Anti-overflow high-temperature adhesive tape for plastic package of semiconductor lead frame and preparation method of anti-overflow high-temperature adhesive tape

Abstract

The invention discloses an anti-overflow high-temperature adhesive tape for plastic package of a semiconductor lead frame and a preparation method of the anti-overflow high-temperature adhesive tape. The anti-overflow high-temperature adhesive tape comprises a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer which are sequentially laminated, the organic silicon pressure-sensitive adhesive layer comprises the following components in parts by mass: 90-50 parts of vinyl-containing methyl silicone rubber, 10-50 parts of methyl MQ resin, 0.2-10 parts of hydrogen-containing silicone oil, 0.5-2 parts of a platinum catalyst and 0.1-2 parts of a peroxide catalyst. According to the organic silicon pressure-sensitive adhesive layer, a platinum catalyst and a peroxide catalyst are added into vinyl-containing methyl silicone rubber and a hydrogen-containing silicone oil cross-linking agent, and the platinum catalyst catalyzes addition reaction cross-linking curing of vinyl and silicon-hydrogen bonds during low-temperature drying; the peroxide catalyst decomposes free radicals during high-temperature plastic packaging to initiate a cross-linking reaction between residual vinyl and methyl in the silicone rubber, so that the binding power is increased; the adhesive tape is low in normal-temperature film sticking adhesion and easy to rework, the high-temperature adhesion is increased, and glue overflowing of a sealing material is effectively prevented.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature adhesive tapes to prevent glue overflow, and in particular to a high-temperature adhesive tape to prevent glue overflow for plastic sealing of semiconductor lead frames and a preparation method thereof. Background Art

[0002] In recent years, with the promotion of large-scale integrated circuit assembly, leadless packaging (such as quad flat leadless packaging QFN, leadless frame packaging LCC) technology has attracted more and more attention in the field of semiconductor packaging in terms of miniaturization and high density. Leadless packaging is to stick a high-temperature resistant tape on the back of the package body, and then inject the sealing material through a prefabricated mold at high temperature to the side of the package body to be protected, protect the chip and bonding wires in the package body, cure the sealing material at high temperature, and finally tear off the protective tape.

[0003] As the size decreases, the size of the peripheral pins is also tending to be miniaturized and high-density, which causes the sealant to easily overflow from the peripheral pins during the high-temperature injection process. In mild cases, subsequent grinding is required, and in severe cases, the plastic-encapsulated parts will be directly scrapped. Because the metal lead frame is thin, if the protective tape is too sticky, it will be difficult to rework after filming, and insufficient stickiness of the protective tape will cause the sealant to overflow during the plastic sealing process.

[0004] In order to prevent the overflow of sealing materials during high-temperature plastic sealing, silicone pressure-sensitive tapes with good high-temperature resistance are often used as protective tapes. However, the viscosity of silicone pressure-sensitive tapes is stable, and the lower viscosity at high temperatures cannot completely prevent the overflow of sealing materials.

[0005] In view of the plastic encapsulation process without lead frames, the high temperature resistant protective tape needs to have a small adhesive force on the lead frame at room temperature, and a high adhesive force during the high temperature plastic encapsulation process to prevent the overflow of the sealing material. Because the lead frame is often very thin and easy to deform, at room temperature, too high adhesive force is not conducive to rework, and rework after filming will deform the frame; in addition, too high adhesive force at room temperature will also inhibit the discharge of gas bubbles generated during the frame filming process, and bubbles will cause the overflow of the sealing material during plastic encapsulation. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a high-temperature adhesive tape for preventing overflow of semiconductor lead frame plastic sealing and a preparation method thereof. A platinum catalyst and a peroxide catalyst are added to a vinyl-methyl silicone rubber and a hydrogen-containing silicone oil cross-linking agent, and the mixture is coated on a high-temperature resistant high-molecular polymer substrate layer. During the drying process, the platinum catalyst catalyzes the addition reaction of vinyl and silicon-hydrogen bonds, plays a cross-linking and curing role, and increases the cohesive force. During the high-temperature plastic sealing process, the peroxide catalyst decomposes free radicals, which continue to induce a cross-linking reaction between the residual vinyl and the methyl in the silicone rubber, further increasing the adhesion of the tape, thereby preventing the overflow of the sealing material during high-temperature treatment.

