TW201633572A - Lead frame and method of manufacturing the same - Google Patents

Abstract

The present invention provides a lead frame and method of manufacturing the same. The lead frame is for mounting a semiconductor element to enhance the adhesion of external resin to a die pad part and/or a lead part, and be able to dissipate the heat generated from a semiconductor element or an LED element more quickly. The lead frame of the present invention includes: a die pad part (1) for mounting a semiconductor element or an LED element, and a lead part (2) arranged on the periphery of the die pad part (1) via a space. There is a thin wall part at the edge of the die pad part (1) or lead part (2), also, at least one downward protrusion (1a, 2a) on the lower surface of the thin wall part.

Description

Lead frame and method of manufacturing same

The present invention relates to a lead frame for a semiconductor device, and more particularly to a lead frame suitable for mounting an optical semiconductor element and a method of manufacturing the same.

An optical semiconductor device equipped with an LED element is gradually used for various devices such as general illumination, displays such as televisions, mobile phones, and OA equipment. In order to reduce the thickness and mass production of these optical semiconductor devices, a package in which an LED element is mounted using a lead frame and resin-sealed is developed.

An optical semiconductor device using a lead frame generally has a structure as shown in Figs. 6(A), (B), and (C). In other words, the wafer pad portion 1 on which the LED element is mounted and the lead frame 2 in which the lead portion 2 is disposed at intervals around the wafer pad portion 1 are formed, and the LED element is mounted on the wafer pad portion 1 and the LED element and the lead portion 2 are mounted. Bonding by wire bonding or the like. In addition, an external resin portion (reflector) made of a resin that reflects light is disposed around the LED element, and is filled with a sealing resin portion that surrounds the LED element and the periphery of the wire bonding with a transparent resin. Such an optical semiconductor device is described in Patent Document 1 and Patent Document 2.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-274027

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-151069

In recent years, optical semiconductor devices have been increasingly installed in mobile devices represented by mobile phones, and these mobile devices have been strongly demanded to be reduced in size, weight, and impact resistance. Therefore, of course, it is required to increase the size, thickness, and impact resistance of the optical semiconductor device itself.

In the structure of the optical semiconductor device using the lead frame, as shown in FIG. 6(A), the space between the wafer pad portion 1 and the lead portion 2 is filled with resin, but since the gap is very narrow and long, the resin itself Since the strength is weak and the contact area with the lead frame is small, when an external force is applied from the outside, particularly from the vertical direction, the resin portion is peeled off from the wafer pad portion 1 and the lead portion 2, and the impact resistance is hindered. .

Patent Document 1 discloses the following invention: as shown in FIG. 6(B), in order to prevent resin from falling off in the gap between the wafer pad portion 1 and the lead portion 2, the lead pad portion on the lower surface side of the wafer pad portion 1 and the lead portion 2 is shown. A part of the half etching is performed so that the thickness of the portion becomes half the thickness of the plate, and the space to be filled with the resin is enlarged, whereby the adhesion between the wafer pad portion 1 and the lead portion 2 is improved.

Further, Patent Document 2 discloses an invention in which the opposite surface of the wafer pad portion 1 and the lead portion 2 is provided in the vicinity of the intermediate portion of the cross section of the wafer pad portion 1 and the lead portion 2 as shown in Fig. 6(C). The protrusion formed by the etching process from the upper and lower sides transmits the protrusion to prevent the resin filled in the gap between the wafer pad portion 1 and the lead portion 2 from falling off.

