JP2017055044A - Lead frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead frame capable of achieving high adhesiveness by forming a roughening part efficiently, thereby enhancing the productivity dramatically, while reducing the environmental load.SOLUTION: A lead frame includes an element mounting part 21, and a plurality of lead parts 22 provided around the element mounting part 21. The element mounting part 21 includes a base material 21a, a roughening part 21b provided partially on one surface 21a-1 of the base material 21a, and a roughening part 21c provided partially on the other surface 21a-2 of the base material 21a. The roughening part 21b is provided in the element mounting part 21, and placed between a portion for connecting a bonding wire 4 and a semiconductor element 3 to be mounted on the element mounting part 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lead frame, and more particularly to a lead frame for forming a semiconductor package structure formed by resin molding a semiconductor element.

 In recent years, with the rapid development of various industries such as electronics and automobiles, the diversification and high functionality of materials have progressed, and in particular, the demand for components that efficiently combine resins and metals with different characteristics has increased. Higher adhesion is becoming more important from the viewpoints of weight reduction of parts, improvement of design freedom, and cost reduction.

For example, in the semiconductor package structure, the following problems have arisen, and high adhesion between the resin for molding the substrate and the lead frame is required.
(1) The reflow temperature of board mounting is high due to lead-free (2) Semiconductor elements are mounted in automobiles, and ICs such as ICs mounted around engines and sensors related to safety The temperature conditions of the reliability test are severe. (3) When exposed to high temperature after resin packaging, moisture in the package structure expands, causing resin cracks and chip peeling. (4) Due to the difference in thermal expansion between the resin and the lead frame. , Chip peeling occurs

  In order to solve the above problems, for example, a base material, an element mounting portion provided on a part of the first surface of the base material, on which a semiconductor element can be mounted, and a semiconductor element mounted on the element mounting portion are sealed There has been proposed a lead frame that is a region in contact with a sealing material to be contacted and includes a roughened surface formed by etching from the outer edge of the sealing material (see, for example, Patent Document 1).

  Further, the lead frame includes an element mounting portion and a lead portion, and a part of a portion of the surface of the lead frame located inside the mold resin, for example, the surface of the element mounting portion, has adhesion with the resin. There has been proposed a roughening process for increasing the external connection surface of the lead portion that has not been roughened (for example, see Patent Document 2).

Japanese Patent No. 5376540 JP 2006-140265 A

  However, in the technique of Patent Document 1, a masking tape is attached to the first surface of the base material to mask a part of the first surface, and chemically etched by bringing an etching solution into contact with the unmasked surface, Thereafter, the masking tape is removed and the etched surface is cleaned. Therefore, at least a masking step, a masking tape removing step, and a cleaning step are required to obtain a roughened surface, which is complicated and takes time, and the roughened surface cannot be efficiently formed. In addition, in the wet etching as described above, it is difficult to roughen the surface with a fine pattern, and it cannot be said that it can sufficiently meet the needs for IC miniaturization and further improvement in adhesion. In addition, an excessive roughened surface may be formed on the first surface of the base material, and if the roughened surface and the resin burr of the sealing portion are in contact, the adhesion between the base material and the resin burr is Therefore, it is difficult to remove the resin burrs during the exterior processing, and there is a possibility that the base material may be deformed or scratched on the base material when the resin burrs are removed. Furthermore, when an etching solution is used, the used etching solution becomes a waste solution, and the environmental load is large. In particular, in the automotive industry where technological innovation is remarkable, in order to dramatically improve the productivity of semiconductor devices, it is required to more efficiently form a lead frame having high adhesion.

  In the technique of Patent Document 2, a roughened surface is formed by a plating process involving masking. However, as described above, it cannot be said that the roughened surface is efficiently formed, and the plating solution needs to be subjected to a waste liquid treatment. In addition to the plating treatment, chemical treatment, sand blasting, and laser irradiation are mentioned, but a specific method for forming a roughened surface using laser irradiation or the like is not described.

  An object of the present invention is to provide a lead frame that can efficiently form roughened portions to achieve high adhesion, dramatically improve productivity, and reduce environmental burden. There is.

  In order to achieve the above object, a lead frame of the present invention is a lead frame having an element mounting portion and at least one lead portion provided around the element mounting portion, and the lead frame is roughened. And the roughened portion is provided along the boundary between the resin-made sealing portion that seals the semiconductor element and the portion that is not sealed, and is closer to the sealing portion than the boundary. A first roughened portion disposed on the element mounting portion, a portion provided on the element mounting portion and connected to a bonding wire of the lead portion, and a semiconductor element mounted on the element mounting portion. It includes at least one of two roughened portions.

  The first roughened portion is disposed between a portion of the lead portion to which the bonding wire is connected and the portion that is not sealed.

  The lead portion includes at least a plating layer, and the first roughened portion is not disposed on the plating layer.

  Further, the second roughened portion constitutes a belt-like portion provided so as to surround the periphery of the semiconductor element mounted on the element mounting portion.

  It is preferable that the first roughened portion constitutes a belt-like portion, and the width of the belt-like portion is 25 μm to 1200 μm.

  Furthermore, the arithmetic average height of the roughened portion is preferably 0.13 μm to 20 μm.

  Moreover, it is preferable that the specific surface area of the said roughening part is 1.08-4.

  According to the present invention, the first roughened portion is along the boundary between the resin sealing portion that seals the semiconductor element of the lead portion and the portion that is not sealed, and closer to the sealing portion than the boundary. Be placed. The second roughened portion is disposed between the portion provided on the element mounting portion and connected to the bonding wire of the lead portion and the semiconductor element mounted on the element mounting portion. Thus, for example, by providing a roughened portion by laser irradiation, it is possible to efficiently form the roughened portion without requiring masking or cleaning, thereby realizing high adhesion between the roughened surface and the sealing portion. Can do. In addition, it is possible to suppress the formation of an extra roughened portion on the one surface of the lead frame, and it is possible to easily remove the resin burrs from the sealing portion, thereby dramatically improving productivity. can do. In addition, it is possible to prevent the organic solvent such as silver paste from oozing out and to realize high adhesion of the bonding wire. Further, since the roughened portion constitutes a band-shaped portion and the width of the band-shaped portion is 25 μm to 1200 μm, a stable roughened structure can be formed and the deformation of the lead frame can be suppressed. In addition, since the surface of the lead frame can be roughened with a fine pattern, it is possible to sufficiently respond to the need for IC miniaturization and further improvement in adhesion. Furthermore, no waste liquid is generated when the roughened portion is formed, and the environmental load can be reduced.

