JPH0442921Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a semiconductor device, and in particular a semiconductor device using a lead frame having a die pad and a die pad tape having a specific structure for mounting semiconductor pellets. It is related to.

[Conventional technology]

A conventional semiconductor device has a die bonding adhesive layer 5 as shown in FIG. 2 on 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. A semiconductor pellet 4 is placed through the pellet 4 and is integrated with a bonding wire 6 that connects the electrode 7 formed on the pellet 4 and the lead 2 using a sealing resin 8.

In this case, since 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 the semiconductor device on the circuit board. During the heat treatment in the soldering process, this causes internal stress in the sealing resin etc. due to rapid expansion of moisture, causing a problem of cracks occurring in the semiconductor pellets, the sealing resin etc.

[Problems to be solved by the invention] The present invention was made in view of the above-mentioned circumstances, and avoids diametral contact between the die pad and the sealing resin, and instead uses a die pad that is compatible with the sealing resin. The purpose of this invention is to provide a semiconductor device with excellent reliability by improving the adhesive sealing properties between the lead frame and the sealing resin by interposing the lead frame and the sealing resin.

[Means for solving problems]

The outline of the present invention is that a semiconductor pellet is placed on a die pad at the center of the lead, at least the bottom surface of the die pad is well adhered to an adhesive die pad tape, and the electrode and the lead provided on the top of the semiconductor pallet are connected to each other. This is a semiconductor device in which the two are connected with bonding wires and these are hermetically sealed with a sealing resin.

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 FIG. Glue to. This die pad tape 10 can be selected from various types as shown in FIG. 4. That is, as shown in A, the entire support body 10a has adhesive properties, as shown in B, an adhesive layer 11 is provided on the top surface of the support body 10b, and as shown in C, that the support body 10a is adhesively bonded to the top surface of the support body 10b. A support 10b having an adhesive layer 11 and an adhesive layer 12a on its lower surface, and a support 10b having an adhesive layer 11 on its upper surface and a surface treatment layer 12b on its lower surface as shown in d are selectively used. The rest of the structure is the same as the conventional one, and the electrode 7 on the upper surface of the semiconductor pellet and the upper surface of the leads 2, 2 are electrically connected by bonding wires 6. Further, the entire structure is hermetically sealed with a sealing resin 8, which adheres well to the die pad tape 10, resulting in a highly reliable semiconductor device.

In Figure 3B, the only difference is that the top surface of the die pad tape is adhered to the bottom surface of the die pad and the bottom surface of the leads.
This is different from Figure 3A, but the rest is exactly the same.

The difference in use between the two is when the die pad tape covers the leads, as shown in Figure 3 (B), and when it does not, as shown in Figure 3 (A), the effect of the sealing resin is more fully demonstrated in Figure 3 (A). It can be said that it is more preferable.

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

Examples of adhesive die pad tape materials include:

If the entire tape is made of adhesive, thermosetting resin: A semi-cured (B-stage) type of resin that cures under heat, such as epoxy resin or polyimide resin, with a melting point of about 80°C, and can be used as is. Examples include those that exhibit strong adhesive properties when cured by heating.

Thermoplastic resin: polyphenylene sulfide (PPS), polyethylene terephthalate film, etc.
Examples include those that have a melting point of 300°C or higher and exhibit adhesive properties.

When consisting of other adhesive tapes, the support may have a thickness of, for example, 10 to 10 μm, preferably 25 to
Heat-resistant films such as 75μm polyimide, polyetherimide, polyphenylene sulfide, polyether/etherketone, etc.; epoxy glass cloth impregnated with epoxy resin and cured or semi-cured by heating; epoxy/polyimide/glass Cloth, glass cloth impregnated with bismaleimide triazine resin (BT resin)
Heat-resistant tape such as BT resin glass cloth is used.

Adhesive layer The adhesive layer on the lower surface of the support and the adhesive layer on the upper surface are made of heat-resistant epoxy resin, polyimide resin, etc.
It is formed by coating in a semi-cured state to a coating thickness of 50 μm, preferably 20 to 30 μm. However, since both are provided in a semi-cured state (B stage), it is desirable that the curing temperature of the lower adhesive layer is higher than that of the upper adhesive layer. The reason for this is that the adhesive layer on the upper surface of the support is first brought into contact with the semiconductor chip and the lower surface of the leads, and then cured by heat. This is because it becomes difficult to bond.

Surface Treatment Layer The lower surface of the support is subjected to surface treatments such as pine graining, chemical oxidizing gas flame oxidation, corona discharge treatment, embossing, matte matte finishing, etc.
It is provided to improve the adhesion with the sealing resin by providing fine irregularities, imparting polarity, and making the oxide film fracture and brittle.

Due to the presence of this surface treatment layer, it is possible to provide a semiconductor device that achieves strong adhesion of the sealing material without increasing the thickness or weight.

Die pad tape with such a structure is usually processed into a tape shape with a width of 3 to 10 mm and a length of 200 to 300 m, and can be supplied wound on a reel, in which case the dimensions of the semiconductor pellet are The material is cut to match the desired size, then applied and glued to a designated lead frame.