As compared with the conventional structure as shown in FIG. 6(A), these inventions are capable of semi-etching the lower surface of the wafer pad portion 1 and the lead portion 2 as described in Patent Documents 1 and 2, and increasing the number of the wafers. Filling the space portion of the resin and increasing the contact between the resin and the lead frame The area is increased in strength and the adhesion to the resin to be contacted is increased. However, in the case described in Patent Document 1, the half-etched surface of the wafer pad portion 1 and the lead portion 2 is a flat surface, and The adhesion of the resin to be contacted is low. Further, the impact from the vertical direction is weak, and it is desired to further improve the adhesion, and it is more desirable to improve the impact resistance of the optical semiconductor device. In the invention of Patent Document 2, protrusions are provided in the vicinity of the intermediate portion in the cross-sectional direction of the wafer pad portion 1 and the lead portion 2, and the interval between the wafer pad portion 1 and the lead portion 2 is substantially narrowed, and it is necessary to increase the wafer pad portion 1 and The interval design value of the lead portion 2 is contrary to the thinning and miniaturization of the optical semiconductor device.

Further, in order to reduce the size and size of the optical semiconductor device, high performance is required. For example, the LED element is increased in brightness. Therefore, the size of the LED element is increased, and accordingly, countermeasures against heat generation are also an important issue, and as a lead frame for LEDs, heat dissipation is required to be improved.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a lead frame which is a lead frame for a semiconductor device, particularly a lead frame with a resin for use in an optical semiconductor device and an optical semiconductor device, which is capable of The adhesion between the external resin and the wafer pad portion 1 and/or the lead portion 2 is improved, and heat generation from the semiconductor element or the LED element can be released more quickly.

In order to achieve the above object, a lead frame according to the present invention includes: a wafer pad portion on which a semiconductor element or an LED element is mounted, and a lead portion disposed around a space around the wafer pad portion, and the wafer pad portion And/or the edge portion of the lead portion has a thin portion, and at least one protrusion facing downward is provided on the lower surface of the thin portion.

Further, according to the invention, the height of the protrusion is 0.005 mm or more.

Further, according to the present invention, the shape of the protrusion is a plane circle Shape or plane elliptical.

Further, according to the present invention, the longitudinal cross-sectional shape of the protrusion is a mountain shape or a substantially conical shape in which the shape of the Mount Fuji or the top is circular.

Further, the method of manufacturing a lead frame according to the present invention includes the steps of: preparing a metal plate to be a base material of the lead frame; and forming a portion of the wafer pad portion and the lead portion on the surface side of the metal plate a part of a portion of the back surface of the metal plate corresponding to the wafer pad portion, a portion where the protrusion portion is formed, a portion of the portion corresponding to the lead portion, and a portion where the protrusion portion is formed to form an etching resist layer. And a step of etching the front and back surfaces of the metal plate by using the resist layer for etching as a corrosion-resistant film, and forming a facing surface facing each other in the wafer pad portion and the lead portion in the etching step, and At least one protrusion is formed under the etched underside of the wafer pad portion and/or the lead portion.

According to the present invention, the wafer pad portion on which the semiconductor element or the LED element is mounted and the lead portion disposed around the wafer pad portion with a space therebetween are provided, and a part of the wafer pad portion and/or the lead portion is opposite to the element mounting surface. The etching process is performed, and has one or more protrusions on the lower surface of the thin portion which is thinner than the other portions, so that the contact area between the resin and the lead frame is greatly increased as compared with the conventional plane having no protrusion, and the adhesion is improved. Further, since the projections protrude downward, when the external resin is applied from the vertical direction, the adhesion is further increased, and the resin can be prevented from falling off. In particular, in the semiconductor device or the optical semiconductor device, there is an advantage that, in the case of an impact from the up and down direction, the protrusion disposed under the thin portion serves to prevent the thin-walled resin from acting in the spatial direction of the wafer pad portion and the lead portion. The strength, therefore the impact resistance is improved.

Further, there is an advantage in that since the contact area between the resin and the lead frame is greatly increased, the heat generated by the semiconductor element and the LED element is also released, and the heat dissipation property is also improved.