It is a figure showing roughly the composition of the semiconductor device provided with the lead frame concerning the embodiment of the present invention. (A) is sectional drawing which shows the structure of the lead frame which concerns on this embodiment, (b) is a top view of the lead frame, (c) is a bottom view. It is an electron microscope image which shows an example of a roughening part, (a) is a plane image, (b) is a cross-sectional image. (A)-(d) is a schematic diagram for demonstrating the detailed structure of a strip | belt-shaped part. (A)-(d) is a figure explaining the process of forming the sealing part in FIG. 3A and 3B are diagrams showing a modification of the lead frame in FIG. 2, in which FIG. 3A is a cross-sectional view, FIG. 3B is a plan view, and FIG. FIG. 7 is a diagram illustrating an exterior process when manufacturing a semiconductor device having the lead frame of FIG. 6. (A)-(e) is a schematic diagram which shows the roughening position of the lead frame in each Example. (A)-(c) is a schematic diagram which shows the roughening position of the lead frame in each comparative example. (A)-(c) is an electron microscope image of the laser roughening partial surface in each Example and a comparative example. It is a figure explaining the Z-axis displacement measured in Examples 1, 3 and Comparative Example 4. (A) is a top view which shows the part peeled in the comparative example 1, (b) is a part which peeled in the comparative example 3. FIG. It is a graph which shows the result of having performed the EPMA analysis of the roughening partial surface after a laser process or a chemical | medical solution process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Configuration of semiconductor device and lead frame>
FIG. 1 is a perspective view schematically showing a configuration of a semiconductor device including a lead frame according to the present embodiment. Note that the semiconductor device in the figure shows an example, and the configuration of the semiconductor device according to the present invention, the shape, dimensions, and the like of each component are not limited to those in FIG.

  As shown in FIG. 1, the semiconductor device 1 includes a lead frame 2 having an element mounting portion 21 and a plurality of lead portions 22 provided around the element mounting portion, and a semiconductor element 3 mounted on the element mounting portion 21. Then, the bonding wires 4 and 4 ′ (4 ′ is a bonding wire for grounding) for electrically connecting the semiconductor element 3 and the lead portion 22, and the element mounting portion 21, the semiconductor element 3 and the bonding wire 4 are sealed. And a resin sealing portion 5. The semiconductor device 1 has a semiconductor package structure formed by resin molding the semiconductor element 3, for example. The semiconductor element 3 is an integrated circuit such as a microprocessor, a microcontroller, a memory, or a semiconductor sensor.

  2A is a cross-sectional view showing the configuration of the lead frame according to the present embodiment, FIG. 2B is a plan view of the lead frame, and FIG. 2C is a bottom view. Note that FIG. 2A is a cross-sectional view taken along line AA in FIG.

  The element mounting portion 21 includes a base material 21a, a roughened portion 21b (second roughened portion) provided on a part of one surface 21a-1 (front surface) of the base material 21a, and a base material 21a. And a roughened portion 21c provided on a part of the other surface 21a-2 (back surface). In the present embodiment, the element mounting portion 21 includes the roughened portion 21c. However, the present invention is not limited to this, and the other surface 21a-2 of the base material 21a may not include the roughened portion. You may provide the roughening part provided in the whole surface 21a-2 (back surface). Moreover, although the plating layer is not provided in the element mounting part 21 of this embodiment, a plating layer may be provided, for example, the element mounting part 21 is a part of one surface 21a-1 of the base material 21a. Or you may provide the plating layer provided in all.

The lead portion 22 is a rough portion provided on a part of the base material 22a and the other surface 22a-2 (back face) of the base material 22a and in contact with the sealing part 5 that seals the semiconductor element 3. And a modified portion 22b. The roughened portion 22b is disposed along the boundary between the sealing portion 5 of the lead portion 22 and the portion that is not sealed, and closer to the sealing portion than the boundary (see FIG. 2C). And the roughening part 22b is arrange | positioned between the part to which the bonding wires 4 and 4 'of the lead part 22 are connected, and the part which is not sealed. The roughened portion 22b may include a boundary between the sealing portion 5 of the lead portion 22 and a portion that is not sealed, and may be provided on the sealing portion side from the boundary. The base materials 21a and 22a are integrally formed by pressing a metal original plate. In the present embodiment, the lead portion 22 includes the roughened portion 22b. However, the present invention is not limited to this, and the other surface 22a-2 of the base material 22a may not include the roughened portion.
Although the plating layer is not provided in the lead part 22 of this embodiment, it is not restricted to this, A plating layer may be provided in one surface 22a-1 of the base material 22a. You may provide the plating layer formed in a part or whole of one side 22a-1 of the material 22a.

  As shown in FIG. 2B, the roughened portion 21 b is disposed between the portion provided on the element mounting portion 21 and connected to the bonding wire 4 and the semiconductor element 3 mounted on the element mounting portion 21. The In the present embodiment, the roughened portion 21 b constitutes a belt-like portion disposed around the semiconductor element 3. The width D1 of the strip portion is preferably 25 μm to 1200 μm. When laser roughening is performed with a width of less than 25 μm, it is difficult to control the spot size formed on the lead frame by the laser, and stable roughening cannot be realized. Further, when the width of the roughened region is larger than 1200 μm, the lead frame is likely to be deformed. The width of the roughened portion in the present embodiment is a length in the direction perpendicular or substantially perpendicular to the direction along the boundary line between the lead frame 2 and the outer edge of the sealing portion 5.

