Lead frame material and method for producing same, and semiconductor package

Abstract

Provided are: a lead frame material which, even when being subjected to a heat cycle assuming a severe use environment, is capable of improving airtightness of a package, and in which drop of powder hardly occurs; and a method for producing the same and a semiconductor package using the same. 　A lead frame material 1 has: an electrically conductive substrate 2; a surface coating film 3 formed on at least a portion of the obverse surface 21 and / or the reverse surface 22 of the substrate 2; and a lateral surface coating film 4 that is located adjacent to the surface coating film 3 and that is formed in at least a portion of a lateral surface 23 of the substrate 2. The surface coating film 3 and the lateral surface coating film 4 respectively have roughened upper surfaces 30, 40. When h1 represents the average roughness height of the surface coating film 3 and h2 represents the average roughness height of the lateral surface coating film 4, the ratio h2 / h1 of the average roughness height h2 of the lateral surface coating film 4 with respect to the average roughness height h1 of the surface coating film 3 is 1.35 or more.

Description

Lead frame material, manufacturing method thereof, and semiconductor package

[0001] The present invention relates to a lead frame material, a manufacturing method thereof, and a semiconductor package. More specifically, the present invention relates to a lead frame material having a coating (e.g., an electroplated layer) of a predetermined shape on the surface and side of a conductive substrate, which electrically connects semiconductor elements to each other in a resin-encapsulated semiconductor device, a manufacturing method thereof, and a semiconductor package using the lead frame material.

[0002] Many resin-sealed semiconductor devices are incorporated into electronic devices, electrical devices, and the like. These resin-sealed semiconductor devices are formed by sealing a semiconductor element and a lead frame material, which are electrically connected to each other by wires or the like, with a molded resin. In such resin-sealed semiconductor devices, the lead frame material is often plated with Au, Ag, Sn, or the like to impart functions such as bonding properties, heat resistance, and sealing properties.

[0003] In recent years, in order to simplify the assembly process and reduce costs, lead frame materials (pre-plated leadframes) have been used in which the surface of the lead frame material is pre-plated with a plating (e.g., Ni / Pd / Au) that is designed to enhance wettability with solder when mounted on a printed circuit board by soldering or the like (see, for example, Patent Document 1).

[0004] Furthermore, in order to improve the adhesion between the lead frame material and the mold resin in a resin-sealed semiconductor device, a technique has been proposed in which a coating made of a roughened plating layer is formed on the surface and side surfaces of the lead frame material (see, for example, Patent Documents 2 and 3).

[0005] These techniques for roughening the plating layer are expected to have the following effects: (1) increase the adhesive area between the lead frame material and the molding resin; and (2) make it easier for the molding resin to adhere to the irregularities on the roughened plating film surface (i.e., anchor effect).

[0006] As a result, the adhesion of the molding resin to the lead frame material is improved, making it possible to prevent separation between the lead frame material and the molding resin, thereby improving the reliability of the resin-sealed semiconductor device.

[0007] Patent No. 2543619 Patent No. 6736719 Patent No. 6479265

[0008] The roughening of the plating surface as described above certainly improves the resin adhesion of the lead frame material compared to conventional methods. However, with the recent demand for smaller and thinner semiconductor packages, it is expected that the pass level for package airtightness will become more stringent. For example, when a heat cycle test simulating a harsh operating environment was conducted, for example, a heat cycle test in which a cycle of holding at -50°C for 30 minutes followed by holding at 105°C for 30 minutes was repeated 50 times, it was found that gaps appeared between the resin and the lead frame, reducing the package's airtightness and potentially causing defects. This is thought to be due to the widespread use of smaller packages such as QFN (Quad Flat Non-Leaded Package) and SOP (Small Outline Package), which were not widely used in the past, reducing the bonding area between the mold resin and the lead frame material, as well as increasing temperature loads due to operating environments such as automotive applications. In particular, the airtightness of the package was significantly reduced due to gaps between the lead frame material and the molding resin on the side surfaces of the lead frame material. As such, it was found that there is still room for improvement in the airtightness of the package.

[0009] In particular, Patent Document 1 improves the mounting characteristics of lead frames by forming a 0.001 μm to 0.1 μm thick Au plating film on a Pd or Pd alloy film formed on the outer leads of the lead frame. However, the lead frame material has poor adhesion to the molded resin, making it prone to peeling at the interface with the molded resin. Patent Document 2 improves adhesion between the lead frame material and the molded resin by controlling the crystal orientation on at least the top or side surface of the lead frame material to form a group of needle-like protrusions. However, in high-temperature environments or environments subject to thermal shock, the molded resin is prone to peeling from the side surfaces, where the adhesive area with the molded resin is small. Patent Document 3 improves adhesion to the molded resin by shaping the roughening particle protrusions so that the maximum width measured at a cross section in the thickness direction of the roughening film is 1 to 5 times the minimum width measured at a lower portion closer to the conductive base than the maximum width measurement position. However, further improvement in the airtightness of packages is required in more severe usage environments.

[0010] In addition, if the roughness of the entire surface of the lead frame material is increased to further improve adhesion with the mold resin, a portion of the roughened layer tends to fall off from the front and back surfaces of the lead frame material, which is known as powder shedding. Powder shedding from the roughened layer increases resistance when the mold resin is injected into a mold, and also reduces the wettability of the mold resin to the lead frame material, which can reduce productivity when sealing the lead frame material with the mold resin. Therefore, it is desirable to minimize powder shedding on the front and back surfaces of the lead frame material.

[0011] The object of the present invention is to provide a lead frame material that can improve the airtightness of the package and is less likely to cause powder falling even when subjected to a heat cycle that simulates a harsh usage environment, a method for manufacturing the same, and a semiconductor package using the same.

[0012] As a result of intensive research and development into the above-mentioned conventional problems, the present inventors have focused on the fact that in a lead frame material having a surface coating formed on one or both of the front and back surfaces of at least a portion of a substrate, and a side coating formed adjacent to the surface coating and on at least a portion of the side surface of the substrate, by controlling the average roughness height of the surface coating and the side coating, the adhesiveness to the resin after being subjected to a heat cycle changes, and thereby the airtightness of the package changes, and in particular, by controlling the average roughness height of the surface coating to h １ , the average roughness height of the side coating is h ２ When the average roughness height of the surface coating is １ The average roughness height h of the side coating ２ The ratio h ２ / h １ It was confirmed that by making the value of the porosity at or above 1.35, it is possible to obtain a lead frame material that is less likely to cause powder shedding and has high adhesion to resin even when subjected to heat cycles simulating harsh usage environments, thereby improving the airtightness of the package. The present invention was completed based on this finding.

