JP6638951B2 - Lead frame and manufacturing method thereof - Google Patents

Description

  The present invention relates to a lead frame that constitutes a product unit in a multi-row type lead frame formed by etching, in which a portion connected to a terminal and a portion not connected to a terminal adjacent to the portion are respectively formed in a longitudinal direction. The present invention relates to a lead frame used for manufacturing a non-lead type semiconductor package having a dam bar and having a plurality thereof alternately, and a method of manufacturing the same.

Conventionally, there has been proposed a non-lead type semiconductor package in which a plurality of terminals connected to the outside are exposed on a mounting surface side which is a back surface side of a sealing resin.
This type of semiconductor package includes a semiconductor element mounted on a pad of a lead frame, a terminal disposed around the pad, and a bonding wire for electrically connecting the semiconductor element, and these are sealed. It has a structure.
This type of semiconductor package is manufactured using a so-called MAP (mold array package) technology in which a plurality of packages are collectively resin-sealed for cost reduction. After resin sealing, the dam bar is used as a cutting line. By removing, each lead frame is cut into units. Therefore, the lead frame before cutting has a pattern in which lead frames constituting a plurality of product units are connected to each other, and terminal portions of adjacent lead frames are connected line-symmetrically via dam bars. .

By the way, as described above, the dam bar is a portion that is removed by the cutting process. However, when a semiconductor element is mounted on a lead frame, and the volume of a metal portion when performing a cutting process for separating into product units after sealing with a resin is increased, a blade that simultaneously cuts a resin and a metal tends to be clogged. And the continuous processing time does not increase. For this reason, conventionally, the dam bar has a structure thinned by half etching from the back side. Conventionally, in a lead frame used for manufacturing this type of semiconductor package, a structure in which the entire back surface of the dam bar is thinned to a thickness of 40 to 60% by half etching is generally used.
However, the terminal part is connected to the dam bar in a cantilever state, and if the dam bar is thinned by half etching, internal stress is released and distortion is easily generated, and this distortion causes the entire frame to undulate and warp And deformation. And, the larger the area of the half-etching is, the larger the depth of the half-etching is, the larger the degree of the warping or deformation becomes.

  Conventionally, lead frames for securing the strength and dicing property of a dam bar to be cut have been proposed in, for example, Patent Documents 1 and 2 below.

  In the lead frame described in Patent Literature 1, for example, as a means for thinning the dam bar, half etching is performed from the back side of the dam bar, and a predetermined portion including edges on both sides excluding the center portion in the short side direction on the back side of the dam bar. 5 and 6 show a configuration in which a substantially inverted trapezoidal or substantially T-shaped cross-sectional shape is formed by removing along the longitudinal direction with respect to. In addition, half-etching is performed from the back side of the dam bar, and removed along the longitudinal direction with respect to a predetermined portion including the center portion excluding the edges on both sides in the short side of the back side of the dam bar to form a substantially inverted concave cross-sectional shape. The formed structure is shown in FIGS. Further, FIGS. 11 and 12 show a configuration in which half-etching is performed from the back side of the dam bar, and only portions connected to the terminals are removed from the portions along the longitudinal direction on the back side of the dam bar.

  Further, in the lead frame described in Patent Literature 2, for example, a portion along a longitudinal direction targeting a predetermined portion including edges on both sides excluding a center portion in a lateral direction on a front side of a dam bar is removed by half etching. In addition, FIG. 12 shows a configuration in which a predetermined portion including a central portion in a short direction is removed by half etching only for a portion connected to a terminal among portions along a longitudinal direction on a back side of a dam bar. .

  As described above, the lead frames described in Patent Literatures 1 and 2 facilitate cutting by partially reducing the thickness of the back surface of the dam bar instead of reducing the entire thickness of the back surface, and also reduce the thickness of the cut. The strength of the multi-row lead frame is ensured by forming a portion that is thicker and secures the strength as compared with a portion that is more likely to be made.

JP 2008-182175 A JP-A-2005-72946

  However, as shown in, for example, FIG. 5 and FIG. 6 of Patent Document 1, along a longitudinal direction of a predetermined portion including edges on both sides excluding a central portion in the short side of the back side of the dam bar. In a lead frame having a half-etched portion formed into a substantially inverted trapezoidal or substantially T-shaped cross-sectional shape by being removed by removal, the half-etched amount of the dam bar is small because the center portion of the back surface of the dam bar remains, and the thickness is reduced. Is not sufficiently reduced. Also, as shown in FIG. 9 and FIG. 10, a substantially inverted concave type is removed by removing along a longitudinal direction a predetermined portion including a central portion excluding edges on both sides in a lateral direction on the back side of the dam bar. In a lead frame having a cross-sectional shape of half, only the center portion in the width direction on the back side of the narrow dam bar is half-etched, so that the amount of etching in the depth direction is limited, and it is not possible to etch deeply. The amount of half etching is small, and the volume of metal for thinning is not sufficiently reduced. Further, in the lead frame having a configuration in which the thickness is reduced only for a portion connected to the terminal among the portions along the longitudinal direction on the back side of the dam bar as shown in FIGS. 11 and 12, the thickness is not reduced in the dam bar. Since the large-volume portion remains intermittently along the longitudinal direction, the blade for cutting the dam bar is easily clogged by that amount, and the continuous processing time is hardly extended. The lead frames shown in FIGS. 5 and 6, FIGS. 9 and 10, and FIGS. 11 and 12 described in Patent Document 1 each have a configuration in which a thin portion is formed only on the back side of a dam bar. For this reason, there is a problem that the internal stress cannot be canceled and distortion occurs to cause deformation.

