JP4418764B2 - Manufacturing method of resin-encapsulated semiconductor package - Google Patents

Description

  The present invention relates to a method capable of manufacturing a resin-encapsulated semiconductor package in which outer leads protrude from a side surface using single-sided collective sealing.

  In a conventional semiconductor package, a semiconductor element is bonded onto a lead frame, the semiconductor element and the lead frame are joined with a wire, and then the entire lead frame except the outer leads is sealed with a sealing resin. Such packages include QFP (Quad Flat Package). However, this package still has room for improvement in terms of reduction in area and thickness, and there is a problem that productivity is low because each semiconductor element is individually sealed.

  A method of manufacturing a semiconductor package proposed to solve this problem will be described (see, for example, Patent Document 1 or 2). First, a plurality of semiconductor elements on the lead frame are collectively sealed on one side with a sealing resin. Next, it separates into individual pieces. Examples of packages manufactured by this method include QFN (Quad Flat Non-leaded package) and SON (Small Outline Non-leaded package). In this package, since the lead frame does not protrude from the sealing resin, the area and thickness can be reduced. Further, productivity is high because a plurality of semiconductor elements on the lead frame are sealed on one side with resin.

Japanese Patent Laid-Open No. 10-12773 JP 2003-86614 A

  In a semiconductor package obtained by a conventional manufacturing method, a lead frame exposed from the sealing resin on the back surface of the package is used as an external connection electrode. For this reason, there is a problem that the solder joint strength is low because the solder joint area is small in mounting on the mother board. There is also a problem that there is no place to buffer the stress when the substrate is bent, and the reliability after mounting is low.

  On the other hand, the semiconductor package with the outer leads protruding from the side surface has high solder joint strength and strong substrate bending resistance since the entire periphery of the outer leads is wet when mounted on the mother board. However, it has been difficult to manufacture the semiconductor package having this structure by the conventional manufacturing method. This is because one side is collectively sealed with a resin including the outer leads, and therefore, the clean outer leads protruding from the side surfaces of the package cannot be exposed at the time of individualization.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to manufacture a resin-encapsulated semiconductor package in which outer leads protrude from the side surface using single-sided collective sealing. Get the method.

A method for manufacturing a resin-encapsulated semiconductor package according to the present invention includes a step of die-bonding a semiconductor element to a die pad of each pattern of a lead frame in which a plurality of identical patterns are formed in a grid pattern, and electrode pads and leads of the semiconductor element A step of wire bonding the inner leads of the frame with wires, a step of providing a solvent-soluble resin on the outer leads between adjacent packages of the lead frame, and a plurality of semiconductor elements mounted on the lead frame on one side with a sealing resin It possesses a sealing step of collectively sealing a step of dissolving and removing the solvent-soluble resin by immersing after the sealing step the lead frame in a solvent, and separating individual pieces in each package,
The solvent-soluble resin is prepared by dissolving styrene butadiene rubber, acrylic resin, butyral resin, or ethyl cellulose having a weight fraction of 30 to 50% in toluene, xylene, or methyl ethyl ketone . Other features of the present invention will become apparent below.

  According to the present invention, even when single-sided collective sealing is used, a resin-encapsulated semiconductor package in which outer leads protrude from the side surfaces can be manufactured. As a result, it is possible to reduce the area and thickness, and to obtain a resin-encapsulated semiconductor package with high productivity, high solder joint strength, and strong substrate bending resistance.

Embodiment 1 FIG.
Hereinafter, a method for manufacturing a resin-encapsulated semiconductor package according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view in each process, and FIG. 2 is a cross-sectional view seen from another direction at the outer lead cutting position in each process.

  First, as shown in FIGS. 1A and 2A, the semiconductor element 12 is die-bonded to the die pad of each pattern of the lead frame 11. The lead frame 11 is a plate made of 42 alloy or copper, and a plurality of identical patterns are formed in a grid pattern by etching or punching. Further, the inner lead of the lead frame 11 is plated with silver or the like so that a metal bond with the wire 13 can be obtained by a later wire bond.

  Then, the electrode pads of the semiconductor element 12 and the inner leads of the lead frame 11 are wire-bonded with wires 13. The material of the wire 13 is mainly gold. The material used for bonding is an adhesive such as solder or silver paste.

  Furthermore, a solvent-soluble resin 14 is provided on the outer lead between adjacent packages of the lead frame 11 with a width of 0.3 mm or more. It is preferable to place a film so that the solvent-soluble resin 14 is in close contact with the lower surface of the lead frame 11 so that the solvent-soluble resin 14 does not hang down on the lower surface of the lead frame 11. Examples of the film material include a fluorine-based resin such as PET (polyethylene terephthalate), silicone, or FEP (tetrafluoroethylene-hexafluoropropylene copolymer). The solvent-soluble resin contains a styrene butadiene rubber, an acrylic resin, a butyral resin, ethyl cellulose, and the like that are diluted by dissolving in an organic solvent such as toluene, xylene, methyl ethyl ketone, and the like at a weight fraction of about 30-50%. Furthermore, an inorganic powder such as silica may be included as a filler. The solvent-soluble resin is applied by a method such as printing, dispensing, or inkjet. After application of the solvent-soluble resin 14, the solvent-soluble resin 14 is solidified by volatilizing the solvent contained therein. Thereafter, the film is removed.