[0013] In order to achieve the above object, the gist of the present invention is as follows: (1) A lead frame material having a conductive substrate, a surface coating formed on at least one or both of a front surface and a back surface of at least a portion of the substrate, and a side coating formed adjacent to the surface coating and on at least a portion of a side surface of the substrate, wherein the surface coating and the side coating both have roughened upper surfaces, and the average roughness height of the surface coating is h １ , the average roughness height of the side coating is h ２ When the average roughness height h of the surface coating is １ The average roughness height h of the side coating ２ The ratio h ２ / h １ (2) The lead frame material, wherein the average roughness height h of the surface coating is 1.35 or more. １ is in the range of 0.5 μm or more and 3.5 μm or less, and the average roughness height h ２(3) When viewed from the cross section of the surface coating, an imaginary line l passing through the position of the highest point on the upper surface of the surface coating and drawn parallel to the surface of the base is １ and an imaginary line n drawn parallel to the surface of the substrate and passing through the lowest point of the upper surface of the surface coating. １ The first porosity in the first measurement area partitioned by １ When viewed from the cross section of the side surface coating, an imaginary line l is drawn parallel to the side surface of the base body, passing through the position of the highest point on the upper surface of the side surface coating. ２ and an imaginary line n drawn parallel to the side surface of the substrate, passing through the lowest point of the upper surface of the side coating. ２ The second porosity in the second measurement area partitioned by V ２ When the first porosity V １ The second porosity V ２ The ratio V ２ / V １ (4) The lead frame material according to (1) or (2), wherein the first porosity V is in the range of 0.50 or more and 0.91 or less. １ and the second porosity V ２ (5) The lead frame material according to any one of (1) to (4), wherein the base is made of copper, a copper alloy, iron, an iron alloy, aluminum, or an aluminum alloy. (6) When the thickness of the base is T, the average roughness height h of the side coating is ２ The ratio of the thickness T of the substrate to the thickness (T / h ２The lead frame material according to any one of (1) to (5) above, wherein the ratio (ratio) is in the range of 15.0 or more and 200.0 or less. (7) The lead frame material according to any one of (1) to (6) above, wherein the surface coating and the side coating both have a roughened layer. (8) The lead frame material according to (7) above, wherein the roughened layer is made of copper, a copper alloy, nickel, or a nickel alloy. (9) The lead frame material according to (7) or (8) above, wherein the roughened layer is an electroplated layer. (10) The lead frame material according to any one of (7) to (9) above, wherein the surface coating and the side coating further have at least one surface coating layer formed on an upper surface of the roughened layer. (11) The lead frame material according to (10) above, wherein the surface coating layer is a metal or alloy having a different composition from the roughened layer, and is made of copper, a copper alloy, nickel, a nickel alloy, cobalt, a cobalt alloy, palladium, a palladium alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, platinum, a platinum alloy, iridium, an iridium alloy, gold, a gold alloy, silver, a silver alloy, tin, a tin alloy, indium, or an indium alloy. (12) A method for manufacturing the lead frame material according to any one of (1) to (11) above, comprising a coating formation step of forming the surface coating and the side coating, each having a roughened upper surface, on the base by electroplating. (13) A semiconductor package comprising a lead frame formed using the lead frame material according to any one of (1) to (11) above.

[0014] According to the present invention, it is possible to provide a lead frame material and a manufacturing method thereof, as well as a semiconductor package using the same, which can improve the airtightness of the package and make it less likely to powder off, even when subjected to a heat cycle that simulates a harsh usage environment.

[0015] 1 is a schematic cross-sectional view showing a part of a lead frame material according to an embodiment of the present invention; FIG. 2 is a cross-sectional view showing a surface coating formed on the surface of a base of a lead frame material having the same configuration as FIG. 1; １ , n １ The relationship between the virtual line m １and the average roughness height h of the surface coating １ 3 is a cross-sectional view showing an evaluation area M1 in a surface coating formed on the surface of a substrate and having the same structure as in FIG. １ , n １ 1 is a cross-sectional view showing a side surface coating formed on a side surface of a substrate of a lead frame material having the same configuration as that of FIG. 1, and shows a relationship between the top surface of the surface coating and an evaluation area M1, and a relationship between the evaluation area M1 and an area P1 where the surface coating is present and an area S1 where the surface coating is absent. ２ , n ２ and the virtual line m ２ and the average roughness height h of the surface coating ２ 5 is a cross-sectional view showing an evaluation area M2 in a side coating having the same configuration as in FIG. 4, formed on the side surface of a substrate, and is shown by a virtual line l ２ , n ２ 1 is a diagram for explaining the relationship between the evaluation area M2 and the surface coating presence region P2, and the relationship between the evaluation area M2 and the surface coating absence region S2. FIG. 2 is a cross-sectional view showing an outline of a lead frame material according to another embodiment of the present invention. FIG. 3 is a schematic diagram showing the positional relationship between the lead frame material and resin in measuring adhesion to resin performed on the lead frame material of an example of the present invention. FIG. 4 is a secondary electron image observed by SEM of the cross section of the lead frame material of example 1 of the present invention.

[0016] Preferred embodiments of the lead frame material, the manufacturing method thereof, and the semiconductor package of the present invention will be described in detail below.

[0017] <Lead Frame Material> Fig. 1 is a cross-sectional view showing an outline of a lead frame material according to an embodiment of the present invention. As shown in Fig. 1, the lead frame material 1 of the present invention comprises a conductive substrate 2, a surface coating 3 formed on at least one or both of a front surface 21 and a back surface 22 of at least a portion of the substrate 2, and a side coating 4 adjacent to the surface coating 3 and formed on at least a portion of a side surface 23 of the substrate 2, and both the surface coating 3 and the side coating 4 have roughened upper surfaces 30, 40. In this lead frame material 1, the surface coating 3 has an average roughness height of h １, the average roughness height of the side coating 4 is h ２ When the average roughness height h of the surface coating 3 is １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ is 1.35 or more.

[0018] In this way, the average roughness height h １ , h ２ By controlling the average roughness height h of the side surface coating 4, it is possible to change the adhesiveness of the lead frame material 1 to the resin after the heat cycle and the airtightness of the package. ２ is the average roughness height h １ By increasing the average roughness height h of the surface coating 3 relative to the molded resin, the adhesion of the side coating 4 to the molded resin, which has conventionally been low due to a small contact area with the molded resin, can be increased relative to the adhesion of the surface coating 3 to the molded resin, thereby improving the airtightness of the package. １ When the average roughness height h of the side coating 4 is large, powder falling from the surface coating 3 becomes easy to occur. ２ is the average roughness height h １ By making it larger relative to , powder falling can be made less likely to occur.

[0019] Therefore, the average roughness height h of the surface coating 3 １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ By making the average roughness height h of the surface coating 3 of the present invention 1.35 or more, it is possible to obtain a lead frame material that can improve the airtightness of the package even when subjected to a heat cycle that simulates a severe usage environment. １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ The lead frame material 1 having a value of 1.35 or more is also excellent in that it is less likely to cause powder falling.

[0020] Here, the average roughness height h of the surface coating 3 and the side coating 4 １ , h２ The control of (a) is carried out by, for example, forming the roughened layer 5 of the surface coating 3 and the side coating 4 by electroplating (roughening plating), and, when carrying out the electroplating (roughening plating), placing a shielding plate between the surface 21 of the substrate 2 and the counter electrode, adjusting the aperture ratio of the shielding plate, and controlling the current density to 5 A / dm ２ 80A / dm or more ２ This can be achieved by adjusting the following ranges.

[0021] (Regarding the conductive base (substrate)) The lead frame material 1 of the present invention has a conductive base 2, a surface coating 3 formed on one or both of at least a portion of the front surface 21 and back surface 22 of the base 2, and a side coating 4 adjacent to the surface coating 3 and formed on at least a portion of the side surface 23 of the base 2.

[0022] Among these, the base 2 is preferably made of a metal or alloy containing copper (Cu), iron (Fe), or aluminum (Al). More specifically, from the viewpoint of improving electrical conductivity and heat dissipation, the base 2 is preferably made of copper, a copper alloy, iron, an iron alloy, aluminum, or an aluminum alloy.

[0023] When the base 2 is made of an alloy, the alloy composition is not particularly limited and can be appropriately selected depending on the characteristics required of the lead frame material. Examples of copper alloys that make up the base 2 include pure copper (oxygen-free copper (OFC): C1020 or tough pitch copper (TPC): C1100, etc.), as well as alloys listed in the Copper Development Association (CDA), such as C18045 (Cu-0.3Cr-0.25Sn-0.52Zn) and C19400 (Cu-2.3Fe-0.03P-0.15Zn). An example of an iron alloy that makes up the base 2 is 42 alloy (Fe-42Ni). The number before each element indicates the content in mass% of the alloy.

[0024] The base 2 is preferably in the form of a metal foil or alloy foil, and examples of such metal foil or alloy foil include rolled foil, electrolytic foil, etc. In particular, from the viewpoint of configuring the base 2 to have anisotropic mechanical properties, a rolled foil formed by press working or the like may be used for the base 2.

