JP7270023B2 - Mask sheet for QFN semiconductor package - Google Patents

Description

The present invention relates to a QFN (Quad Flat Non-leaded) semiconductor package mask sheet, and to a lead frame and a semiconductor package using the QFN (Quad Flat Non-leaded) semiconductor package mask sheet.

From the past to the present, semiconductor technology, which has been led by the development of personal computers, has focused mainly on the integration of semiconductor circuits. Along with the trend, the semiconductor technology is focused on improving the degree of integration by miniaturizing and thinning the semiconductor package, and thus the manufacturing process of the semiconductor device is also changing.

For example, QFN, Stacked CSP, WLP, Flip Chip Bare Die, Fine-Pitch BGA, MCP, MIS package, etc. are expected to lead the market in the future.

QFN (Quad Flat Non-lead Package) is a type of CSP (Chip Scale Package). , Ultimately, it has the effect of maximizing the board space, but due to its structure, the packaging process must be performed with the electrical connection exposed at the bottom, so it is not exposed during the manufacturing process. A process of masking the site with a mask sheet is always required.

A method for manufacturing such a QFN semiconductor package includes the following sequence.

First, after attaching a mask sheet to one surface of the lead frame, semiconductor chips are individually mounted on semiconductor element mounting portions (die pads or lead pads) formed on the lead frame.

After plasma processing the lead frame, the leads arranged around each semiconductor chip mounting portion of the lead frame and the semiconductor chip are electrically connected by bonding wires.

Next, the semiconductor chip mounted on the lead frame is sealed with sealing resin.

A QFN unit in which the QFN packages are arranged is formed by peeling off the mask sheet from the lead frame.

Individual QFN semiconductor packages are manufactured by sawing a QFN unit along the perimeter of each QFN package.

As described above, a mask sheet is always used in manufacturing a QFN semiconductor package, and the mask sheet should have physical properties that can withstand high heat and plasma processing during the manufacturing process of the QFN semiconductor package.

Moreover, the mask sheet is usually rolled up and stored for a long period of time. When the mask sheet is rolled up, the adhesive layer and the support film slip each other, so that the mask sheet can be rolled up well and the physical properties of the mask sheet are not degraded even after long-term storage. However, especially in the case of a mask sheet using a support film having a reinforcing layer, when the mask sheet is wound up, the adhesive layer and the reinforcing layer tend to stick to each other without slipping, causing air bubbles or wrinkles on the mask sheet. There is a problem that occurs.

As a result, the QFN semiconductor package has physical properties that can withstand the high heat and plasma treatment process associated with the manufacturing process of the QFN semiconductor package, and does not deteriorate in durability and physical properties even though it is wound and stored for a long period of time. A mask sheet is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mask sheet for a QFN semiconductor package in which a slip property is imparted between an adhesive layer and a reinforcing layer in order to solve the above technical problems.

Another object of the present invention is to provide a mask sheet for a QFN semiconductor package having physical properties to withstand the high heat and plasma treatment process associated with the manufacturing process of the QFN semiconductor package.

Another object of the present invention is to provide a lead frame and a QFN semiconductor package having the mask sheet.

In order to solve the above problems, the mask sheet for a QFN semiconductor package according to the present invention comprises a support film, an adhesive layer located on one side of the support film, and a surface of the support film opposite to the surface on which the adhesive layer is located. and a reinforcing layer, and is structurally characterized in that the slip frictional force of the reinforcing layer with respect to the adhesive layer is 700 gf/50 mm or less.

The mask sheet for a QFN semiconductor package according to the present invention has improved slip properties between the adhesive layer and the reinforcing layer, and is excellent in that the durability and physical properties do not deteriorate even when the mask sheet is rolled up and stored for a long period of time. have an effect.

In addition, the mask sheet for QFN semiconductor packages according to the present invention has an excellent effect of not deteriorating physical properties in spite of the high heat and plasma treatment processes involved in the manufacturing process of QFN semiconductor packages.

FIG. 4 is a cross-sectional view showing a mask sheet for a QFN semiconductor package according to one embodiment of the present invention;

The above objects, features and advantages will be described in detail later, so that those skilled in the art to which the present invention pertains can easily implement the technical ideas of the present invention. In the description of the present invention, when it is determined that the detailed description of the known technology related to the present invention may obscure the gist of the present invention, the detailed description will be omitted. In the following, preferred embodiments according to the invention will be described in detail.

