JPH10168409A - Copper foil coated with heat-resistant adhesive layer, and lead frame fitted with heat dissipation plate and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-sealed semiconductor device capable of being produced by a simplified step of producing a heat spreader, excellent in electrical properties and free from reflow cracking. SOLUTION: This invention provides a copper foil coated with a heat-resistant adhesive layer, prepared by forming a layer of an adhesive of a heat-resistant resin composition containing 10-80wt.%, based on the heat-resistant resin, silicone rubber filler having surface epoxy or amido groups, 0.5-10wt.% organic solvent, 0.5-20wt.% crosslinking agent and at least one heat-resistant resin selected among aromatic polyamides, aromatic polyimides, aromatic polyamide imides, aromatic polyether amides, aromatic polyether imides and aromatic polyether amide imides on either surface of a 50-200μm thick copper foil and a lead frame and a semiconductor using the foil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper foil with a heat-resistant adhesive layer for a radiator plate used in a semiconductor device, particularly a resin-sealed semiconductor device on which a semiconductor element having a large amount of heat is mounted. And a semiconductor device using the same.

[0002]

2. Description of the Related Art In recent years, with the increase in the degree of integration of semiconductor chips, circuit malfunctions and deterioration in reliability due to heat generation of the chips have become problems. A semiconductor device with a so-called heat spreader has been developed and put into practical use, in which the heat generated by the chip is radiated to the outside through the heat radiating plate by adhering to the die pad and the back surface of the inner lead. The heat sink is attached to the back surface of the die pad or the surface opposite to the bonding surface of the inner lead using a film with a double-sided adhesive or a coating type adhesive. However, in the method using a film with a double-sided adhesive, the material cost of the film is high, and a step of bonding the adhesive film to a heat sink and then bonding the film to a lead frame is required. It was difficult to apply to the device. On the other hand, in the method using the coating type adhesive, the work is complicated because the adhesive layer is applied by a special method such as screen printing, and a problem of contamination occurs in each process. There were also quality problems.

As a method for solving these problems, Japanese Patent Application Laid-Open No. Hei 5-218284 discloses a method in which an adhesive layer is formed on a metal foil for a heat sink, then processed into a predetermined shape, and pressure-bonded to an inner lead frame. Proposed. However, although this method simplifies the manufacturing process, it does not disclose an adhesive, and when using a normal thermosetting adhesive, when bonding a copper foil with an adhesive layer to a lead frame, At the time of wire bonding, outgas is generated from the adhesive, which causes a problem of contaminating the lead frame. In addition, when a general thermoplastic resin is used, not only is the reflow resistance poor, but also the adhesive layer becomes soft at the time of wire bonding, the inner lead portion of the lead frame sinks into the adhesive layer, and the copper foil and They may come into contact with each other, causing a decrease in insulation or a short circuit. On the other hand, JP-A-7-235626
Japanese Patent Application Laid-Open Publication No. H11-163873 proposes a copper foil with an adhesive that does not cause a decrease in insulation during wire bonding or a short circuit by forming a two-layer structure of a polyimide layer and a polyimide layer having a lower elastic modulus than the polyimide layer. . However, even with this adhesive structure, it is difficult to completely prevent sinking of a lead frame having a small width such as a fine pitch lead frame, and it is not sufficient as a measure against a decrease in insulation or a short circuit. In addition, since a polyimide resin is used, it has to be bonded to a copper lead frame at a high temperature, and it is necessary to be in a nitrogen atmosphere in order to suppress oxidation of copper, and there is a problem in workability.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a copper foil with an adhesive layer for a heat spreader which can be bonded at a low temperature and has excellent heat resistance, a lead frame using the same, and electrical characteristics. And a semiconductor device having good reflow resistance.