1‧‧‧ wafer pad

1a‧‧‧ wafer pad protrusion

1b‧‧‧LED component mounting surface

1c‧‧‧ face on the opposite side of the LED component mounting surface

2‧‧‧ lead parts

2a‧‧‧Lead portion protrusion

P‧‧‧metal plate

R‧‧‧Resist layer for etching

R'‧‧‧ Relief layer for protrusion formation

Fig. 1 is a cross-sectional view showing an example of a lead frame having projections on a lower surface of a thin portion according to the present invention.

2 is a cross-sectional view showing an optical semiconductor device using a lead frame according to the present invention.

3 is a flow chart showing an example of a method of manufacturing a lead frame according to the present invention.

4 is a plan view showing various shapes and arrangements of protrusions formed by the method of the present invention, and a cross-sectional view corresponding thereto.

Fig. 5 is a photograph showing two examples of the arrangement state of the projections formed by the method of the present invention.

FIG. 6 is a cross-sectional view showing a conventional configuration example in which optical semiconductor devices are different from each other.

Hereinafter, embodiments of the present invention will be described based on the illustrated embodiments.

Further, the present invention is applied to a semiconductor device and an optical semiconductor device, but will be described below based on an example of the optical semiconductor device.

First, the configuration of the optical semiconductor device and its effects will be described before explaining the embodiment. 2 shows an example of an optical semiconductor device using the lead frame according to the present invention, wherein the lead frame used is a wafer pad portion 1 on which an LED element is mounted, and a lead portion 2 disposed around a space around the wafer pad portion 1 Composition. An LED element is mounted on the upper surface of the wafer pad portion 1, and the electrode portion of the LED element is electrically connected to the lead portion 2 by wire bonding or the like. An outer resin portion is formed on the lead frame of the wafer pad portion 1 and the lead portion 2 in such a manner as to surround the LED element and the electrical connection portion. Further, the space portion of the wafer pad portion 1 opposed to the lead portion 2 and the respective lower portions are also filled with the external resin at the same time. The periphery of the LED element and the electrical connection portion surrounded by the outer resin portion is transparent A resin-filled sealing resin portion.

In the lead frame for an optical semiconductor device, the metal plate is etched to form the wafer pad portion 1 and the lead portion 2, and a copper-based alloy is generally used as the material of the metal plate. Regarding the plate thickness, 0.1 mm to 0.3 mm is mostly used. One or more of the lead portions 2 are disposed corresponding to the wafer pad portion 1.

A part of the edge of the wafer pad portion 1 and/or the lead portion 2 or an entire circumference is etched from a surface on the opposite side of the LED element mounting surface, and a thickness is formed from the edge of the wafer pad portion 1 and/or the lead portion 2 toward the inside. Thin wall portion thinner than the plate.

In the optical semiconductor device, since the space portion of the wafer pad portion 1 opposed to the lead portion 2 is connected only by the resin, it is the portion having the weakest impact. Therefore, it is important to provide a thin portion at the opposite surface portion.

Further, in order to improve heat dissipation, it is preferable to provide a thin portion on the entire circumference of the wafer pad portion 1 and the lead portion 2. In addition, when the wafer pad portion 1 and the lead portion 2 are provided to have a connection portion with another wafer pad portion, a lead portion, a frame, or the like, the thinning of the connection portion is eliminated.

The thickness of the thin portion is about 1/4 to a plate thickness of -0.03 mm. When the thickness is 1/4 or less, the strength of the wafer pad portion 1 is weak, and deformation or the like may occur. If the thickness is -0.03 mm or more, the thickness of the outer resin portion filled under the thin portion is reduced, and the strength of the outer resin is increased. It becomes weak, and the possibility of peeling off the resin itself is large. The thickness of the thin portion is preferably about 1/2 of the thickness of the plate.

The length of the thin portion from the edge of the wafer pad portion 1 and the edge of the lead portion 2 toward the inside direction needs to be 0.15 mm or more. If it is 0.15 mm or less, it is difficult to form a protrusion. There is no specific upper limit, and it is possible to freely set the wafer bonding and wire bonding without causing defects and securing the external connection region, and it is preferably a plate thickness.