[0007] In order to solve the above technical problems, the first aspect of the present invention provides a high-temperature adhesive tape for preventing overflow of semiconductor lead frames for plastic sealing, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence;

[0008] In parts by mass, the organic silicone pressure-sensitive adhesive layer comprises 90-50 parts of vinyl methyl silicone rubber, 10-50 parts of methyl MQ resin, 0.2-10 parts of hydrogenated silicone oil, 0.5-2 parts of platinum catalyst, and 0.1-2 parts of peroxide catalyst.

[0009] The present invention adds a platinum catalyst and a peroxide catalyst to a vinyl-containing methyl silicone rubber and a hydrogen-containing silicone oil crosslinking agent, and after mixing, coats the mixture on a high-temperature resistant polymer substrate layer, and after drying and cooling, adheres a fluorine release film for protection to prepare a desired semiconductor lead frame plastic sealing anti-overflow high-temperature adhesive tape. Among them, the platinum catalyst catalyzes the addition reaction of vinyl and silicon-hydrogen bonds at 130-150°C under low-temperature drying conditions, and the reaction rate is fast, which plays a cross-linking and curing role and increases cohesion; while the peroxide catalyst decomposes free radicals during the high-temperature (>150°C) plastic sealing process used for semiconductor lead frame plastic sealing, and continues to induce a cross-linking reaction between the residual vinyl and the methyl in the silicone rubber. Further cross-linking reactions will increase the bonding force between the protective tape and the lead frame, thereby preventing the overflow of the sealing material.

[0010] Furthermore, the 0.1h half-life decomposition temperature T of the peroxide catalyst is: 150°C<T<240°C. The decomposition temperature T is greater than the drying temperature after the silicone pressure-sensitive adhesive layer is coated, ensuring the stability of the peroxide catalyst during the drying process, and decomposing and exerting its effect at a higher high-temperature treatment temperature of the plastic packaging material (>150°C).

[0011] Further, the peroxide catalyst is one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (156°C), di-tert-butyl peroxide (164°C), 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane (170°C), isopropyl hydroperoxide (183°C), cumene hydroperoxide (195°C), and tert-butyl hydroperoxide (207°C). The specific selection depends on the temperature of the sealing material during plastic sealing. Too low a decomposition temperature will lead to decomposition and failure of the platinum catalytic cross-linking, and the storage stability will be reduced.

[0012] Furthermore, the mass fraction of vinyl in the vinyl-methyl silicone rubber is 0.03%-0.3%, and the molecular weight of the vinyl-methyl silicone rubber is 200,000-1,000,000. Too low a vinyl content will lead to insufficient crosslinking and residual glue, while too high a vinyl content will lead to excessive crosslinking, reduced viscoelasticity, and reduced bonding strength; too low a molecular weight will lead to insufficient crosslinking, while too high a molecular weight will lead to excessively high glue viscosity when preparing the glue layer, making it difficult to construct.

[0013] Furthermore, the molecular weight of the methyl MQ resin is 2000-8000.

[0014] The mixture of vinyl methyl silicone rubber and methyl MQ resin is mainly used to adjust the bonding strength. Different mixing ratios have different bonding strengths to the adhered objects. The larger the ratio, the smaller the bonding strength. The mass ratio of vinyl methyl silicone rubber to methyl MQ resin can be 90:10 to 50:50. Too high a mass ratio will result in too low bonding strength and inability to play an initial fixing role. Too high a mass ratio will result in too high bonding strength and difficulty in rework.

[0015] Furthermore, the hydrogen content of the hydrogen-containing silicone oil is 0.05%-1.5% by mass. Too low a hydrogen content will lead to incomplete reaction, while too high a hydrogen content will lead to excessive crosslinking and reduced bonding strength.

[0016] Furthermore, the platinum catalyst is a Custer catalyst.

[0017] Furthermore, the material of the polymer substrate layer is polyethylene naphthalate or polyimide.