  In the present embodiment, the belt-like portion is provided on the surface of the element mounting portion 21 on the side where the semiconductor element 3 is mounted so as to surround the periphery of the semiconductor element 3. That is, the roughened portion 21b is an annular portion that is continuously formed on the surface of the substrate 21a. The width of the roughened portion in the present embodiment is a length in the direction perpendicular or substantially perpendicular to the direction along the boundary line between the lead frame 2 and the outer edge of the sealing portion 5.

  As shown in FIG. 2C, the roughened portion 21c is an annular roughened portion arranged so as to overlap the roughened portion 21b on the projection plane. That is, the roughened portion 21 c is provided on the surface of the element mounting portion 21 opposite to the surface on which the semiconductor element 3 is mounted so as to surround the semiconductor element 3.

  The roughened portion 22b is composed of a plurality of planar roughened portions provided outside the roughened portion 21c. The roughened portion 22b is formed at the end of each lead portion.

  As described above, in this embodiment, the roughened portions 21b and 21c are arranged on both surfaces of the element mounting portion 21 and roughened on one surface of the lead portion 22 (the surface opposite to the surface on the element mounting side). A portion 22b is arranged.

  The sealing portion 5 is a resin molded body provided so as to cover the roughened portions 21 b, 21 c, and 22 b disposed on both surfaces of the lead frame 2. In the sealing portion 5, the element mounting portion 21 and a part of the plurality of lead portions 22 arranged on the outer edge thereof are embedded. In other words, the sealing portion 5 is molded so as to integrally seal the element mounting portion 21 on which the semiconductor element 3 is mounted and a part of the lead portion 22, whereby the metal lead frame 2 and the resin are made. The sealing portion 5 is joined.

  Next, each structure of the lead frame 2 and the sealing part 5 will be described in detail below.

(1-1) Specific Configuration of Lead Frame 2 Each substrate constituting the element mounting portion 21 and the lead portion 22 has a shape that is bent into a desired shape such as a plate shape, a linear shape, a box shape, a spherical shape, An arbitrary shape such as a shape obtained by joining a plurality of these can be used.
There is no restriction | limiting in particular as a material of a base material, According to a use, it can select from a well-known metal suitably. For example, copper, copper alloy, aluminum, aluminum alloy, iron, iron alloy, iron nickel alloy (42 alloy), titanium, titanium alloy iron, various stainless steels, zinc, magnesium, lead, tin, and alloys containing them Can be mentioned.

  When a base material is plate shape, it is preferable that the thickness is 1 micrometer-10 mm, and it is more preferable that it is 30 micrometers-2 mm. When the thickness of the substantially plate-shaped metal part is small, the shape is likely to be distorted when a roughened portion is partially provided.

  When the plating layer is provided on the substrate, the plating layer is preferably composed of at least one selected from the group consisting of silver or a silver alloy, and palladium or a palladium alloy. By forming the plating layer on the base material, there is an effect of improving element bonding property, wire bonding property, and solder wettability. In addition, a reflective layer can be provided, and a lead frame excellent in glossiness or light reflectance can be obtained.

  One or a plurality of intermediate layers (other plating layers) may be formed between the substrate and the plating layer. The intermediate layer is selected from the group consisting of nickel or nickel alloy, cobalt or cobalt alloy, palladium or palladium alloy, rhodium or rhodium alloy, ruthenium or ruthenium alloy, iridium or iridium alloy, gold or gold alloy, and copper or copper alloy. It is preferable to consist of at least one kind. By providing the intermediate layer, the adhesion between the substrate and the plating layer can be improved, and the heat resistance of the lead frame can be improved.

(1-2) Structure of Roughening Portions 21b, 21c, and 22b and Adhesion Mechanism The lead frame 2 has roughening portions 21b, 21c, and 22b at least at a part of the interface with the sealing portion 5. 3A and 3B are electron microscope images showing an example of a roughened portion formed by irradiating a substrate with laser. The roughened portions 21b, 21c, and 22b of the present embodiment have a concavo-convex aggregate as shown in the figure, and in particular, in the cross-sectional view (FIG. 3B), a part of the concavo-convex is coral. Alternatively, it is formed in an anchor shape. Such a roughened portion is configured to be located at the interface between the metal lead frame 2 and the resin sealing portion 5. Thereby, when the sealing portion 5 is molded, the resin enters the unevenness of the roughened portion, and a portion where the resin and the metal are overlapped one or more times in the thickness direction of the lead frame 2 is formed, thereby improving the adhesion.

  The specific surface areas of the roughened portions 21b, 21c, and 22b are preferably 1.08 or more and less than 4. If the specific surface area is less than 1.08, sufficient adhesion cannot be obtained, and if the specific surface area is 4 or more, the lead frame is likely to be deformed.

  The roughened portion is formed by using a laser from the viewpoint of locally roughening. Thereby, the rough part of a fine pattern can be formed easily. The roughened portion refers to a region irradiated with laser, and is a portion where the surface shape is changed from flat to uneven by laser irradiation. For example, in the case of a pulse laser, a roughened portion is formed by forming a predetermined pattern on a metal surface by spots formed by a plurality of laser irradiations.

  Here, when the adhesion at the interface between the resin and the metal is low, molecules such as water vapor or molecular clusters pass through the interface, and functional parts such as semiconductor elements are easily damaged by condensation or oxidation. Therefore, the roughened portion is preferably formed so as to surround the semiconductor element 3 from the viewpoint of preventing damage to the functional component.

  The depth of the irregularities is preferably 100 nm or more, and more preferably 500 nm or more, from the viewpoint of obtaining sufficient adhesion strength. Further, from the viewpoint of suppressing distortion of the metal part and suppressing deterioration of the metal due to oxidation, it is preferably 50 μm or less, more preferably 20 μm or less, and further preferably 10 μm or less.