The present invention may be embodied in various different forms and should not be construed as limited to the embodiments disclosed below. However, these embodiments are provided so that this disclosure will be complete and will fully convey the scope of the invention to those skilled in the art.

Hereinafter, a mask sheet for a QFN semiconductor package, a lead frame including the same, and a semiconductor package according to the present invention will be described in detail.

<Mask sheet for QFN semiconductor package>
Referring to FIG. 1, a mask sheet 100 for a QFN semiconductor package according to the present invention includes a support film 10, an adhesive layer 20 located on one side of the support film 10, and a side of the support film opposite to the side where the adhesive layer is located. and a reinforcing layer 30 located on the face of the laminate. Furthermore, the laminated structure is directly applied to a semiconductor package.

In particular, in the QFN semiconductor package mask sheet 100 according to the present invention, the slip frictional force of the reinforcing layer 30 against the adhesive layer 20 is 700 gf/50 mm or less.

Here, the slip friction force is obtained by placing the reinforcing layer on the adhesive layer and then lifting a weight of 1 kg on it to apply a horizontal force to the reinforcing layer, causing the reinforcing layer to slip from the adhesive layer. slip).

The mask sheet 100 for a QFN semiconductor package according to the present invention has a slip frictional force of 700 gf/50 mm or less, and when the mask sheet is wound, air bubbles and wrinkles are generated due to an appropriate slip phenomenon between the adhesive layer and the reinforcing layer. do not. If the slim frictional force exceeds 700 gf/50 mm, the adhesive layer and the reinforcing layer stick to each other without slipping, so there is a problem that air bubbles and wrinkles are likely to occur.

As described above, referring to FIG. 1, the mask sheet 100 for a QFN semiconductor package according to the present invention includes a support film 10, an adhesive layer 20 positioned thereon, and a reinforcing layer 30 positioned under the support film 10. including.

First, the support film 10 will be described. The support film 10 is not particularly limited, and a heat-resistant resin film can be used. The heat-resistant resin film has the advantage of not deteriorating under high temperature conditions of 200° C. or higher. Moreover, the glass transition temperature (Tg) of the support film 10 is preferably 200° C. or higher from the viewpoint of improving heat resistance.

The heat-resistant resin film includes aromatic polyimide, aromatic polyamide, aromatic polyamideimide, aromatic polysulfone, aromatic polyethersulfone, polyphenylene sulfide, aromatic polyetherketone, polyarylate, aromatic polyetheretherketone, and polyethylene. Naphthalate, polyethylene terephthalate, and the like can be used.

More preferably, the support film 10 can use a polyimide film because it has heat resistance and can further improve adhesion to the adhesive layer. The polyimide film may be subjected to high adhesion treatment such as plasma treatment, corona treatment, or primer treatment. If the support film 10 has low adhesion to the adhesive layer 20, peeling occurs at the interface between the adhesive layer 20 and the support film 10 when the mask sheet 100 is removed from the lead frame and the sealing layer. Also, there is a problem that the adhesive layer 20 remains on the sealing layer side. Therefore, it is preferable that the support film 10 has sufficiently high adhesion to the adhesive layer 20 .

The thickness of the support film 10 is not particularly limited, but may be 5 μm to 50 μm in order to reduce the residual stress of the lead frame.

Next, the adhesive layer 20 included in the QFN semiconductor package mask sheet 100 according to the present invention will be described.

Although the component of the adhesive layer 20 is not limited, it may contain a thermoplastic resin as a main component.

In particular, the adhesive layer 20 includes an amide group (--NHCO--), an ester group (--CO--O--), an imide group (--NR2, where R is --CO--), an ether group (--O -) or a thermoplastic resin having a sulfone group (-SO2-). More specifically, the adhesive layer 20 is made of aromatic polyamide, aromatic polyester, aromatic polyimide, aromatic polyamideimide, aromatic polyether, aromatic polyetheramideimide, aromatic polyetheramide, aromatic polyesterimide. , and aromatic polyetherimides.

Preferably, the adhesive layer 20 may contain a thermoplastic resin having an imide group (-NR2, where each R is -CO-) from the viewpoint of improving slip properties.