  Also, in the lead frame shown in FIG. 12 described in Patent Document 2, the dam bar is thinned by performing half etching from both the front and back sides of the dam bar, but along the longitudinal direction of the dam bar. Of the parts that are not connected to the terminals, half-etching is performed only from one side (front side) of the dam bar, so that the thickness is insufficiently reduced, and the volume of the metal to be cut cannot be reduced efficiently. In addition, the blade for cutting the dam bar is easily clogged, and the continuous processing time is hardly extended.

  The present invention has been made in view of the above-mentioned conventional problems, and has a lead frame capable of efficiently reducing the volume of metal to be cut, facilitating cutting, and sufficiently suppressing deformation and warpage of a dam bar. And a method for producing the same.

In order to achieve the above object, a lead frame according to the present invention constitutes a product unit in a multi-row lead frame, and is connected to a first portion connected to a terminal and the terminal adjacent to the first portion. A plurality of second portions which are not alternately provided in the longitudinal direction, each of which is provided with a dam bar which is removed by cutting, and each terminal in each adjacent lead frame region is line-symmetric with respect to the dam bar. In a lead frame formed of a metal plate connected in an arrangement as described above, the dam bar is formed by half etching formed along a longitudinal direction with respect to a predetermined portion in a short direction of each of a front side and a back side. Part, and all the half-etched parts of the dam bar are formed in a continuous linear shape over the entire area in the longitudinal direction of the dam bar. The thickness between the surfaces on which the half-etched portions are not formed in the short direction of the front side and the back side of the dam bar, the thickness between the front and back surfaces of the metal plate over the longitudinal direction of the dam bar. Maintaining the same thickness, the portion where the half-etched portion is not formed in the short direction on each of the front and back sides of the dam bar is 0.450 with respect to the total length in the short direction on each of the front and back sides of the dam bar. above 0.556 has a length equal to or less than the percentage, and the half etching portion of s front and back sides of each of the dam bar is 0.300 or more 0.475 or less of the split to the thickness of the metal plate It is characterized in that it has a depth that the mixture.

In the lead frame of the present invention, the dam bar was made form along the longitudinal direction directed to a predetermined portion including a central portion excluding the both side edges in the lateral direction of the s front and back sides of each said Having a half-etched portion, all the half-etched portions of the dam bar are formed in a continuous straight line over the entire area in the longitudinal direction of the dam bar, and the half in the short side direction on the front side of the dam bar. sites etched portion is not formed has a length which is a ratio of 0.45 0 with respect to the total length of the lateral direction of the front side of the dam bar and the half-etched portions of the front side of the dam bar is the metal A portion having a depth of 0.475 with respect to the thickness of the plate, wherein the half-etched portion is not formed in the short direction on the back side of the dam bar Position has a 0.55 6 ratio to become the length of the relative lateral direction entire length of the back side of the dam bar and the half-etched portion of the back side of the dam bar is 0 to the thickness of the metal plate. preferably it has 3 00 ratio to become depth.

Further, in the lead frame of the present invention, the dam bar has a predetermined portion including a central portion excluding edges on both sides in a lateral direction on the front side and a side portion excluding a central portion in the lateral direction on the back side. has the half-etched portion was made form along the respective longitudinal targeting a predetermined portion including having the dam bar, all of the half-etched portion, respectively, of the dam bar lengthwise end over a series of linearly formed, the site of the no half-etched portions are formed in the lateral direction of the front side of the dam bar is have a length which is a ratio of 0.45 0 with respect to the total length of the lateral direction of the front side of the dam bar And the half-etched portion on the front side of the dam bar has a depth of 0.475 with respect to the thickness of the metal plate, and has a short side on the back side of the dam bar. Sites not the half-etched portion is formed in the direction, has a length which is a ratio of 0.55 0 with respect to the total length of the lateral direction of the back side of the dam bar and the half-etched portion of the back side of the dam bar but preferably it has a depth which is a ratio of 0.35 0 to the thickness of the metal plate.