In the case of processing using a pulse laser, the irradiation density of the spots is preferably 20 pieces / mm ² or more, more preferably 50 pieces / mm ² or more, and further preferably 100 pieces / mm ² or more. Also, from the viewpoint of suppressing distortion of metal parts, from the viewpoint of suppressing the generation of scattered materials, and from the viewpoint of suppressing deterioration due to oxidation, 2000 / mm ² or less is preferable, 1000 / mm ² or less is more preferable, and 500 / Mm ² or less is more preferable.

  As described above, the roughened portions 21b, 21c, and 22b may be provided on the exposed portion of each base material, or provided on the plating layer when a plating layer is formed on a part of the base material. May be. Moreover, it may be provided across the plating layer and the exposed portion of the substrate.

  The arithmetic average height (Sa) of the roughened portions 21b, 21c, and 22b is preferably 0.13 μm to 20 μm, and more preferably 0.2 μm to 10 μm. The arithmetic average height Sa is obtained by extending the two-dimensional arithmetic average roughness Ra to three dimensions, and is a three-dimensional roughness parameter (three-dimensional height direction parameter). Specifically, the arithmetic average height Sa is obtained by dividing the volume of the portion surrounded by the surface shape curved surface and the average surface by the measurement area. When the average plane is the xy plane, the vertical direction is the z-axis, and the measured surface shape curve is z (x, y), the arithmetic average height Sa is defined by the following equation (1).

Here, “A” in the formula (1) is a measurement area. The arithmetic average height can be calculated from the surface shape data measured with a laser microscope by the method described in the ISO standard (ISO 25178). The measurement conditions are a value obtained by measuring a square area with a magnification of 1000 times and a cut-off value of 80 μm, and a measurement area of 50 μm to 500 μm in the x direction and 50 μm to 500 μm in the y direction.

  The surface roughness of the roughened portions 21b, 21c, and 22b greatly affects the transmittance of gas that passes through the interface between the resin and the metal. That is, when the surface roughness is large, the partial exfoliation caused by the difference in the thermal expansion coefficient between the resin and the metal and the force applied to the interface between the resin and the metal due to the pressure difference between the inside and outside increases, and the gas molecules It becomes easy to penetrate. On the other hand, when the surface roughness is small, the partial peeling is small, and gas molecules or clusters formed from gas molecules are difficult to permeate. As described above, the arithmetic average height is preferably 0.13 μm to 20 μm, and more preferably 0.2 μm to 10 μm, from the size of gas molecules or clusters formed from gas molecules. The arithmetic average height representing the surface roughness and its physical properties can be appropriately adjusted by adjusting the roughening distribution and the like from the laser output, spot diameter, spot interval (ΔX, ΔY), and the like.

  4A to 4D are schematic views for explaining the detailed configuration of the belt-like portion. The belt-like portion 51 may be configured by overlapping a plurality of laser irradiation regions 51a (roughened portions) roughened by laser irradiation in the in-plane direction (FIG. 4A). Moreover, the strip | belt-shaped part 52 may be comprised by arrange | positioning the several laser irradiation area | region 52a at predetermined intervals, without mutually overlapping in an in-plane direction (FIG.4 (b)). That is, the belt-like portion may be substantially composed of only a roughened portion, or may be composed of a roughened portion and an unroughened portion. Further, the belt-like portion 53 may be formed continuously in the longitudinal direction (FIG. 4C), or the belt-like portion 54 may be formed discontinuously in the longitudinal direction (FIG. 4D).

  Further, the roughened portions 21b, 21c, and 22b may have a pattern that is repeated in a striped pattern. Further, it is preferable that a pattern repeated in a stripe shape is provided along the boundary between the lead frame 2 and the sealing portion 5, and a plurality of annular roughened portions are provided so as to surround the periphery of the semiconductor element. It may be provided.

(2) Configuration of Sealing Part 5 The resin used for the sealing part 5 is not particularly limited as long as it is a material that can be joined at a temperature lower than the melting point of the metal used for the base materials 21a and 22a. Mention may be made of thermoplastic resins, thermosetting resins, elastomers or plastic alloys. Furthermore, it may be a material that cures by energy other than heat, such as a photo-curing resin, or a material that cures by other than heat, such as chemically solidifying by mixing a plurality of components. More specifically, as the thermoplastic resin (general purpose resin), for example, polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile / styrene resin (AS), acrylonitrile / butadiene / styrene resin (ABS), Examples of methacrylic resin (PMMA), vinyl chloride (PVC), and thermoplastic resin (general-purpose engineering resin) include polyamide (PA), polyacetal (POM), ultrahigh molecular weight polyethylene (UHPE), polybutylene terephthalate (PBT), Examples of GF reinforced polyethylene terephthalate (GF-PET), polymethylpentene (TPX), polycarbonate (PC), modified polyphenylene ether (PPE), and thermoplastic resin (super engineering resin) include, for example, polyphenyle Sulfide (PPS), polyetheretherketone (PEEK), liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), polyetherimide (PEI), polyarylate (PAR), polysulfone (PSF), polyethersulfone ( PES), polyamideimide (PAI), and thermosetting resin include, for example, phenol resin, urea resin, melamine resin, unsaturated polyester, alkyd resin, epoxy resin, diallyl phthalate, and elastomer as thermoplastic elastomer and Examples of the rubber include styrene / butadiene, polyolefin, urethane, polyester, polyamide, 1,2-polybutadiene, polyvinyl chloride, and ionomer. Furthermore, what added the glass fiber to the thermoplastic resin, a polymer alloy, etc. can be mentioned. Addition of various conventionally known inorganic and organic fillers, flame retardants, ultraviolet absorbers, heat stabilizers, light stabilizers, colorants, carbon black, mold release agents, plasticizers, etc., within a range that does not deteriorate the airtightness It may be one containing an agent.

These thermoplastic resins, thermosetting resins, and thermoplastic elastomers can be filled with known fibrous fillers. Examples of known fibrous fillers include carbon fibers, inorganic fibers, metal fibers, and organic fibers.
Carbon fibers are well known, and PAN, pitch, rayon, lignin and the like can be used. Examples of inorganic fibers include glass fibers, basalt fibers, silica fibers, silica / alumina fibers, zirconia fibers, boron nitride fibers, and silicon nitride fibers. Examples of the metal fiber include fibers made of stainless steel, aluminum, copper and the like.