Any of the thermoplastic resins described above is a polycondensation of an aromatic diamine or bisphenol, etc., which is a base component, and a dicarboxylic acid, tricarboxylic acid, tetracarboxylic acid, or aromatic chloride, or a reactive derivative thereof, which is an acid component. can be produced by In other words, it can be carried out by a usual method used for the reaction of amine and acid, and many conditions are not particularly limited. Conventional methods are used for the polycondensation reaction of aromatic dicarboxylic acids, aromatic tricarboxylic acids, or reactive derivatives thereof and diamines.

More specifically, pyromellitic dianhydride (PMDA) and oxydiphthalic dianhydride are used as the tetracarboxylic dianhydride to produce the thermoplastic resin having an imide group contained in the adhesive layer 20 of the present invention. (ODPA), biphenyl-3,4,3′,4′-tetracarboxylic dianhydride (BPDA), benzophenone-3,4,3′,4′-tetracarboxylic dianhydride (BTDA), diphenyl sulfone -3,4,3′,4′-tetracarboxylic dianhydride (DSDA), 4,4′-(2,2′-hexafluoroisopropylidene)diphthalic dianhydride (6FDA), m(p) -terphenyl-3,4,3',4'-tetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), 1-carboxydimethyl-2,3, 5-cyclopentanetricarboxylic acid-2,6,3,5-dianhydride (TCAAH), cyclohexane-1,2,4,5-tetracarboxylic dianhydride (CHDA), butane-1,2,3, 4-tetracarboxylic dianhydride (BuDA), 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 5-(2,5-dioxotetrahydrofuryl)-3-methylcyclohexane- 1,2-dicarboxylic dianhydride (DOCDA), 4-(2,5-dioxotetrahydrofuryl-3-yl)-tetralin-1,2-dicarboxylic dianhydride (DOTDA), bicyclooctene-2, 1 kind of tetracarboxylic dianhydride selected from 3,5,6-tetracarboxylic dianhydride (BODA), naphthalene-1,4,5,8-tetracarboxylic dianhydride (NTDA), etc. or Two or more kinds can be used.

On the other hand, aromatic diamines that are still other monomers include siloxane derivatives, 2′-(methacryloyloxy)ethyl 3,5-diaminobenzoic acid, 3,5-diaminobenzene cinnamate, coumaronyl 3,5-diamino An aromatic diamine containing one or more photosensitive functional groups selected from benzoic acid is used as an essential component.

In addition to the diamine monomers described above, the present invention also provides aromatic diamine monomers commonly used in the relevant field, such as paraphenylenediamine (PPD), metaphenylenediamine (MPD), 2,4- toluenediamine (TDA), 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminodiphenyl ether (DPE), 3,4'-diaminodiphenyl ether (3,4'-DPE), 3,3'-dimethyl -4,4'-diaminobiphenyl (TB), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-bis(trifluoromethyl)-4,4'-diamino Biphenyl (TFMB), 3,7-diamino-dimethyldibenzothiophene-5,5-dioxide (TSN), 4,4'-diaminobenzophenone (BTDA), 3,3'-diaminobenzophenone (3,3'-BTDA) , 4,4′-diaminodiphenyl sulfide (ASD), 4,4′-diaminodiphenyl sulfone (ASN), 4,4′-diaminobenzanilide (DABA), 1,n-(4-aminophenoxy)alkane (DAnMG ), 1,3-bis(4-aminophenoxy)2,2-dimethylpropane (DANPG), 1,2-bis[2-(4-aminophenoxy)ethoxy]ethane (DA3EG), 9,9-bis( 4-aminophenyl)fluorene (FDA), 5(6)-amino-1-(4-aminomethyl)-1,3,3-trimethylindane (PIDN), 1,4-bis(4-aminophenoxy)benzene (TPE-Q), 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4′-bis(4-amino phenoxy)biphenyl (BAPB), 4,4′-bis(3-aminophenoxy)biphenyl (BAPB-M), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2 - bis(3-aminophenoxyphenyl)propane (BAPP-M), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(3-aminophenoxy)phenyl]sulfone (BAPS-M) ), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), 3,3′-dicarboxy-4,4′-diaminodiphenylmethane (MBAA), 4,6-dihydroxy- 1,3-phenylenediamine (DADHB), 3,3′-dihydroxy-4,4′-diaminobiphenyl (HAB), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), 3,3′,4,4′-tetraaminobiphenyl (TAB), 1,6-diaminohexane (HMD), 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethylsiloxane , 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (DAIP), 4,4′-methylenebis(4-cyclohexylamine) (DCHM), 1,4-aminocyclohexane (DACH), bicyclo[ 2,2,1]heptanebis(methylamine) (NBDA), tricyclo[3,3,1,13,7]decane-1,3-diamine, 4-aminobenzoic acid-4-aminophenyl ether (APAB), 2-(4-aminophenyl)-5-aminobenzoxazole (5ABO), 9,9-bis[4-(4-aminophenoxy)phenyl)fluorene (BAOFL), 2,2-bis(3-bis(3 -sulfopropoxy)-4,4′-diaminobiphenyl (3,3′-BSPB), 4,4′-bis(4-aminophenoxy)biphenyl-3,3′-disulfonic acid (pBAPBDS), bis(4- aminophenyl)hexafluoropropane (HFDA), 5-diaminobenzoic acid, 2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid, 2,2-diaminobenzenedisulfonic acid, etc., or Two or more diamine monomers can be used.