Further, the lead frame manufacturing method according to the present invention is a method of forming a product unit in a multi-row lead frame, wherein a first portion connected to a terminal and a second portion not connected to the terminal adjacent to the first portion are formed. It has a plurality of parts, each having a plurality of parts alternately with respect to the longitudinal direction, is provided with a dam bar, which is removed by a cutting process, and each terminal in each adjacent lead frame region is arranged in line symmetry with respect to the dam bar. In the method for manufacturing a connected lead frame formed of a metal plate, a step of performing a penetrating process for forming a contour shape of the lead frame, and a partial predetermined process in a short side direction of each of a front side and a back side of the dam bar. The half-etched portions along the longitudinal direction of the part are all connected to the whole area in the longitudinal direction of the dam bar. And the thickness between the surfaces on which the half-etched portions are not formed in the short side of the front side and the back side of the dam bar, and the metal plate extends in the longitudinal direction of the dam bar. The same thickness as the thickness between the front and back surfaces of the dam bar is maintained, and the portions where the half-etched portions are not formed in the short sides of the front and back sides of the dam bar are shorter than the short sides of the front and back sides of the dam bar. has a ratio to become the length of 0.556 hereinafter 0.450 or more with respect to the total length of the longitudinal direction, and the half etching part front and back sides of each of said dam bar is 0 to the thickness of the metal plate. so as to have a depth of 300 or more 0.475 percentage follows it is characterized by having a step, subjected to half-etching.

In the method for manufacturing a lead frame according to the present invention, in the step of performing the half-etching process, a predetermined portion including a center portion excluding edges on both sides in a short direction of a front side and a back side of the dam bar is targeted. as a Yan right wing-safe etched portion in the longitudinal direction, all of the half-etched portion, respectively, serve as a series of straight across the longitudinal direction of the entire area of the dam bar and the half etching in the lateral direction of the front side of the dam bar sites that do not form part has a 0.45 0 ratio to become the length of the of the total length of the lateral direction of the front side of the dam bar and the half-etched portions of the front side of the dam bar is, the thickness of the metal plate Having a depth of 0.475 with respect to the height, and not forming the half-etched portion in the lateral direction on the back side of the dam bar. 0.3 but has a length which is a ratio of 0.55 6 with respect to the total length of the lateral direction of the back side of the dam bar and the half-etched portion of the back side of the dam bar is to the thickness of the metal plate It is preferable to form it so as to have a depth of 00 .

In the method for manufacturing a lead frame according to the present invention, in the step of performing the half-etching process, a predetermined portion including a central portion excluding edges on both sides in a short direction on a front side of the dam bar and a short direction on a back side. in the Yan right wing-safe etched portions respectively longitudinally targeting a predetermined portion including the both side edges except for the central portion, all of the half-etched portion, respectively, straight stretches across the longitudinal direction of the entire area of the dam bar becomes Jo, and, a portion not forming the half etching portion in the lateral direction of the front side of the dam bar has a length which is a ratio of 0.45 0 with respect to the total length of the lateral direction of the front side of the dam bar, and The half-etched portion on the front side of the dam bar has a depth of 0.475 with respect to the thickness of the metal plate; Sites that are not forming the half etching portion in the lateral direction, has a length which is a ratio of 0.55 0 with respect to the total length of the lateral direction of the back side of the dam bar and the half-etched portion of the back side of the dam bar but to have a depth which is a ratio of 0.35 0 to the thickness of the metal plate, preferably formed.

  ADVANTAGE OF THE INVENTION According to this invention, the lead frame which can reduce the volume of the metal to be cut efficiently, facilitates the cutting process, and can sufficiently suppress the deformation and warpage of the dam bar and the method for manufacturing the same are obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view conceptually showing a dam bar of a lead frame according to a first embodiment of the present invention, where (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a). It is explanatory drawing which shows the dam bar of the lead frame concerning 2nd Embodiment of this invention notionally, (a) is a top view, () is CC sectional drawing of (a).

Prior to the description of the embodiment, the operation and effect of the present invention will be described.
The lead frame of the present invention constitutes a product unit in a multi-row type lead frame, and a first portion connected to a terminal and a second portion not connected to a terminal adjacent to the first portion are respectively formed in a longitudinal direction. A plurality of alternately provided dam bars which are removed by cutting, each terminal in each adjacent lead frame region is connected to each other in a line-symmetric arrangement with respect to the dam bar, and is formed of a metal plate. In a lead frame, the dam bar has a half-etched portion formed along the longitudinal direction with respect to a partial predetermined portion in the short direction of each of the front side and the back side, and all the half-etched portions included in the dam bar are provided. Are respectively formed in a continuous linear shape over the entire lengthwise direction of the dam bar, and each half in the short side direction on the front side and the back side of the dam bar is formed. The thickness between the surfaces where the notched portion is not formed maintains the same thickness over the longitudinal direction of the dam bar as the thickness between the front and back surfaces of the metal plate, and in the short direction of the front and back sides of the dam bar, respectively. sites half etching portion is not formed, has a front and 0.450 or 0.556 at a ratio follows the length to the back side of the respective lateral direction entire length of the dam bar and the front side of the dam bar and half-etching portion of the back side of each is, have a depth which is a ratio of 0.300 or more 0.475 hereinafter relative to the thickness of the metal plate.