  Examples of organic fibers include polyamide fibers (fully aromatic polyamide fibers, semi-aromatic polyamide fibers in which one of diamine and dicarboxylic acid is an aromatic compound, aliphatic polyamide fibers), polyvinyl alcohol fibers, acrylic fibers, polyolefin fibers, Synthetic fibers such as polyoxymethylene fibers, polytetrafluoroethylene fibers, polyester fibers (including wholly aromatic polyester fibers), polyphenylene sulfide fibers, polyimide fibers, liquid crystal polyester fibers, natural fibers (cellulosic fibers, etc.) and regenerated cellulose ( Rayon) fiber or the like can be used.

<Method for Manufacturing Semiconductor Device 1>
In order to manufacture the semiconductor device 1, first, a metal original plate is etched or punched to produce a lead frame 2 having an element mounting portion 21 and a lead portion 22. When forming a plating layer, the plating layer can be formed on the substrate 21a before etching or punching, or the plating layer can be formed after etching or punching. Thus, a lead frame molded body in which a plurality of lead frames 2 are arranged in a matrix is obtained. Moreover, the above-mentioned other plating layer is formed on a plating layer as needed.

  Next, a part of each surface of the lead frame 2 is irradiated with laser to form a roughened portion having a predetermined pattern on the surface. Specifically, a roughened portion 21b is formed in the element mounting portion 21 on one surface (front surface) of the lead frame 2, and the element mounting portion 21 and the lead portion 22 are formed on the other surface (back surface). Roughened portions 21c and 22b are formed on both sides. Thereby, both surfaces of the lead frame 2 are partially roughened.

  When the roughened portion is formed by laser irradiation, a laser having a wavelength from visible light to near infrared is relatively easy to obtain. Moreover, copper and aluminum have a high absorptance at wavelengths from visible light to near infrared. Therefore, when using copper, aluminum, or these alloys as a material of the base materials 21a and 22a, it is preferable to process with a laser having a wavelength from visible light to near infrared.

  As the laser light, a CW laser or a pulse laser can be used. In the case of a pulse laser, a pulse width of about 0.1 picosecond to 1 millisecond can be preferably used from the viewpoint of achieving the processed shape of the present embodiment. Regarding the energy per pulse, a laser beam of preferably 10 μJ to 1000 μJ can be used.

The spot diameter of the laser beam is preferably 300 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less from the viewpoint of increasing the energy density and forming fine irregularities. Moreover, from a viewpoint of laser condensing, 20 micrometers or more are preferable. The spot interval (pitch) of the laser light is preferably 100 μm or less. The energy density of the laser beam spot is preferably 1 to 50 J / cm ² . Here, the energy density is a value obtained by dividing the pulse energy by the area of the spot. If the energy density is less than 1 J / cm ² , sufficient processing cannot be performed. In addition, when the energy density is 50 J / cm ² or more, a phenomenon occurs in which a metal melted or broken by laser irradiation is scattered and adhered to the periphery. For example, since the adhesion reduces the bonding force when wire bonding is performed, it is not preferable that the adhesion occurs. The wavelength of the laser is preferably 300 nm to 20000 nm. For example, in the case of copper or aluminum, it is preferable to use a laser having a wavelength of about 300 nm to 600 nm, which is a wavelength with high absorption.

  Thereafter, the semiconductor element 3 is fixed to the element mounting portion 21, one end of the bonding wire 4 is bonded to the upper surface of the semiconductor element 3, and the other end is bonded to the lead portion 22 disposed around the element mounting portion 21. . Thereby, the semiconductor element 3 and the lead part 22 can be electrically connected.

  Next, the resin sealing portion 5 is joined to the metal lead frame 2. A well-known injection molding can be used for the joining in this embodiment. The injection molding may be either outsert molding or insert molding. Also included are methods such as heat fusion, varnish application, and potting.

  Specifically, as shown in FIG. 5A, the lead frame 2 to which the semiconductor element 3 and the bonding wire 4 are attached is placed on the lower mold 41, and the sealing resin is placed in the lower mold sleeve 42. The tablet 43 is inserted. Next, the upper die 44 is brought into pressure contact with the lower die 41, the lead frame 2 is disposed in a closed section between the lower die 41 and the upper die 44, and the plunger 45 in the sleeve 42 is pressed upward (FIG. 5B). ). After being heated and melted, the tablet 43 pressurized by the plunger 45 passes through the gate 46 and is sent to the cavity 47, and the cavity is filled with the molten resin (FIG. 5C). When the molten resin is cured in the cavity 47, the sealing portion 5 is molded. Thereafter, the lower die 41 and the upper die 44 are separated (FIG. 5D), and the semiconductor device 1 is taken out.

  Next, the resin burr formed on the outer edge of the sealing portion 5 and at the boundary portion between the lead portion 22 and the sealing portion 5 is removed (exterior treatment). Since resin burrs are generated at the outer edge of the sealing portion 5 during molding, the resin burrs are removed by a high-pressure water method or a liquid honing method in the subsequent exterior processing. At this time, since the roughened portion is not formed on the element mounting side surface 22a-1 of the lead portion 22, the adhesiveness between the resin burr and the lead portion 22 is low, and the resin burr can be easily removed. In addition, when it is difficult to remove the resin burr with high-pressure water, the resin burr is usually removed by alkali treatment. At this time, the alkaline liquid may damage the semiconductor element. On the other hand, in the present embodiment, alkali treatment is unnecessary, and damage to the semiconductor element 3 can be reduced as much as possible.

