KR102313245B1 - Masking tape for semiconductor packaging - Google Patents

Abstract

A masking tape for a semiconductor package of the present invention has a structure in which a first pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer and a base film are stacked on top of each other sequentially. The first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer are pressure-sensitive adhesive layers comprising a thermoplastic polyimide, having a structure in which two different pressure-sensitive adhesive layers are stacked on top of each other, wherein the glass transition temperature of the first pressure-sensitive adhesive layer is lower than that of the second pressure-sensitive adhesive layer. Therefore, the masking tape for a semiconductor package of the present invention is capable of exhibiting high adhesive strength and excellent wire bonding properties at the same time.

Description

Masking tape for semiconductor package {MASKING TAPE FOR SEMICONDUCTOR PACKAGING}

The present invention relates to a masking tape used for semiconductor packaging, and more specifically, to a QFN (Quad Flat No-lead semiconductor package) semiconductor packaging that can maintain excellent wire bondability while having high adhesion during high-temperature lamination. It relates to a masking tape for semiconductor packages.

In general, a semiconductor device is composed of a semiconductor chip (Chip, IC), a motherboard (Mother Board), and various wiring boards for connecting the two accessory devices. Typically, the semiconductor chip is connected to the motherboard. It is either directly attached to the substrate before it becomes a semiconductor package, or after assembly with the substrate in the form of a semiconductor package, it undergoes a process of being connected to the motherboard.

The semiconductor technology led by the personal computer (PC) for the past few decades has mainly focused on the integration of semiconductor circuits. The technology is concentrating on improving the degree of integration by miniaturization and thinning of the semiconductor package, and the manufacturing process of the semiconductor device for this purpose is also continuously changing.

For example, light, thin, compact and high value-added packaging technologies such as QFN, Stacked CSP, WLP, Flip Chip Bare Die, Fine-Pitch BGA, MCP, and MIS package are expected to lead the market in the future. Among them, QFN (Quad Flat Non-lead Package) is a type of CSP (Chip Scale Package), and its small size reduces the connection area on the board and enables a large number of payloads, thereby maximizing the space of the motherboard. However, since the packaging process must be performed in a state in which the electrical connection part is exposed at the lower part of the structure, a process of masking the exposed part with an adhesive sheet in the manufacturing process is essential.

A method of manufacturing such a QFN semiconductor package is schematically performed in the following order. After attaching a masking tape to one side of the lead frame, the semiconductor chips are individually mounted on the semiconductor device mounting portions (die pads, or lead pads) formed on the lead frame, and the leads arranged around each semiconductor chip mounting portion of the lead frame and the semiconductor chip are electrically connected by bonding wires. Then, after sealing the semiconductor chip mounted on the lead frame with an encapsulating resin, the adhesive sheet is peeled off from the lead frame to form a QFN unit in which QFN packages are arranged. Thereafter, individual QFN semiconductor packages are manufactured by sawing the QFN units along the outer periphery of each QFN package.

As for the masking tape used in the QFN semiconductor packaging process as described above, in response to the high-temperature lamination process, the masking tape must be in close contact with the lead frame without forming bubbles, and excellent die adhesion and wire bonding properties are required. During the temperature and time in the process, the masking tape should not physically and/or chemically change and denature.

A conventional masking tape used to manufacture a QFN semiconductor package is a room temperature adhesive tape attached to a lead frame at room temperature (20 to 35° C.) depending on the physical and chemical properties of the pressure-sensitive adhesive layer or the adhesive layer provided on the tape, or A heat-adhesive tape that is attached to a lead frame by applying an arbitrary temperature (170° C. or higher) in a state where it is temporarily bonded to the lead frame is known.