[0005]

Means for Solving the Problems The present inventors have found that when a heat-resistant resin containing a solvent is used as an adhesive, even a heat-resistant resin having a high glass transition temperature can be bonded at a low temperature. Eliminates contact between the inner lead and the heat sink due to sinking of the inner lead into the adhesive layer during wire bonding, which can prevent insulation deterioration and short-circuit, and improve reflow resistance And led to the present invention. That is, the present invention, on one side of a copper foil having a thickness of 50 to 200 μm,
10-8 silicone rubber fillers for heat resistant resin
0% by weight, containing 0.5 to 10% by weight of an organic solvent, and at least one of aromatic polyamide, aromatic polyimide, aromatic polyamideimide, aromatic polyetheramide, aromatic polyetherimide and aromatic polyetheramideimide Copper foil with a heat-resistant adhesive layer formed with an adhesive layer of a heat-resistant resin composition containing one or more heat-resistant resins, and the above-mentioned heat-resistant adhesive using a silicon rubber filler having an epoxy group or an amide group on the surface. Copper foil with layer, copper foil with heat-resistant adhesive layer containing 0.5 to 20% by weight of crosslinking agent with respect to resin, copper foil with heat-resistant adhesive layer on the side opposite to the bonding surface of inner lead And a semiconductor device using this lead frame.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The heat-resistant resin used in the present invention includes aromatic polyamide, aromatic polyimide, aromatic polyamideimide, aromatic polyetheramide, aromatic polyetherimide and aromatic polyetheramideimide. A resin selected from at least one or more types is exemplified. As the silicone rubber filler, a spherical or irregularly shaped ultrafine silicone rubber elastic material is used,
In particular, a silicone rubber filler having an amino group or an epoxy group on the surface is preferable from the viewpoint of compatibility and bonding with a heat-resistant resin. When a silicone rubber filler having an epoxy group on the surface is used, the heat-resistant resin and the sealing resin react with the epoxy group during a heat drying step of forming an adhesive layer on the copper foil or a molding step with the sealing resin. And a crosslinked structure having good heat resistance. The particle size of the silicone rubber filler is 0.
It is preferably from 1 to 20 μm, more preferably from 1 to 5 μm.

[0007] The amount of the silicone rubber filler is preferably from 10 to 80% by weight, more preferably from 20 to 40% by weight, based on the heat-resistant resin. Silicon rubber filler amount is 80
If it exceeds 10% by weight, the adhesive strength of the adhesive layer tends to decrease, and if it is less than 10% by weight, the insulating property and the reflow resistance tend to decrease. The solvent is not particularly limited, but may dissolve the above-mentioned heat-resistant resin, for example, dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone, m-cresol, pyridine, cyclohexanone, diethylene glycol dimethyl ether, triethylene Examples include polar solvents such as glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, dioxane and the like.

[0008] The amount of the solvent contained in the resin composition,
It is preferably from 0.5 to 10% by weight, more preferably from 1 to 5% by weight. When the solvent content is less than 0.5% by weight, the bonding temperature of the resin does not decrease. Particularly, when bonding the heat-resistant resin to a copper-based lead frame at a high temperature, the lead frame is oxidized. Occur. On the other hand, if the solvent content exceeds 10% by weight, the amount of the solvent vaporized at the reflow temperature during mounting is large, the internal pressure is increased, and problems such as cracks in the sealing resin occur. 50 thickness for copper foil
A rolled copper foil and an electrolytic copper foil of up to 200 μm are used. If the thickness of the copper foil is less than 50 μm, the heat radiation characteristics deteriorate,
If it exceeds 0 μm, it will be difficult to handle the adhesive as a roll when forming the adhesive on the surface of the copper foil, and workability will deteriorate. The method of forming a resin layer containing an organic solvent on the surface of a copper foil is such that a heat-resistant resin is dissolved in the above-mentioned solvent and applied to the surface of the copper foil so that the amount of the solvent is 0.5 to 10% by weight. To dry.

[0009] The coating method is not particularly limited,
For example, a roll coat, a reverse roll coat, a gravure coat, a bar coat and the like can be mentioned. The thickness of the adhesive layer is preferably from 1 to 75 μm, more preferably from 10 to 30 μm. If the thickness of the adhesive layer exceeds 75 μm, it is difficult to reduce the thickness of the semiconductor device, and if it is less than 1 μm, the adhesive strength tends to decrease.