  As described above, according to the present embodiment, the roughened portion 21 b is provided in the element mounting portion 21 and the portion of the lead portion 22 to which the bonding wire 4 is connected and the semiconductor element 3 mounted on the element mounting portion 21. Between. Thereby, for example, by forming the roughened portion 21b by laser irradiation, masking or cleaning is not required, and the roughened portion 21b can be efficiently formed to provide high adhesion between the roughened portion and the sealing portion. Can be realized. In addition, the organic solvent contained in the silver paste or the like as the die bonding agent can be prevented from oozing out, and high bonding property of the bonding wire 4 ′ can be realized. Further, since the roughened portion 21b constitutes a belt-like portion and the width D1 of the belt-like portion is 25 μm to 1200 μm, a stable roughened structure can be formed and deformation of the lead frame 2 can be suppressed. In addition, since the surface of the lead frame 2 can be roughened with a fine pattern, it is possible to sufficiently meet the needs for downsizing of the IC and further improvement of adhesion. Furthermore, no waste liquid is generated when the roughened portion is formed, and the environmental load can be reduced.

  6A and 6B are views showing a modification of the lead frame 2 of FIG. 2, wherein FIG. 6A is a cross-sectional view, FIG. 6B is a plan view, and FIG. 6C is a bottom view. The lead frame 6 in FIG. 6 differs from the lead frame in FIG. 2 in the arrangement and shape of the roughened portion on the side where the semiconductor element is mounted. Hereinafter, parts different from the lead frame of FIG. 2 will be described.

  The element mounting portion 21 includes a base material 21a and a roughened portion 21c provided on a part of the other surface 21a-2 (back surface) of the base material 21a. In this modification, a roughened portion is not provided on one surface 21a-1 of the base material 21a. In this modification, the element mounting portion 21 includes the roughened portion 21c. However, the present invention is not limited to this, and the other surface 21a-2 of the base material 21a may not include the roughened portion. You may provide the roughening part provided in the whole surface 21a-2.

  The lead portion 22 is formed on the base material 22a, the roughened portion 62b (first roughened portion) formed on the one surface 22a-1 of the base material 22a, and the other surface 22a-2 of the base material 22a. And a roughened portion 62c. In the present embodiment, the lead portion 22 includes the roughened portion 22c. However, the present invention is not limited to this, and the other surface 22a-2 of the base material 22a may not include the roughened portion.

  As shown in FIG. 6B, the roughened portion 62b is provided in each of the plurality of lead portions 22 around the semiconductor element 3, and along the boundary between the sealing portion 5 and the portion that is not sealed. It arrange | positions rather than this boundary on the sealing part side. And the roughening part 62b is arrange | positioned between the part to which the bonding wire 4 of the lead part 22 is connected, and the part which is not sealed. The roughened portion 62c is provided in each of the plurality of lead portions 22, and is disposed along the boundary between the sealing portion 5 and the portion that is not sealed, and closer to the sealing portion than the boundary. It is arranged at a predetermined distance from the boundary.

  In the present modification, the belt-shaped portion that is the roughened portion 62 b is disposed over the entire width direction of the lead portion 22. Further, the roughened portion 62b is formed along the boundary line between the lead portion 22 and the outer edge of the sealing portion 5, and is formed with a width D2 inside from the boundary line. The width D2 of the roughened portion 62b is preferably 25 μm to 1200 μm, more preferably 50 μm to 500 μm. When laser roughening is performed with a width of less than 25 μm, it is difficult to control the laser spot size, and stable roughening cannot be realized. Further, when the width of the roughened region is larger than 1200 μm, the lead frame is likely to be deformed.

  The roughened portion 62b may be arranged at a predetermined distance from the boundary line. Further, the roughened portion 62b may not be provided over the entire width direction of the lead portion 22, and may be provided in a part of the width direction.

  As shown in FIG. 6C, the roughened portion 62c is composed of a plurality of planar roughened portions provided outside the roughened portion 21c. The roughened portion 62c is disposed at a predetermined distance from the boundary line. As described above, in this modification, the roughened portion 21 c is disposed on one surface of the element mounting portion 21 (the surface opposite to the surface on the element mounting side), and the roughened portion 62 b is formed on both surfaces of the lead portion 22. , 62c are arranged.

  According to this modification, the roughened portion 62b is along the boundary between the resin-made sealing portion 5 that seals the semiconductor element 3 of the lead portion 22 and the portion that is not sealed, and the sealing portion is more than the boundary. Since it is arranged on the side, the same effects as described above can be obtained.

  FIG. 7 is a view for explaining exterior processing when manufacturing a semiconductor device having the lead frame 6 of FIG. As described above, in the exterior processing, the liquid L made of water or slurry is sprayed from the nozzle 71 to the resin burr C formed at the boundary portion between the lead portion 22 and the sealing portion 5 at a predetermined pressure, and the resin Physically remove burrs. Here, if the roughened portion is located on the bonding surface between the resin burr and the lead frame, the adhesion between the resin burr and the lead frame is improved, and therefore it is difficult to remove the resin burr.

  In the lead frame 6 of this modification, the roughened portion 62b is disposed along the boundary between the lead portion 22, the sealing portion 5, and the portion that is not sealed. Moreover, the roughened part 62b comprises a strip | belt-shaped part, and the width | variety D2 of this strip | belt-shaped part is 25 micrometers-1000 micrometers. In this way, by restricting the roughened portion 62b to a minute width and forming it with a fine pattern, it is possible to prevent an extra roughened portion from being disposed at the interface between the resin burr C and the lead frame 6. it can. Therefore, the resin burr C can be easily removed during the exterior processing while improving the adhesion between the lead frame 6 and the sealing portion 5, and the productivity can be improved. Further, the roughened area can be reduced as compared with the roughened portion 21b provided in an annular shape, and the productivity can be further improved while ensuring the necessary adhesion between the lead frame 6 and the sealing portion 5. It becomes possible.

  The lead frame and the semiconductor device according to the above embodiment have been described above, but the present invention is not limited to the described embodiment, and various modifications and changes can be made based on the technical idea of the present invention.