Conventionally known adhesive components of room temperature pressure-sensitive adhesive tapes include acrylic, silicone, etc., and heat-adhesive tape adhesive components include thermosetting resins or thermoplastic resins, mainly epoxy-based, polyimide-based, and epoxy-rubber. compounding system, siloxane-imide compounding system, and the like. However, the room temperature adhesive tape can be easily attached to the lead frame due to the pressure sensitive characteristics of the adhesive layer, but due to the lack of holding power and elastic modulus at high temperature, thermocompression during wire bonding. Dispersing the strength reduces the bonding strength of the wire, and there is a risk that the sealing resin may easily leak during the encapsulation process. In addition, there is a problem that the semiconductor device is seriously contaminated by cohesive failure and failure to withstand the deterioration caused by the thermal history of the high-temperature process. fundamentally unresolved. On the other hand, the heat-adhesive tape has relatively high glass transition temperature (hereinafter, Tg), cohesive force, and elastic modulus compared to the room-temperature adhesive tape, and thus has been proposed as a masking tape suitable for the high-temperature process of the QFN package manufacturing process.

For example, Korean Patent Application Laid-Open No. 2002-0060143 proposes a mask sheet that improves the disadvantages of a room temperature adhesive tape and includes a polyimide resin on the substrate, which has less leakage of the encapsulant and has excellent wire bonding properties. did. However, when initially attaching the lead frame and the sheet, it is not adhered to the lead frame or the wiring board at room temperature, so it is necessary to implement strong adhesion through heat treatment in the lamination process, and in this process, There is a problem that alignment defects are easy to occur due to the difference in thermal expansion coefficient of metal/plastic), which disperses the bonding strength during wire bonding, thereby reducing bonding reliability and still causing leakage of the encapsulant during the encapsulation process. .

In order to improve this problem, Korean Patent Laid-Open Publication No. 2013-0113377 discloses a method of modifying a polyimide resin or appropriately mixing other components in order to lower the glass transition temperature (Tg) of the heated adhesive sheet, through a method of heating type adhesion. It is said that the problem can be solved by lowering the bonding temperature of the sheet, but in this case, the reliability problem of wire bonding due to softening of the sheet during wire bonding at high temperature as in room temperature adhesive sheets remains, and the same For this reason, it is difficult to solve the leakage of the encapsulation resin in the encapsulation process for protecting the semiconductor chip.

In addition, in Korea Patent Laid-Open Publication No. 2013-0109070, in the process of laminating a heat-adhesive sheet to a lead frame, it is first easily bonded at a low temperature and then naturally goes through a high-temperature process between the lead frame and the heat-adhesive sheet. The mask sheet which can reduce the leakage of sealing resin by aiming at the raise of adhesive force is proposed. However, the present inventors have confirmed that the bondability of wire bonding and the barrier properties of the encapsulant do not improve even if the adhesive force is increased to 2,000 gf/inch or more, and thus simply increasing the adhesive force is not a means to effectively solve the problem. was recognized. In particular, when the mask sheet maintained an adhesive strength of 2,000 gf/inch or more, it was impossible to peel the sheet smoothly during the peeling process after the encapsulation process. Therefore, it can be seen that it is difficult to remarkably improve the leakage defect of the encapsulation resin only by increasing the adhesive strength, and it is not fundamentally related to the improvement of wire bonding properties.

That is, the mask tape for QFN semiconductor packaging is required to have a low glass transition temperature (Tg) in order to realize the adhesive force required during high-temperature lamination, but the low glass transition temperature reduces the problem of lowering wire bondability. Have.

Korean Patent Publication No. 2002-0060143 Korean Patent Publication No. 2013-0113377 Korean Patent Publication No. 2013-0109070

The present invention has been devised to solve the above-described problems, and the problem to be solved by the present invention is to have excellent wire bonding properties while maintaining high adhesion during high-temperature lamination, so that leakage of the encapsulating resin in the encapsulation process can be effectively prevented. To provide a masking tape for a semiconductor package.

In addition, an object of the present invention is to provide a masking tape for a semiconductor package capable of increasing the reliability of the QFN semiconductor package and productivity and efficiency in the manufacturing process.

These and other objects and advantages of the present invention will become more apparent from the following description of preferred embodiments.

For the above purpose, a first adhesive layer, a second adhesive layer and a base film are sequentially stacked, wherein the first adhesive layer and the second adhesive layer are adhesive layers comprising a thermoplastic polyimide, and the glass transition temperature of the first adhesive layer is achieved by the masking tape for a semiconductor package lower than the glass transition temperature of the second adhesive layer.