[0025] The thickness of the substrate 2 is not particularly limited, but is, for example, in the range of 1 μm to 500 μm, preferably 5 μm to 200 μm.

[0026] (Regarding the surface coating and side coating) The surface coating 3 is a coating formed on one or both of the front surface 21 and the back surface 22 of at least a portion of the base 2. The side coating 4 is a coating adjacent to the surface coating 3 and formed on at least a portion of the side surface 23 of the base 2. Therefore, the lead frame material 1 of the present invention has the above-mentioned conductive base 2, the surface coating 3, and the side coating 4.

[0027] The surface coating 3 and the side coating 4 both have roughened upper surfaces 30, 40, and the average roughness height of the upper surface 30 of the surface coating 3 is h １ , the average roughness height of the upper surface 40 of the side coating 4 is h ２ When the average roughness height h of the surface coating 3 is １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ is 1.35 or more. As a result, the roughness of the side coating 4 formed on the side surface 23 of the substrate 2 is greater than that of the surface coating 3 formed on the front surface 21 and the back surface 22 of the substrate 2, making it difficult for gaps to form between the side coating 4 and the resin (mold resin) on the side surface 23 of the substrate 2. In addition, the average roughness height h １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ By making the average roughness height h １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ If the average roughness height h of the surface coating 3 is less than 1.35, the adhesive strength of the side coating 4 to the resin is significantly reduced compared to the adhesive strength of the surface coating 3 to the resin, and therefore, gaps are likely to occur between the side surface 23 of the substrate 2 and the resin during heat cycles, resulting in a decrease in the airtightness of the package.１ The average roughness height h of the side coating 4 ２ The ratio of h is set to 0.015 mm from the viewpoint of further increasing the airtightness of the package. ２ / h １ is preferably in the range of 1.35 or more and 5.00 or less, and more preferably in the range of 1.66 or more and 5.00 or less.

[0028] Here, the average roughness height h of the surface coating 3 １ is preferably in the range of 0.5 μm or more and 3.5 μm or less, and more preferably in the range of 0.8 μm or more and 2.5 μm or less. In particular, from the viewpoint of increasing the adhesive strength of the surface coating 3 with the resin and further increasing the airtightness of the package, the average roughness height h １ In order to increase the adhesion of the surface coating 3 to the substrate 2 and make it more difficult for powder to fall off from the lead frame material 1, the average roughness height h １ is preferably 3.5 μm or less, and more preferably 2.5 μm or less.

[0029] The average roughness height h of the side coating 4 ２ is preferably in the range of 1.0 μm or more and 6.5 μm or less, and more preferably in the range of 1.2 μm or more and 4.8 μm or less. In particular, from the viewpoint of increasing the adhesive strength of the side coating 4 with the resin and further increasing the airtightness of the package, the average roughness height h ２ is preferably 1.0 μm or more, more preferably 1.2 μm or more, and even more preferably 1.5 μm or more. In addition, from the viewpoint of increasing the adhesive strength of the side coating 4 with the base 2 and making it more difficult for powder to fall off of the lead frame material 1, the average roughness height h ２ is preferably 6.5 μm or less, and more preferably 4.8 μm or less.

[0030] Average roughness height h of the surface coating 3 １ and the average roughness height h of the side coating 4 ２can be determined by observing a microtomed cross section of the surface coating 3 and the side coating 4 in the thickness direction using a scanning electron microscope (SEM). Here, in the SEM observation, three fields of view are randomly selected for the surface coating 3 formed on the front surface 21, the surface coating 3 formed on the back surface 22, and the side coating 4 formed on the side surface 23, with ten consecutive irregularities in the coating being one field of view. For each of the three SEM images, an evaluation area (evaluation area M1 for the surface coating 3 or evaluation area M2 for the side coating 4) is defined by an imaginary line drawn parallel to the front surface (or back surface or side surface) of the substrate 2 passing through the highest point of the irregularity (the highest point on the top surface of the coating), and another imaginary line drawn parallel to the front surface (or back surface or side surface) of the substrate 2 passing through the lowest point of the irregularity (the lowest point on the top surface of the coating). Within this evaluation area, the area occupied by the surface coating 3 or the side coating 4 (existence area P1 of the surface coating 3, existence area P2 of the side coating 4) can be calculated. The area occupied by the surface coating 3 or side coating 4 can be calculated using image processing software ImageJ by setting the lower threshold to 128 and the upper threshold to 255, and performing binarization processing to exclude separation points while filling in the interior of the areas where the surface coating 3 and side coating 4 are present. The value obtained by dividing the area occupied by the surface coating 3 or side coating 4 obtained in this way by the length of the line segment (the width of 10 irregularities) can be used as the average roughness height of the coating (surface coating 3 or side coating 4) for each field of view.

[0031] For example, as shown in FIG. 2, when calculating the area of ​​the surface coating 3 formed on the surface 21 of the substrate 2, a virtual line l drawn parallel to the surface 21 passing through the highest point A1 of the upper surface 30 of the surface coating 3 is used for each field of view. １ and an imaginary line n drawn parallel to the surface 21 passing through the lowest point B1 of the upper surface of the surface coating 3. １ At this time, as shown in Figure 3, the imaginary line l １ and virtual line n １The area defined by the above equations is defined as an evaluation area M1, and the area of ​​the portion of the evaluation area M1 occupied by the surface coating 3 can be calculated by calculating the area of ​​the presence region P1 of the surface coating 3 in the evaluation area M1 on the surface 21. When calculating the area of ​​the surface coating 3 formed on the back surface 22 of the substrate 2, the area of ​​the presence region P1 of the surface coating 3 in the evaluation area M1 on the back surface 22 can be calculated in a similar manner. The value obtained by dividing the area of ​​the presence region P1 of the surface coating 3 obtained in this manner by the length of the line segment (the width of the 10 irregularities) L1 can be used as the average roughness height of the surface coating 3 for each field of view. Here, when the surface coating 3 is formed on both the front surface 21 and the back surface 22 of the substrate 2, the average of the average roughness heights of the surface coating 3 for a total of six fields of view, three fields of view on the front surface 21 side and three fields of view on the back surface 22 side, is calculated to obtain the average roughness height h of the surface coating 3. １ In addition, when the surface coating 3 is formed on either the front surface 21 or the back surface 22 of the substrate 2, the average of the average roughness heights of the surface coating 3 for three fields of view on the side on which the surface coating 3 is formed can be calculated as the average roughness height h １ It can be said that:

[0032] 4, when calculating the area of ​​the side surface coating 4 formed on the side surface 23 of the substrate 2, a virtual line l drawn parallel to the side surface 23 passing through the highest point A2 of the upper surface 40 of the side surface coating 4 is ２ and an imaginary line n drawn parallel to the side surface 23 passing through the lowest point B2 of the upper surface of the side surface coating 4. ２ At this time, as shown in Figure 5, the imaginary line l ２ and virtual line n ２ The area defined by the above is taken as the evaluation area M2, and the area of ​​the presence region P2 of the side coating 4 in this evaluation area M2 can be calculated by calculating the area of ​​the presence region P2 of the side coating 4 in the evaluation area M2 on the side surface 23. The value obtained by dividing the area of ​​the presence region P2 of the side coating 4 obtained at this time by the length of the line segment (the width of the 10 irregularities) L2 can be used as the average roughness height of the side coating 4 for each field of view. Furthermore, the average roughness height h of the side coating 4 can be calculated by averaging the average roughness heights of the side coating 4 for the three fields of view where the side coating 4 is formed. ２ It can be said that:

[0033] 2 is a cross-sectional view showing the surface coating 3 formed on the surface 21 of the base 2 of a lead frame material 1 having the same configuration as that of FIG. 1 , but for convenience in explaining the surface coating presence region P1, the portion of the surface coating 3 included in the evaluation area M1 (the portion included in the surface coating presence region P1) and the portion not included in the evaluation area M1 (the portion not included in the surface coating presence region P1 in the evaluation area M1) are hatched differently. Similarly, FIG. 4 is a cross-sectional view showing the side surface coating 4 formed on the side surface 23 of the base 2 of a lead frame material 1 having the same configuration as that of FIG. 1 , but for convenience in explaining the surface coating presence region P2, the portion of the side surface coating 4 included in the evaluation area M2 and the portion not included in the evaluation area M2 are hatched differently.

