JPH0469822B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device, and particularly relates to a lead frame having a specific shape that excludes a die pad, and a specific structure for fixing the lead frame to the lead frame and mounting a semiconductor pellet thereon. This invention relates to a semiconductor device using a die pad tape.

[Conventional technology]

In a conventional semiconductor device, a die pad 1 of a lead frame, which is composed of a die pad 1, leads 2, and support bars 3 as shown in FIGS. It has a structure in which a semiconductor pellet 4 is placed on the pellet, and is integrated with a sealing resin 8 together with a bonding wire 6 that connects an electrode 7 formed on the pellet to a lead.

In this case, it is necessary to change the dimensions and shape of the die pad that makes up the lead frame to accommodate the wide variety of sizes and shapes of semiconductor pellets, and accordingly, the dimensions and shape of the leads must also be changed. be forced to. Changing the design of the lead frame to suit a wide variety of semiconductor pellets requires making many types of lead frame molds, which increases the cost of the molds and, by extension, the cost of the lead frame. There are many problems.

In addition, because the back surface of the die pad has poor adhesive sealing properties with the encapsulating resin, moisture from the outside that enters through the interface between the leads and the encapsulating resin tends to accumulate, making it difficult to surface-mount semiconductor devices on circuit boards. During the heat treatment in the soldering process, cracks are likely to occur in the sealing resin due to the rapid expansion of moisture.Furthermore, there is a large difference in the coefficient of thermal expansion between the semiconductor pellet and the die pad, and the thermal expansion of both is large. There are problems such as cracks occurring in the semiconductor pellet due to stress caused by the difference in rate.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above-mentioned circumstances, and aims to standardize the lead frames of semiconductor devices to have the same number of leads, and to make it easier to assemble semiconductor devices in order to accommodate semiconductor pellets having various sizes and shapes. The purpose of this invention is to provide a semiconductor device that is not complicated and has excellent reliability.

[Means for solving problems]

The outline of the present invention is to provide a semiconductor device in which semiconductor pellets are mounted via a die bonding adhesive on a lead frame from which a die pad has been removed and a die pad tape having a size that includes and covers the lead tips of the lead frame, and the semiconductor pellets are sealed. A desired number of leads among the leads constituting the lead frame protrude toward the die pad cavity,
The tip of the lead is configured with a larger area than other leads, and the die pad tape is made of a heat-resistant support made of a polyimide resin film, and an epoxy resin or polyimide resin for fixing the support to the lead. The first invention is a semiconductor device comprising an adhesive layer made of at least one type of resin selected from polyurethane resins and polyamide resins, and the above die pad tape is improved and a die bonding adhesive is applied to the support of the die pad tape. A second invention provides a semiconductor device having a resin layer such as a thermosetting resin on the side thereof, and a surface treatment in which the die bonding adhesive side of the support of the die pad tape is subjected to corona discharge machining or roughening treatment. A third invention is a semiconductor device provided with layers.

Next, the present invention will be explained with reference to the drawings.

An example of the semiconductor device of the present invention is as shown in the cross-sectional views shown in FIGS. 3A and 3B, and as a die pad tape, as shown in FIG. A case in which a layer 12 is provided is shown in FIG. 3A, and a case in which a resin layer 11-1 is provided on the upper side of the support as shown in FIG. 5B,
Alternatively, a case where a surface treatment layer 11-2 is provided on the upper side of the support as shown in FIG. 3C is shown in FIG. 3B.
(In Figure 3 B, 11 is 11-1 and 11-2 mentioned above.
This is a comprehensive display. ) FIG. 3A relates to the first invention, in which the adhesive layer 12 on the lower surface of the support 10 of the die pad tape is adhered onto the leads 2 of the lead frame, and the semiconductor pellet 4 is bonded on the surface side with a die bonding adhesive 5. is fixed, and is integrated with a bonding wire 6 that connects the electrode 7 and the lead 2 using a sealing resin 8. Note that the semiconductor device of the present invention is not limited to resin sealing, and may be sealed using, for example, a cerdip type or a cerpack type. FIG. 3B relates to the second invention and the third invention, and the same parts as in FIG. 3B are given the same reference numerals. As already mentioned, the die pad tape is different from that shown in Fig. 3A, and a thermosetting resin layer is provided on the upper side (second invention) or a surface treatment layer is provided (third invention). The bonding force between the support of the die pad tape and the semiconductor pellet 4 is further increased than that shown in FIG. 3A, and the reliability is improved by stabilizing the assembled structure of the semiconductor device.