Preferably, the thickness of the first adhesive layer may be 0.1 to 1 μm, and the thickness of the second adhesive layer may be 0.2 to 1.8 μm.

Preferably, the thickness of the first adhesive layer and the total thickness of the second adhesive layer may be 0.5 to 2㎛.

Preferably, the thickness ratio of the first adhesive layer and the second adhesive layer may be 0.1 to 1:1.

Preferably, the glass transition temperature of the base film may be higher than that of the second adhesive layer.

Preferably, the glass transition temperature of the first adhesive layer may be 190 to 210 ℃.

Preferably, the glass transition temperature of the second adhesive layer may be 211 to 250 ℃.

Preferably, the glass transition temperature of the base film may be 300 °C or higher.

Preferably, the coefficient of thermal expansion (CTE) of the base film may be 15 to 25 ppm/℃.

Preferably, the thickness of the base film may be 25 to 38㎛.

Preferably, the elastic modulus of the base film may be 200 to 400 MPa.

Preferably, the base film may be at least one of polyimide, polyamide, polyethersulfone, polyphenylenesulfide, polyetherketone, polyetheretherketone, triacetylcellulose and polyetherimide film.

According to the present invention, it is possible to increase the reliability of the QFN semiconductor package and the productivity and efficiency in the manufacturing process by effectively preventing leakage of the encapsulating resin in the encapsulation process by having excellent bonding properties while maintaining high adhesion during high-temperature lamination.

In addition, the present invention fundamentally blocks the leakage of the encapsulant through excellent die bonding and wire bonding properties and does not leave residues due to leakage of the encapsulant, so there is no need for a cleaning process, thereby increasing the productivity of the QFN semiconductor package. have an effect

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a block diagram of a masking tape for a semiconductor package according to an embodiment of the present invention.
2 is a diagram illustrating a warpage evaluation method of a masking tape for a semiconductor package according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Terms and words used in this specification are terms selected in consideration of functions in the embodiments, and the meaning of the terms may vary according to the intention or custom of the invention. Therefore, the terms used in the following examples, when specifically defined in the present specification, follow the definition, and when there is no specific definition, it should be interpreted as a meaning generally recognized by those skilled in the art.

1 is a block diagram of a masking tape for a semiconductor package according to an embodiment of the present invention.

Referring to FIG. 1 , the masking tape for a semiconductor package according to an embodiment of the present invention has a structure in which a first adhesive layer 101 , a second adhesive layer 102 , and a base film 103 are sequentially stacked.

The first adhesive layer 101 is a first adhesive layer positioned at the outermost and in direct contact with the lead frame, and the second adhesive layer 102 is located between the first adhesive layer 101 and the base film 103 . It corresponds to the second adhesive layer.

Here, both the first adhesive layer 101 and the second adhesive layer 102 may be adhesive layers including thermoplastic polyimide. More specifically, the first adhesive layer 101 is a thermoplastic polyimide, and may include an imide group or an ether group in a main chain and optionally one of a hydroxyl group and a carboxyl group.

Masking tape has adhesive properties to prevent leakage of the encapsulant, but when the adhesive layer is not strong, it is easy to cause bonding defects due to tilting or sliding during die bonding. Although the bonding temperature is required to be 190 to 250°C, since the adhesive layer of the masking tape is softened, it cannot withstand the bonding stress, resulting in serious bonding defects such as micro-bouncing.

In order to solve the above problems, it is required to increase the heat resistance and adhesive strength of the masking tape. When the glass transition temperature of the adhesive layer is increased, the heat resistance of the masking tape can be increased. However, in order to increase the heat resistance of the masking tape, the glass transition temperature is 250 ° C. When an excess adhesive layer is used, it is difficult to express adhesiveness in the lamination process, and when heating to 250° C. or higher for adhesive expression, the warpage problem of the lead frame is seriously raised, and there is a problem that the semiconductor device is deformed. , in this case, residual stress is generated in the attached lead frame, and it is easy to cause joint defects due to positional deviation in post-processes such as continuous die bonding or wire bonding, which leads to delamination in reliability evaluation after package completion. is likely to cause Conversely, when the glass transition temperature is lowered to increase the adhesive strength of the adhesive layer, the adhesive strength is increased, but the wire bondability is poor.