[0018] The second aspect of the present invention provides a method for preparing the high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to the first aspect, comprising the following steps:

[0019] S1, dissolving vinyl methyl silicone rubber, methyl MQ resin, hydrogen-containing silicone oil, platinum catalyst and peroxide catalyst in an organic solvent to obtain an organic silicone pressure-sensitive adhesive layer coating liquid;

[0020] S2, coating the coating liquid on the polymer substrate layer through a coating process, drying and curing in an oven, cooling, and then laminating a fluorine release film on the silicone pressure-sensitive adhesive layer to obtain an anti-overflow high-temperature adhesive tape for semiconductor lead frame plastic sealing;

[0021] Wherein, the polymer film is subjected to corona treatment on the side to be coated before coating, and the corona surface dyne value is greater than 58.

[0022] Further, in S2, the oven is sequentially provided with temperature zones of 70°C, 100°C, 140°C, 150°C, 120°C, and 60°C, and each temperature zone is 2±0.2 m long;

[0023] And / or, the coating rate is 3±0.5 m / min.

[0024] Furthermore, the solvent is toluene or xylene.

[0025] Beneficial effects of the present invention:

[0026] The organic silicon pressure-sensitive adhesive layer of the present invention is prepared by adding a platinum catalyst and a peroxide catalyst to a vinyl-methyl silicone rubber and a hydrogen-containing silicone oil crosslinking agent. The platinum catalyst catalyzes the addition reaction of vinyl and silicon-hydrogen bonds at 130-150° C. under low-temperature drying conditions, and the reaction rate is fast, so it plays a crosslinking and curing role and increases the cohesive force. The peroxide catalyst decomposes free radicals during the high-temperature (>150° C.) plastic sealing process used for semiconductor lead frame plastic sealing, and continues to induce a crosslinking reaction between the residual vinyl and the methyl in the silicone rubber. Further crosslinking reaction will increase the bonding force between the protective tape and the lead frame, thereby preventing the overflow of the sealing material.

[0027] The anti-overflow high-temperature adhesive tape of the present invention has low adhesive force at room temperature, and is convenient to tear off and rework after being pasted on the frame without causing deformation of the frame; at the same time, under high temperature conditions, the adhesive force with the lead frame is increased, effectively preventing the overflow of the sealant. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of the high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames of the present invention;

[0030] Explanation of the numbers in the figure: 1. Fluorine release film, 2. Silicone pressure-sensitive adhesive layer, 3. Polymer substrate layer. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] This embodiment relates to a high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames, Figure 1 As shown, it comprises a fluorine release film 1, an organic silicon pressure-sensitive adhesive layer 2 and a polymer substrate layer 3 which are sequentially stacked. The preparation method of the high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames comprises the following steps:

[0034] (1) 80 parts of vinyl methyl silicone rubber XB-601 (Guangzhou Sibo Chemical Technology Co., Ltd.), 20 parts of methyl MQ resin SH-5201P (Hubei Longsheng Sihai Co., Ltd.), 2 parts of hydrogen-containing silicone oil RH-H23 (hydrogen content 0.42%, Zhejiang Runhe Silicone New Material Co., Ltd.), 1 part of platinum catalyst Q339 (Shenzhen Tyco Technology Co., Ltd.), 0.5 parts of di-tert-butyl peroxide, and 250 parts of xylene were weighed and mixed, and after stirring to completely dissolve, a solution with a solid content of 30% was prepared and used as a coating solution for standby;

[0035] (2) corona treating the polyimide base film until the corona value is 60, coating the coating liquid prepared in step (1) on the corona surface of the polyimide base film by micro-dimpled coating at a speed of 3 m / min, the coating adhesive layer thickness is 10 um, and drying in an oven to obtain an organic silicone pressure-sensitive adhesive layer, wherein the oven temperatures from front to back are 70° C., 100° C., 140° C., 150° C., 120° C., and 60° C., respectively, and each oven zone is 2 m long;

[0036] (3) A fluorine release film is attached to the adhesive layer of the tape obtained in step (2), and the tape is rolled up to obtain a two-component curing high-temperature tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames.

[0037] Example 2

[0038] This embodiment relates to an anti-overflow high-temperature adhesive tape for semiconductor lead frame plastic sealing, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the anti-overflow high-temperature adhesive tape and that of Example 1 is that the addition amount of the vinyl methyl silicone rubber is adjusted to 60 parts, the addition amount of the methyl MQ resin is adjusted to 40 parts, and the other parameters and steps remain unchanged.