Below the thin portion, protrusions 1a, 2a projecting downward are formed. The height of the protrusion is 0.005 mm or more. If the height of the protrusion is less than 0.005 mm, the adhesion to the external resin is small. The upper limit is not particularly set, but if it is too high, it may be exposed from the external resin. At least the protrusion is set to be 0.02 mm or more in comparison with the external resin. Preferably, it is set to embed 0.03 mm or more.

The shape of the protrusion is a flat circular shape or a substantially flat elliptical shape, and the longitudinal cross-sectional shape may be set to a shape of a Mount Fuji or a mountain shape having a round shape at the top or a substantially conical shape. Further, the cross section of the protrusion in the direction orthogonal to the edge of the wafer pad portion 1 and/or the lead portion 2 is substantially bilaterally symmetrical with respect to the perpendicular line passing through the vertex.

The arrangement of the projections on the lower surface of the thin portion is arranged such that the projections do not overlap. When the region of the thin portion is not sufficiently ensured, for example, when the width of the thin portion is a plate thickness, the edges of the wafer pad portion 1 are arranged in a line. In the case where the region of the thin portion can be sufficiently ensured, it is desirable to arrange in a staggered manner and in a plurality of rows. Further, it may be arranged in an elongated elliptical shape along the edge portion.

When the width of the thin-walled portion is the thickness of the plate, it is preferable that the planar shape of the projection is a circular or nearly circular elliptic shape, and is formed at an interval of a thickness of 0.05 mm from the thickness of the plate to a thickness of the plate. Configuration.

Further, the protrusions in the thin portion may be set in such a manner that the apex portion of the protrusion in the direction parallel to the edge of the wafer pad portion 1 and/or the lead portion 2 is located near the edge of the wafer pad portion 1 and/or the lead portion 2. One side. By setting in this way, the cross section of the protrusion perpendicular to the edge of the wafer pad portion 1 and/or the lead portion 2 is slightly asymmetrical to the left and right with respect to the perpendicular line passing through the apex portion.

This is because the shape of the edge side of the wafer pad portion 1 and the lead portion 2 is etched from the upper and lower surfaces. Therefore, the etching speed is fast, and when the apex portion of the protrusion is not brought closer to the edge side of the wafer pad portion 1 and the lead portion 2 Compared with the symmetrical mountain shape, the inclination tends to be sharp. On the other hand, the distance from the edge portion of the wafer pad portion 1 and/or the lead portion 2 is increased in accordance with the distance from the edge portion of the wafer pad portion 1 and/or the lead portion 2, and the etching can be performed over a wide range to increase the height of the protrusion. Processed higher. In particular, when the projections are arranged in a narrow portion of the thin portion, it is effective to approach the edge portions of the wafer pad portion 1 and the lead portion 2. For example, when the length from the edge of the thin portion toward the inside is a plate thickness, the effect is large. At this time, the distance to be approached is about 1/4 to 1/2 of the radius of the protrusion size. If the distance to be approached is 1/4 or less of the radius of the root of the projection, the effect of the approaching effect is small. If it is close to 1/2 or more, although it depends on the etching speed, it sometimes affects the shape of the top and bottom of the protrusion, and it is also possible to reduce the height of the protrusion. Therefore, the value is preferably about 1/3.

Here, in particular, in the longitudinal cross-sectional shape of the projection, since the inclination on the surface side facing the wafer pad portion 1 and the lead portion 2 is severe, the adhesion strength when the force is applied from the vertical direction can be further improved.

When the lead frame is formed as a lead frame for an optical semiconductor device, precious metal plating is applied to the outermost layer of the wafer pad portion 1 and the lead portion 2 on the optical semiconductor element mounting surface side for mounting the optical semiconductor element and the optical semiconductor element. It is used for bonding with the wire of the lead portion 2 and for efficiently reflecting light from the light-emitting element. Regarding the plating of the outermost layer, Ag or Ag alloy plating is suitable from the viewpoint of spectral reflectance.