〔Example〕

Example 1 A die-pad tape made of a 200 μm thick epoxy glass cloth nonwoven fabric prepreg impregnated with glass cloth epoxy resin and semi-cured (“Silbon T61” manufactured by Shinko Kagaku Kogyo Co., Ltd.) was cut into a desired size and cut into pieces. A lead frame made by punching an iron-based metal plate, such as a Kovar plate, as shown in Fig. 1, is heat-bonded to the lower surface of the die pad, and the semiconductor pellets are placed, the leads are attached, and the resin sealing is performed in the conventional manner. A semiconductor device as shown in Figure 3A was then assembled.

85℃, 85%RH for the obtained semiconductor device
After being left in an atmosphere of (relative humidity) for 24 hours, it was immersed in a 260°C solder bath for 3 hours, and then tested for 250 hours using a pressure vacuum test (PCT), with no abnormalities at all.

Example 2 On one side of a support made of a polyimide resin film ("Upilex S" manufactured by Ube Industries, Ltd.) with a thickness of 50 μm, a coating liquid of the following composition was applied as an adhesive layer on the lower surface so that the coated layer after drying was 20 μm. Dry.

Epoxy resin (“Epicote 1001” manufactured by Yuka Ciel Epoxy Co., Ltd.) 80% MEK solution …120 parts by weight Dicyandiamide (manufactured by Wako Pure Chemical Industries, Ltd.) …10 parts by weight Polyamide resin (“#6900” manufactured by Henkel Hakusuisha) Methanol/ 20% toluene (1:1) solution...100 parts by weight Next, a coating liquid having the following composition was applied as an adhesive layer on the upper surface so that the coating thickness after drying was 20 μm.

Epoxy resin (“EOCN-102”, manufactured by Nippon Kayaku Co., Ltd.) …100 parts by weight Polyester resin (“KA-1036”, manufactured by Arakawa Chemical Co., Ltd.) …50 parts by weight Imidazole-based curing agent (“2PZ”, Shikoku Kasei )...10 parts by weight Methyl ethyl ketone...100 parts by weight Die pads and leads for lead frames are made by cutting the obtained die pad tape into desired sizes and punching out iron-based metal plates such as Kovar plates. The rest is Example 1.
In the same manner as above, a semiconductor device as shown in FIG. 3B 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 and a reliable semiconductor device can be constructed. Also, after being left in an atmosphere of 85°C and 85% RH for 24 hours, soldering at 260°C is possible. After being immersed in the bath for 3 seconds, it was tested using PCT for 250 hours, but no abnormalities were found.

Example 3 On the lower surface 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) of dimethylformamide/methyl ethyl ketone = 2 was applied as an adhesive layer. A mixture of 70 parts by weight of a 43% solution of 1/1 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 parts by weight. A die pad tape was prepared by applying the film under heating conditions of 5 minutes at °C so that the coating thickness after drying was 40 μm.

The resulting die pad tape was cut to a desired size and then heated and bonded to the lower surface of the die pad of the lead frame using an adhesive layer, and 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 4 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) of dimethylformamide/methyl ethyl ketone = 2 was applied as an adhesive layer. A mixture of 70 parts by weight of a 43% solution of 1/1 and 30 parts by weight of a 20% solution of phenol novolac epoxy resin (EPPN-201 manufactured by Nippon Kayaku Co., Ltd.) in methyl ethylmethone was brought to a semi-cured state. The film was applied under heating conditions of 120° C. for 5 minutes to a coating thickness of 40 μm after drying, and the opposite side was surface-treated by blasting to create a die pad tape.

The resulting die pad tape was cut to a desired size and then heated and bonded to the lower surface of the die pad of the lead frame shown in FIG. 1 using an adhesive layer to assemble the semiconductor device shown in FIG. 3A.

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, but no abnormalities were found.

[Effect of idea]

As shown in the above configuration, the present invention improves the sealing performance of the resin because the back surface of the die pad and the sealing resin are not in direct contact and the adhesion between the die pad and the sealing resin is improved. A reliable semiconductor device can be provided.

In addition, if the adhesive strength between the die pad and the die pad tape and between the die pad tape and the sealing resin is strong to a certain extent, this die pad tape has the effect of absorbing distortion due to the difference in thermal expansion coefficient between the die pad and the sealing resin. .

[Brief explanation of the drawing]

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.
Figures A and B are cross-sectional views of the semiconductor device of the present invention.
FIG. 4 is a sectional view of each example of die pad tape used in the present invention. DESCRIPTION OF SYMBOLS 1... Die pad, 2... Lead, 3... Support bar, 4... Semiconductor pellet, 5... Die bonding adhesive layer, 6... Bonding wire, 7... Electrode, 8... Sealing resin, 10 ... Die pad tape, 10a ... Adhesive support, 10b
...Support, 11...Top adhesive layer, 12a...
Adhesive layer on lower surface, 12b...Surface treatment layer.

Claims (1)

[Scope of utility model registration request] A semiconductor pellet is arranged and bonded on a die pad in the center of a lead frame, and at least the lower surface of the die pad is adhered to an insulating die pad tape, and the electrode provided on the upper part of the semiconductor pellet and the lead are connected with a bonding wire. , a semiconductor device characterized in that these are hermetically sealed with a sealing resin.