[0039] Example 3

[0040] This embodiment relates to an anti-overflow high-temperature adhesive tape for semiconductor lead frame plastic sealing, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the anti-overflow high-temperature adhesive tape and that of embodiment 1 is that the peroxide catalyst is adjusted to isopropyl hydroperoxide, and other parameters and steps remain unchanged.

[0041] Example 4

[0042] This embodiment relates to an anti-overflow high-temperature adhesive tape for semiconductor lead frame plastic sealing, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the anti-overflow high-temperature adhesive tape and that of Example 1 is that the addition amount of hydrogen-containing silicone oil is adjusted to 0.7 parts, and hydrogen-containing silicone oil RH-H512 (hydrogen content 1.2%) is used, and other parameters and steps remain unchanged.

[0043] Comparative Example 1

[0044] This comparative example relates to a semiconductor lead frame plastic sealing tape, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the tape and Example 1 is that no peroxide catalyst is added, and other parameters and steps remain unchanged.

[0045] Comparative Example 2

[0046] This comparative example relates to a semiconductor lead frame plastic sealing tape, comprising a fluorine release film, a silicone pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the tape and Example 1 is that no platinum catalyst is added, and other parameters and steps remain unchanged.

[0047] Comparative Example 3

[0048] This comparative example relates to an adhesive tape for plastic sealing of semiconductor lead frames, comprising a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer stacked in sequence. The difference between the preparation method of the adhesive tape and that of Example 1 is that the addition amount of the vinyl methyl silicone rubber is adjusted to 40 parts, the addition amount of the methyl MQ resin is adjusted to 60 parts, and the other parameters and steps remain unchanged.

[0049] Test Case

[0050] The tapes prepared in Examples 1-4 and Comparative Examples 1-3 were attached to the surface of a copper plate made of the same material as the frame, and the 180° peel force was tested at room temperature to indicate the adhesion of the tape to the frame; specifically, the prepared tapes were attached to an unpunched copper plate made of the same material as the lead frame (made of CW-003A), and the 180° peel force was tested using an electronic tensile testing machine at a temperature of 25°C±1°C and a humidity of 50%±5%.

[0051] Test the peeling force at the high temperature curing sealant plastic sealing temperature to indicate the adhesive force of the tape to the frame at high temperature; specifically: stick the prepared tape on the unpunched copper plate of the same material as the lead frame (material is CW-003A), place it in an environment of 180°C for 5 minutes (simulating the temperature and time of the sealant plastic sealing), and then use a high temperature electronic tensile machine to test the 180° peeling force at 180°C. At the same time, test the normal temperature peeling force after 180°C treatment: stick the prepared tape on the unpunched copper plate of the same material as the lead frame (material is CW-003A), place it in an environment of 180°C for 5 minutes (simulating the temperature and time of the sealant plastic sealing), and then use an electronic tensile machine to test the 180° peeling force at a temperature of 25°C±1°C and a humidity of 50%±5%.

[0052] The prepared tape is attached to the semiconductor lead frame to be plastic-sealed and plastic-sealed. After the plastic sealing is completed, whether there is glue overflow under a 100x optical microscope, that is, whether the plastic sealing material overflows to the side of the adhesive tape.

[0053] The room temperature peeling force of the lead frame plastic sealing refers to the 180° peeling force value of the tape tested by an electronic tensile testing machine after the plastic sealing is completed. The peeling force value is used to indicate the difficulty of tearing off the tape.

[0054] The test of the difficulty of removing the tape is to see whether it is easy to peel off the tape after the plastic sealing is completed.

[0055] The test method for the contamination of the frame after the tape is removed is to peel off the tape after the plastic packaging is completed, and observe whether there is any adhesive layer residue on the frame surface in contact with the tape under an 8x optical microscope.

[0056] The test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] It can be seen from Table 1 that the anti-overflow high-temperature tapes prepared in Examples 1-4 of the present invention did not have any overflowing glue phenomenon during the plastic packaging process, and the tapes were easy to remove, and there was no residual glue pollution on the surface of the lead frame after removal.

[0060] From the comparison between Comparative Example 1 and Example 1, it can be seen that no peroxide catalyst is added in Comparative Example 1, the adhesive force between the tape and the adhered object is poor at high temperature, and the peeling force at 180° C. is only 3 gf / cm, resulting in overflow.