In addition, even if the adhesive force of the masking tape is increased to a very high value, it is difficult to sufficiently resist the shear stress generated during die bonding and wire bonding. In principle, no matter how high the adhesive strength of the mask sheet, there is a limit to effectively preventing mold bleed and mold flash defects, which result in the encapsulation resin leaking to the weak bonding interface between the lead frame and the mask sheet. .

Therefore, in the present invention, the adhesive layer is divided into a first adhesive layer 101 as an outermost layer and a second adhesive layer 102 as an intermediate layer, and the glass of the first adhesive layer 101 and the second adhesive layer 102 . The problem was solved by changing the transition temperature. In the present invention, the glass transition temperature (Tg) of the first adhesive layer 101 is preferably lower than the glass transition temperature of the second adhesive layer (102). At this time, when the glass transition temperature of the first adhesive layer 101 is higher than the glass transition temperature of the second adhesive layer 102, the adhesive strength of the tape is lowered, so that the tape is peeled off from the lead frame during the packaging process, and the process is completed. It becomes impossible or it does not hold the lead frame well due to low adhesive force, so there is a problem that the wire bonding property is deteriorated during the wire bonding process.

More specifically, the glass transition temperature of the first adhesive layer 101 is preferably 190 to 210 ℃, the glass transition temperature of the second adhesive layer 102 is preferably 211 to 250 ℃.

If the glass transition temperature of the first adhesive layer 101 is less than 190 ℃, there is a problem that thermal decomposition products are generated at high temperature due to lack of heat resistance and contaminate the lead frame. Peel-off occurs during the process and, accordingly, the tape does not support the leadframe, which may cause a problem of deterioration of wire bondability.

In addition, when the glass transition temperature of the second adhesive layer 102 is less than 211 ℃, the property of hard supporting the first adhesive layer 101 in contact therewith is lowered, and the wire bondability is deteriorated, and when it exceeds 250 ℃, the wire Since a problem of wire bouncing occurs during bonding, there is a problem that wire bonding strength or wire bonding property is lowered.

In the present invention, the thermoplastic polyimide constituting the first adhesive layer 101 and the second adhesive layer 102 necessarily includes an amide group or an ether group in the main chain, and any one of a hydroxyl group and a carboxyl group is optional. It is characterized in that it is included in the main chain. Since the first adhesive layer 101 and the second adhesive layer 102 include an amide group or an ether group in the main chain of the thermoplastic polyimide, flexibility at the molecular level of the main chain is increased, so that the glass transition temperature of the adhesive layer can be easily adjusted. Not only that, but it is easy to form an imprinting contact step. In addition, by selectively including any one of a hydroxyl group and a carboxyl group, the first adhesive layer 101 and the second adhesive layer 102 have a polar group on the surface to maintain adhesive force. Specific examples thereof include aromatic polyamideimide, aromatic polyetheramideimide, aromatic polyetheramide, and aromatic polyetherimide. Among them, aromatic polyetheramideimide, aromatic polyetherimide and aromatic polyetheramide are more preferable in view of flexibility at the molecular level.

As an acid component used in the synthesis of aromatic polyetherimide, aromatic polyetheramideimide or aromatic polyetheramide, for example, an aromatic dianhydride modified with a hydroxyl group or a carboxyl group may be used, which is a known method. this is used In the case of a polyimide modified with a hydroxyl group or a carboxyl group, there is an effect that the clamping effect due to the contact step can be further strengthened. That is, by introducing a polar group having a surface energy value similar to that of the metal surface into the adhesive layer of the mask sheet, there is an effect of increasing the adhesion by improving the wettability in the lamination process. It has the effect of strengthening the support of the die pad with improved adhesion.