  Next, as shown in FIGS. 1B and 2B, a plurality of semiconductor elements 12 mounted on the lead frame 11 are sealed on one side with a sealing resin 15. At this time, the solvent-soluble resin 14 provided in the outer lead region of the lead frame 11 is simultaneously sealed on one side with the sealing resin 15. Here, a sheet-like resin is used as the sealing material, and the apparatus uses a vacuum laminator or a vacuum press. Further, a transfer molding method may be used. In this case, it is desirable to use a sealing sheet in order to prevent the sealing resin 15 from entering the back surface of the lead frame 11 during sealing. This sealing sheet may be provided in advance on the lead frame 11 before the semiconductor element 12 is mounted. In a vacuum laminator and a vacuum press, a film such as PET is generally used for conveyance. Therefore, when the sealing resin 15 is molded and pressurized, the lower surface of the lead frame 11 and the film are in close contact, and the sealing resin to the lower surface of the lead frame 11 is used. 15 wraparound can be suppressed. Of course, as with the transfer molding method, it is possible to use a sealing sheet to form with a vacuum laminator or a vacuum press.

  Next, as shown in FIGS. 1C and 2C, the solvent-soluble resin 14 is dissolved and removed by immersing the lead frame 11 that is sealed on one side with the sealing resin 15 in a solvent. When a sealing sheet is used at the time of sealing, the sealing sheet is peeled off from the lead frame 11 after batch sealing. As the solvent to be immersed, a solvent that has diluted the solvent-soluble resin 14 may be used. By doing so, the location where the solvent-soluble resin 14 originally exists, that is, the outer lead portion becomes the cavity 16.

  Next, as shown in FIGS. 1D and 2D, after the solvent-soluble resin 14 is dissolved and removed, exterior plating is performed on the outer leads. Plating is by electroplating in a solder bath. The plating film 17 adheres to the entire exposed lead frame 11 surface by exterior plating. Since the place where the solvent-soluble resin 14 originally exists is a cavity, the plating film 17 also adheres to the surface (the semiconductor element 12 mounting surface side) and the side surface of the outer lead.

  Next, as shown in FIGS. 1E and 2E, each package is separated into individual pieces. The singulation is performed in two stages using a dicing method. The dicing method is a method of cutting a wafer or the like while rotating a rotary blade obtained by sintering diamond powder on the outer periphery of a disk. First, the sealing resin 15 remaining on the cavity of the outer lead region is removed from the semiconductor element 12 mounting surface side of the lead frame 11 that is collectively sealed on one side with the sealing resin 15. When the width of the sealing resin 15 to be removed is about 0.3 mm, an unnecessary resin portion may be scraped off by one scan using a thick dicing blade. The depth of dicing is set to a position of 0 to 100 μm from the surface of the lead frame 11 upward. Next, the second stage dicing is performed from the mounting surface side of the semiconductor element 12 to cut the outer lead. The rotary blade used is thinner than the rotary blade used in the first stage. Thus, the individual semiconductor packages are completed. In addition, the protrusion of the outer lead from the side surface of the semiconductor package can be set to 0.2 mm or more by setting the width of the solvent-soluble resin 14 to 0.3 mm or more. Further, instead of dicing at the second stage, it may be divided into pieces by lead cutting with a mold. Further, in the above description, the exterior plating is performed before dicing, but the same finished product can be obtained even if the exterior plating process is inserted between the first stage dicing and the second stage dicing.

  By the manufacturing method described above, a resin-encapsulated semiconductor package in which the outer leads 18 protrude from the side surfaces can be manufactured using single-sided collective sealing. As a result, it is possible to reduce the area and thickness, and to obtain a resin-encapsulated semiconductor package with high productivity, high solder joint strength, and strong substrate bending resistance.

  Further, since the surface of the outer lead 18 is in contact with the solvent-soluble resin 14 instead of the sealing resin 15 that is difficult to remove, the surface of the outer lead can be easily cleaned by immersion in the solvent. As a result, a semiconductor package in which exterior plating adheres to the entire outer lead surface excluding the lead cut surface can be obtained. Therefore, when the semiconductor package according to the present embodiment is mounted on the external substrate, a good solder joint having a large joining force is formed, and the mounting reliability is improved.

Embodiment 2. FIG.
Hereinafter, a method for manufacturing the resin-encapsulated semiconductor package according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view in each process, and FIG. 4 is a cross-sectional view seen from another direction at the outer lead cutting position in each process. Constituent elements similar to those in FIG. 1 or FIG.