Furthermore, the adhesive layer 20 may, of course, further contain additional components such as an inorganic filler, if necessary.

Further, the adhesive layer 20 included in the mask sheet 100 for QFN semiconductor packages according to the present invention preferably has an adhesive strength of 5 gf/25 mm or more and 600 gf/25 mm or less after pressing at 230°C to 250°C. After the pressing, if the adhesive strength is less than 5 gf/25 mm, there is a problem that the mask sheet is easily peeled off from the lead frame during handling such as moving or loading equipment. When the sheet is peeled off, there is a problem that it may be peeled off well or may leave a lot of adhesive residue.

Here, the adhesion means the adhesion of the mask sheet 100 to the lead frame and the encapsulation layer, and means the adhesion after the encapsulation process by heat treatment.

In addition, the adhesive layer 20 included in the mask sheet 100 for QFN semiconductor packages according to the present invention preferably has a glass transition temperature of 100 to 250° C. in order to maintain adhesion at room temperature. Here, although the method for measuring the glass transition temperature is not particularly limited, it generally means a value measured by differential scanning calorimetry, differential thermal measurement, dynamic viscoelasticity measurement, or thermomechanical analysis.

Next, the reinforcing layer 30 included in the QFN semiconductor package mask sheet 100 according to the present invention will be described.

Although the reinforcing layer 30 is not particularly limited, it can be made of the same components as the adhesive layer 20 described above.

However, in particular, the reinforcing layer 30 according to the present invention preferably contains 0.1 to 5% by weight of inorganic particles in order to improve the slip property with the adhesive layer 20 . If the inorganic particles are included in the reinforcing layer 30 in an amount of less than 0.1% by weight, there is a problem that the effect of improving the slip property is weak. Conversely, if the reinforcing layer 30 contains more than 5% by weight of the inorganic particles, the effect of improving the slip property is improved, but the function as the reinforcing layer may be restricted. From the viewpoint of improving the slip friction force, it is particularly preferable that the reinforcing layer 30 contains 0.5 to 3% by weight of the inorganic particles.

Although the inorganic particles are not particularly limited, inorganic particles such as fumed silica can be used, and the particle size of the inorganic particles is preferably 5 nm to 30 nm from the viewpoint of improving slip properties.

Next, the QFN semiconductor package mask sheet 100 according to the present invention preferably has an elastic modulus of 5 MPa or more at 230.degree. The elastic modulus means solid shear elastic modulus measured at 230°C. Since the elastic modulus is 5 MPa or more, the mask sheet 100 according to the present invention suppresses the generation of adhesive residue on the lead frame and the sealing layer after the sealing process. Here, the elastic modulus is measured by setting a mask sheet test piece having a size of 5 mm×8 mm in a solid shear measurement jig and using a dynamic viscoelasticity measuring device (for example, Rheogel-E4000 manufactured by UBM Co., Ltd.). can be measured by

Further, the mask sheet 100 for a QFN semiconductor package according to the present invention preferably has a 5% weight loss temperature of 400° C. or higher. As a result, the mask sheet 100 according to the present invention has a reduced amount of outgassing and a better wire bondability. The 5% weight loss temperature can be measured using a differential thermal balance (for example, SSC5200, manufactured by Seiko Instruments Inc.) at a heating rate of 10° C./min in an air atmosphere.