[0061] From the comparison between Comparative Example 2 and Example 1, it can be seen that no platinum catalyst was added in Comparative Example 2, and no cross-linking reaction occurred in the adhesive layer during the coating process of preparing the tape, resulting in poor cohesion between the adhesive layers, resulting in residual adhesive when peeling at room temperature and overflow during plastic sealing.

[0062] From the comparison between Comparative Example 3 and Example 1, it can be seen that the ratio of methyl MQ resin to vinyl-containing silicone rubber is increased in Comparative Example 3, resulting in an increase in the peeling force, making it difficult to remove the tape after plastic sealing.

[0063] In summary, the organic silicone pressure-sensitive adhesive layer of the present invention adds a platinum catalyst and a peroxide catalyst to the vinyl-methyl silicone rubber and the hydrogen-containing silicone oil crosslinking agent. The platinum catalyst catalyzes the addition reaction of the vinyl group and the silicon-hydrogen bond at 130-150° C. under low-temperature drying conditions, and the reaction rate is fast, which plays a cross-linking and curing role and increases the cohesive force; while the peroxide catalyst decomposes free radicals during the high-temperature (>150° C.) plastic sealing process used for semiconductor lead frame plastic sealing, and continues to induce a cross-linking reaction between the residual vinyl group and the methyl group in the silicone rubber. Further cross-linking reaction will increase the bonding force between the protective tape and the lead frame, thereby preventing the overflow of the sealing material; the adhesive force of the tape at room temperature is low, and it is convenient to tear off and rework after pasting the frame, and will not cause deformation of the frame; at the same time, under high temperature conditions, the bonding force with the lead frame is increased, effectively preventing the overflow of the sealing material.

[0064] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames, characterized in that: It includes a fluorine release film, an organic silicon pressure-sensitive adhesive layer and a polymer substrate layer which are sequentially stacked; In parts by mass, the organic silicone pressure-sensitive adhesive layer comprises 90-50 parts of vinyl methyl silicone rubber, 10-50 parts of methyl MQ resin, 0.2-10 parts of hydrogenated silicone oil, 0.5-2 parts of platinum catalyst, and 0.1-2 parts of peroxide catalyst.

2. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 1, characterized in that: The 0.1h half-life decomposition temperature T of the peroxide catalyst is: 150°C<T<240°C.

3. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frame according to claim 2, characterized in that: The peroxide catalyst is one or more of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, di-tert-butyl peroxide, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxynonane, isopropyl hydroperoxide, cumene hydroperoxide, and tert-butyl hydroperoxide.

4. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 1, characterized in that: The mass fraction of vinyl in the vinyl methyl silicone rubber is 0.03%-0.3%, and the molecular weight of the vinyl methyl silicone rubber is 200,000-1,000,000.

5. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frame according to claim 1, characterized in that: The molecular weight of the methyl MQ resin is 2000-8000.

6. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 1, characterized in that: The mass percentage of hydrogen in the hydrogen-containing silicone oil is 0.05%-1.5%.

7. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 1, characterized in that: The platinum catalyst is a Custer catalyst.

8. The high temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 1, characterized in that: The material of the polymer substrate layer is polyethylene naphthalate or polyimide.

9. A method for preparing the high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to any one of claims 1 to 8, characterized in that: The steps include: S1, dissolving vinyl methyl silicone rubber, methyl MQ resin, hydrogen-containing silicone oil, platinum catalyst and peroxide catalyst in an organic solvent to obtain an organic silicone pressure-sensitive adhesive layer coating liquid; S2, coating the coating liquid on the polymer substrate layer through a coating process, drying and curing in an oven, cooling, and then laminating a fluorine release film on the silicone pressure-sensitive adhesive layer to obtain an anti-overflow high-temperature adhesive tape for semiconductor lead frame plastic sealing; Wherein, the polymer film is subjected to corona treatment on the side to be coated before coating, and the corona surface dyne value is greater than 58.

10. The method for preparing the high-temperature adhesive tape for preventing overflow of adhesive for plastic sealing of semiconductor lead frames according to claim 9, characterized in that: In S2, the oven is sequentially provided with temperature zones of 70°C, 100°C, 140°C, 150°C, 120°C, and 60°C, and each temperature zone is 2±0.2 m long; And / or, the coating rate is 3±0.5 m / min.

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