In one embodiment, the first adhesive layer 101 and the second adhesive layer 102 are 4,4'-oxydianiline (ODA), 4,4'-(4,4') -Isopropylidenediphenoxy)bis(phthalic anhydride) (4,4′-(4,4′-Isopropylidenediphenoxy)bis(phthalic anhydride), BPADA), 3,3′,4,4′-bi Phenyltetracarboxylic dianhydride (3,3',4,4'-biphenyltetracarboxylic dianhydride, 　BPDA), solvent DMAc and polyamic acid as a pressure-sensitive adhesive composition prepared using a general manufacturing method in the art using a phenoxy resin After forming the solution as a precursor layer, it may be prepared by imidization.

In the present invention, the thickness ratio of the first adhesive layer 101 and the second adhesive layer 102 is preferably 0.1 to 1:1. When the thickness ratio is less than 0.1, the thickness of the first adhesive layer is too thin to form an adhesive force properly, or there is a problem in coating properties, so that a uniform coating layer cannot be formed.

In addition, the sum of the thicknesses (total thickness) of the first adhesive layer 101 and the second adhesive layer is preferably 0.5 to 2 μm. When the sum of the thicknesses is less than 0.5 μm, the first adhesive layer 101 and the second adhesive layer are easily separated from the base film 103, and when the thickness is more than 2 μm, the curl of the masking tape for semiconductor package manufactured becomes severe and can be used. because there is no

In one embodiment, the base film 103 is a base film, and the glass transition temperature of the base film 103 is preferably higher than that of the second adhesive layer 102 . When the glass transition temperature of the base film 103 is less than the glass transition temperature of the second adhesive layer 102, deformation or wrinkles may occur due to the high temperature during the lamination process, and the base film may have an adhesive force on the press plate of the laminator equipment. There is a problem in that it sticks to the press plate, sticks to it, and then falls again, causing an error in equipment operation. Specifically, the glass transition temperature of the base film 103 is preferably 300 ℃ or more.

In an embodiment, the coefficient of thermal expansion (CTE) of the base film 103 is preferably 15 to 25 ppm/°C. Since the thermal expansion coefficient of the metal lead frame used in the semiconductor packaging process has a value of 17 to 25 ppm/℃, when the thermal expansion coefficient of the mask sheet is less than 15 ppm/℃ or exceeds 25 ppm/℃, the lead frame (~20 ppm), the difference in coefficient of thermal expansion increases, so that warpage is unavoidable in a cooled state after lamination. Therefore, the coefficient of thermal expansion (CTE) of the base film 103 is preferably within the above range.

In one embodiment, the thickness of the base film 103 is preferably 25 to 38㎛. When the thickness of the base film 103 is less than 25 μm, a handling problem occurs in the semiconductor package process, and when the thickness exceeds 38 μm, a lamination problem occurs.

In one embodiment, the elastic modulus of the base film 103 is preferably 200 to 400 MPa. When the modulus of elasticity of the base film 103 is less than 200 MPa, there is a problem in that it is not laminated at an accurate position due to deformation of the film during high-temperature lamination, whereas when it exceeds 400 MPa, the masking tape laminated to the lead frame adheres to the curve of the lead frame die pad area. This causes bubbles to form, which leads to deterioration of wire bonding properties.

In one embodiment, the base film 103 is preferably at least one of polyimide, polyamide, polyethersulfone, polyphenylenesulfide, polyetherketone, polyetheretherketone, triacetylcellulose and polyetherimide film. .

Hereinafter, the present invention will be described in more detail through examples. The present embodiment is intended to explain the present description in more detail, and the scope of the present invention is not limited to the embodiment.

[Example]

[Production Example]

The pressure-sensitive adhesive composition for forming the first pressure-sensitive adhesive layer 101 and the second pressure-sensitive adhesive layer 102 was prepared using the composition and content according to Table 1 below, and the glass transition temperature of the pressure-sensitive adhesive composition prepared therefrom was shown. That is, 4,4'-oxydianiline (4,4'-oxydianiline, ODA), 4,4'-(4,4'-isopropylideenediphenoxy)bis(phthalic anhydride) (4,4 '-(4,4'-Isopropylidenediphenoxy)bis(phthalic anhydride), BPADA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-biphenyltetracarboxylic dianhydride, BPDA), DMAc solution as a solvent, and phenoxy resin (YP-50) were prepared using a general manufacturing method in the art using the contents of Table 2 below, and the glass transition temperature thereof was confirmed. The first adhesive layer 101 and the second adhesive layer 102 may be prepared by imidizing a polyamic acid solution, which is an adhesive composition, as a precursor layer.