The plating on the inner side closer to the substrate than the outermost layer may be generally used for plating the lead frame.

The back side of the wafer pad portion 1 and the lead portion 2 serves as a mounting terminal surface of the substrate, and plating for improving solder wettability at the time of mounting is applied. In the same manner as the plating on the side of the optical semiconductor element mounting surface, the outermost layer is plated with Ag or Ag alloy, and the plating on the inner layer side closer to the substrate than the outermost layer is generally used. The lead frame can be plated. In consideration of cost, etc., it is also possible to set only the solder mounting surface side to Ni/Pd/Au plating or the like.

The lead frame with a resin is formed by forming an external resin portion on the lead frame, and connecting the electrode portion of the LED element to the lead portion 2 in addition to the portion of the wafer pad portion 1 on which the LED element is mounted and through wire bonding or the like. An outer resin portion is formed on the wafer pad portion 1 and the lead portion 2 other than the periphery of the connection portion. Further, at the same time, the gap portion of the surface facing the wafer pad portion 1 and the lead portion 2 is filled with the external resin.

Since the outer resin portion also functions to reflect light from the LED element, the surface surrounding the LED element and the wire-bonded connection portion is tapered, and the light is reflected upward.

The gap between the wafer pad portion 1 and the opposing surface of the lead portion 2 is extremely narrow, and is generally about 0.1 mm to 0.3 mm. Therefore, the volume of the external resin filled therein is small, and the strength of the resin itself is insufficient. Further, the outer resin and the lead frame have a small contact area, and the adhesion is also weak. Therefore, as described above, the surface facing the wafer pad portion 1 and the lead portion 2 is etched from the surface on the opposite side to the LED element mounting surface to form a thin portion having a thickness smaller than the thickness of the plate. Thereby, a space for filling the external resin is generated under the thin portion, and the space and the gap between the wafer pad portion 1 and the lead portion 2 are integrally filled with the resin, so that the adhesion area between the lead frame and the resin is greatly increased, and the adhesion is tight. Sexual improvement.

Further, on the lower surface of the thin portion, a projection is provided as described above, and the surface of the lead frame that is in contact with the external resin is greatly increased by the projection, and the adhesion is further improved.

Further, on the lower surface of the thin portion, a protrusion is provided as described above, and the protrusion is passed through the lead frame. The area in which the surface is in contact with the external resin is greatly increased, and the adhesion is further improved.

Further, by increasing the contact area with the resin in this way, heat dissipation is accelerated, and as a result, heat dissipation is excellent.

Next, a method of manufacturing the lead frame according to the present invention will be described with reference to Fig. 3 .

First, a flat metal plate P is prepared. The material of the metal plate can be a copper alloy. The prepared metal plate P is degreased and cleaned to remove unnecessary dross and organic matter (see Fig. 3(A)).

Next, using the resist for etching, a resist layer R is formed so that the wafer pad portion 1 and the lead portion 2 form a predetermined pattern. In detail, a photosensitive resist is applied to the front and back surfaces of the metal plate P. Then, the predetermined pattern is exposed through the photomask. Then, development is performed to form a resist layer R (see FIG. 3(B)).

Next, the opening portion not covered by the resist layer R is etched with an etching solution. Thereby, the wafer pad portion 1 and the lead portion 2 are formed (see FIG. 3(C)).

The thin portion of the wafer pad portion 1 and the lead portion 2 is set to a part or the entire circumference of the edge of the wafer pad portion 1 and/or the lead portion 2. FIG. 3 shows an example in which a thin portion is formed in the wafer pad portion 1. The manufacturing method of setting the thin portion in the lead portion 2 is the same as that of the wafer pad portion 1. The manufacturing method of the protrusions is also the same.