Examples of the present invention will be described below.
First, the lead frame was roughened under the conditions shown in Table 1. The lead frame material was a copper alloy (product name “EFTEC-64T-C” manufactured by Furukawa Electric Co., Ltd.). As the pulse laser, an ultrashort pulse laser device (manufactured by Hamamatsu Photonics, device name “MOIL-ps L11590”) was used. The wavelength was 515 nm and the pulse energy was 90 μJ. The “spot interval” in Table 1 is the distance between the centers of the processing marks formed on the lead frame by one laser pulse. Moreover, the outline of the position of the laser roughening part formed in the Example and the comparative example is shown in FIG. The roughened portion of Example 1 is FIG. 8 (a), the roughened portion of Example 2 is FIG. 8 (b), and the roughened portions of Examples 3 to 9 and Comparative Example 4 are FIG. 8 (c). 8 (d), the roughened portion of Example 11 is FIG. 8 (e)), the roughened portion of Comparative Example 1 is FIG. 9 (a) (no roughened portion), and Comparative Example 2 9B corresponds to FIG. 9B, and the roughened portion of Comparative Example 3 corresponds to FIG. 8C.

  In FIGS. 8A to 8E and FIGS. 9B to 9C, regions (P1 to P7) indicated by dots are laser-treated regions (roughened portions). In Examples 1 to 9, 11 and Comparative Examples 2 to 3, each of the annular roughened portions formed on the element mounting portion has a width of 50 μm and a spot interval of 20 μm, and is subjected to laser processing of the same pattern. . Moreover, the dashed-two dotted line in FIG.8 and FIG.9 has shown the position of the outer edge of mold resin.

  Subsequently, the arithmetic average height Sa and specific surface area of the roughened portion of the lead frame obtained by the laser treatment were measured with a laser microscope (VK-X250, manufactured by Keyence Corporation). The laser microscope measurement conditions were a magnification of 1000 times and a cut-off value of 80 μm, and a rectangular region of 500 μm × 350 μm was measured. Moreover, the state of the roughened part was observed with SEM, and the image was acquired. These results are shown in Table 2 and FIG. The relationship between the roughening positions in Examples 1 to 11 and Comparative Examples 1 to 4 and the SEM images shown in FIGS. 10 (a) to 10 (c) is as shown in Table 2.

  Next, the substrate (semiconductor element) was die-bonded with a silver paste (die bonding agent) to the roughened lead frame, and then wire bonding was performed. Example 11 is a lead frame in which laser processing is performed on a part of the region where the bonding wire is bonded (FIG. 8E). In this lead frame, 18 of 100 bonding wires in the laser-processed portion are provided. It peeled at the spot. This is thought to be because fine particles generated by the laser treatment were scattered and adhered to the bonding portion of the bonding wire, thereby weakening the bonding property of the bonding wire. Therefore, it turned out that Examples 1-10 which do not perform a laser processing to a bonding wire junction part are more preferable from a viewpoint of the adhesiveness of a lead part and a bonding wire.

  Further, the lead frame was molded with an epoxy resin. In Comparative Example 2, as a result of performing laser treatment on the inside and outside of the outer edge of the mold resin (sealing part) (FIG. 9B), resin burrs were generated on the outside of the outer edge of the mold resin. This is presumably because the mold resin easily oozes out from the outer edge during resin molding because the surface was roughened by laser treatment. When the resin burrs are generated, it is necessary to remove them with a water jet or the like, which increases the number of manufacturing processes and increases costs. Therefore, it turned out that it is not preferable to laser-process the part straddling the inner side and outer side of the outer edge of mold resin like the comparative example 2. FIG.

  Further, the Z-axis displacement was measured for the lead frames of Examples 1 to 3, 5, 10, Example 8, and Comparative Example 4. As shown in FIG. 11, the Z-axis displacement is the height of point D on the semiconductor element with reference to point C on the lead portion. As a result of measurement, the Z-axis displacement of Example 1 was 2 μm, the Z-axis displacement of Example 2 was 4 μm, the Z-axis displacement of Example 3 was 3 μm, the Z-axis displacement of Example 5 was 4 μm, and the Z-axis of Example 10 The displacement was 2 μm, and the Z-axis displacement of Comparative Example 4 was 36 μm. If the Z-axis displacement is 10 μm or more, it may cause variations in performance when the product becomes a semiconductor package or the like. Therefore, it was found that Comparative Example 4 in which the arithmetic surface height Sa is 20 μm or more is not preferable because the lead frame is greatly deformed. As another comparative example, a lead frame was manufactured by laser irradiation with a width of 1500 μm at the position shown in FIG. 8C under the laser irradiation conditions of the same laser spot diameter and spot interval as in Example 5, and the Z-axis displacement was measured. did. As a result, the Z-axis displacement was 22 μm. Therefore, it was found that when the width of the roughened portion is larger than 1200 μm, the Z-axis displacement is large, which is not preferable.

  Subsequently, for each of the examples and comparative examples, the resin-molded sample was allowed to stand for 168 hours under the conditions of a temperature of 85 ° C. and a humidity of 85%, and then passed once through a 260 ° C. reflow furnace. Thereafter, the presence or absence of peeling between the mold resin and the lead frame was evaluated using an ultrasonic imaging apparatus (manufactured by Hitachi Power Solutions, apparatus name “FineSAT 300III”). The results are shown in Table 3 and FIG.

In Examples 1 to 11, it was found that no peeling occurred at the interface between the mold resin and the lead frame, and the adhesion between the resin and the lead frame was improved by the laser treatment.
On the other hand, when the laser treatment is not performed as in Comparative Example 1 or the laser treatment is performed outside the outer edge of the resin mold as in Comparative Example 3, the mold resin and the lead frame are separated as shown in FIG. did. The shaded area shown in FIG. 12A is the part peeled off in Comparative Example 1, and the shaded area shown in FIG. 12B is the part peeled off in Comparative Example 3. Therefore, in Comparative Examples 1 and 3, it was found that the adhesion between the mold resin and the lead frame was not sufficient.

  For the lead frame of Example 8, the substrate was die-bonded with a silver paste, followed by wire bonding, and a peel test similar to the above was performed.