As described above, the purpose of half-etching the dam bar is to reduce the metal volume when simultaneously cutting the resin and the metal after mounting the semiconductor element on the lead frame and sealing with the resin, thereby facilitating the cutting process. That is.
However, when half-etching is performed on the entire surface only from the back side of the metal plate as in the prior art, the distortion generated during the rolling process of the rolled metal plate forming the lead frame material has one side. Focus on As a result, warpage and deformation are likely to increase due to a decrease in strength caused by half etching and distortion remaining on one side.

  5 and 6 of Patent Document 1 along a longitudinal direction with respect to a predetermined portion including edges on both sides excluding a central portion in the short side of the back side of the dam bar. In the configuration having a half-etched portion formed into a substantially inverted trapezoidal or substantially T-shaped cross-section by removing by removing, the center portion of the back surface of the dam bar remains, so the amount of half-etching of the dam bar is small, and the metal for thinning is reduced. The volume is not sufficiently reduced. In addition, by removing along a longitudinal direction a predetermined portion including a central portion excluding edges on both sides in the short side of the back side of the dam bar, such as the lead frame shown in FIGS. In the configuration in which a substantially inverted concave cross-sectional shape is formed, since only the center portion in the width direction on the back side of the narrow dam bar is half-etched, the amount of etching in the depth direction is limited, and it is not possible to etch deeply. The amount of half etching is small, and the volume of metal for thinning is not sufficiently reduced. Further, in a configuration such as a lead frame shown in FIG. 11 and FIG. 12 of Patent Document 1 in which the thickness is reduced only for a portion connected to a terminal among portions along the longitudinal direction of the dam bar, the thickness of the dam bar is reduced. Since a large-volume portion that is not formed remains intermittently along the longitudinal direction, the blade that cuts the dam bar is easily clogged and the continuous processing time is hardly increased. Further, in a configuration in which a thin portion is formed only on the back side of a dam bar, such as the lead frame shown in FIGS. 5 and 6, FIGS. 9 and 10, and FIGS. The stress cannot be offset, causing distortion and deformation.

  Also, as in Patent Literature 2, half-etching is performed on a portion along the longitudinal direction targeting a predetermined portion in the short direction on the front side of the dam bar, and the terminal is connected to a terminal among the portions along the longitudinal direction on the back side of the dam bar. Even if only a part is targeted and half-etching is performed on a predetermined part in the transverse direction, the part that is not connected to the terminal is not half-etched from the back side of the dam bar, so the thickness becomes insufficient and cutting is performed. The volume of metal to be reduced cannot be reduced efficiently, and the blade for cutting the dam bar is likely to be clogged, and the continuous processing time is hardly increased.

However, as a result of trial and error, the inventors of the present invention partially damped the dam bar, in which the respective terminals in the adjacent lead frame regions were connected in a line-symmetric arrangement, to the front side and the back side, respectively. Having a cut portion makes it difficult to generate distortion by canceling internal stress, efficiently reducing the amount of metal to be cut, and maintaining the thickness of the metal plate even in the thickness direction. Thus, the present inventor has conceived a configuration of the present invention in which deformation due to distortion hardly occurs.
As in the lead frame of the present invention, a half-etched portion formed along the longitudinal direction with respect to the dam bar to be cut, with respect to partial predetermined portions in the lateral direction of each of the front side and the rear side of the metal plate. All the half-etched portions of the dam bar are formed in a continuous straight line over the entire area in the longitudinal direction of the dam bar, and the respective half-etched portions in the short side direction on the front side and the back side of the dam bar are formed. The thickness between the unformed surfaces is maintained in the longitudinal direction of the dam bar at the same thickness as the thickness between the front and back surfaces of the metal plate, and the half-etched portions in the short sides of the front and back sides of the dam bar are respectively provided. length but the site is not formed, at a ratio of 0.556 hereinafter 0.450 or more with respect to front and back respectively lateral direction entire length of the people of the dam bar A, and the half etched portion of s front and back respectively of the dam bar is, if to have a ratio to become depth of 0.300 or more 0.475 hereinafter relative to the thickness of the metal plate, only the back side of the dam bar As compared with the case where the entire surface is thinned, the metal remains along the longitudinal direction at predetermined portions in the short direction on the front side and the back side of the dam bar, so that warpage is suppressed. Moreover, all the half-etched portions formed along the longitudinal direction on both the front side and the back side of the dam bar are formed in a continuous linear shape over the entire area in the longitudinal direction of the dam bar. The amount of metal to be produced can be reduced efficiently. Furthermore, internal stress can be offset by half-etching from the front side and the back side of the dam bar, and deformation is less likely to occur.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First Embodiment FIG. 1 is an explanatory view conceptually showing a dam bar of a lead frame according to a first embodiment of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along line AA of (a). is there.
The lead frame of the first embodiment is a lead frame constituting a product unit in a multi-row type lead frame. The lead frame is provided with a dam bar 1 at a position for partitioning each lead frame, and each of the lead frames in each adjacent lead frame region is provided. The terminals are formed of a metal plate connected in a line-symmetric arrangement with respect to the dam bar 1.
The dam bar 1 has a plurality of first portions 1a connected to the terminals 2 and a plurality of second portions 1b adjacent to the first portions 1a and not connected to the terminals 1 in the longitudinal direction, respectively. .
Further, the dam bar 1 has half-etched portions 4 and 5 formed along the longitudinal direction with respect to a predetermined portion including a central portion excluding edges on both sides in the short direction of the front side and the back side. I have.
The half-etched portions 4 and 5 are all the half-etched portions included in the dam bar 1, and are each formed in a continuous linear shape over the entire area of the dam bar 1 in the longitudinal direction.
The thickness between the surfaces of the dam bar 1 where the half-etched portions 4 and 5 are not formed in the short direction of the front side and the back side is equal to the thickness between the front and back surfaces of the metal plate over the entire area of the dam bar 1 in the longitudinal direction. Maintain the same thickness as the thickness.
Further, the portion where the half-etched portion 4 in the short side direction on the front side of the dam bar 1 is not formed has a length which is 0.450 of the total length in the short side direction on the front side of the dam bar 1, and The portion where the half-etched portion 5 is not formed on the back side in the short direction has a length which is 0.556 with respect to the entire length of the back side of the dam bar 1 in the short direction.
The half-etching portion 4 of the front side of the dam bar 1 has a depth which is a ratio of 0.475 hereinafter relative to the thickness of the metal plate, the half etching portion 5 of the back side of the dam bar 1, the thickness of the metal plate It has a depth of 0.300 with respect to the depth .