[0034] On the other hand, when viewed in cross section of the surface coating 3, an imaginary line l passing through the position of the highest point A1 of the upper surface 30 of the surface coating 3 and drawn parallel to the surface 21 (or the back surface 22) of the substrate 2 is １ and an imaginary line n drawn parallel to the surface 21 of the substrate 2 and passing through the lowest point B1 of the upper surface 30 of the surface coating 3. １ The first porosity in the first measurement area (for example, the area of ​​the evaluation area M1) defined by １ When viewed from the cross section of the side surface coating 4, an imaginary line l is drawn parallel to the side surface 23 of the substrate 2, passing through the position of the highest point A2 of the upper surface 40 of the side surface coating 4. ２ and an imaginary line n drawn parallel to the side surface 23 of the substrate 2, passing through the lowest point B2 of the upper surface 40 of the side surface coating 4. ２ The second porosity in the second measurement area (for example, the area of ​​the evaluation area M2) defined by ２ When the first porosity V １ Second porosity V ２ The ratio V ２ / V １ is preferably in the range of 0.50 or more and 0.91 or less. ２ / V １ If V is smaller than 0.50, the adhesion of the side surface 23 to the resin will be weaker than that of the front surface 21 and the back surface 22, and V ２ / V１ Compared with when V is 0.50 or more, the airtightness of the package when sealed with resin decreases, and therefore the heat cycle resistance decreases. ２ / V １ If V is greater than 0.91, the resin does not penetrate into the irregularities on the upper surface 40 of the side coating 4 as much, making it difficult to obtain an anchor effect. Therefore, when subjected to a heat cycle simulating a severe usage environment, V ２ / V １ Compared with the case where the first porosity V is 0.91 or less, the adhesiveness of the lead frame material 1 to the resin decreases, and the airtightness of the package decreases, so the heat cycle resistance decreases. １ Second porosity V ２ The ratio V ２ / V １ is preferably in the range of 0.50 or more and 0.91 or less, and more preferably in the range of 0.62 or more and 0.83 or less.

[0035] Here, the resin and the lead frame material 1 have different thermal expansion coefficients, and the resin undergoes a larger change in volume due to heat than the lead frame material 1. Therefore, it is preferable to control the ratio of the space for the resin to enter in the portion where the resin and the lead frame material 1 can come into contact, that is, the porosity of the surface coating 3 and the side coating 4 of the lead frame material 1, within an appropriate range. More specifically, the first porosity V １ and the second porosity V ２ The first porosity V is preferably in the range of 32% or more and 64% or less. １ and the second porosity V ２ If the porosity of at least one of the first porosity V is less than 32%, the resin will have difficulty penetrating the unevenness of the upper surfaces 30, 40 of the surface coating 3 or the side coating 4, and therefore, compared to when the porosity is 32% or more, gaps may occur between the lead frame material 1 and the resin, resulting in a decrease in adhesion. １ and the second porosity V ２If the porosity of at least one of these is less than 32%, there is a risk that the lead frame material 1 will not be able to keep up with the expansion and contraction of the resin, and therefore, when subjected to a heat cycle simulating a severe usage environment, the resin will be more likely to peel off from the lead frame material 1 than when the porosity of these is 32% or more, which will reduce the adhesion between them and reduce the airtightness of the package, thereby reducing the heat cycle resistance. １ and the second porosity V ２ If the porosity of at least one of the first porosity V is greater than 64%, it becomes difficult to obtain an anchor effect with the resin, and therefore there is a risk that the adhesion of the lead frame material 1 to the resin will be reduced compared to when the porosity of these porosities is 64% or less. １ and the second porosity V ２ If the porosity of at least one of these is greater than 64%, the pressure applied to the surface coating 3 and the side coating 4 increases when the resin expands due to heating, and when this is repeated through heat cycles, the surface coating 3 and the side coating 4 are more likely to be damaged and gaps will form. Therefore, compared to when the porosity of these is 64% or less, the adhesion to the resin decreases, the airtightness of the package decreases, and the heat cycle resistance decreases. Therefore, when the first porosity V １ is preferably in the range of 32% or more and 64% or less, and more preferably in the range of 45% or more and 60% or less. ２ is preferably in the range of 32% or more and 64% or less, more preferably in the range of 32% or more and 52% or less, and even more preferably in the range of 35% or more and 50% or less.

[0036] First porosity V １ and the second porosity V ２ is the average roughness height h of the surface coating 3 １ and the average roughness height h of the side coating 4 ２ Using the SEM images used in the measurement, the porosity for each field of view can be determined by calculating the ratio of the void area, which is the area of ​​the evaluation areas M1 and M2 minus the area of ​​the coating portion P, to the total area of ​​the evaluation areas M1 and M2, for each of the surface coating 3 formed on the front surface 21, the surface coating 3 formed on the back surface 22, and the side coating 4 formed on the side surface 23.

[0037] From the porosity for each field of view, in an example in which the surface coating 3 is formed on both the front surface 21 and the back surface 22 of the substrate 2, the porosity of the surface coating 3 for a total of six fields of view, three fields of view on the front surface 21 side and three fields of view on the back surface 22 side, is averaged to obtain the first porosity V １ In an example in which the surface coating 3 is formed on one of the front surface 21 and the back surface 22 of the substrate 2, the first porosity V can be calculated by averaging the porosities of the surface coating 3 for three fields of view on the side on which the surface coating 3 is formed. １ In addition, for the side coating 4, the average of the porosities of the three fields of view is taken to obtain the second porosity V ２ (%).

[0038] In the lead frame material 1 of the present invention, when the thickness of the substrate 2 is T, the average roughness height h of the side coating 4 is ２ The ratio of the thickness T of the substrate 2 to ２ The ratio (T / h) is preferably in the range of 15.0 or more and 200.0 or less. ２ If the ratio is smaller than 15.0, the roughness height of the side coating 4 becomes excessively large relative to the area of ​​the side surface 23 of the substrate 2. ２ Powder falling is more likely to occur than when the ratio is 15.0 or more. ２ If the ratio is greater than 200.0, the roughness height of the side coating 4 relative to the area of ​​the side surface 23 becomes low, so that T / h ２ Compared with the case where the ratio is 200.0 or less, it becomes difficult to obtain adhesion with the resin. ２ The ratio of the thickness T of the substrate 2 to ２ The ratio is preferably in the range of 15.0 or more and 200.0 or less, and more preferably in the range of 20.0 or more and 125.0 or less.

[0039] As shown in Fig. 1 , when the lead frame material 1 of the present invention does not have a surface coating layer 6 described later, the surface coating 3 and the side coating 4 are each formed by a roughened layer 5. On the other hand, as shown in Fig. 6 , when the lead frame material 1A has a surface coating layer 6 described later, the coating having the surface coating layer 6 out of the surface coating 3A and the side coating 4A is formed by the roughened layer 5 and the surface coating layer 6. Here, it is preferable that both the surface coating 3 (3A) and the side coating 4 (4A) have a roughened layer 5.

[0040] The roughened layer 5 is formed on at least a part of the surface of the substrate 2. The roughened layer 5 is formed by adhering roughening particles to the surface 21, rear surface 22, or side surface 23 of the substrate 2.