  In Example 8, the bonding wires were peeled at 10 points out of 100 points. This is because in Example 8, the organic solvent contained in the silver paste used for die bonding oozes out and reaches the bonding portion of the bonding wire 4 ′ for grounding through the surface of the lead frame to weaken the adhesive strength. On the other hand, in Examples 1 to 9 and 11 described above, the organic solvent was blocked by the roughened portion of the element mounting portion, so the organic solvent did not reach the bonding portion of the bonding wire, and the adhesiveness was maintained. Therefore, it has been found that it can be said that roughening the element mounting portion has an effect of preventing the organic solvent in the silver paste from exuding.

  Further, the arithmetic average height of the roughened portion of the lead frame (manufactured by Atotech Co., Ltd., EFTEC-64T-C mold prep-treated product) whose surface was treated with a chemical solution was measured by the same method as in Example 3. Subsequently, for each of the lead frame that was laser-treated under the conditions of Example 4 and the lead frame that was entirely surface-treated with chemical treatment, the contact angle of the roughened water was measured, and an electron beam microanalyzer (EPMA) was used. An analysis based on the oxygen element abundance ratio on the surface of the roughened portion was performed. The results are shown in Table 4 and FIG. In FIG. 13, the X-axis is the characteristic X-ray wavelength, and the Y-axis is the signal intensity. Table 4 shows the peak intensities of characteristic X-rays (oxygen) in the above two samples.

  As shown in Table 4, the arithmetic average height Sa was almost the same for the lead frame treated with the chemical solution and the lead frame laser-treated under the conditions of Example 4. On the other hand, the contact angle of water was larger for the chemical-treated lead frame than for the laser-treated lead frame. From the results of EPMA analysis, the abundance ratio of oxygen element on the treated lead frame surface was higher in the laser-treated lead frame than in the chemical-treated one (2: 1). Therefore, it is considered that an oxide layer is formed on the surface of the lead frame subjected to the laser treatment by heat, and as a result, the wettability is improved.

  Subsequently, an epoxy resin was molded on each of the two lead frames subjected to the chemical treatment and the laser treatment to form a sealing portion, and the adhesion of the epoxy resin was evaluated. The adhesion strength between the lead frame and the epoxy resin was measured using SAICAS (manufactured by Daipura Wintes). The results are shown in Table 5.

  As shown in Table 5, the adhesion strength between the lead frame and the epoxy resin was more than twice as high as that of the lead frame subjected to the laser treatment as compared with the chemical treated with the lead frame. This is considered to be because the resin wettability of the lead frame surface is improved and the bonding property of the epoxy resin is increased in the laser treatment. Therefore, it was found that the laser treatment is superior to the chemical treatment in terms of enhancing the adhesiveness of the mold resin.

  Since the lead frame of the present invention is excellent in the adhesion between the resin part and the metal part, the semiconductor device of the present invention is used for applications that require the inside to be kept airtight or applications that require adhesion between the metal and the resin. It can be preferably used. For example, the semiconductor device of the present invention is suitable as a composite molded body having therein electric / electronic components that are easily affected by humidity and moisture. In particular, it can be more suitably used as a part for electrical or electronic equipment that is expected to be used in fields requiring high level waterproofing, such as rivers, pools, ski resorts, and baths. In addition, the semiconductor device of the present invention is useful as a housing for electric / electronic devices including a resin boss, a holding member, and the like inside. The electrical / electronic equipment casing includes portable video electronic equipment casings such as mobile phones, cameras, video integrated cameras, digital cameras, notebook computers, pocket computers, calculators, electronic notebooks, PDC, PHS, Portable information such as mobile phones or communication terminal housings, MDs, cassette headphone stereos, portable acoustic electronic device housings such as radios, home appliances such as LCD TVs / monitors, telephones, facsimiles, hand scanners, etc. A housing or the like can be given. Moreover, since it is excellent in the adhesiveness in a high temperature use environment, it can be used more suitably as a part used in a high temperature environment, especially as an automobile part.

DESCRIPTION OF SYMBOLS 1 Semiconductor device 2 Lead frame 3 Semiconductor element 4 Bonding wire 4 'Bonding wire 5 Sealing part 6 Lead frame 21 Element mounting part
21a base material 21a-1 surface 21b roughened portion 21c roughened portion 22 lead portion
22a substrate 22a-1 surface
22a-2 surface 22b roughened portion 41 lower mold 42 sleeve 43 tablet 44 upper mold 45 plunger 46 gate 47 cavity 51 band 51a laser irradiation area 52 band 52a laser irradiation area 53 band 54 54 band 62b roughened 62c rough 71 Nozzle D1 Width D2 Width C Resin Burr L Liquid

Claims (7)

A lead frame having an element mounting portion and at least one lead portion provided around the element mounting portion;
The lead frame includes a roughened portion;
The roughened portion is disposed along the boundary between the resin-made sealing portion that seals the semiconductor element and the non-sealed portion that is provided in the lead portion and closer to the sealing portion than the boundary. A first roughened portion, and a second roughened portion disposed between the portion provided on the element mounting portion and connected to the bonding wire of the lead portion and the semiconductor element mounted on the element mounting portion A lead frame comprising at least one of the following.   2. The lead frame according to claim 1, wherein the first roughened portion is disposed between a portion to which a bonding wire of the lead portion is connected and a portion that is not sealed. 3. The lead portion includes a plating layer at least in part,
The lead frame according to claim 1, wherein the first roughened portion is not disposed on the plating layer.   2. The lead frame according to claim 1, wherein the second roughened portion constitutes a belt-like portion provided so as to surround the periphery of the semiconductor element mounted on the element mounting portion. The first roughened portion constitutes a belt-like portion;
5. The lead frame according to claim 1, wherein a width of the belt-shaped portion is 25 μm to 1200 μm.   The lead frame according to claim 1, wherein an arithmetic average height of the roughened portion is 0.13 μm to 20 μm. The lead frame according to any one of claims 1 to 6, wherein the roughened portion has a specific surface area of 1.08 to 4.