A procedure for forming a dam bar in the lead frame of the first embodiment configured as described above will be described.
First, a resist layer such as a photosensitive dry film resist is attached to both sides of a metal plate (for example, a copper plate) forming a lead frame material.
As a photomask in which the shape of the lead frame is formed, a half-etched portion is formed along a longitudinal direction targeting a predetermined portion including a central portion excluding edges on both sides in a short side direction of each of a front side and a back side of a dam bar. A photomask on which a pattern is formed is formed, and exposure and development are performed using the photomask to form an etching resist mask on both surfaces of the metal plate.
Next, using a ferric chloride solution, the entire shape of the required lead frame is formed by half-etching and penetrating processing.
Next, a lead frame is obtained by performing a cleaning process and a stripping process of the etching resist mask. These steps are conventional steps.

According to the lead frame of the first embodiment, only the predetermined portion including the center portion of the dam bar 1 to be cut is predetermined except for the edges on both sides in the short direction of the front and back sides of the metal plate. has a half-etched portions 4 and 5 was made form along the longitudinal direction at a depth of, having a dam bar 1, all of the half-etched portions 4 and 5, respectively, one across the longitudinal direction of the entire area of the dam bar 1 The thickness between the surfaces that are formed in a continuous straight line and on which the respective half-etched portions 4 and 5 are not formed in the short side of the front side and the back side of the dam bar 1 is equal to the thickness of the metal plate over the longitudinal direction of the dam bar 1. The same thickness as the thickness between the front surface and the back surface is maintained, and the portion where the half-etched portion 4 is not formed in the short direction on the front side of the dam bar 1 corresponds to the total length of the dam bar 1 in the short direction on the front side. It has a length which is a ratio of 0.45 0, and the front side of the half-etched portion 4 of the dam bar 1 has a depth which is a ratio of 0.475 or less with respect to the thickness of the metal plate, also, dam bars site half-etching portion 5 is not formed in the first lateral direction of the back side has a length which is a 0.55 6 ratio of relative lateral direction entire length of the back side of the dam bar 1, and the dam bar 1 is half-etched portion 5 of the back side, it has a depth which is a ratio of 0.3 00 to the thickness of the metal plate.
For this reason, only the central part on the back side of the conventional dam bar along the longitudinal direction is removed by a continuous linear half-etching over the entire region in the longitudinal direction and the front side is compared with the dam bar which has a substantially inverted concave cross-sectional shape Since a continuous linear half-etching is performed along the entire longitudinal direction along the longitudinal direction, the entire dam bar can be made thinner, and all the half-etched portions 4 and 5 of the dam bar 1 are Since the dam bar 1 is formed in a continuous straight line over the entire area in the longitudinal direction, the amount of metal to be cut can be reduced efficiently. In addition, the thickness between the surfaces of the dam bar 1 where the half-etched portions 4 and 5 are not formed in the short side of the front side and the back side is set to be equal to the distance between the front side and the back side of the metal plate over the entire area of the dam bar 1 in the longitudinal direction. maintaining the thickness of the same thickness as of, sites not half-etched portion 4 is formed in the lateral direction of the front side of the dam bar 1, a 0.45 ratio of zero with respect to the lateral direction entire length of the front side of the dam bar 1 The half-etched portion 4 on the front side of the dam bar 1 has a depth of 0.475 or less with respect to the thickness of the metal plate, and has a depth in the short side of the back side of the dam bar 1. site half-etching portion 5 is not formed, it has a 0.55 6 ratio to become the length of the relative lateral direction entire length of the back side of the dam bar 1, and the half-etched portion of the back side of the dam bars 1 5 , It was to have a 0.3 00 ratio to become depth to the thickness of the metal plate, as compared with the case where the thinned only entire surface from the back side of the dam bar, dam bars of front and back sides of each of the short Since the metal remains at a predetermined position in the hand direction along the longitudinal direction, warpage is suppressed. Furthermore, internal stress can be offset by half-etching from the front side and the back side of the dam bar 1, and deformation does not easily occur.

