Low-silicon migration adhesive tape for plastic package of semiconductor lead frame and preparation method of low-silicon migration adhesive tape

Abstract

The invention discloses a low-silicon migration adhesive tape for plastic package of a semiconductor lead frame and a preparation method of the low-silicon migration adhesive tape. The low-silicon migration adhesive tape comprises a polymer base material layer, an organic silicon pressure-sensitive adhesive layer and a fluorine release film layer which are sequentially laminated, the organic silicon pressure-sensitive adhesive layer comprises the following components in parts by mass: 90-60 parts of vinyl-containing silicone rubber, 10-40 parts of vinyl-containing MQ resin, 1-20 parts of hydrogen-containing silicone oil and 0.2-2 parts of a platinum catalyst. The organic silicon pressure-sensitive adhesive layer adopts high-molecular-weight vinyl-containing silicone rubber, vinyl-containing MQ resin and low-hydrogen-content hydrogen-containing silicone oil, and the hydrogen-containing silicone oil reacts with the vinyl-containing silicone rubber and the vinyl-containing MQ resin at the same time in the drying process to form the organic silicon pressure-sensitive adhesive layer with a net structure. Organic silicon micromolecule migration of the protective adhesive tape during high-temperature treatment of the epoxy sealing material is avoided; and after the adhesive tape is torn off, the subsequent process can be carried out without cleaning by a chemical reagent, so that the operation steps are simplified, and the working efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of protective tapes, and in particular to a low silicon migration tape for plastic sealing of semiconductor lead frames and a preparation method thereof. Background Art

[0002] Leadless packaging (such as QFN, LCC) technology is gaining 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, inject the epoxy sealant that protects the chip and metal bonding wires through the prefabricated mold cavity into the surface of the lead frame to be packaged at high temperature, and then remove the protective tape after sealing is completed, thus completing the entire sealing process.

[0003] Epoxy sealants need to be sealed at high temperatures, and high-temperature resistant silicone pressure-sensitive tapes are often selected as protective tapes. The silicone pressure-sensitive tapes in the prior art often use methyl MQ resin as a toughening agent, but its molecular weight is relatively low. When treated at high temperatures, the small silicone molecules in the silicone tape often migrate to the protected lead frame metal and the surface of the epoxy sealant after sealing, thereby reducing the surface energy of the lead frame, thereby affecting the reflow soldering in the subsequent process.

[0004] In the prior art, the lead frame after packaging is often cleaned with chemical reagents to remove residual small molecular silicone. However, the chemical reagents used in the cleaning process will cause environmental pollution and damage the epoxy resin of the sealing material, affecting the sealing effect. Summary of the invention

[0005] The present invention aims at the deficiencies in the prior art and provides a low silicon migration adhesive tape for semiconductor lead frame plastic sealing and a preparation method thereof. A cross-linking agent low hydrogen silicone oil and a platinum catalyst are added to high molecular weight vinyl silicone rubber and vinyl MQ resin, and the mixture is coated on a high temperature resistant polymer substrate layer. During the drying process, the hydrogen silicone oil reacts with the vinyl silicone rubber and the vinyl MQ resin simultaneously to form an organic silicon pressure-sensitive adhesive layer with a mesh structure, which not only avoids the occurrence of organic silicon small molecule migration, but also maintains the viscoelasticity of the prepared organic silicon pressure-sensitive adhesive layer. After the metal lead frame is sealed, the subsequent process can be carried out without the need for chemical reagent cleaning.

[0006] In order to solve the above technical problems, the present invention provides a low silicon migration tape for semiconductor lead frame plastic sealing, comprising a polymer substrate layer, an organic silicon pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence;

[0007] In parts by mass, the organic silicone pressure-sensitive adhesive layer comprises 90-60 parts of vinyl-containing silicone rubber, 10-40 parts of vinyl-containing MQ resin, 1-20 parts of hydrogen-containing silicone oil and 0.2-2 parts of platinum catalyst.