[0041] Roughened layer 5 is preferably made of a metal or alloy containing at least one of copper (Cu) and nickel (Ni). More specifically, roughened layer 5 is preferably made of copper, a copper alloy, nickel, or a nickel alloy, from the viewpoint of forming a roughened shape that has excellent adhesion to resin.

[0042] The roughened layer 5 can be formed by, for example, electroplating, focused ion beam (FIB), or mechanical polishing. Among these, it is particularly preferable that the roughened layer 5 be formed as an electroplated layer by electroplating.

[0043] (Surface Coating Layer) As shown in FIG. 6, the surface coating 3A and the side coating 4A preferably further include at least one surface coating layer 6 formed on the upper surface 50 of the roughened layer 5. In this case, the average roughness height h １ , the average roughness height h of the side coating 4 ２ The surface coating 3A and side coating 4A to be measured have a roughened layer 5 and a surface coating layer 6 formed on at least the surface of the roughened layer 5. By having such a surface coating layer 6, the adhesion to the resin is improved depending on the surface properties of the roughened layer 5, and the composition of the surface of the lead frame material 1A changes, so that it is possible to improve both the wettability with solder and the adhesion to the resin while improving the adhesion to the base 2.

[0044] The presence or absence of the surface coating layer 6 and the number of surface coating layers 6 are appropriately selected depending on the application of the lead frame material.

[0045] Here, at least one layer of the surface coating layer 6 is preferably composed of a metal or alloy layer having a composition different from that of the roughened layer 5. More specifically, at least one layer of the surface coating layer 6 is preferably composed of a metal or alloy containing one or more elements selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), palladium (Pd), rhodium (Rh), ruthenium (Ru), platinum (Pt), iridium (Ir), gold (Au), silver (Ag), tin (Sn), and indium (In). More specifically, at least one layer of the surface coating layer 6 is preferably composed of copper, a copper alloy, nickel, a nickel alloy, cobalt, a cobalt alloy, palladium, a palladium alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, platinum, a platinum alloy, iridium, an iridium alloy, gold, a gold alloy, silver, a silver alloy, tin, a tin alloy, indium, or an indium alloy.

[0046] In particular, the surface coating layer 6 is the surface that comes into contact with the outside of the lead frame material 1A, and it is preferable that it has excellent wettability with solder, etc. Therefore, it is preferable that the surface coating layer 6 is made of a metal or alloy containing one or more elements selected from the group consisting of gold (Au), silver (Ag), copper (Cu), and tin (Sn). In particular, from the viewpoint of improving wettability with solder, it is preferable that the surface coating layer 6 is made of a gold-cobalt alloy, gold, silver, copper, or tin.

[0047] The thickness of the surface coating layer 6 is not particularly limited, but if the thickness is too large, the irregularities formed in the roughened layer 5 may be filled in, potentially impairing at least a portion of the effect of improving resin adhesion. Therefore, the thickness of the surface coating layer 6 is preferably 3.00 μm or less. Furthermore, when the surface coating layer 6 is made of a metal or alloy containing a precious metal such as gold or silver, the thickness of the surface coating layer 6 is more preferably 2.00 μm or less from the viewpoint of not unnecessarily increasing material costs. The thickness of the surface coating layer 6 can be measured using a film thickness meter such as a fluorescent X-ray film thickness meter.

[0048] <Regarding the Manufacturing Method of Lead Frame Material> The manufacturing method of the above-described lead frame material is not particularly limited, but it is preferable to increase productivity and reduce the average roughness height h of the surface coating 3. １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ From the viewpoint of facilitating control of the above, the method preferably includes a coating formation step of forming the surface coating 3 and the side coating 4 having roughened upper surfaces 30, 40 on the substrate 2 by electroplating. As an example, a method of forming a roughened layer 5 on the substrate 2 by electroplating is preferred.

[0049] One example of a method for manufacturing a lead frame material is to prepare a conductive substrate 2 whose size and thickness have been adjusted in advance by pressing, and then perform cathodic electrolytic degreasing and pickling as pretreatments, followed by forming the roughened layer 5. Examples of methods for forming the roughened layer include electroplating, focused ion beam (FIB), and mechanical polishing. Among these, it is particularly preferable to form the roughened layer 5 by electroplating. Examples of conditions for forming the electroplated layer when forming a copper plating layer as the roughened layer 5 are shown below.

[0050] [Conditions for forming electroplated layer] Plating bath: Copper sulfate 10 g / L to 35 g / L (copper (atom) equivalent), sulfuric acid 60 g / L to 180 g / L, ammonium molybdate with a molybdenum concentration of 0.1 g / L to 5.0 g / L Plating conditions: Bath temperature 20°C to 60°C, current density 30 A / dm ２ ~80A / dm ２

[0051] Here, the average roughness height h of the surface coating 3 of the lead frame material 1 １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １As a method for controlling the above, for example, when forming the roughened layer 5 by electroplating (roughening plating), a shielding plate is placed between the front surface 21 of the substrate 2 and the counter electrode, and the shielding area is adjusted to be 10% or more and 30% or less of the total plating area of ​​the front surface 21 and the back surface 22 of the substrate 2, and the current density is set to 5 A / dm ２ 80A / dm or more ２ In this way, the ratio of the area shielded by the shielding plate to the total plating area of ​​the front surface 21 and the back surface 22 of the substrate 2 (opening ratio of the shielding plate) is adjusted, and the current density is set to 5 A / dm ２ 80A / dm or more ２ By adjusting the average roughness height h of the surface coating 3 within the following range, １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ Therefore, the lead frame material 1 can be obtained in which the value of the hardness is 1.35 or more.

[0052] <Uses of Lead Frame Materials> Lead frame materials are used as connection terminals for supporting and fixing semiconductor elements and for exchanging electricity and signals with the outside via wires, printed circuit boards, etc., and are preferably used, for example, in semiconductor packages that include lead frames formed using the lead frame material. Here, examples of semiconductor elements that can be mounted in semiconductor packages include, but are not limited to, transistors, capacitors, LEDs, etc.

[0053] The lead frame material of the present invention can maintain good resin adhesion to the lead frame with almost no deterioration, even when subjected to heat cycles that simulate harsh usage environments, and is less likely to suffer from failures or defects due to powder falling off from the roughened layer, thereby achieving high reliability, especially for semiconductor packages used in automobiles.

[0054] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention.

[0055] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0056] (Invention Examples 1 to 19, Comparative Examples 1 to 7) A substrate 2 was prepared as a conductive substrate made of the type of metal or alloy shown in Table 1, and having a thickness shown in Table 1, which was previously pressed to a size of 30 mm length x 10 mm width. Cathodic electrolytic degreasing and pickling were then performed as pretreatment.

[0057] Here, the cathodic electrolytic degreasing is carried out by heating an aqueous solution of sodium hydroxide with a concentration of 60 g / L as a degreasing solution in an electrolytic cell, immersing the substrate 2 in the degreasing solution heated to 60°C and connecting it to the anode of the electrolytic cell, and applying a current of 2.5 A / dm ２ The treatment was carried out by passing a current at a current density of 1000 kJ / min for 60 seconds.

[0058] The pickling was carried out by immersing the substrate 2 after cathodic electrolytic degreasing in 10 mass % sulfuric acid at room temperature for 30 seconds.

[0059] Thereafter, for Inventive Examples 1 to 19 and Comparative Examples 3 to 7, a roughened layer 5 (or a Cu layer) was formed on all surfaces (front surface, back surface, and side surface) of the substrate 2 by electroplating under the conditions shown below. For Inventive Example 14, the front surface 21 of the substrate 2 was masked with tape, so that the Cu roughened layer 5 was formed on the surfaces (back surface 22 and side surface 23) of the substrate 2 other than the front surface 21. For Comparative Example 3, the front surface 21 and side surface 23 of the substrate 2 were masked with tape, so that the Cu layer was formed only on the back surface 22 of the substrate 2, and then the Cu layer was brought into contact with the surface of the etching solution, thereby roughening the Cu layer formed on the back surface 22 of the substrate 2. On the other hand, for Comparative Examples 1 and 2, the surface coating 3 and side coating 4 were not formed on the substrate 2.

