JP2006319108A - Lead frame for semiconductor package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead frame for semiconductor packages, wherein it requires no hydroscopic agent, and its storage and its delivery are made possible with small space, and further, its oxidation and the cracking of a semiconductor package can be prevented. <P>SOLUTION: The lead frame for semiconductor packages comprises a jointing location (die pad) 2 for so mounting a semiconductor element thereon as to joint it thereto, inner leads 3 for electrically connecting the semiconductor element 5 therewith, and outer leads 4 for connecting an external substrate, etc. therewith. The inside of the jointing place (die pad) 2 is so brought into a hollow portion as to hermetically fill thereinto a viscosity substance (hydroscopic agent) 6, having hydroscopicity. The constituting raw material of the hydroscopic agent 6 is a natural viscosity substance, having silica alumina gel as the main component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lead frame of a semiconductor package for bonding and sealing semiconductor elements.

  In the semiconductor package, a semiconductor element is mounted and bonded to a lead frame obtained by processing a metal plate and sealed with a resin or the like. The lead frame used in this semiconductor package is made of Cu alloy, Fe-Ni42 alloy (42 alloy) or the like, and is connected to a die pad for mounting and bonding a semiconductor element, an inner lead for electrical connection with the semiconductor element, and an external substrate. It consists of an outer lead that performs.

  In the lead frame of this semiconductor package, moisture contained in the atmosphere (ambient environment) has caused various harmful effects. Specific examples include, for example, cracks in the sealed portion of the semiconductor package due to moisture and poor contact due to oxidation of the lead frame of the semiconductor package (contact failure between the inner lead and the semiconductor element, outer lead and the external connection portion, etc.). And so on. For this reason, semiconductor packages cause malfunctions, failures, and low lifetimes due to moisture in the atmosphere. To date, various measures have been taken for moisture countermeasures (moisture absorption) of such semiconductor packages.

  As a specific example of such moisture countermeasures, measures are taken to prevent lead frame oxidation and package cracking by providing a moisture absorption effect by sealing a desiccant inside the semiconductor package. In addition, a desiccant is attached to the lead frame storage case when the lead frame is shipped and transported and when the lead frame is stored in the semiconductor package process.

  Hereinafter, the moisture countermeasure of the conventional semiconductor package will be described in more detail with reference to the gazette of the prior patent application.

  First, a silicone gel-like hygroscopic resin filled with a desiccant such as silica gel and a dark pigment is dropped onto the part other than the main surface of the semiconductor element inside the semiconductor package to remove condensation inside the semiconductor package. A technique for absorbing moisture is disclosed (see Patent Document 1).

  Next, a technique is disclosed in which, when a semiconductor element and a lead frame are die-bonded inside the semiconductor package, moisture is absorbed by removing condensation inside the semiconductor package by mixing a desiccant with the die-bonding agent (see Patent Document 2). .

  Next, a technique is disclosed in which a desiccant is sealed under a portion of a lead frame where a semiconductor element is installed inside a semiconductor package to remove condensation within the semiconductor package and absorb moisture. (See Patent Document 3).

  Next, in order to maintain the stability over time of the lead frame used in the manufacture of semiconductor packages, the lead frame is sealed by sealing the lead frame in a gas barrier container from which oxygen and moisture have been removed. Is disclosed (see Patent Document 4).

In addition, a semiconductor package using an epoxy resin molding material for semiconductor sealing in a bag made of a packaging resin film is packaged, and a desiccant is also packaged and sealed in the same bag. A packaging method for an epoxy resin molding material is disclosed (see Patent Document 5).
JP 2004-22928 A Japanese Patent Laid-Open No. 10-242336 JP-A-10-289963 JP 09-207966 A JP 2004-90971 A

  However, in the conventional semiconductor package described in the above background art, for example, in the case of the techniques disclosed in Patent Document 1 and Patent Document 3 described above, the desiccant covers few portions of the semiconductor package, and moisture absorption is completely There was a problem that it was not.

  Further, in the case of the technique disclosed in the above-mentioned Patent Document 2, there is a problem that the moisture absorption effect may be lowered by mixing a desiccant with the die bond agent.

  Further, in the case of the technique disclosed in the above-mentioned Patent Document 4, since the size of the container is required when storing the lead frame, storage space is taken, and the lead frame is removed from the gas barrier container being stored. When taken out and stored in a semiconductor package, there is a problem that the moisture absorption effect is lost.

  In the case of the technique disclosed in Patent Document 5 described above, it is difficult to maintain the moisture absorption effect after opening the package, and further, if the lead frame is stored in the semiconductor package, the moisture absorption effect is lost. There was a problem.

  The present invention has been made in view of the above-described conventional problems, and does not require a desiccant, enables storage and shipping in a small space, and can prevent oxidation and cracking of a semiconductor package. The object is to provide a lead frame for a semiconductor package.

  The present invention is characterized in that, in a lead frame of a semiconductor package on which a semiconductor element is mounted and bonded, the inside of a die pad for bonding the semiconductor element is made hollow, and a hygroscopic agent is sealed in the hollow.

  Further, the present invention is characterized in that a hygroscopic agent is coated on a bonding surface of a die pad for bonding the semiconductor element.

  Further, the present invention is characterized in that a hygroscopic agent is coated on a bonding back surface of a die pad for bonding the semiconductor element.

  The hygroscopic agent is preferably a material mainly composed of silica alumina gel. For example, a natural clay material mainly composed of silica-alumina gel is applied and naturally dried, or a material obtained by curing the viscosity material in a baking process is joined.