[Example 1]

A second adhesive layer composition having a glass transition temperature of 240° C. is coated on the surface of a polyimide film having a thickness of 25 μm (a glass transition temperature of 310° C., an elastic modulus of 300 MPa, and a coefficient of thermal expansion of 16 ppm/° C.) using a casting method. After forming a second adhesive layer, the first adhesive layer composition having a glass transition temperature of 200° C. was coated to form a first adhesive layer. At this time, the coated thickness of the second adhesive layer and the first adhesive layer was adjusted to be 0.5 μm, respectively, after curing and fixing was finished. Thereafter, after drying at a temperature of 150° C. for 45 minutes, the temperature was raised to 300° C. to advance the imidization reaction to prepare a masking tape having a first adhesive layer and a second adhesive layer, which are thermoplastic polyimide adhesive layers.

[Example 2]

Except for the first adhesive layer composition having a glass transition temperature of 190°C, the second adhesive layer composition having a glass transition temperature of 211°C, and the thickness of the first adhesive layer being 0.1 μm and the thickness of the second adhesive layer being 1 μm and a masking tape was prepared in the same manner as in Example 1.

[Example 3]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer composition having a glass transition temperature of 210° C. and the second adhesive layer composition having a glass transition temperature of 250° C. were used.

[Comparative example]

[Comparative Example 1]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer composition was coated on the polyimide film so that the thickness of the first adhesive layer was 1 μm, and the second adhesive layer was not coated.

[Comparative Example 2]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer was not coated, and the second adhesive layer was coated on the polyimide film to have a thickness of 1 μm.

[Comparative Example 3]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer had a thickness of 1.5 μm and the second adhesive layer had a thickness of 1 μm.

[Comparative Example 4]

A masking tape was prepared in the same manner as in Example 1, except that a polyimide film having an elastic modulus of 410 MPa was used as the base film.

[Comparative Example 5]

A masking tape was prepared in the same manner as in Example 1, except that a polyimide film having a thermal expansion coefficient of 14 ppm/° C. was used as the base film.

[Comparative Example 6]

A masking tape was prepared in the same manner as in Example 1, except that a polyimide film having a thermal expansion coefficient of 30 ppm/° C. was used as the base film.

[Comparative Example 7]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer had a thickness of 0.1 μm and the second adhesive layer had a thickness of 0.3 μm.

[Comparative Example 8]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer composition having a glass transition temperature of 180° C. and the second adhesive layer composition having a glass transition temperature of 205° C. were used.

[Comparative Example 9]

A masking tape was prepared in the same manner as in Example 1, except that the first adhesive layer composition having a glass transition temperature of 215° C. and the second adhesive layer composition having a glass transition temperature of 255° C. were used.

[Comparative Example 10]

A masking tape was prepared in the same manner as in Example 1, except that in Example 1, the first adhesive layer composition was used as the second adhesive layer and the second adhesive layer composition was used as the first adhesive layer.

Tg(℃) ODA BPADA BPDA DMAc (solvent) phenoxy resin
(YP-50) g mol g mol g mol g (ml) g 180 4.65 0.0232 15.11 0.0290 160 1.98 190 4.65 0.0232 15.11 0.0290 160 200 5.08 0.0254 14.67 0.0282 160 205 5.29 0.0264 14.47 0.0278 160 210 5.37 0.0268 14.39 0.0276 160 211 5.11 0.0255 14.48 0.0278 0.16 0.0005 160 215 5.25 0.0262 13.71 0.0263 0.82 0.0028 160 240 5.80 0.0290 10.38 0.0199 3.60 0.0122 160 250 6.01 0.0300 9.11 0.0175 4.66 0.0158 160 255 6.23 0.0311 7.73 0.0149 5.80 0.0197 160

For the masking tapes prepared in Examples 1 to 3 and Comparative Examples 1 to 10, physical properties were evaluated through the following experimental examples, and the results are shown in Table 2.