  In the second embodiment, as shown in FIGS. 3A and 4A, before the semiconductor element 12 is die-bonded to the lead frame 11, the outer frame is plated on at least the region serving as the outer lead. . In the figure, the case where the plating film 17a is formed on the entire surface of the lead frame 11 is shown. The plating applied in advance to the lead frame 11 is called pre-plating. Moreover, the structure of the plating film 17a assumes nickel-palladium-gold. Then, after forming the plating film 17a, the solvent-soluble resin 14 is provided on the outer leads between the adjacent packages of the lead frame 11 in the same manner as in the first embodiment.

  Next, as shown in FIGS. 3B and 4B, the plurality of semiconductor elements 12 mounted on the lead frame 11 are sealed on one side with a sealing resin 15.

  Next, as shown in FIGS. 3C and 4C, the solvent-soluble resin 14 is dissolved and removed by immersing the lead frame 11 that is sealed on one side with the sealing resin 15 in a solvent. As a result, the location where the solvent-soluble resin 14 originally exists, that is, the outer lead portion becomes the cavity 16, and the preplating surface previously applied to the outer lead surface is exposed.

  Next, as shown in FIGS. 3D and 4D, each package is separated into individual pieces. In the first embodiment, the outer plating is performed before the separation, but in the second embodiment, since the lead frame 11 is pre-plated in advance, it is not necessary to perform the outer plating at this point. .

  By the manufacturing method described above, a resin-encapsulated semiconductor package in which the outer leads 18 protrude from the side surfaces can be manufactured using single-sided collective sealing. As a result, it is possible to reduce the area and thickness, and to obtain a resin-encapsulated semiconductor package with high productivity, high solder joint strength, and strong substrate bending resistance.

  Further, since it is not the sealing resin 15 that is difficult to remove but the solvent-soluble resin 14 that is in contact with the plating film 17a of the outer lead 18 at the time of sealing, the outer lead can be easily immersed in the solvent after sealing. The lead surface can be cleaned over the entire surface, and the pre-plated surface previously applied to the lead frame 11 can be exposed and reproduced. As a result, a semiconductor package in which exterior plating adheres to the entire outer lead surface excluding the lead cut surface can be obtained. Therefore, when the semiconductor package according to the present embodiment is mounted on the external substrate, a good solder joint having a large joining force is formed, and the mounting reliability is improved.

Embodiment 3 FIG.
FIG. 5 is a cross-sectional view showing a sealing step in the method of manufacturing a semiconductor package according to the third embodiment of the present invention. As shown in the drawing, a sheet-like resin 15 a used for one-sided collective sealing is placed on the lead frame 11. A vacuum laminator or a vacuum press is used as the sealing device.

  Here, in the third embodiment, the height of the solvent-soluble resin 14 is set higher than the height of the wire 13 that wire-bonds the inner lead of the lead frame 11 and the semiconductor element 12. Other steps are the same as those in the first or second embodiment. Thereby, even if the sheet-like resin 15a is placed on the lead frame 11 before sealing, the wire 13 is not deformed.

It is a cross-sectional view in each process of the manufacturing method of the resin sealing type semiconductor package which concerns on Embodiment 1 of this invention. It is sectional drawing seen from the other direction in the outer lead cutting position in each process of the manufacturing method of the resin sealing type semiconductor package which concerns on Embodiment 1 of this invention. It is a cross-sectional view in each process of the manufacturing method of the resin sealing type semiconductor package which concerns on Embodiment 2 of this invention. It is sectional drawing seen from the other direction in the outer lead cutting position in each process of the manufacturing method of the resin sealing type semiconductor package which concerns on Embodiment 2 of this invention. It is a cross-sectional view which shows the sealing process in the manufacturing method of the semiconductor package which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Lead frame 12 Semiconductor element 13 Wire 14 Solvent soluble resin 15 Sealing resin 15a Sheet-like resin 17, 17a Plating film

Claims (4)

A step of die-bonding a semiconductor element to a die pad of each pattern of a lead frame in which a plurality of identical patterns are formed in a grid pattern;
Wire bonding the electrode pads of the semiconductor element and the inner leads of the lead frame with wires;
Providing a solvent-soluble resin on the outer leads between adjacent packages of the lead frame;
A sealing step of collectively sealing one side of the plurality of semiconductor elements mounted on the lead frame with a sealing resin;
A step of dissolving and removing the solvent-soluble resin by immersing the lead frame in a solvent after the sealing step;
Possess and separating individual pieces to each package,
The solvent-soluble resin is obtained by dissolving styrene butadiene rubber, acrylic resin, butyral resin, or ethyl cellulose having a weight fraction of 30 to 50% in toluene, xylene, or methyl ethyl ketone and diluting them. Manufacturing method.   2. The method of manufacturing a semiconductor package according to claim 1, further comprising a step of performing exterior plating on the outer lead after dissolving and removing the solvent-soluble resin.   2. The method of manufacturing a semiconductor package according to claim 1, further comprising a step of performing exterior plating on at least a region to be an outer lead of the lead frame before die-bonding a semiconductor element to the lead frame. The height of the said solvent soluble resin is made higher than the height of the said wire, and sheet-like resin is used for the said single-sided package sealing, The manufacturing of the semiconductor package of any one of Claims 1-3 characterized by the above-mentioned. Method.

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