The LED mounting surface 1b of the wafer pad portion 1 is covered with a resist R, and the resist layer R forms an opening in the surface 1c on the side opposite to the LED mounting surface. Therefore, the surface 1c on the opposite side to the LED mounting surface 1b is etched to form a thin portion. At this time, since the root bottom portion of the thin portion has an arc shape, it is necessary to adjust the opening portion of the resist layer R to be larger than the setting of the thin portion.

The thickness of the thin portion can be adjusted by adjusting the etching time and the ejection pressure of the upper and lower etching liquids. The force, the flow rate of the etching solution, the flow rate, and the like are performed.

Next, a method of forming a protrusion on the lower surface of the thin portion will be described. In the manufacturing process of the thin-walled portion, the LED element mounting surface 1b is covered with the resist layer R, and the surface 1c opposite to the LED element mounting surface 1b has no resist layer to form an opening, but the transparent portion should be provided. The projection of the opening is provided at a position where the protrusion forming resist layer R' is provided. As shown in FIG. 3(C), a resist layer R' for forming a protrusion is provided, and etching is performed from the lower opening of the wafer pad thin portion and the gap between the wafer pad portion 1 and the lead portion 2 with respect to etching. The etching on the lower side starts simultaneously, and if the etching is continued, the etching is performed as shown in FIG. 3(D), and if further etching is performed, the predetermined protrusion 1a is formed as shown in FIG. 3(E). The height of the protrusion 1a is adjusted by the etching rate of the etching liquid and the size of the etching rate control resist layer R' provided at the position where the protrusion is applied. That is, if the resist portion for forming the protrusion 1a is large, the predetermined protrusion height is raised, and in the worst case, it becomes the same thickness as the other thicknesses. At this time, it is exposed from the outer resin portion. On the other hand, when the resist portion for forming the protrusion 1a is small, the etching proceeds quickly, and the protrusion is lower than the predetermined height, and the effect of the adhesion cannot be obtained. Therefore, in order to form the protrusion 1a to a predetermined height, it is important to adjust the etching speed and the size of the resist provided at the position where the protrusion 1a is formed.

Next, a description will be given of a manufacturing method in which the wafer pad portion 1 and/or the lead portion are adjacent to the apex portion of the protrusion 1a in the direction parallel to the edge of the wafer pad portion 1 and/or the lead portion 2 On the edge side of 2, the cross section of the protrusion 1a perpendicular to the edge of the wafer pad portion 1 and/or the lead portion 2 is slightly asymmetrical with respect to the vertical line passing through the vertex. In order to make the cross-sectional shape of the protrusion 1a bilaterally symmetrical, it is necessary to provide the protrusion 1a in the thin-walled portion region. On the other hand, in order to make the protrusion shape slightly asymmetrical to the left and right of the perpendicular line passing through the apex, the apex portion of the protrusion 1a is oriented. The wafer pad portion 1 and the edge side of the lead portion 2 may be set by moving a predetermined distance. Further, as a matter of course, the outer shape of the projection 1a is not formed in a portion beyond the edge of the wafer pad portion 1 and the lead portion 2 by moving the apex portion.

In the above, the method of manufacturing the protrusion and the method of adjusting the protrusion height and the method of manufacturing the protrusion of the protrusion shape when the protrusion is formed on the wafer pad portion 1 side have been described. However, these methods can also be applied to the case where the protrusion 2a is formed on the side of the lead portion 2, Therefore, it will not be repeated.

4 is a view showing various planar shapes and arrangements (A) to (F) of the protrusions 1a produced by the above-described method, and cross-sectional shapes (A') to (parallel to the edge portions of the wafer pad portion 1 and the lead portion 2). An embodiment of F').

The wafer pad portion 1 and the lead portion 2 of the lead frame are subjected to full-surface plating or partial plating.

Regarding the entire surface plating, after forming the lead frame shape described above, the lead frame is directly plated as a whole.