Note that the die pad film in the present invention is applied to a lead frame having a structure that excludes a conventional die pad, as shown in FIG. 4A to D.
A semiconductor pellet is formed into an arbitrary size according to the shape and size of the semiconductor pellet and is adhesively mounted on the lead 2 at the position of the cavity 9. In this case, the dimensions of the die pad tape are set to be large enough to cover all the ends of the leads 13 and 2 of the lead frame. That is, the die pad tape according to the present invention does not cover only the protruding leads 13 and their tips 14 as shown in FIG. . In this way, by extending the die pad tape to the tip of each lead and gluing it,
When wire bonding the electrodes and leads of a semiconductor pellet, the leads may vary vertically or
Accurate and stable wire bonding can be performed without shifting from side to side or twisting.

Next, the materials constituting the die pad film used in the present invention will be described.

The support has a thickness of e.g. 10 to 150 μm, preferably 25 μm.
~75 μm polyimide is used in the present invention.

Die bonding adhesive 5 constituting the present invention
It is desirable to select and use a material that has sufficient adhesion to the support that makes up the die pad tape.
By appropriately selecting this adhesive, the first invention, that is, the intended semiconductor device can be obtained without providing a resin layer or a surface treatment layer on the die pad tape. It has been found that the die pad tape surface must be improved to ensure adhesion with the adhesive. That is, in order to achieve this improvement in adhesion, polyimide resin, epoxy resin,
Thermosetting resin such as polyester resin or approx.
The second invention provides a resin layer 11-1 made of a thermoplastic resin having a melting point of 300°C or higher,
It is usually applied to a thickness of 1 to 10 μm and cured by heat.

The type of resin is the die bonding adhesive 5 mentioned above.
By selecting a material that is compatible with the semiconductor pellet, it is possible to bond extremely easily and strongly, thereby increasing the reliability of the semiconductor pellet. Furthermore, this resin layer 1
Instead of 1-1, surface treatment 11-2 such as pine graining, corona discharge treatment, embossing, and matte matte processing improves adhesion by creating fine irregularities, imparting polarity, and embrittling the oxide film. can be improved (third invention). According to this, it is possible to provide a semiconductor device that achieves strong adhesion without increasing the thickness or weight.

The adhesive layer on the bottom surface of the die pad tape with semiconductor pellets placed on the surface of the leads of the lead frame is coated with at least one type of resin selected from heat-resistant epoxy resin, polyimide resin, polyurethane resin, and polyamide resin to a thickness of 5 to 50 μm, preferably. is 20～
It is formed by applying it in a semi-cured state to a coating thickness of 30 μm.

A die pad tape made of such a layer structure and material is usually made into a material with a width of 3 to 10 mm and a length of 3 to 10 mm.
It can be processed into a tape of 200 to 300 m long and supplied wound on a reel. In this case, it is cut to match the dimensions of the semiconductor pellet, and then applied and bonded to a predetermined lead frame. The die pad tape/lead frame laminate thus obtained is incorporated into the structure shown in FIG. 3 to obtain the semiconductor device of the present invention.

The shape of the lead frame used in the present invention is, for example, as shown in FIGS. It is characterized in that a required number of leads 13 protrude compared to other leads 2, and the tips 14 of the protruding leads have a large area. At this time, the protruding leads should not be placed next to each other as much as possible, for example,
It is preferable to arrange the die pad tape every other book or every second tape in order to balance the die pad tape on which the semiconductor pellets are mounted.

By using a lead frame having such a specific shape, good flatness for mounting the die pad tape can be obtained, and sagging of the tape can be prevented.

〔Example〕

Example 1 A super heat-resistant polyimide resin ("LARC-TPI" manufactured by Mitsui Toatsu Chemical Co., Ltd.) was applied as an adhesive layer on one side of a support made of a 50 μm thick polyimide resin film ("Iupilex {S" manufactured by Ube Industries, Ltd.). N,N
- A die pad tape was prepared by applying a 20% by weight solution of dimethylacetamide to semi-cure (B stage) and heating it at 150° C. for 3 minutes so that the coating thickness after drying was 25 μm.

The obtained die pad tape is cut to a desired size, and the protruding leads and their tips of a lead frame are formed by punching an iron-based metal plate, such as a Kovar plate, into the shape shown in FIG. 4A, After heating and adhering with an adhesive layer so as to cover all the tips of the other leads, a semiconductor device as shown in FIG. 3A was assembled.

When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage was observed in the adhesive layer, and stable adhesiveness was confirmed. In addition, wire bondability is good, and when resin-sealed there is no wire flow, allowing reliable semiconductor devices to be constructed.
After being left for 24 hours, it was immersed in a solder bath at 260°C for 3 seconds, and then tested for 250 hours using a pressure tester (PCT), but no abnormalities were found.