[0060] [Roughened Cu Plating (When the "Type" of the Roughened Layer in Table 1 is Cu)] For Inventive Examples 1, 2, 4 to 17, and 19 and Comparative Examples 4 to 7, an aqueous solution containing copper sulfate having a copper (Cu) metal concentration of 10 g / L to 50 g / L as shown in Table 1, sulfuric acid at 60 g / L to 180 g / L, and ammonium molybdate having a molybdenum (Mo) metal concentration of 0.1 g / L to 5.0 g / L was prepared as an electroplating solution, and 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell having an inner diameter of 80 mm. Next, for Inventive Examples 1, 2, 4 to 17, and 19, a shielding plate was placed between the counter electrode and the substrate 2 so that the shielding plate would shield the area of ​​the surface 21 and the back surface 22 of the substrate 2 at the ratio shown in Table 1 relative to the total plating area. On the other hand, in Comparative Example 4, a shielding plate was installed between the substrate and the counter electrode so as to shield 40% of the total plating area of ​​the front surface 21 and the back surface 22 of the substrate 2. In Comparative Examples 5 to 7, a shielding plate was installed between the substrate and the counter electrode so as to shield 5% of the total plating area of ​​the front surface 21 and the back surface 22 of the substrate 2. Here, a current of 20 A / dm was applied at a temperature of 20°C to 60°C. ２ ~80A / dm ２ The coating formation step was carried out by passing a current at a current density of 1000 kJ / min, and a surface coating 3 and a side coating 4 were formed by electroplating.

[0061] On the other hand, in Comparative Example 3, an aqueous solution containing copper sulfate with a copper (Cu) metal concentration of 250 g / L, 50 g / L of sulfuric acid, and 0.1 g / L of sodium chloride was prepared as an electroplating solution, and 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm. At this time, no shielding plate was placed between the electroplating solution and the counter electrode. Next, the electroplating solution was charged at a temperature of 40°C and a current of 6 A / dm ２ A Cu layer of 10 μm was formed by electroplating by passing a current through the substrate 2 at a current density of 10 μm. Then, the Cu layer formed on the rear surface 22 of the substrate 2 was brought into contact with the liquid surface of an etching solution containing 60 g / L of sulfuric acid and 40 mL / L of hydrogen peroxide at a temperature of 40° C. for 30 seconds, thereby roughening the surface of the Cu layer.

[0062] [Roughened Ni Plating (when the "type" of the roughened layer listed in Table 1 is Ni)] An aqueous solution containing nickel sulfate having a metal concentration of 10 g / L to 50 g / L as listed in Table 1 as the concentration of nickel (Ni) metal, 10 g / L to 30 g / L of boric acid, 30 g / L to 100 g / L of sodium chloride, and 10 mL / L to 30 mL / L of 25% by mass ammonia water was prepared as an electroplating solution. Next, 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and a shielding plate was placed between the electroplating solution and the counter electrode so that the area of ​​the surface 21 and the back surface 22 of the substrate 2 was shielded by the shielding plate at a ratio listed in Table 1 relative to the total plating area. A current of 5 A / dm was applied to the electroplating solution at a temperature of 50°C to 70°C. ２ ~30 A / dm ２ The coating formation step was carried out by passing a current at a current density of 1000 kJ / min, and a surface coating 3 and a side coating 4 were formed by electroplating.

[0063] Next, for Inventive Examples 15 to 19 and Comparative Examples 2, 6, and 7, a surface coating layer 6, which was the outermost layer, was formed. In this case, the surface coating layer 6 was formed over the entire upper surface 50 of the roughened layer 5 (for Comparative Example 2, the front surface 21, rear surface 22, and side surface 23 of the substrate 2) by electroplating under the conditions shown below to a thickness shown in Table 1. In this manner, the lead frame materials of the Inventive Examples and Comparative Examples were obtained.

[0064] [Ni Plating (when the "type" of the surface coating layer 6 in Table 1 is Ni)] An aqueous solution containing nickel sulfamate with a metal concentration of nickel (Ni) of 500 g / L, 30 g / L of nickel chloride, and 30 g / L of boric acid was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 50° C. and a current of 10 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0065] [Pd Plating (when the "type" of the surface coating layer 6 described in Table 1 is Pd)] As an electroplating solution, dichlorotetraamminepalladium (Pd(NH ３ ) ４ Cl ２), 90 mL / L of 25% by mass ammonia water, 50 g / L of ammonium sulfate, and 10 g / L of Palla Sigma LN brightener (trade name, manufactured by Matsuda Sangyo Co., Ltd.). 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating solution was heated at 60°C and 5 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0066] [Au Plating (when the "type" of the surface coating layer 6 in Table 1 is Au)] An aqueous solution containing potassium gold cyanide with a gold (Au) metal concentration of 14.6 g / L, 150 g / L of citric acid, and 180 g / L of potassium citrate was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 40° C. and a current of 1 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0067] [AuCo Plating (when the "type" of the surface coating layer 6 in Table 1 is AuCo)] An aqueous solution containing potassium gold cyanide with a gold (Au) metal concentration of 10 g / L, cobalt carbonate with a cobalt (Co) metal concentration of 0.1 g / L, citric acid at 100 g / L, and dipotassium hydrogen phosphate at 20 g / L was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 40° C. and a current of 1 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0068] [Ag Plating (when the "type" of the surface coating layer 6 in Table 1 is Ag)] An aqueous solution containing silver cyanide with a metal concentration of 93 g / L as a silver (Ag) metal and 132 g / L of potassium cyanide was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the plating was conducted at a temperature of 20° C. and a current of 1 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0069] [Sn Plating (when the "type" of the surface coating layer 6 in Table 1 is Sn)] An aqueous solution containing tin sulfate with a metal concentration of tin (Sn) of 80 g / L, 50 mL / L of sulfuric acid, and 5 mL / L of UTB513Y was prepared as an electroplating solution. 1 L of the electroplating solution was placed in a cylindrical plating electrolytic cell with an inner diameter of 80 mm, and the electroplating was conducted at a temperature of 20° C. and a current of 5 A / dm ２ A surface coating layer 6 was formed by electroplating by passing a current through the wire at a current density of 1000 kJ / cm.sup.2.

[0070] <Various Measurement and Evaluation Methods> Next, the properties of each of the obtained layers and the lead frame material 1 were measured and evaluated as follows. Note that the properties of each of the obtained layers were measured at any time during the production of the lead frame material 1.

[0071] [1] Average roughness height h of the surface coating １ and the average roughness height h of the side coating ２ Measurement of the average roughness height h of the surface coating 3 １was determined by observing, with a scanning electron microscope (SEM), microtomed cross sections including the thickness direction of the surface coating 3. Here, in the SEM observation, SEM images of three fields of view were randomly selected for each of the surface coating 3 formed on the front surface 21 of the substrate 2 and the surface coating 3 formed on the back surface 22, with ten continuous irregularities in the coating being one field of view, and for each of the three SEM images, an evaluation area M1 was defined by an imaginary line drawn parallel to the front surface (or back surface) of the substrate 2 passing through the highest point of the irregularities (the highest point on the upper surface of the coating) and an imaginary line drawn parallel to the front surface (or back surface) of the substrate 2 passing through the lowest point of the irregularities (the lowest point on the upper surface of the coating), and the area of ​​the portion occupied by the surface coating 3 in this evaluation area M1 (region P1 where the surface coating 3 is present) was calculated. The area of ​​the coating portion P was calculated using image processing software ImageJ, with the lower threshold set to 128 and the upper threshold set to 255, and binarization processing was performed to fill in the interior of the coating portion P while excluding separation points. The area of ​​the coating portion P1 obtained at this time was divided by the length of the line segment (the width of 10 irregularities) L1, and the value was calculated as the average roughness height of the surface coating 3 for each field of view. Here, in an example where the surface coating 3 is formed on both the front surface 21 and the back surface 22 of the substrate 2, the average of the average roughness heights of the surface coating 3 for a total of six fields of view, three fields of view on the front surface 21 side and three fields of view on the back surface 22 side, was taken to determine the average roughness height h of the surface coating 3. １ In addition, in an example in which the surface coating 3 is formed on one of the front surface 21 or the back surface 22 of the substrate 2, the average of the average roughness heights of the surface coating 3 for three fields of view on the side on which the surface coating 3 is formed is calculated to obtain the average roughness height h １ The results are shown in Table 1.