[Experimental example]

(1) Lamination evaluation

A lamination process was performed using the masking tape and the lead frame according to Examples and Comparative Examples. At this time, the lamination conditions were that the temperature of the masking tape was 220 ° C, the temperature of the lead frame was 220 ° C, the preheating of LF temperature was 180 ° C, the lamination time was 10 seconds, and the lamination pressure was 3 bar. . As the lead frame, AgCu lead frame for QFN semiconductor package was used. The die pad size in the lead frame was 3 mm x 3 mm x 8 mil, and the surface roughness (Ra) value was measured to be 0.09 μm.

At this time, in the lead frame laminated with the masking tape, after checking whether there are bubbles between the masking tape and the lead frame, if there are bubbles, "NG", and after checking whether wrinkles are formed on the masking tape, wrinkles are formed "NG" if it is, "NG" if it deviates ± 0.3mm from the alignment to check the exact position where the masking tape should be laminated to the leadframe, and "NG" if the adhesion between the leadframe and the masking tape is less than 0.5N/inch ", and in other cases, as "Pass", it is described in Table 2.

(2) Warpage evaluation

The warpage value of Examples and Comparative Examples was measured by placing the laminated lead frame with the masking tape down on a flat floor in a lead frame laminated with masking tape and leaving it at room temperature for 24 hours, and a coil set (coil set) ), cross bow, and twist were measured by type. As shown in FIG. 2, put the laminated lead frame on a flat floor with the tape facing down, and if the largest value among coil set, cross bow, and twist exceeds 0.5 mm, "NG ", and other cases were indicated in Table 2 as "Pass".

(3) Wire pull evaluation

Measure the wire pull value using a bond tester that can measure the wire adhesion. If the wire pull value is less than 10 gf, "NG" and otherwise, "Pass", are listed in Table 2.

adhesive layer
(thickness, μm) glass transition
Temperature (℃) lamination warpage wire
bondability bubble tape
wrinkle tape
location Adhesion (N/in) Example 1 first adhesive layer (0.5) 200 Pass Pass Pass Pass
(1N) Pass
(0.1mm) Pass
(17 gf) Second adhesive layer (0.5) 240 Example 2 first adhesive layer (0.1) 190 Pass Pass Pass Pass
(1.5N) Pass
(0.1mm) Pass
(16 gf) second adhesive layer (1) 211 Example 3 first adhesive layer (0.5) 210 Pass Pass Pass Pass
(0.7N) Pass
(0.1mm) Pass
(17 gf) Second adhesive layer (0.5) 250 Comparative Example 1 first adhesive layer (1) 200 Pass Pass Pass Pass
(1.2N) Pass
(0.1mm) NG
(9 gf) 2nd adhesive layer (0) - Comparative Example 2 first adhesive layer (0) - NG Pass Pass (NG)
(0.1N) Pass
(0.1mm) NG
(6 gf) second adhesive layer (1) 240 Comparative Example 3 first adhesive layer (1.5) 200 Not applicable due to tape curl second adhesive layer (1) 240 Comparative Example 4 first adhesive layer (0.5) 200 NG Pass Pass Pass
(0.6N) NG
(0.8mm) NG
(8 gf) Second adhesive layer (0.5) 240 Comparative Example 5 first adhesive layer (0.5) 200 NG Pass Pass Pass
(0.6N) NG
(0.8mm) NG
(7 gf) Second adhesive layer (0.5) 240 Comparative Example 6 first adhesive layer (0.5) 200 Pass NG NG
(0.5mm) Pass
(0.8N) NG
(0.9mm) NG
(6 gf) Second adhesive layer (0.5) 240 Comparative Example 7 first adhesive layer (0.1) 200 Unable to apply due to uneven coating surface Second adhesive layer (0.3) 240 Comparative Example 8 first adhesive layer (0.5) 180 Pass Pass Pass Pass
(2N) Pass
(0.2mm) NG
(5 gf) Second adhesive layer (0.5) 205 Comparative Example 9 first adhesive layer (0.5) 215 Pass Pass Pass NG
(0.4N) Pass
(0.1mm) NG
(7 gf) Second adhesive layer (0.5) 255 Comparative Example 10 first adhesive layer (0.5) 240 NG Pass Pass NG
(0.1N) Pass
(0.1mm) NG
(6 gf) Second adhesive layer (0.5) 200

Referring to Table 2, it can be seen that Examples 1 to 3 according to the present invention are good in lamination evaluation, warpage evaluation, and wire bonding evaluation.