The crosslinking agent is not particularly limited as long as it is a compound capable of crosslinking the heat-resistant resin by heat. Examples thereof include amino resins, phenol resins, urethane resins, and acid anhydrides. A silane compound is also used. As the silane compound, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-
Aminoethyl) aminopropylmethyldimethoxysilane, aminosilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, hexamethyldisilazane, silane coupling agents such as γ-anilinopropyltrimethoxysilane and vinyltrimethoxysilane, and isopropyltriisostearoyl titanate, isopropyltrioctanoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, etc. Titanate-based coupling agents and aluminum-based couplings such as acetoalkoxyaluminum diisopropylate And the like. When additives such as a cross-linking agent and a filler are added to the adhesive film, the adhesive force with the substrate and the adherend is improved, and the reflow resistance is improved. The amount of the crosslinking agent is 0.5 to 20% by weight based on the total weight of both the heat-resistant resin and the crosslinking agent.
And more preferably 2 to 10% by weight. When the cross-linking agent exceeds 20% by weight, heat resistance decreases,
In addition, contamination of the lead frame due to outgas is a problem.

[0011]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Example 1 5 equipped with a thermometer, a stirrer, a nitrogen inlet tube and a cooling tube
2,2-under a nitrogen atmosphere in a 4-liter four-necked flask
205 g (0.5 mol) of bis [4 (4-aminophenoxy) phenyl] propane, propylene oxide
6 g (1.2 mol) was added and dissolved in 1200 g of N-methyl-2-pyrrolidone. The solution was cooled to -5 ° C and at this temperature 100.5 g (0.4
95 mol) was added so that the temperature did not exceed 20 ° C.
Thereafter, stirring was continued at room temperature for 3 hours. The obtained reaction solution was put into methanol to isolate the polymer. After drying, this was dissolved in dimethylformamide, poured into methanol, and dried under reduced pressure to obtain a purified aromatic polyamide powder. 40 g of the obtained polyamide powder was N-
140 g of methyl-2-pyrrolidone, butyl cellosolve 6
0 g, and 20 g of a silicone rubber filler (Toray Dow Corning Trefil E-601) was added and mixed with a three-roll mill to obtain a varnish. 105μ of this varnish
m on one side of electrolytic copper foil (manufactured by Nihon Denki)
The resultant was dried at 00 ° C. for 6 minutes and then at 160 ° C. for 6 minutes to obtain a copper foil with an adhesive layer having a thickness of 25 μm. When the amount of the residual solvent in the adhesive layer of the obtained copper foil with an adhesive layer was measured, it was 5% by weight. The obtained copper foil with an adhesive was cut into a square of 20 mm, placed on a copper lead frame having a thickness of 0.2 mm, and pressed at 250 ° C. under a pressure of 3 MPa for 3 seconds. After bonding, the lead frame was not warped, and the adhesive layer was examined under a microscope to find no foaming. Thereafter, the semiconductor element was adhered to the adhesive layer with a silver paste, the lead and the semiconductor element were joined with a gold wire, and transfer molding was performed using an epoxy resin molding material, thereby producing a semiconductor device. 85 ° C., 85% of this resin-encapsulated semiconductor device
After absorbing moisture for 168 hours at RH, IR at 245 ° C for 10 seconds
When the failure rate after reflow was examined, it was found that the failure rate was 0/100 (10
(0 out of 0) was excellent.