Further, the QFN semiconductor package mask sheet 100 according to the present invention may further include a protective film (not shown) on the surface of the adhesive layer 20 opposite to the surface on which the support film 10 is located. Although the protective film is not particularly limited, it is preferable to use a polyethylene terephthalate film, and the polyethylene terephthalate film may have a release layer. The protective film may have a thickness of 10 μm to 100 μm or less.

As described above, the QFN semiconductor package mask sheet 100 according to the present invention has improved slip properties of the adhesive layer and the reinforcing layer, and has excellent durability and physical properties even though the mask sheet is rolled up and stored for a long period of time. It has excellent effect without deterioration.

In addition, the mask sheet 100 for a QFN semiconductor package according to the present invention has an excellent effect of not deteriorating physical properties despite the high heat and plasma treatment process associated with the manufacturing process of the QFN semiconductor package.

<Lead frame and QFN semiconductor package>
A lead frame and a QFN semiconductor package according to the present invention will be described in detail below.

A lead frame according to the present invention comprises a lead frame including a die pad and inner leads, and a mask sheet 100 according to the present invention. It has a configuration pasted on.

Further, the QFN semiconductor package according to the present invention includes a lead frame including a die pad and inner leads, a semiconductor element mounted on the die pad, wires connecting the semiconductor element and the inner leads, and sealing the semiconductor element and the wires. and a mask sheet 100 according to the present invention, wherein the adhesive layer is attached to the surface of the lead frame opposite to the surface on which the semiconductor element is mounted. It has a configuration that

A semiconductor package according to the present invention comprises steps of: attaching a mask sheet 100 to the back surface of a lead frame having a die pad and inner leads by means of the adhesive layer 20; mounting a semiconductor element on the other surface of the die pad; A semiconductor package including a lead frame, a semiconductor element and a sealing layer is formed by plasma cleaning, providing a wire connecting the semiconductor element and the inner lead, and forming a sealing layer for sealing the semiconductor element and the wire. It is manufactured by a manufacturing process and a process of peeling off the mask sheet 100 from the semiconductor package.

The step of attaching the mask sheet to the lead frame can be performed by pressing at a high temperature (eg, 150-200° C.).

Although the material of the lead frame is not particularly limited, for example, an iron-based alloy, copper, or a copper-based alloy may be used. When using copper or a copper-based alloy, the surface of the lead frame may be coated with palladium, gold, silver, or the like. The surface of the lead frame can be physically roughened to improve adhesion with the encapsulant. In addition, the surface of the lead frame may be subjected to a chemical treatment such as an epoxy bleed out (EBO) prevention treatment that prevents silver paste from bleeding out.

A semiconductor element is usually mounted on a die pad via an adhesive (eg, silver paste). The adhesive may be cured by heat treatment (eg, 140-200° C., 30 minutes-2 hours).

Although the wire is not particularly limited, for example, gold wire, silver wire, copper wire, or palladium-coated copper wire can be used. As an example, heating at 200-270° C. for 3-60 minutes can be used to bond the semiconductor element and inner leads to the wire using ultrasonic waves and press pressure.

The leadframe may be subjected to a plasma cleaning process prior to the wirebonding process. The plasma cleaning process can further enhance the adhesion between the sealing layer and the lead frame, thereby improving the reliability of the semiconductor package. For the plasma cleaning treatment, for example, a method of injecting a gas such as argon, nitrogen, or oxygen at a predetermined gas flow rate under reduced pressure conditions (for example, 9.33 Pa or less) and irradiating plasma can be used. The plasma irradiation power may be 10 to 1000W. Also, the plasma treatment time may be 5 to 300 seconds. The gas flow rate in plasma processing may be between 5 and 50 sccm.

In the sealing step, a sealing layer is formed using a sealing material. Through the encapsulation process, a semiconductor package including a plurality of semiconductor elements and an encapsulation layer encapsulating them together can be obtained. During the encapsulation process, the mask sheet prevents the encapsulant from reaching the back side of the lead frame.

The sealing temperature may be 140-200.degree. C. or 160-180.degree. The pressure during the sealing process may be 6-15 MPa, and the heating time may be 1-5 minutes.

