is a possibility of calling an ascent. For this reason, the film thickness of each surface coating layer is preferably 1 μm or less, more preferably 0.03 or less as the total film thickness of the laminated surface coating layers (film thickness of the surface coating film).

(About manufacturing method of lead frame material)

Next, the manufacturing method of the lead frame material 10 of this invention is demonstrated below. A conductive base 1 is prepared, and a cathode electrolytic degreasing step and an acid pickling step are performed on the conductive base 1. Next, after forming an intermediate layer by electroplating as needed, the roughened film 3 containing at least one layer of roughened layer 2 is formed by electroplating, and then electroplated again as needed. The lead frame material 10 can be manufactured by forming a surface film containing at least one surface coating layer. As representative examples of specific manufacturing conditions, Table 1 shows cathodic electrolytic degreasing conditions, Table 2 pickling conditions, Table 3 conditions for forming various intermediate layers, conditions for forming various roughened layers 2 in Table 4, and various conditions for forming various roughened layers 2 in Table 5. Formation conditions of the surface coating layer are respectively shown. In the manufacturing method of the lead frame material 10 mentioned above, the case where all the intermediate|middle layer, the roughened layer 2, and the surface coating layer were manufactured by electroplating was illustrated. The roughened layer 2 is preferably formed by an electroplating method in that the shape of the protrusion can be relatively easily controlled by current density, agitation, temperature, treatment time, etc. Although it is preferable to form by the wet plating method like this from a viewpoint of productivity, you may manufacture by dry plating method or another manufacturing method, and it is not specifically limited.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. Various conductive substrates shown in Table 6 having a plate thickness of 0.2 mm cut in advance to a test piece size of 40 mm × 40 mm were prepared, and cathodic electrolytic degreasing was performed under the conditions shown in Table 1 above. Subsequently, after pickling the conductive substrate under the conditions shown in Table 2, at least one roughened layer was formed on the surface of the conductive substrate in the layer configuration shown in Table 6 to obtain a lead frame material test piece. In the formation of the roughened layer, not only the specific surface area but also the ratio of the maximum width to the minimum width of the protrusions of the roughened layer in the cross section was controlled. Among Examples 1 to 30, in Examples 11 to 13, the roughened film is composed of two roughened layers by forming an upper roughened layer in addition to the lower roughened layer, and in Examples 22 to 24, the conductive substrate and the roughened layer are formed. An intermediate layer is further formed between the coatings, and in Examples 29 and 30, the roughened coating forms an upper roughened layer in addition to the lower roughened layer, and is composed of two roughened layers, a lower surface coating layer and an upper surface. A surface film comprising two layers of coating layers is further formed. For reference, as Comparative Example 1, although the specific surface area of the roughened layer is very large at 550%, the ratio of the maximum width to the minimum width of the projections forming the roughened layer is not controlled and outside the scope of the present invention (5.2 times) A test piece of the phosphorus lead frame material was produced.

In each of the above test pieces, the resin mold was injection-molded using a transfer mold tester (product name: Model FTS) manufactured by Kotaki Seiki Co., Ltd. under the conditions of a mold temperature of 130 ° C., a holding time of 90 seconds after molding, and an injection pressure of 6.865 MPa, and a contact area of 10 mm. A purine-like test piece of ² was formed. Each test piece was subjected to a high-temperature, high-humidity test (at 85° C., 85% RH, maintained for 168 hours), and the test piece was evaluated for resin adhesion and powder fall-off under the conditions shown below. Table 7 shows those evaluation results.

(Evaluation of resin adhesion)

Evaluation resin: G630L, manufactured by Sumitomo Bakelite Co., Ltd. (trade name)

Evaluation conditions: Apparatus: 4000Plus, manufactured by Nordson Advanced Technology (trade name),

Load cell: 50kg

Measuring range: 10kg

Test speed: 100μm/s

Test height: 10 μm

Table 7 shows the evaluation results of resin adhesion. In addition, in the evaluation of resin adhesion shown in Table 7, the case where the shear strength (peel strength) was 9.8 MPa or more on average was considered excellent in resin adhesion and was rated as "A", and the shear strength (peel strength) was 4.9 MPa or more 9.8 on average. A case of less than MPa was designated as "B" as having good resin adhesion, and a case of an average shear strength (peel strength) of less than 4.9 MPa was designated as "C" as poor in resin adhesion. Resin adhesion was evaluated by measuring both "initial shear strength" and "shear strength after high-temperature, high-humidity test", respectively. "Shear strength after high-temperature, high-humidity test" is a value after resin molding of each test piece, and then leaving it to stand for 168 hours in an environment of a temperature of 85°C and a humidity of 85%. In addition, "initial shear strength" is the shear strength immediately after resin-molding each test piece (before a high-temperature, high-humidity test).