Second Embodiment FIG. 2 is an explanatory view conceptually showing a dam bar of a lead frame according to a second embodiment of the present invention, where (a) is a plan view and (b) is a sectional view taken along line AA of (a). is there. The procedure for forming the dam bar in the lead frame of the second embodiment is the same as that of the first embodiment, and the pattern is the same as that of the first embodiment except that the pattern formed on the photomask is different. Therefore, the description is omitted.
In the lead frame of the second embodiment, the dam bar 1 includes a predetermined portion including a central portion excluding edges on both sides in the lateral direction on the front side and edges on both sides excluding a central portion in the lateral direction on the back side. and a half-etched portion 4, 5 made form along the respective longitudinal direction directed to the predetermined portion.
The half-etched portions 4 and 5 are all the half-etched portions included in the dam bar 1, and are each formed in a continuous linear shape over the entire area of the dam bar 1 in the longitudinal direction.
The thickness between surface half etching portion 4, 5 of each in the lateral direction of the front and back dam bar 1 is not formed, the thickness between the front and back surfaces of the metal plate over the longitudinal direction of the dam bar 1 And maintain the same thickness.
Also, sites half etching portion 4 in the lateral direction of the front side of the dam bar 1 is not formed has a length which is a 0.45 ratio of zero with respect to the lateral direction entire length of the front side of the dam bar 1, and, The half-etched portion 4 on the front side of the dam bar 1 has a depth of 0.475 with respect to the thickness of the metal plate.
Also, sites half etching part 5 in the lateral direction of the back side of the dam bar 1 is not formed has a length which is a 0.55 ratio of zero with respect to the lateral direction entire length of the back side of the dam bar 1, and, rear side of the half-etched portion 5 of the dam bar 1, has a depth which is a ratio of 0.35 0 relative to the thickness of the metal plate.
Note that the half-etched portion 5 also extends to the vicinity of the connection region between the terminal 2 and the first portion 1 a of the dam bar 1.

According to the lead frame of the second embodiment, the predetermined portion including the central portion excluding the edges on both sides in the lateral direction on the front side of the dam bar 1 and the edges on both sides excluding the central portion in the lateral direction on the back side are arranged. Since a continuous linear half-etching is performed over the entire region in the longitudinal direction along the longitudinal direction, each of the dam bars can be thinned. In addition, since all the half-etched portions 4 and 5 of the dam bar 1 are formed in a continuous straight line over the entire area in the longitudinal direction of the dam bar 1, the amount of metal to be cut is efficiently reduced. it can.
Further, according to the lead frame of the second embodiment, the position of the half-etched portion 5 formed on the dam bar 1 includes the edges on both sides excluding the central portion in the short direction on the back side of the dam bar 1. Therefore, the half-etched portion 5 can be formed near the connection region of the terminal 2 with the first portion 1a of the dam bar 1. As a result, in addition to the dam bar, a part of the terminal portion connected to the dam bar is also reduced in thickness, so that the amount of metal to be cut can be reduced more efficiently.
Other functions and effects are substantially the same as those of the lead frame of the first embodiment.

As an example of a comparative test of the amount of deformation due to the strain generated in the lead frame of the example and the comparative example , a large number of lead frames in the matrix direction (for example, in the matrix direction) each having the configuration of the first and second embodiments in units of products. 20 to 30 pieces each, 25 pieces here.) The thickness of a multi-row lead frame to be connected and, as a comparative example, the thickness of a metal plate whose thickness is the material on the entire back surface of the dam bar located at the position to be cut. A multi-row type lead frame in which a large number of lead frames each having a half-etched portion having a thickness of 50% are connected in a matrix direction (for example, 20 to 30 in each of the matrix directions; 25 in this case) is manufactured. The deformation amounts of the multi-row type lead frames of the example and the comparative example due to respective distortions were compared.