Example 2 5 equipped with a thermometer, a stirrer, a nitrogen inlet tube and a cooling tube
2,2-under a nitrogen atmosphere in a 4-liter four-necked flask
205 g (0.5 mol) of bis [4 (4-aminophenoxy) phenyl] propane was added and dissolved in 1200 g of N-methyl-2-pyrrolidone. The solution was cooled to −10 ° C. and at this temperature trimellitic monochloride.
2 g (0.495 mol) were added so that the temperature did not exceed -5 ° C. When trimellitic acid monochloride was dissolved, 76 g of triethylamine was added so that the temperature did not exceed 5 ° C. After stirring for 1 hour at room temperature,
For 9 hours to complete the imidization. The obtained reaction solution was put into methanol to isolate the polymer.
This was dried, then dissolved in dimethylformamide, poured into methanol, and dried under reduced pressure to obtain a purified aromatic polyamideimide powder. 40 g of the obtained polyamideimide powder was dissolved in 140 g of tetrahydrofuran, and a silicone rubber filler (Trefil E-601) was used.
20 g was added and mixed with three rolls to obtain a varnish. This varnish is applied to one side of a 105 μm thick electrolytic copper foil (manufactured by Nihon Denki), dried at 100 ° C. for 6 minutes, and then at 180 ° C. for 6 minutes to form a copper foil with a 15 μm thick adhesive layer. Obtained. When the amount of the residual solvent in the adhesive layer of the obtained copper foil with an adhesive layer was measured, it was 3%. The obtained copper foil with an adhesive layer was cut into a square of 20 mm, placed on a copper lead frame having a thickness of 0.2 mm, and pressed at a temperature of 250 ° C. at a pressure of 3 MPa for 3 seconds. After bonding, the lead frame was not warped, and the adhesive layer was examined under a microscope to find no foaming. Thereafter, the semiconductor element was adhered to the adhesive layer with a silver paste, the lead and the semiconductor element were joined with a gold wire, and transfer molding was performed using an epoxy resin molding material, thereby producing a semiconductor device. At 85 ° C. of this resin-encapsulated semiconductor device, 85
% RH for 168 hours, IR at 245 ° C for 10 seconds
When the failure rate after reflow was examined, it was found that the failure rate was 0/100 (10
(0 out of 0) was excellent.

Example 3 100 g of the varnish obtained in Example 2 was added to a silane coupling agent ("SH-" manufactured by Dow Corning Toray Silicone Co., Ltd.).
6020 ") to give Varnish 2. This varnish is coated on one side of a 105 μm thick electrolytic copper foil (manufactured by Nihon Denshi), dried at 100 ° C. for 6 minutes, and then at 180 ° C. for 6 minutes, and a copper foil with a 15 μm thick adhesive layer I got When the amount of the residual solvent in the adhesive layer of the obtained copper foil with an adhesive layer was measured, it was 3%. The obtained copper foil with adhesive was
Cut to 0 mm square, put on a copper lead frame with a thickness of 0.2 mm, and press it at 250 ° C. at a pressure of 3 MPa.
Pressure was applied for 2 seconds. After bonding, the lead frame was not warped, and the adhesive layer was examined under a microscope to find no foaming. Thereafter, the semiconductor element was adhered to the adhesive layer with a silver paste, the lead and the semiconductor element were joined with a gold wire, and transfer molding was performed using an epoxy resin molding material, thereby producing a semiconductor device. At 85 ° C., 85% R
After absorbing moisture for 168 hours with H, the failure rate after IR reflow at 245 ° C. for 10 seconds was examined.
(0 of them).

Comparative Example 1 The varnish prepared in Example 1 was coated on one side of a copper foil having a thickness of 105 μm, dried at 100 ° C. for 10 minutes, further dried at 300 ° C. for 10 minutes, and bonded to a thickness of 20 μm. A copper foil with an agent layer was obtained. When the amount of the residual solvent in the adhesive layer of the obtained copper foil with adhesive was measured, it was 0.1% or less.
Cut the obtained copper foil into 20 mm square, 0.2 mm thick
And place it on a copper lead frame at 250 ° C.
No pressure was applied when pressure was applied for 3 seconds at a pressure of MPa. Further, when pressure was applied for 3 seconds at a pressure of 3 MPa at a temperature of 350 ° C. and pressure bonding was performed, the copper foil adhered, but the copper lead frame was oxidized and discolored.