  According to the lead frame of the semiconductor package of the present invention, since it has a hygroscopic property, there is an effect that it is possible to suppress lead frame oxidation due to intrusion of moisture. Thus, a desiccant is not required for storage, and storage in a small space is possible. Further, since the moisture of the lead frame is removed, it is possible to prevent package cracking due to moisture of the semiconductor package using the lead frame and to remove condensation in the semiconductor package.

  Moreover, since the natural raw material which has a silica alumina gel as a main component can be used as a hygroscopic agent, it has the effect that disposal without pollution is also possible for the disposal after use.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail in the order of [First Embodiment] to [Third Embodiment] with reference to the drawings.

[First Embodiment]
FIG. 1 is a side view showing the structure of the lead frame of the semiconductor package according to the first embodiment of the present invention.
In the figure, a lead frame 1 of a semiconductor package according to the present embodiment is connected to a bonding portion (die pad) 2 for mounting and bonding a semiconductor element, an inner lead 3 for electrical connection with the semiconductor element 5, an external substrate, and the like. It is comprised from the outer lead 4 which performs. As the material of the lead frame 1, a Cu alloy, an Fe-Ni42 alloy (42 alloy) or the like is mainly used. The Cu alloy has high heat conductivity and excellent heat dissipation, and the 42 alloy has strength and a thermal expansion coefficient close to that of Si forming a semiconductor element, and is used properly depending on the application. The lead frame 1 is manufactured by etching or stamping.

  The inside of the joining part (die pad) 2 is a hollow part, and a viscous substance (hygroscopic agent) 6 having hygroscopicity is enclosed therein. The constituent material of the hygroscopic agent 6 is a natural viscosity substance mainly composed of silica alumina gel. The hygroscopic agent 6 is naturally cured as it is or is cured in a baking process.

[Second Embodiment]
FIG. 2 is a side view showing the structure of the lead frame of the semiconductor package according to the second embodiment of the present invention.
In the figure, a lead frame 11 of a semiconductor package according to the present embodiment is connected to a bonding portion (die pad) 12 on which a semiconductor element is placed and bonded, an inner lead 13 that is electrically connected to the semiconductor element 15, an external substrate, and the like. It is comprised from the outer lead 14 which performs. The upper surface of the bonding portion 12 (the surface of the semiconductor element 15 on the die bonding side) is coated with a hygroscopic viscous material 16 (hygroscopic agent). The constituent material of the hygroscopic agent 16 is a natural viscosity substance mainly composed of silica alumina gel. The moisture absorbent 16 is applied and cured in a natural curing or baking process.

[Third Embodiment]
FIG. 3 is a side view showing the structure of the lead frame of the semiconductor package according to the third embodiment of the present invention.
In the figure, the lead frame 21 of the semiconductor package of the present embodiment is connected to a bonding portion (die pad) 22 where a semiconductor element is placed and bonded, an inner lead 23 that is electrically connected to the semiconductor element 25, and an external substrate. It is comprised from the outer lead 24 which performs. The upper surface of the bonding portion 22 (the surface of the semiconductor element 25 on the die bonding side) is coated with a hygroscopic viscous material 26 (hygroscopic agent). The constituent material of the hygroscopic agent 26 is a natural viscosity substance mainly composed of silica alumina gel. The hygroscopic agent 26 is applied and cured by natural curing or a baking process.

  Thus, the semiconductor elements 5, 15, 25 are die-bonded on the die pads 2, 12, 22 of the lead frames 1, 11, 21 of the first to third embodiments. The connection pads of the semiconductor elements 5, 15, 25 and the inner leads 3, 13, 23 are electrically connected by wire bonding. Then, the region including the semiconductor element and the inner lead is sealed with resin or the like. In this manner, a semiconductor package having a shape in which the outer leads 4, 14, and 24 protrude outward is formed.

  According to this embodiment, since the lead frame itself has a hygroscopic property, a desiccant that removes moisture is not required in shipping and storage, and it does not take up space, and oxidation of the lead frame can be prevented. In addition, since the moisture is absorbed after the semiconductor package is assembled and moisture is removed, lead frame oxidation can be prevented and package cracking can be prevented.

Further, even in the case of disposal, the hygroscopic agent is a natural clay substance mainly composed of silica alumina gel. Therefore, the hygroscopic agent is harmless at low cost and has an effect of enabling production in consideration of the environment.
Furthermore, the hygroscopic agent to be used is not limited to a natural clay material mainly composed of silica-alumina gel, and any other hygroscopic agent can be used.

1 is a side view showing a structure of a lead frame of a semiconductor package according to a first embodiment of the present invention. It is a side view which shows the structure of the lead frame of the semiconductor package which concerns on the 2nd Embodiment of this invention. It is a side view which shows the structure of the lead frame of the semiconductor package which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

1,11,21 Lead frame 2,12,22 Junction of semiconductor element (die pad)
3, 13, 23 Inner leads 4, 14, 24 Outer leads 5, 15, 25 Semiconductor elements 6, 16, 26 Viscous substances (hygroscopic agents)

Claims (4)

In the lead frame of a semiconductor package on which a semiconductor element is mounted and joined,
A lead frame for a semiconductor package, wherein a die pad for joining the semiconductor elements is hollow and a hygroscopic agent is sealed in the hollow. In the lead frame of a semiconductor package on which a semiconductor element is mounted and joined,
A lead frame for a semiconductor package, wherein a hygroscopic agent is coated on a bonding surface of a die pad for bonding the semiconductor element. In the lead frame of a semiconductor package on which a semiconductor element is mounted and joined,
A lead frame for a semiconductor package, wherein a hygroscopic agent is coated on a bonding back surface of a die pad for bonding the semiconductor element. 4. The lead frame for a semiconductor package according to claim 1, wherein the moisture absorbent is a material mainly composed of silica alumina gel.

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