The lead frame of the example was manufactured as follows.
As a metal plate of a lead frame material, a conventional dry copper material having a thickness of 0.2 mm was used, and a photosensitive dry film resist was stuck on both surfaces to form a resist layer.
Next, two types of photomasks were formed, each having a shape of a lead frame and a half-etching shape in which a dam bar was formed with the respective configurations of the first and second embodiments. .
Next, using the two types of photomasks, each metal plate on which a resist layer is formed is exposed and developed to form an etching resist mask, and sprayed with a ferric chloride solution. Etching was performed.
In the etching process for obtaining these lead frames, pre-processing and post-processing of each step such as formation of a photosensitive resist layer on the front and back surfaces of a metal plate, photomask production, exposure, development, etching, cleaning and drying, etc. Is the same as the conventional method.
After the etching process, an etching resist mask was peeled off to form two types of lead frames.

Of the two types of lead frames, dam bars of the lead frame of an embodiment with the configuration of the first embodiment shown in FIG. 1, the total length in the lateral (width) direction of the front side is formed in 0.200M m, Edges on both sides in the short side (width) direction on the front side are left at a length of about 0.045 mm in the short side (width) direction, respectively, at predetermined portions including the central part in the short side (width) direction on the front side. A half-etched portion having a length in the short side (width) direction of 0.110 mm and a depth of about 0.095 mm was formed. Also, the total length in the lateral (width) direction of the rear side is formed in 0.180M m, both side edges in the lateral (width) direction of the back side, shorter (width) direction to about 0.050 M m respectively A half-etched portion having a length of 0.080 mm and a depth of about 0.060 mm in a short (width) direction is formed at a predetermined portion including a central portion in a short (width) direction on the back side, which is left as a length. I was doing it.

Further, dam bars of the lead frame of the embodiment having the configuration of the second embodiment shown in FIG. 2, the total length in the lateral (width) direction of the front side is formed in 0.200M m, the front side in the short (width Edges on both sides in the short side (width) direction remain in the short side (width) direction at a length of about 0.045 mm, and a predetermined portion including the central part in the short side (width) direction on the front side has a short side (width) direction. A half-etched portion having a length of 0.110 mm and a depth of about 0.095 mm was formed. In addition, the central portion in the short side (width) direction on the back side remains at a length of about 0.110 mm in the short side (width) direction, and is located at a predetermined portion including both side edges in the short side (width) direction on the back side. A half-etched portion having a length of about 0.045 mm and a depth of about 0.07 mm in the short (width) direction was formed.

  The lead frame of the comparative example was subjected to half-etching only from the back side of the dam bar to the entire surface so that the thickness of the metal plate became 0.1 mm.

In addition, the lead frame of the Example and the comparative example was formed using the same copper material and having the same shape and dimensions except for the dam bar.
Then, the amounts of deformation due to distortion in the two types of examples and the multi-row lead frame of the comparative example were compared.
The amount of deformation due to distortion was confirmed by irradiating light from above the etched multi-row lead frame and visually observing the degree of light reflection from oblique sides. In a multi-row lead frame having a large amount of deformation due to distortion, deformation (non-uniform reflection) is observed in the shape of the illumination light reflected on the surface of the multi-row lead frame in visual observation. In the examples, no significant deformation was recognized in the shape of the reflected illumination light.
On the other hand, in the lead frame of the comparative example, a large deformation was partially observed in the shape of the reflected illumination light in visual observation.

DESCRIPTION OF SYMBOLS 1 Dam bar 1a 1st part 1b 2nd part 2 Terminal 4, 5 Half etching part

Claims (6)