Example 2 On one side of a support made of a 50 μm thick polyimide resin film "Kapton 200V" (manufactured by Toray DuPont), a polyurethane resin ("Chitso Rex 372" manufactured by Chitso Corporation) was coated with dimethylformamide/methyl ethyl ketone = 2/ as an adhesive layer. A mixture of 70 parts by weight of a 43% solution of No. 1 and 30 parts by weight of a 20% solution of phenol novolac epoxy resin ("EPPN-201", manufactured by Nippon Kayaku Co., Ltd.) in methyl ethyl ketone was heated to a semi-cured state at 120°C. A die pad tape was prepared by coating under heating conditions for 5 minutes so that the coating thickness after drying was 40 μm.

After cutting the obtained die pad tape to a desired size, it was heated and bonded with an adhesive layer so as to cover the protruding leads and their tips of the lead frame shown in Figure 4 (b), as well as all the tips of the other leads. The semiconductor device shown in FIG. 3A was assembled.

When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage was observed in the adhesive layer, and stable adhesiveness was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed. Also 85℃, 85%
After being left in a RH atmosphere for 24 hours, it was immersed in a 260°C solder bath for 3 seconds and then tested using PCT for 250 hours, with no abnormalities at all.

Example 3 As the adhesive layer in Example 2, a mixed composition of polyamide and epoxy resin ("OX-035" manufactured by Toray Hysole Co., Ltd.) was prepared using trichlene/methanol = 1/
A semiconductor device of the present invention was produced in the same manner as in Example 2 except that a 30% by weight solution of Example 2 was used.

When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage was observed in the adhesive layer, and stable adhesion was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed. Also, after being left in an atmosphere of 85% RH for 24 hours, it was immersed in a solder bath at 260°C for 3 seconds and then tested using PCT for 250 hours, and no abnormalities were found.

Example 4 A thermosetting resin layer having the following composition was provided on one side of a support made of a 50 μm thick polyimide resin film (“Upilex S” manufactured by Ube Industries, Ltd.).

Epoxy resin ("Epicote 1001" manufactured by Yuka Ciel Epoxy Co., Ltd.) 80% methyl ethyl ketone solution 100 parts by weight Reactive acrylonitrile copolymer ("NIPOL1072" manufactured by Nippon Zeon Co., Ltd.) 20% methyl ethyl ketone solution 40 parts by weight Hardening agent DICY/2- Ethyl 4-methylimidazole (5/1) 12 parts by weight Solvent (methyl ethyl ketone) 80 parts by weight The coating thickness was 3 μm, and after drying at 150°C for 3 minutes, it was completely cured at 250°C for 5 minutes.

Next, super heat-resistant polyimide resin (“LARC-TPI”,
A 20% by weight solution of N,N-dimethylacetamide (manufactured by Mitsui Toatsu Chemical Co., Ltd.) was semi-cured (B stage) and heated at 150℃ for 3 minutes so that the coating thickness after drying was 25μm. A die pad tape of the present invention was prepared by coating. The obtained die pad tape was heat-bonded with an adhesive layer so as to cover the protruding leads and their tips of the lead frame shown in FIG. The semiconductor device shown was created.

When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage was observed in the adhesive layer, and stable adhesion was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed.

Example 5 A thermosetting resin layer having the following composition was provided on one side of the support of Example 4. The coating thickness at this time was 5 μm, 150
After drying at 250°C for 2 minutes, it was completely cured at 250°C for 5 minutes. Thereafter, the adhesive layer used in Example 4 was provided on the opposite side to produce a die pad tape of the present invention.

Polyester resin ("Vylon 200" manufactured by Toyobo Co., Ltd.) 20% methyl ethyl ketone solution 100 parts by weight Isocyanate ("Coronate L" manufactured by Nippon Polyurethane Co., Ltd.) 2 parts by weight Solvent Toluene 20 parts by weight The obtained die pad tape is shown in Figure 4 (b). The protruding leads of the lead frame and their tips, as well as the tips of all other leads, were bonded together by heating with an adhesive layer, and then the semiconductor device shown in FIG. 3B was fabricated.

When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage from the adhesive layer was found, and stable adhesion was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed.

Example 6 The support of Example 4 had a surface roughness Ra of 0.2 to 0.3 μm,
A die pad tape is prepared by performing matte treatment so that Rmax is 1 to 2 μm and providing a surface treatment layer. After heating and adhering with an adhesive layer so as to cover all the tips of the other leads, the semiconductor device shown in FIG. 3B was fabricated.