Comparative Example 2 A varnish was obtained by dissolving 25 g of the polyamideimide powder obtained in Example 2 in 75 g of tetrahydrofuran. This varnish is applied to one side of a 105 μm thick electrolytic copper foil (manufactured by Nihon Denki), dried at 100 ° C. for 6 minutes, and then at 180 ° C. for 6 minutes to form a copper foil with a 15 μm thick adhesive layer. Obtained. When the amount of the residual solvent in the adhesive layer of the obtained copper foil with an adhesive layer was measured, it was 3%. The obtained copper foil with an adhesive layer was cut into a square of 20 mm, placed on a copper lead frame having a thickness of 0.2 mm, and pressed at a temperature of 250 ° C. at a pressure of 3 MPa for 3 seconds. After bonding, the lead frame was not warped, and the adhesive layer was examined under a microscope to find no foaming. Thereafter, the semiconductor element was adhered to the adhesive layer with a silver paste, the lead and the semiconductor element were joined with a gold wire, and transfer molding was performed using an epoxy resin molding material, thereby producing a semiconductor device. 85 ° C., 85% of this resin-encapsulated semiconductor device
After absorbing moisture for 168 hours at RH, the failure rate after IR reflow at 245 ° C. for 10 seconds was examined.
(95 out of 0) was bad.

Comparative Example 3 5 g of the polyamideimide powder obtained in Example 2 was dissolved in 140 g of tetrahydrofuran, 45 g of a silicone rubber filler (Trefil E-601) was added, and mixed with a three-roll mill to obtain a varnish. This varnish was applied on one side of a copper foil having a thickness of 105 μm, dried at 100 ° C. for 6 minutes, and further dried at 160 ° C. for 6 minutes to obtain a copper foil having an adhesive layer having a thickness of 25 μm. When the amount of the residual solvent in the adhesive layer of the obtained copper foil with an adhesive layer was measured, it was 1%. The obtained copper foil with an adhesive layer was cut into a square of 20 mm, and the thickness was 0.2 mm.
When placed on a copper lead frame having a thickness of 250 mm and pressed at a temperature of 250 ° C. at a pressure of 3 MPa for 3 seconds and pressure-bonded, it was peeled off without bonding.

[0017]

The copper foil with a heat-resistant adhesive layer of the present invention is excellent in low-temperature adhesiveness and can simplify the manufacturing process for bonding a heat spreader on a lead frame. Moreover, it has excellent insulation properties and is suitable for a resin-sealed semiconductor device with a heat spreader. Further, the semiconductor device of the present invention is a semiconductor device with a heat spreader that has excellent electric characteristics and also has excellent solder reflow resistance.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yoshiyuki Tanabe 14 Goi South Coast, Ichihara City, Chiba Prefecture Inside the Goi Plant of Hitachi Chemical Co., Ltd. (72) Inventor Masashi Iioka 14 Goi Minami Coast, Ichihara City, Chiba Prefecture Inside the Goi Plant (72) Inventor Satoshi Yanagisawa 14 Goi South Coast, Ichihara-shi, Chiba

Claims (5)

[Claims] 1. One side of a copper foil having a thickness of 50 to 200 μm,
10-8 silicone rubber fillers for heat resistant resin
0% by weight, containing 0.5 to 10% by weight of an organic solvent, and at least one of aromatic polyamide, aromatic polyimide, aromatic polyamideimide, aromatic polyetheramide, aromatic polyetherimide and aromatic polyetheramideimide A copper foil with a heat-resistant adhesive layer formed with an adhesive layer of a heat-resistant resin composition containing one or more heat-resistant resins. 2. The copper foil with a heat-resistant adhesive layer according to claim 1, wherein a silicone rubber filler having an epoxy group or an amide group on the surface is used. 3. The copper foil with a heat-resistant adhesive layer according to claim 1, wherein the cross-linking agent is contained in an amount of 0.5 to 20% by weight based on the resin. 4. A lead frame with a heat sink, wherein the adhesive layer surface of the copper foil with a heat-resistant adhesive layer according to claim 1, 2 or 3 is attached to a side of the inner lead opposite to a bonding surface. 5. A semiconductor device using the lead frame with a heat sink according to claim 4.