A first part connected to a terminal and a second part which is not connected to the terminal adjacent to the first part and constitutes a product unit in the multi-row type lead frame are alternately arranged in the longitudinal direction. A lead frame formed of a metal plate, comprising a dam bar, which is removed by cutting, and having respective terminals in adjacent lead frame regions connected in a line-symmetric arrangement with respect to the dam bar. At
The dam bar has a half-etched portion formed along the longitudinal direction with respect to a partial predetermined portion in the lateral direction of each of the front side and the back side,
All the half-etched portions having the dam bar are each formed in a continuous linear shape over the entire area in the longitudinal direction of the dam bar,
The thickness between the surfaces on which the half-etched portions are not formed in the short direction of the front side and the back side of the dam bar is the same as the thickness between the front and back surfaces of the metal plate over the longitudinal direction of the dam bar. To maintain
Site where the half etching portion is not formed in the front and back sides of each of the lateral direction of the dam bar is of 0.556 hereinafter 0.450 or more with respect to front and back respectively lateral direction entire length of the people of the dam bar Having a length that is a percentage, and
Leadframe the half etching part of s front and back sides of each of the dam bar, characterized in that it has a ratio to become depth of 0.300 or more 0.475 hereinafter with respect to the thickness of the metal plate. The dam bar has the half-etched portion formed along a longitudinal direction for a predetermined portion including a central portion excluding edges on both sides in a lateral direction of each of a front side and a back side,
All the half-etched portions having the dam bar are each formed in a continuous linear shape over the entire area in the longitudinal direction of the dam bar,
The portion where the half-etched portion in the short direction on the front side of the dam bar is not formed has a length that is a ratio of 0.450 with respect to the total length in the short direction on the front side of the dam bar, and
The half-etched portion on the front side of the dam bar has a depth of 0.475 with respect to the thickness of the metal plate,
The portion where the half-etched portion is not formed in the short direction on the back side of the dam bar has a length of 0.556 with respect to the total length in the short direction on the back side of the dam bar, and
2. The lead frame according to claim 1, wherein the half-etched portion on the back side of the dam bar has a depth that is 0.300 of the thickness of the metal plate. 3. In the longitudinal direction, the dam bar is directed to a predetermined portion including a central portion excluding the edges on both sides in the lateral direction on the front side and a predetermined portion including the edges on both sides excluding the central portion in the lateral direction on the back side. Having the half-etched portion formed along,
All the half-etched portions having the dam bar are each formed in a continuous linear shape over the entire area in the longitudinal direction of the dam bar,
The portion where the half-etched portion in the short direction on the front side of the dam bar is not formed has a length that is a ratio of 0.450 with respect to the total length in the short direction on the front side of the dam bar, and
The half-etched portion on the front side of the dam bar has a depth of 0.475 with respect to the thickness of the metal plate,
The portion where the half-etched portion in the short direction on the back side of the dam bar is not formed has a length of 0.550 with respect to the total length in the short direction of the back side of the dam bar, and
2. The lead frame according to claim 1, wherein the half-etched portion on the back side of the dam bar has a depth of 0.350 with respect to the thickness of the metal plate. 3. A first part connected to a terminal and a second part which is not connected to the terminal adjacent to the first part and constitutes a product unit in the multi-row type lead frame are alternately arranged in the longitudinal direction. A lead frame formed of a metal plate, comprising a dam bar, which is removed by cutting, and having respective terminals in adjacent lead frame regions connected in a line-symmetric arrangement with respect to the dam bar. In the manufacturing method of
Performing a penetration process to form a contour shape of the lead frame;
The half-etched portions along the longitudinal direction targeting the predetermined predetermined portions in the respective lateral directions of the front side and the back side of the dam bar are all covered by one half-etched portion over the entire area in the longitudinal direction of the dam bar. The thickness between the surfaces on which the half-etched portions are not formed in the short side of the front side and the back side of the dam bar is formed so as to be a continuous straight line, and the metal is formed over the longitudinal direction of the dam bar. Maintaining the same thickness as the thickness between the front and back surfaces of the plate, the portions not forming the half-etched portions in the short sides of the front and back sides of the dam bar are the front and back sides of the dam bar, respectively. It has a ratio to become the length of 0.556 hereinafter 0.450 or more with respect to the total length of the lateral direction, and front and back of each of said half of the dam bar Etching portion, so as to have a ratio to become depth of 0.300 or more 0.475 hereinafter with respect to the thickness of the metal plate, the step of half etching process,
A method for manufacturing a lead frame, comprising:   In the step of performing the half-etching process, all the half-etched portions along the longitudinal direction targeting a predetermined portion including a central portion excluding edges on both sides in the short side of the front side and the back side of the dam bar, The half-etched portion is a continuous linear shape over the entire region in the longitudinal direction of the dam bar, and a portion where the half-etched portion is not formed in the short direction on the front side of the dam bar is a short side on the front side of the dam bar. Having a length that is a ratio of 0.450 with respect to the total length in the direction, and the half-etched portion on the front side of the dam bar has a depth that is a ratio of 0.475 with respect to the thickness of the metal plate; A portion where the half-etched portion is not formed in the short direction on the back side of the dam bar is 0.5% of the total length in the short direction on the back side of the dam bar. 6, and the half-etched portion on the back side of the dam bar is formed so as to have a depth of 0.300 with respect to the thickness of the metal plate. The method for manufacturing a lead frame according to claim 4.   In the step of performing the half-etching process, the dam bar includes a predetermined portion including a central portion excluding edges on both sides in a lateral direction on a front side and a predetermined portion including edges on both sides excluding a central portion in a lateral direction on a back side. The half-etched portions along the longitudinal direction for each of the portions, all the half-etched portions each become a continuous linear shape over the entire region in the longitudinal direction of the dam bar, and in the lateral direction on the front side of the dam bar. The portion where the half-etched portion is not formed has a length of 0.450 with respect to the total length of the front side of the dam bar in the lateral direction, and the half-etched portion on the front side of the dam bar is formed of the metal plate. And has a depth of 0.475 with respect to the thickness of the dam bar, and does not form the half-etched portion in the short direction on the back side of the dam bar. And the half-etched portion on the back side of the dam bar has a length of 0.350 with respect to the thickness of the metal plate. The method for manufacturing a lead frame according to claim 4, wherein the lead frame is formed so as to have a depth corresponding to the following ratio.

Images