There are two methods for partial plating. That is, similarly to the entire surface plating, after forming the shape of the lead frame, the cover is covered with a portion that does not need to be partially plated to prevent plating, and only the required portion is plated, and then the cover is removed; And another method of first forming a partial plating resist for a metal material, plating, and then peeling off the plating resist, forming an etching resist pattern on the surface of the metal material, and then performing etching treatment , thereby forming a method of etching the pattern.

In the etching resist pattern at this time, an etching pattern larger than the plating pattern by 30 to 50 μm is formed in the portion where the partial plating is performed first.

Further, the lead frame in which the wafer pad portion 1 and the lead portion 2 are formed and to which a predetermined plating is applied can be cut into a sheet shape every predetermined number and a fixed resin can be fixed when the external resin is sealed as needed. The resin tape for grease is attached to the surface opposite to the LED mounting surface.

Next, a method of manufacturing a lead frame with a resin will be described. The outer resin portion is formed on the lead frame by transfer molding and injection molding of the lead frame manufactured as described above. As the external resin, a thermoplastic resin is generally used. The outer resin portion is also formed on the lead frame while filling the space portion where the wafer pad portion 1 faces the lead portion 2. The external resin portion is formed to surround the periphery of the connection portion electrically connected to the lead portion 2 such as an LED element to be described later and a transmission wire bond. Further, the surface of the peripheral portion is formed in a tapered shape so that light generated by the LED element is reflected upward through the external resin.

Next, a method of manufacturing an optical semiconductor device will be described. The LED element is mounted on the wafer pad portion 1 by using the lead frame with resin described above. In advance, a solder paste or the like is applied onto the surface of the wafer pad portion 1 to fix the LED element on the wafer pad portion 1.

Next, the electrode portion of the LED element is electrically connected to the lead portion 2 by a connection method such as wire bonding.

Next, the peripheral portion of the portion electrically connected to the lead portion 2 such as the LED element surrounded by the external resin and the through-wire bonding is molded with a transparent resin.

Finally, when a plurality of rows are arranged in order to achieve a predetermined package size, singulation is performed. When molding is performed at one time, it is singulated by cutting or the like, and when it is separately molded, it is die-cut by a press machine or the like to be singulated.

Further, although the optical semiconductor device has been described above, the present invention is also applicable to a lead frame for a semiconductor device and a semiconductor device.

Example

An optical semiconductor device can be fabricated by the method described above, and then, An embodiment of a method of manufacturing a lead frame according to the present invention.

As a metal plate for a lead frame, a strip-shaped steel material (KLF-194 manufactured by Kobe Steel Co., Ltd.) having a thickness of 0.2 mm and a width of 180 mm was used. First, the metal plate for the lead frame is degreased and cleaned. Then, a resist layer for forming a lead pattern is formed. Specifically, first, a photosensitive resist having a thickness of 0.02 mm was applied to the surface of the substrate. As the resist, a negative photosensitive resist (manufactured by Asahi Kasei Electronic Materials Co., Ltd.) was used. Next, the resist layer is exposed using a glass mask to form the wafer pad portion 1 and the lead portion 2 into a predetermined pattern.

A thin portion around the edge portion of the wafer pad portion 1 and the lead portion 2 is formed over the entire circumference of the edge portion excluding the connection portion of each of the frames. The thin portion was set to have a thickness of 0.1 mm and a width of 0.2 mm. The LED mounting surface is covered with a resist, and the opposite surface is set as an opening. Further, the resist size is adjusted to a set shape size in consideration of an etching speed or the like. Further, regarding the protrusion 1a facing the lower surface of the thin portion, a resist layer for forming a protrusion is provided in a part of the opening, and a plurality of patterns are formed as shown in Table 1 and FIG. 4 with respect to the shape of the protrusion.

Further, regarding the pattern in which the shape of the protrusion is close to the edge side, it is set as the shape of the protrusion 0.15 mm, so that the shape of the protrusion is 0.03 mm close to the edge side.

After the above various patterns were exposed, development was carried out. Thereby, in the metal plate, the opening portion is disposed at a portion to be etched, and the resist layer is disposed at a portion where etching is not required.