On the other hand, it can be seen that Comparative Example 1 in which only the first adhesive layer was formed had poor wire bondability, and Comparative Example 2 in which only the second adhesive layer was formed had poor lamination evaluation and wire bondability evaluation at the same time.

In addition, it can be seen that in Comparative Example 3 because the thickness of the first adhesive layer is thick and the thickness ratio is out of the range, the evaluation cannot be proceeded due to severe tate curl, and the total thickness of the first adhesive layer and the second adhesive layer are thin It can be seen that in Comparative Example 7 with a small deviation, the evaluation could not proceed because the coating surface was non-uniform.

In addition, in Comparative Example 4, in which the elastic modulus of the base film is excessive, bubbles are generated between the masking tape and the lead frame in the lead frame laminated with the masking tape during lamination evaluation, and it can be seen that the warpage evaluation and wire bonding property evaluation are poor, Similarly, in Comparative Example 5 with a small coefficient of thermal expansion of the film and Comparative Example 6 with a large coefficient of thermal expansion of the base film, bubbles are generated during lamination evaluation or wrinkles of the tape occur, and it can be seen that the warpage paper evaluation and wire bonding property evaluation are poor.

In addition, it can be seen that Comparative Example 8 having a glass transition temperature too low has poor wire bonding properties, and Comparative Example 9 having a glass transition temperature too high has a problem of poor adhesion and poor wire bonding properties in lamination evaluation.

In addition, although the adhesive layer has a multilayer structure of two layers, when the glass transition temperature of the first adhesive layer is higher than the glass transition temperature of the second adhesive layer, it can be confirmed that both lamination evaluation and wire bondability evaluation are poor.

Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited to the above-described embodiments, and various modifications may be made by those skilled in the art within the scope of the technical spirit of the present invention. possible.

101: first adhesive layer
102: second adhesive layer
103: base film

Claims (12)

The first adhesive layer, the second adhesive layer and the base film are sequentially laminated,
The first adhesive layer and the second adhesive layer are adhesive layers comprising a thermoplastic polyimide,
The glass transition temperature of the first adhesive layer is lower than the glass transition temperature of the second adhesive layer,
The glass transition temperature of the first adhesive layer is 190 to 210 ℃,
The glass transition temperature of the second adhesive layer is 211 to 250 ℃, a masking tape for a semiconductor package. According to claim 1,
The thickness of the first adhesive layer is 0.1 to 1㎛, and the thickness of the second adhesive layer is 0.2 to 1.8㎛, a masking tape for a semiconductor package. According to claim 1,
The thickness of the first adhesive layer and the total thickness of the second adhesive layer is 0.5 to 2㎛, a masking tape for a semiconductor package. According to claim 1,
The thickness ratio of the first adhesive layer and the second adhesive layer is 0.1 to 1:1, a masking tape for a semiconductor package. According to claim 1,
The glass transition temperature of the base film is higher than that of the second adhesive layer, a masking tape for a semiconductor package. delete delete According to claim 1,
The glass transition temperature of the base film is 300 ℃ or more, a masking tape for a semiconductor package. According to claim 1,
The coefficient of thermal expansion (CTE) of the base film is 15 to 25 ppm / ℃, a masking tape for a semiconductor package. According to claim 1,
The thickness of the base film is 25 to 38㎛, a masking tape for a semiconductor package. According to claim 1,
The elastic modulus of the base film is 200 to 400 MPa, a masking tape for a semiconductor package. According to claim 1,
The base film is at least one of polyimide, polyamide, polyethersulfone, polyphenylenesulfide, polyetherketone, polyetheretherketone, triacetylcellulose, and polyetherimide film, a masking tape for a semiconductor package.

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