[0008] The present invention adds cross-linking agent low hydrogen content hydrogen-containing silicone oil and platinum catalyst to high molecular weight vinyl-containing silicone rubber and vinyl-containing MQ resin, mixes to form a coating liquid, and then applies it to a high temperature resistant high molecular polymer substrate layer. After drying and curing, a fluorine release film is attached to the silicone pressure-sensitive adhesive layer for protection to prepare a low silicon migration tape. In the drying process, under the action of the platinum catalyst, the cross-linking agent low hydrogen content hydrogen-containing silicone oil reacts with the vinyl-containing silicone rubber and the vinyl-containing MQ resin at the same time to form a silicone pressure-sensitive adhesive layer with a mesh structure, thereby avoiding the migration of small silicone molecules when the protective tape is subjected to high temperature treatment of the epoxy sealant, and maintaining the viscoelasticity of the silicone pressure-sensitive adhesive layer. The problem of using methyl MQ resin as a toughening agent in the silicone pressure-sensitive adhesive layer in the prior art is avoided, which is very likely to cause the migration of small silicone molecules due to the low molecular weight. After the metal lead frame is sealed and torn off, the protective tape of the present invention can be processed in the subsequent process without the need for chemical reagent cleaning, thereby improving work efficiency and simplifying operation steps. At the same time, the present invention adopts high molecular weight vinyl-containing silicone rubber to increase the degree of cross-linking, and after the protective tape is torn off, it is not easy to cause residual glue.

[0009] Furthermore, the mass fraction of vinyl in the vinyl-containing silicone rubber is 0.03%-0.2%, and the molecular weight of the vinyl-containing silicone rubber is 500,000-1,000,000. Too low a vinyl content will result in insufficient crosslinking and easy occurrence of residual adhesive, while too high a vinyl content will result in excessive crosslinking and reduced viscoelasticity; too low a molecular weight will easily result in migration of small molecules of organic silicon, while too high a molecular weight will result in excessively high viscosity of the adhesive when preparing an organic silicon pressure-sensitive adhesive layer, making construction difficult.

[0010] Furthermore, the mass fraction of vinyl in the vinyl-containing MQ resin is 0.2%-5%, and the molecular weight of the vinyl-containing MQ resin is 2000-8000. Too low vinyl content will lead to insufficient crosslinking and easy silicone migration, while too high vinyl content will lead to too high crosslinking degree and loss of viscoelasticity.

[0011] Furthermore, the hydrogen content of the hydrogen-containing silicone oil is 0.02%-0.8%. Too low a hydrogen content will result in an incomplete reaction, while too high a hydrogen content will result in excessive crosslinking and the adhesive layer will easily lose its viscoelasticity. The silicon-hydrogen bonds in the hydrogen-containing silicone oil are located at the end group, the side group or the end-side group.

[0012] Furthermore, the platinum catalyst is a Custer catalyst, and the platinum content in the catalyst is 2000ppm-5000ppm, for example: 2000ppm, 3000ppm, 4000ppm, 5000ppm, etc., including but not limited to these.

[0013] Furthermore, the material of the polymer substrate layer is polyethylene naphthalate or polyimide.

[0014] The second aspect of the present invention provides a method for preparing the low silicon migration tape for semiconductor lead frame plastic sealing according to the first aspect, comprising the following steps:

[0015] S1, mixing and dissolving vinyl-containing silicone rubber, vinyl-containing MQ resin, hydrogen-containing silicone oil and platinum catalyst in an organic solvent to obtain an organic silicone pressure-sensitive adhesive layer coating liquid;

[0016] S2. The coating liquid is coated on the polymer film by a coating process, and after being placed in an oven for drying and curing and cooling, a fluorine release film is attached to the silicone pressure-sensitive adhesive layer to obtain a low-silicon migration tape for plastic sealing of semiconductor lead frames.

[0017] Furthermore, 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.

[0018] Furthermore, in S2, the coating rate is 3±0.5 m / min.

[0019] Further, in S2, temperature zones of 70°C, 100°C, 140°C, 150°C, 120°C, and 60°C are sequentially arranged in the oven, and each temperature zone is 2±0.2 m long.