Then, etching is performed with an etching solution. As the etching solution, a ferric chloride solution was used. In addition, in order to secure the height and shape of the thin portion and the projection, the discharge direction of the etching liquid, the ejection pressure, and the like are appropriately adjusted as needed.

Then, after the etching is completed, the resist is peeled off to form the wafer pad portion 1 and the lead portion 2.

Fig. 5 is a photograph of Example 1. As is clear from the photograph, a plurality of circular projections are formed in the thin portion, and irregularities are formed on the surface, and the contact area with the resin is increased.

Further, in order to confirm the adhesion, a simple test using a shear tester was carried out. The test method is simply shown. First, a similar pattern corresponding to Table 1 is produced on the test piece, and the diameter is made thereon. 2 mm cylindrical resin molding. The test piece was fixed to a table of a shear tester, and the tip end of the test machine was aligned with the root of the cylindrical resin molded portion, and the cutter was moved to measure the peeling force of the cylindrical resin molded portion. The front end position of the cutter was aligned at a position 50 μm higher than the upper surface of the test piece, and the moving speed was set to 5 mm/min. The measurement was performed 4 times, and the average value was used as the adhesion force. The results of the simple test of Table 1 were evaluated based on the adhesion force of Comparative Example 1 having no protrusions. The evaluation was performed by taking Δ as 1.05 times less than the standard, ○ of 1.05 times or more and less than 1.2 times as a standard, and ◎ as a reference of 1.2 times or more. It is known that Examples 1 to 9 have an effect. It has been found that particularly, by making the height of the protrusions high and arranging the protrusions in a staggered manner, it is more effective. Further, it is also known that the apex portion of the protrusion shape is closer to the edge side.

Further, using the lead frame described above, the external resin was molded to produce a lead frame with a resin.

Then, an LED device is mounted on a lead frame with a resin, and after wire bonding, transparent sealing is performed, and dicing is performed to perform singulation to complete the optical semiconductor device.

1‧‧‧ wafer pad

1a‧‧‧ wafer pad protrusion

2‧‧‧ lead parts

2a‧‧‧Lead portion protrusion

Claims (6)

A lead frame comprising: a wafer pad portion on which a semiconductor element or an LED element is mounted; and a lead portion disposed around a space around the wafer pad portion, wherein the edge portion of the wafer pad portion and/or the lead portion has a thin portion At least one protrusion facing downward is provided below the thin portion. The lead frame according to claim 1, wherein the height of the protrusion is 0.005 mm or more. The lead frame according to claim 1 or 2, wherein the protrusion has a flat circular shape or a flat elliptical shape. The lead frame according to claim 1 or 2, wherein the longitudinal cross-sectional shape of the protrusion is a mountain-shaped shape or a mountain-like shape having a round shape at the top or a substantially conical shape. The lead frame according to claim 1 or 2, wherein a apex portion of the plurality of protrusions arranged in parallel with an edge of the wafer pad portion and/or the lead portion is adjacent to an edge of the wafer pad portion and the lead portion On the side, the cross section of the protrusion perpendicular to the edge of the wafer pad portion and the lead portion is bilaterally asymmetrical with respect to a perpendicular line passing through the apex portion. A method of manufacturing a lead frame, comprising: preparing a metal plate to be a substrate of the lead frame; forming a portion of the wafer pad portion and the lead portion on a surface side of the metal plate, and a back side of the metal plate a step of forming a portion of the portion corresponding to the wafer pad portion and a portion where the protrusion portion is to be formed, and a portion corresponding to the portion of the lead portion and a portion where the protrusion portion is to be formed, respectively forming a resist layer for etching; and The resist layer acts as a corrosion-resistant film, and an etching step is applied to the front and back surfaces of the metal plate. In the etching step, the wafer pad portion and the lead portion are respectively formed with opposing faces opposed to each other, and protrusions are formed under the etched underside of the wafer pad portion and/or the lead portion.