When the reliability of the obtained semiconductor device was checked through mounting experiments, no current leakage was observed in the adhesive layer, and stable adhesion was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed.

Example 7 The surface of the support of Example 1 was treated with a corona discharge treatment machine (“Pillar Corona Treater 12”, manufactured by Toyo Pillar Co., Ltd.)
A die pad tape was created by applying corona discharge machining at a voltage of 320 Volt and a speed of 50 m/min to provide a surface treatment layer.

The obtained die-pat tape was heat-bonded with an adhesive layer so as to cover the protruding leads and their tips of the lead frame shown in FIG. The semiconductor device shown was created. When the reliability of the obtained semiconductor device was checked through a mounting test, no current leakage from the adhesive layer was found, and stable adhesion was confirmed. Furthermore, a reliable semiconductor device with good wire bondability could be constructed.

〔Effect of the invention〕

Since the present invention has the above configuration, the die pad tape can be arbitrarily cut according to the shape and size of the semiconductor pellet and supplied to the semiconductor pellet mounting part of the lead frame, which improves efficiency in designing and manufacturing the lead frame. Effective for cost reduction.
In addition, since the adhesive layer that makes up the die pad tape and the sealing resin have good adhesion, there is no need to worry about cracks occurring in the sealing resin due to rapid expansion of moisture.
In addition, since the difference in thermal expansion coefficient between the semiconductor pellet and the die pad tape is small, there is no cracking of the semiconductor pellet, and the gap between the lead tip and the die pad is similar to that in conventional lead frames. Since there is no bonding wire, it is expected that the bonding wire will not flow or break during mold processing, and an extremely reliable semiconductor device can be obtained. Especially the second and third
In the invention, since a resin layer such as a thermosetting resin or a surface treatment layer is provided on the surface side of the support, sufficiently strong adhesion can be achieved without using a special die bonding adhesive. However, since the third invention requires a thinner layer than the second invention, it is effective in reducing the weight and size of semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a lead frame according to the prior art, FIG. 2 is a sectional view of a conventional semiconductor device, and FIG. 3 is a sectional view of a conventional semiconductor device.
The figure is a cross-sectional view of the semiconductor device of the present invention, Figures 4A to 4D are plan views of the lead frame constituting the present invention, and Figures 5A, B, and C show the layer structure of the die pad tape constituting the present invention. FIG. 2...Lead, 4...Semiconductor pellet, 5...
Die bonding adhesive, 6... bonding wire, 7... electrode, 8... sealing resin, 9... void, 10... support, 11-1... resin layer, 1
1-2...Surface treatment layer, 12...Adhesive layer.

Claims (1)

[Claims] 1. A semiconductor pellet mounted via a die bonding adhesive on a lead frame from which a die pad has been removed and a die pad tape having a size that includes and covers the lead tips of the lead frame. In the semiconductor device, a desired number of the leads constituting the lead frame protrude toward the die pad cavity, and the tips of the protruding leads have a larger area than the other leads. , and the die pad tape includes a heat-resistant support made of a polyimide resin film and an adhesive layer made of at least one resin selected from epoxy resin, polyimide resin, polyurethane resin, and polyamide resin for fixing the support to the lead. A semiconductor device comprising: the die pad tape extending to and being fixed to the tip of the other lead. 2. A semiconductor device comprising a lead frame from which a die pad has been removed and a semiconductor pellet mounted via a die bonding adhesive on a die pad tape having a size that includes and covers the lead tips of the lead frame. , a desired number of leads constituting the lead frame protrude toward the die pad cavity, and the tips of the protruding leads have a larger area than other leads, and the die pad tape is a heat-resistant support made of a polyimide resin film, an adhesive layer made of at least one resin selected from epoxy resin, polyimide resin, polyurethane resin, and polyamide resin for fixing the support to the lead, and a die bonding adhesive side. 2. A semiconductor device comprising a resin layer, wherein the die pad tape extends to and is fixed to the tip of the other lead. 3. A semiconductor device comprising a lead frame from which a die pad has been removed and a semiconductor pellet mounted via a die bonding adhesive on a die pad tape having a size that includes and covers the lead tips of the lead frame. , a desired number of leads constituting the lead frame protrude toward the die pad cavity, and the tips of the protruding leads have a larger area than other leads, and the die pad tape is a heat-resistant support made of a polyimide resin film, an adhesive layer made of at least one resin selected from epoxy resin, polyimide resin, polyurethane resin, and polyamide resin for fixing the support to the lead, and a die bonding adhesive side. a surface treatment layer subjected to corona discharge machining or roughening treatment, and the die pad tape extends to and is fixed to the tip of the other lead.