[0020] Furthermore, the solvent is toluene or xylene.

[0021] Beneficial effects of the present invention:

[0022] The organic silicon pressure-sensitive adhesive layer of the present invention adopts high molecular weight vinyl-containing silicone rubber, vinyl-containing MQ resin, low hydrogen-containing silicone oil and platinum catalyst. During the drying process, the low hydrogen-containing silicone oil reacts with the vinyl-containing silicone rubber and the vinyl-containing MQ resin simultaneously to form an organic silicon pressure-sensitive adhesive layer with a network structure, thereby avoiding the migration of small organic silicon molecules in the adhesive tape when the epoxy sealant is subjected to high-temperature treatment, and maintaining the viscoelasticity of the organic silicon pressure-sensitive adhesive layer.

[0023] After the metal lead frame is sealed and torn off, the adhesive tape of the present invention can be used for subsequent processes without the need for cleaning with chemical reagents, thereby improving work efficiency and simplifying operation steps.

[0024] The invention adopts high molecular weight vinyl-containing silicone rubber to increase the cross-linking degree, and after the protective tape is torn off, it is not easy to have residual adhesive. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 It is a schematic structural diagram of a low silicon migration tape for plastic sealing of a semiconductor lead frame of the present invention;

[0027] Explanation of the numbers in the figure: 1. Fluorine release film layer, 2. Silicone pressure-sensitive adhesive layer, 3. Polymer substrate layer. DETAILED DESCRIPTION

[0028] 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.

[0029] Example 1

[0030] This embodiment relates to a low silicon migration protective tape for semiconductor lead frame plastic packaging, referring to Figure 1 As shown, it comprises a polymer substrate layer 3, a silicone pressure-sensitive adhesive layer 2 and a fluorine release film layer 1 which are sequentially stacked. The preparation method of the protective tape comprises the following steps:

[0031] (1) 90 parts of vinyl-containing silicone rubber (vinyl content 0.1 wt%, weight average molecular weight 800,000), 10 parts of vinyl-containing MQ resin (vinyl content 1.3 wt%), 8 parts of hydrogen-containing silicone oil (hydrogen content 0.2 wt%), 1 part of platinum catalyst (Castell catalyst, platinum content 3000 ppm), and 250 parts of xylene were weighed and mixed, stirred until completely dissolved, and a solution with a solid content of 30% was prepared as a coating solution for standby use;

[0032] (2) corona treating the polyimide base film until the corona value is 60, coating the solution prepared in step (1) on the corona surface of the polyimide base film by micro-concave coating at a speed of 3 m / min, and the coating thickness is 10 μm, and drying in an oven, wherein the temperatures of the ovens 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;

[0033] (3) After cooling, a fluorine release film is attached to the adhesive layer of the protective tape obtained in step (2), and the tape is rolled up to obtain a two-component curing low silicon migration protective tape for plastic sealing of semiconductor lead frames.

[0034] Example 2

[0035] This embodiment relates to a low silicon migration protective tape for semiconductor lead frame plastic sealing, comprising a polymer substrate layer, a silicone pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the addition amount of vinyl-containing silicone rubber is adjusted to 70 parts, the addition amount of vinyl-containing MQ resin is adjusted to 30 parts, and the addition amount of hydrogen-containing silicone oil is adjusted to 16 parts, and other steps and parameters remain unchanged.

[0036] Example 3

[0037] This embodiment relates to a low silicon migration protective tape for semiconductor lead frame plastic packaging, comprising a polymer substrate layer, an organic silicon pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the vinyl content of the vinyl-containing MQ resin is 1wt%, and the other steps and parameters remain unchanged.

[0038] Example 4

[0039] This embodiment relates to a low silicon migration protective tape for semiconductor lead frame plastic sealing, comprising a polymer substrate layer, a silicone pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the addition amount of hydrogen-containing silicone oil is adjusted to 4 parts, and the hydrogen content of the hydrogen-containing silicone oil is adjusted to 0.4wt%, and the other steps and parameters remain unchanged.