[0072] The average roughness height h of the side coating 4 ２ For the side coating 4 formed on the side surface 23, three fields of view were randomly selected, each of which consisted of 10 continuous irregularities on the coating, and the average roughness height h of the surface coating 3 was measured for each of the three fields of view. １In the same manner as in the measurement of (1), the area of ​​the portion occupied by the side coating 4 in the evaluation area M2 was calculated. The area of ​​the coating portion P2 obtained at this time was divided by the length of the line segment (the width of the 10 irregularities) L2 to obtain the average roughness height of the side coating 4 for each visual field. The average of the average roughness heights of the side coating 4 for the three visual fields was then taken to obtain the average roughness height h of the side coating 4. ２ It was decided.

[0073] Furthermore, the average roughness height h of the obtained surface coating 3 １ and the average roughness height h of the side coating 4 ２ From the results, the average roughness height h of the surface coating 3 １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ and the average roughness height h of the side coating 4. ２ The ratio of the thickness T of the substrate 2 to the thickness T (T / h ２ The results are shown in Table 1.

[0074] [2] First porosity V １ and the second porosity V ２ Measurement of first porosity V １ is the average roughness height h of the surface coating described above. １ and the average roughness height h of the side coating ２ Using the SEM images used in the "measurement of the surface coating 3 formed on the front surface 21" and the surface coating 3 formed on the back surface 22, the porosity for each visual field was determined by calculating the ratio of the area of ​​the void portion (area S1 where the surface coating 3 is not present) obtained by subtracting the area of ​​the area P1 where the surface coating 3 is present from the area of ​​the evaluation area M1 to the area of ​​the entire evaluation area M1. That is, the porosity of the surface coating 3 for each visual field was calculated using the following formula (1). Porosity of surface coating 3 (%) = 100 × {(area of ​​evaluation area M1) - (area of ​​area P1 where the surface coating 3 is present)} / (area of ​​evaluation area M1) ... (1) From these porosities for each visual field, in an example where the surface coating 3 is formed on both the front surface 21 and the back surface 22 of the substrate 2, the average roughness heights of the surface coating 3 for a total of six visual fields, three visual fields on the front surface 21 side and three visual fields on the back surface 22 side, were averaged to determine the first porosity V １In addition, in an example in which the surface coating 3 is formed on either the front surface 21 or the back surface 22 of the substrate 2, the average of the porosities of the surface coating 3 for three fields of view on the side on which the surface coating 3 is formed is taken as the first porosity V １ It was decided.

[0075] Also, the second porosity V ２ is the average roughness height h of the surface coating described above. １ and the average roughness height h of the side coating ２ Using the SEM images used in the "measurement of" for each of the side coatings 4 formed on the side surfaces 23, the porosity for each visual field was determined by calculating the ratio of the area of ​​the void portion (area S2 where the side coating 4 does not exist) obtained by subtracting the area of ​​the area P2 where the side coating 4 exists from the area of ​​the evaluation area M2 to the area of ​​the entire evaluation area M2. That is, the porosity for each visual field was calculated using the following formula (2). Porosity of side coating 4 (%) = 100 × {(area of ​​evaluation area M2) - (area of ​​area P2 where the side coating 4 exists)} / (area of ​​evaluation area M2) ... (2) From the porosities for each visual field, the porosities of the side coatings 4 for the three visual fields were averaged to obtain the second porosity V ２ (%).

[0076] Furthermore, the obtained first porosity V １ and the second porosity V ２ From the results, the first porosity V １ Second porosity V ２ The ratio V ２ / V １ The results are shown in Table 1.

[0077] [3] Measurement of Surface Coating Layer Thickness The thickness of the surface coating layer 6 was measured by a fluorescent X-ray testing method in accordance with JIS H8501:1999. Specifically, a fluorescent X-ray film thickness meter (SFT9400, manufactured by SII NanoTechnology Inc.) was used with a collimator diameter of 0.5 mm to measure the thickness at 10 random locations on each layer, and the average of these measurements was calculated to obtain the thickness of the surface coating layer 6. The results are shown in Table 1.

[0078] [4] Evaluation of Airtightness Figure 7 is a schematic diagram showing the positional relationship between lead frame material 1 and resin in measuring adhesion to resin performed on lead frame materials of examples of the present invention. For the lead frame materials 1 obtained in examples of the present invention and comparative examples, a gross leak test was performed on structures molded with resin 7 so as to cover lead frame material 1, as shown in Figure 7. Here, the gross leak test was performed by immersing the structure in Fluorinert FC-40 (registered trademark), a high-boiling point solvent heated to 120°C ± 10°C, for 30 seconds or 120 seconds, and determining whether air leaks from lead frame material 1 occurred based on whether air bubbles were generated during immersion. The airtightness of lead frame material 1 was evaluated from the determination results.

[0079] Here, the structure immediately after the lead frame material 1 was molded with resin was subjected to a gross leak test, and the result of the evaluation of airtightness obtained was taken as the airtightness of the initial structure. Next, a heat cycle test was performed on the structure obtained by molding the lead frame material 1 with resin 7, in which a cycle of holding at a temperature of -50°C for 30 minutes and then immediately holding at a temperature of 105°C for 30 minutes was repeated 50 times, and the result of the evaluation of airtightness obtained by the gross leak test on the structure after the heat cycle test was taken as the airtightness of the structure after the heat cycle test.

[0080] Regarding the airtightness of the initial structure and the airtightness of the structure after the heat cycle test, if no bubbles were generated for 120 seconds after the start of immersion in the high-boiling point solvent, the structure was evaluated as having particularly excellent airtightness and given an "A" rating. If no bubbles were generated for 30 seconds after the start of immersion in the high-boiling point solvent but bubbles were generated within 120 seconds after the start of immersion, the structure was evaluated as having excellent airtightness and given an "B" rating. If bubbles were generated within 30 seconds after the start of immersion, the structure was evaluated as having low airtightness and being undesirable and given an "C" rating. The results are shown in Table 2.

[0081] [5] Measurement and Evaluation of Powder Falling Amount For the lead frame materials 1 obtained in the examples of the present invention and the comparative examples, the lead frame materials were cut into 60 mm widths and subjected to a tape peeling test as specified in JIS H 8504. The amount of mass loss before and after the test was measured and evaluated as the amount of powder falling off. The measured amount of powder falling off was 3 mg / dm ２ When the amount of powder released was less than 3 mg / dm, the result was evaluated as "A" as it was considered to be particularly excellent in terms of the amount of powder release being less likely to occur. ２ 12mg / dm or more ２ When the amount of powder released was in the range of less than 12 mg / dm, it was evaluated as "B" as it was considered to be excellent in terms of the fact that powder falling off was unlikely to occur. ２ If the value was more than this, it was evaluated as "C" since powder fall was likely to occur. The results are shown in Table 2.