(Evaluation of powder dropability)

The powder fall-off property was sensitized and evaluated visually. The evaluation results are shown in Table 7. In addition, for the powder fall-off properties shown in Table 7, the case where powder fall-off from the surface could not be recognized was rated as "A (excellent)", the case where powder fall-off occurred a little was rated as "B (good)", and the powder fall-off was The case where it occurs very often is indicated as "C (impossible)", and "A" and "B" are levels used for practical use.

From the evaluation results in Table 7, Examples 1 to 30 all had "A" or "B" in shear strength at the initial stage and shear strength after high-temperature, high-humidity testing, maintaining good resin adhesion, and also exhibiting "A" or "B" powder fall-off properties. It was a level used for practical use as "B". On the other hand, although the specific surface area of the roughened layer is very large at 550%, the ratio of the maximum width to the minimum width of the projections forming the roughened layer is not controlled, and Comparative Example 1, which is outside the scope of the present invention (5.2 times), Regarding the initial shear strength, resin adhesion was excellent at "A", but the shear strength after the high temperature and high humidity test became "C", and the resin adhesion greatly deteriorated, and the powder fall-off property also fell to "C", which was not a level used for practical use. .

Even when the lead frame material of the present invention is subjected to a high-temperature, high-humidity durability test, for example, a high-temperature, high-humidity test under severe conditions in which it is left in an environment of a temperature of 85 ° C. and a humidity of 85% for 168 hours, good resin adhesion to the lead frame is almost deteriorated. Since it can be maintained without causing it, the semiconductor package constructed using this lead frame material can realize high reliability.

1: conductive substrate
2: roughened layer
2-1: 1st roughened layer (1st roughened layer from the base material side)
2-2: 2nd roughened layer (2nd roughened layer from the base material side)
3, 3-1: roughened film
4, 4-1: projection
10, 10A: lead frame material
A: length of the cross-sectional line of the outermost surface of the roughened film
B: Length of cross-sectional line segment of the surface of the conductive substrate

Claims (7)

A conductive substrate having a tensile strength of 350 to 800 N/mm ² , a conductivity of 30 to 90% IACS, a thickness of 0.1 to 2 mm, and being a copper alloy;
On at least one surface of the conductive substrate, a roughened film including at least one roughened layer formed of projections of a plurality of roughened particles directly or through an intermediate layer is provided, ,
The roughened layer is composed of a metal of copper or nickel,
The protrusion has a shape in which the maximum width when measured in the cross section of the roughened film in the thickness direction is 1 to 5 times greater than the minimum width when measured at a lower portion located on the conductive substrate side from the measurement position of the maximum width. has,
A surface coating comprising at least one surface coating layer is further provided on at least a part of the surface of the roughened coating, and the surface coating layer comprises palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, and platinum. A lead frame material comprising a metal or alloy selected from the group of alloys, iridium, iridium alloys, gold, gold alloys, silver and silver alloys.
The lead frame material according to claim 1, wherein the intermediate layer is nickel, a nickel alloy, cobalt, a cobalt alloy, copper or a copper alloy.
Tensile strength of 350 to 800 N/mm ² , conductivity of 30 to 90% IACS, thickness of 0.1 to 2 mm, and a plurality of layers by electroplating, directly or through an intermediate layer, on at least one side of a conductive base material of a copper alloy. A step of forming a roughened film comprising at least one roughened layer formed of projections of roughened particles of
The roughened layer is composed of a metal of copper or nickel,
The protrusion has a shape in which the maximum width when measured in the cross section of the roughened film in the thickness direction is 1 to 5 times greater than the minimum width when measured at a lower portion located on the conductive substrate side from the measurement position of the maximum width. has,
A surface coating comprising at least one surface coating layer is further provided on at least a part of the surface of the roughened coating, and the surface coating layer comprises palladium, palladium alloy, rhodium, rhodium alloy, ruthenium, ruthenium alloy, platinum, and platinum. A method for producing a lead frame material comprising a metal or alloy selected from the group of alloys, iridium, iridium alloys, gold, gold alloys, silver and silver alloys.
A semiconductor package comprising the lead frame material according to claim 1 or 2. delete delete delete

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