[0040] Comparative Example 1

[0041] The comparative example relates to a protective tape for plastic sealing of semiconductor lead frames, comprising a polymer substrate layer, a silicone pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the vinyl-containing MQ resin is replaced by a methyl MQ resin, and the other steps and parameters remain unchanged.

[0042] Comparative Example 2

[0043] The comparative example relates to a protective tape for plastic sealing of semiconductor lead frames, comprising a polymer substrate layer, an organic silicon pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the hydrogen content of the hydrogen-containing silicone oil is 1.2wt%, and the other steps and parameters remain unchanged.

[0044] Comparative Example 3

[0045] The comparative example relates to a protective tape for plastic sealing of semiconductor lead frames, comprising a polymer substrate layer, a silicone pressure-sensitive adhesive layer and a fluorine release film layer stacked in sequence. The difference between the preparation method of the protective tape and that of Example 1 is that the addition amount of the vinyl-containing silicone rubber is adjusted to 50 parts, the addition amount of the vinyl-containing MQ resin is adjusted to 50 parts, and the addition amount of the hydrogen-containing silicone oil is adjusted to 25 parts, and the other steps and parameters remain unchanged.

[0046] Test Case

[0047] The protective tapes prepared in Examples 1-4 and Comparative Examples 1-3 were attached to the surface of a copper plate of the same material as the frame to perform a 180° peel test to measure the peel strength at room temperature, which is used to indicate the adhesive force of the tape to the frame. The specific steps are as follows: attach the prepared protective tape to an unpunched copper plate (made of CW-003A), and test the 180° peel strength using an electronic tensile tester at a temperature of 25°C ± 1°C and a humidity of 50% ± 5%.

[0048] The protective tape was attached to the lead frame, and the lead frame was molded with epoxy molding compound. After molding, it was baked and matured at 180°C for 6 hours. After the end, it was cooled to room temperature, and the protective tape was torn off for the following tests: Observe whether the sealing material overflowed to the side of the tape under a 100x microscope; test the dyne value of the tape side of the lead frame, and the dyne value is used to indicate the amount of organic silicon small molecules transferred on the frame surface; observe whether there is any glue layer residue on the frame surface in contact with the tape under an 8x optical microscope. The results are shown in Table 1.

[0049] Table 1

[0050]

[0051] As can be seen from Table 1, the protective tapes prepared in Examples 1-4 of the present invention did not have any glue overflow during the sealing process of the sealant, and there was no residual glue pollution on the surface of the lead frame after the protective tape was removed, and the dyne value met the requirements of the subsequent process.

[0052] From the comparison between Comparative Example 1 and Example 1, it can be seen that methyl MQ resin is used in Comparative Example 1. Since methyl MQ resin does not participate in the cross-linking reaction with hydrogen-containing silicone oil, when the sealing material is treated at high temperature, small molecular silicone in the organic pressure-sensitive adhesive layer of the protective tape migrates, resulting in a low dyne value on the surface of the frame; at the same time, the degree of cross-linking in Comparative Document 1 is insufficient, resulting in residual glue after the protective tape is removed.

[0053] From the comparison between Comparative Example 2 and Example 1, it can be seen that the use of high hydrogen-containing silicone oil as a cross-linking agent in Comparative Example 2 results in excessively high cross-linking, reduced viscoelasticity of the silicone pressure-sensitive adhesive layer, significantly reduced peel force, and thus sealant overflow.

[0054] From the comparison between Comparative Example 3 and Example 1, it can be seen that the content of vinyl MQ resin in Comparative Example 3 is too high, resulting in excessive crosslinking. Similar to Comparative Example 2, it also leads to reduced viscoelasticity of the silicone pressure-sensitive adhesive layer and a significant reduction in peel force, resulting in overflow of the sealing material.