[0082] [6] Overall Evaluation Among these evaluation results, for the three evaluation results regarding the airtightness of the initial structure, the airtightness of the structure after the heat cycle test, and the amount of powder falling, if all three were rated "A," it was rated "A," meaning that the airtightness was high both before and after the heat cycle test and that powder falling was particularly excellent. Furthermore, if all three of these evaluation results were rated "A" or "B" (excluding cases where all three were rated "A"), it was rated "B," meaning that the airtightness was high both before and after the heat cycle test and that powder falling was excellent. On the other hand, if at least one of these three evaluation results was rated "C," it was rated "C," meaning that the airtightness at least before or after the heat cycle test was unacceptable, or that powder falling was likely to occur. The results are shown in Table 2.

[0083] [7] Evaluation of Heat Cycle Resistance Furthermore, with regard to the evaluation results of the airtightness of the initial structure and the evaluation results of the airtightness of the structure after the heat cycle test, if the initial airtightness was rated as "A" or "B" and the airtightness after the heat cycle test was rated as "A", or if the initial airtightness was rated as "B" and the airtightness after the heat cycle test was rated as "B", the structure was rated as having particularly excellent heat cycle resistance and was rated as "A". Furthermore, if the initial airtightness was rated as "A" and the airtightness after the heat cycle test was rated as "B", the structure was rated as having excellent heat cycle resistance and was rated as "B". On the other hand, if at least one of the evaluation results of the initial airtightness and the airtightness after the heat cycle test was rated as "C", it was rated as being undesirable in terms of low heat cycle resistance and was rated as "C". The results are shown in Table 2.

[0084]

[0085]

[0086] From the results in Tables 1 and 2, it can be seen that the lead frame materials 1 of Examples 1 to 19 of the present invention have both the surface coating 3 and the side coating 4 having a roughened upper surface, and the average roughness height h １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ In this case, the lead frame materials 1 of Examples 1 to 19 of the present invention were evaluated as "A" or "B" in all three evaluation results regarding the airtightness of the initial structure, the airtightness of the structure after the heat cycle test, and the amount of powder falling off, and were also evaluated as "A" or "B" in the overall evaluation.

[0087] Figure 8 shows a secondary electron image observed by SEM of a cross section of the lead frame material of Inventive Example 1. The secondary electron image in Figure 8 also shows that the lead frame material of Inventive Example 1 has a roughened upper surface for both the surface coating 3 and the side coating 4, and that the average roughness height of the side coating 4 formed on the side surface 23 of the substrate 2 is clearly greater than the average roughness height of the surface coating 3 formed on the surface 21 of the substrate 2.

[0088] Therefore, the lead frame materials 1 of Examples 1 to 19 of the present invention were all rated as "A" or "B" in the overall evaluation, and therefore were able to improve the airtightness of the package and were less likely to cause powder falling, even when subjected to a heat cycle that simulates a harsh usage environment.

[0089] In particular, the lead frame materials 1 of Examples 1 to 5, 7, and 12 to 19 of the present invention all had a first porosity V １ and the second porosity V ２ and both of the first porosity V １ Second porosity V ２ The ratio V ２ / V １ When the ratio was in the range of 0.50 or more and 0.91 or less, the structure was rated as "A" in the evaluation of heat cycle resistance, and was therefore particularly excellent in that it was even less likely to experience a decrease in airtightness due to the heat cycle test.

[0090] On the other hand, the lead frame materials of Comparative Examples 1 and 2 did not have either the surface coating 3 or the side coating 4, and in Comparative Examples 3 to 7, the average roughness height h １ The average roughness height h of the side coating 4 ２ The ratio h ２ / h １ Therefore, the lead frame materials of Comparative Examples 1 to 7 were evaluated as "C" in at least one of the three evaluation results regarding the initial airtightness of the structure, the airtightness of the structure after the heat cycle test, and the amount of powder falling off, and were also evaluated as "C" in the overall evaluation.

[0091] REFERENCE SIGNS LIST 1 Lead frame material 2 Base (or substrate) 21 Surface of base 22 Back surface of base 23 Side surface of base 3, 3A Surface coating 30 Upper surface of surface coating 4 Side coating 40 Upper surface of side coating 5 Roughened layer 50 Upper surface of roughened layer 6 Surface coating layer 7 Resin h １ Average roughness height of the surface coating h ２Average roughness height of side coating A1: Highest point on the upper surface of the surface coating B1: Lowest point on the upper surface of the surface coating P1: Area in the evaluation area where the surface coating is present S1: Area in the evaluation area where the surface coating is not present A2: Highest point on the upper surface of the side coating B2: Lowest point on the upper surface of the side coating P2: Area in the evaluation area where the side coating is present S2: Area in the evaluation area where the side coating is not present L1, L2: Length of the line segment (width of 10 irregularities) M1, M2: Evaluation area

Claims

1. A lead frame material having a conductive substrate, a surface coating formed on at least one or both of a front surface and a back surface of at least a portion of the substrate, and a side coating adjacent to the surface coating and formed on at least a portion of a side surface of the substrate, wherein the surface coating and the side coating each have a roughened upper surface, and the average roughness height of the surface coating is h １ , the average roughness height of the side coating is h ２ When the average roughness height h of the surface coating is １ The average roughness height h of the side coating ２ The ratio of ２ / h １ is 1.35 or more.

2. The average roughness height h of the surface coating １ is in the range of 0.5 μm or more and 3.5 μm or less, and the average roughness height h ２ The lead frame material according to claim 1 , wherein the thickness is in the range of 1.0 μm or more and 6.5 μm or less.

3. When viewed in cross section of the surface coating, an imaginary line l is drawn parallel to the surface of the substrate, passing through the highest point of the upper surface of the surface coating. １ and a virtual line n drawn parallel to the surface of the substrate, passing through the lowest point of the upper surface of the surface coating. １ The first porosity in the first measurement area divided by and is defined as V １ When viewed from the cross section of the side coating, an imaginary line l is drawn parallel to the side surface of the base body, passing through the position of the highest point of the upper surface of the side coating. ２ and a virtual line n drawn parallel to the side surface of the base body, passing through the lowest point of the upper surface of the side coating. ２ The second porosity in the second measurement area partitioned by and is defined as V ２ When the first porosity V １ The second porosity V ２ Ratio of V ２ / V １ The lead frame material according to claim 1 , wherein is in the range of 0.50 or more and 0.91 or less.

4. The first void ratio V １ and the second porosity V ２ The lead frame material according to claim 3 , wherein each of the ratios is in the range of 32% or more and 64% or less.

5. The lead frame material according to claim 1, wherein the substrate is made of copper, a copper alloy, iron, an iron alloy, aluminum or an aluminum alloy.

6. When the thickness of the substrate is T, what is the average roughness height h of the side coating? ２ The ratio of the thickness T of the substrate to the thickness (T / h ２ 2. The lead frame material according to claim 1, wherein the ratio is in the range of 15.0 to 200.

0.

7. The lead frame material according to claim 1, wherein the surface coating and the side coating both have a roughened layer.

8. The lead frame material according to claim 7, wherein the roughened layer is made of copper, a copper alloy, nickel or a nickel alloy.

9. The lead frame material according to claim 7, wherein the roughened layer is an electroplated layer.

10. The lead frame material according to claim 7, wherein the surface coating and the side coating further comprise at least one surface coating layer formed on an upper surface of the roughened layer.

11. The lead frame material according to claim 10, wherein the surface coating layer is a metal or alloy having a different composition from that of the roughening layer and is made of copper, a copper alloy, nickel, a nickel alloy, cobalt, a cobalt alloy, palladium, a palladium alloy, rhodium, a rhodium alloy, ruthenium, a ruthenium alloy, platinum, a platinum alloy, iridium, an iridium alloy, gold, a gold alloy, silver, a silver alloy, tin, a tin alloy, indium or an indium alloy.

12. A method for producing a lead frame material according to any one of claims 1 to 11, comprising a coating formation step of forming the surface coating and the side coating having a roughened upper surface on the base by electroplating.

13. A semiconductor package comprising a lead frame formed using the lead frame material according to any one of claims 1 to 11.