[0055] In summary, the present invention adds cross-linking agent low hydrogen content hydrogen-containing silicone oil and platinum catalyst to high molecular weight vinyl-containing silicone rubber and vinyl-containing MQ resin, mixes to form a coating liquid, and then applies it to a high temperature resistant polymer substrate layer. After drying and curing, a fluorine release film is attached to the silicone pressure-sensitive adhesive layer for protection to prepare a low silicon migration protective tape. In the drying process, under the action of the platinum catalyst, the cross-linking agent low hydrogen content hydrogen-containing silicone oil reacts with the vinyl-containing silicone rubber and the vinyl-containing MQ resin at the same time to form a silicone pressure-sensitive adhesive layer with a mesh structure, thereby avoiding the migration of small silicone molecules when the protective tape is subjected to high temperature treatment of the epoxy sealant, and maintaining the viscoelasticity of the silicone pressure-sensitive adhesive layer. The problem of using methyl MQ resin as a toughening agent in the silicone pressure-sensitive adhesive layer in the prior art is avoided, which is very likely to cause the migration of small silicone molecules due to the low molecular weight. After the metal lead frame is sealed and torn off, the protective tape of the present invention can be processed in the subsequent process without the need for chemical reagent cleaning, thereby improving work efficiency and simplifying the operating steps. At the same time, the present invention adopts high molecular weight vinyl-containing silicone rubber to increase the degree of cross-linking, and after the protective tape is torn off, it is not easy to cause residual glue.

[0056] 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 low silicon migration tape for semiconductor lead frame plastic sealing, characterized in that: It comprises a polymer substrate layer, an organic silicon pressure-sensitive adhesive layer and a fluorine release film layer which are sequentially stacked; In parts by mass, the organic silicone pressure-sensitive adhesive layer comprises 90-60 parts of vinyl-containing silicone rubber, 10-40 parts of vinyl-containing MQ resin, 1-20 parts of hydrogen-containing silicone oil and 0.2-2 parts of platinum catalyst.

2. The low silicon migration tape for semiconductor lead frame plastic sealing according to claim 1, characterized in that: The mass fraction of vinyl in the vinyl-containing silicone rubber is 0.03%-0.2%, and the molecular weight of the vinyl-containing silicone rubber is 500,000-1,000,000.

3. The low silicon migration tape for semiconductor lead frame plastic sealing according to claim 1, characterized in that: The mass fraction of vinyl in the vinyl-containing MQ resin is 0.2%-5%, and the molecular weight of the vinyl-containing MQ resin is 2000-8000.

4. The low silicon migration tape for semiconductor lead frame plastic sealing according to claim 1, characterized in that: The hydrogen content of the hydrogen-containing silicone oil is 0.02%-0.8% by mass.

5. The low silicon migration tape for semiconductor lead frame plastic sealing as claimed in claim 1, characterized in that: The platinum catalyst is a Custer catalyst, and the platinum content in the catalyst is 2000ppm-5000ppm.

6. The low silicon migration tape for semiconductor lead frame plastic sealing as claimed in claim 1, characterized in that: The material of the polymer substrate layer is polyethylene naphthalate or polyimide.

7. A method for preparing the low silicon migration tape for semiconductor lead frame plastic sealing according to any one of claims 1 to 6, characterized in that: The steps include: S1, mixing and dissolving vinyl-containing silicone rubber, vinyl-containing MQ resin, hydrogen-containing silicone oil and platinum catalyst in an organic solvent to obtain an organic silicone pressure-sensitive adhesive layer coating liquid; S2. The coating liquid is coated on the polymer film by a coating process, and after being placed in an oven for drying and curing and cooling, a fluorine release film is attached to the silicone pressure-sensitive adhesive layer to obtain a low-silicon migration tape for plastic sealing of semiconductor lead frames.

8. The method for preparing the low silicon migration tape for semiconductor lead frame plastic sealing according to claim 7, characterized in that: 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.

9. The method for preparing the low silicon migration tape for semiconductor lead frame plastic sealing according to claim 7, characterized in that: In S2, the coating rate is 3±0.5 m / min.

10. The method for preparing the low silicon migration tape for semiconductor lead frame plastic sealing according to claim 7, characterized in that: In S2, temperature zones of 70°C, 100°C, 140°C, 150°C, 120°C, and 60°C are sequentially arranged in the oven, and each temperature zone is 2±0.2 m long.

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