The sealing layer may be heat-cured if necessary. The curing temperature may be 150-200° C., and the heating time for curing may be 4-7 hours.

Although the material of the sealing material is not particularly limited, epoxy resins such as cresol novolac epoxy resin, phenol novolak epoxy resin, biphenyldiepoxy resin, and naphthol novolak epoxy resin can be used, for example. Additives such as a filler, a flame retardant substance such as a bromine compound, and a wax component may be added to the sealing material.

After the encapsulation step, the mask sheet is peeled off from the lead frame and encapsulation layer in the resulting semiconductor package. When curing the sealing layer, the mask sheet may be peeled off before or after curing.

Although the peeling temperature is not particularly limited, the peeling can be performed at room temperature (eg, 5 to 35°C).

After the peeling step, a step of removing the residue of the adhesive layer remaining on the lead frame and the encapsulating layer may be further performed as necessary. In this case, for example, a solvent can be used to remove the remaining adhesive layer. Examples of solvents that can be used include dimethylsulfoxide, ethylene glycol, and water. A solvent may be used individually by 1 type, and can be used in mixture of 2 or more types. A surfactant may be added to the solvent. When the solvent contains water, the solvent may be a solution adjusted to alkalinity (alkaline solution). The pH of the alkaline solution may be 10 or higher or 12 or higher. Along with solvent removal, mechanical brushing may be performed, if desired.

When the lead frame includes a plurality of patterns having die pads and inner leads, the sealed package can be divided to obtain a plurality of semiconductor packages each having one semiconductor element, if necessary.

Thus, the QFN semiconductor package according to the present invention is excellent in terms of high density, small area, thinness, etc., and is suitable for use in electronic devices such as mobile phones, smart phones, personal computers, and tablets. can be done.

The present invention will be described in more detail below by means of preferred examples. Such examples are provided only by way of illustration to further illustrate the present invention. Therefore, the present invention is not limited to the following examples.

<Example>
1. Preparation of Adhesive Layer An adhesive layer applied to the mask sheet was prepared as shown in Table 1 below.

A varnish was produced using a polyimide resin having the following molar ratio, and a liquid preparation for an adhesive layer was produced.

* TPE-R: 1,3'-Bis (4-aminophenoxy) benzene
*BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane
* p-PDA: p-phenylenediamine
*m-Td: m-tolidine
* PAM-E: Amino-modified reactive silicone fluids (manufactured by Shinetsu silicone)
* BPDA: Biphenyltetracarboxylic dianhydride
* PMDA: Pyromellitic dianhydride
* R972: AEROSIL (registered trademark) R 972 (manufactured by Evonik)

2. Fabrication of Reinforcing Layers The reinforcing layers applied to the mask sheet were fabricated as shown in Table 2 below.

A varnish was produced using a polyimide resin having the following molar ratio, and a preparation solution for a reinforcing layer was produced.

3. Manufacture of mask sheet As shown in Table 3 below, the upper surface of the support film is coated with the preparation prepared in Table 1 above to form an adhesive layer, and the other side of the support film is coated with the preparation prepared in Table 2 above. Then, a reinforcing layer was formed, and mask sheets according to Examples and Comparative Examples were manufactured.

A PI film was used as the support film in the same way.

4. Evaluation of Physical Properties of Mask Sheets According to Examples Physical properties of the mask sheets according to Examples 1 to 7 were evaluated. The physical property evaluation results are shown in Table 4 below.

The physical properties shown in Table 4 above were measured as follows.

1) Using a 5% weight loss temperature differential thermal balance (manufactured by Seiko Instruments Inc., Model SSC5200), measurement was performed in an air atmosphere at a heating rate of 10°C/min.

2) A test piece obtained by cutting an elastic modulus mask sheet into a size of 5 mm × 8 mm is set in a solid shear measurement jig, and a dynamic viscoelasticity measuring device (manufactured by UBM, Rheogel-E4000) is used to measure sine waves, The solid shear elastic modulus was measured under the conditions of 30 to 250° C., a heating rate of 5° C./min, and a frequency of 400 Hz. The input thickness was fixed at 0.1 mm, and the distortion control was set at 1.95 μm and 1.95%. Solid shear modulus at 230° C. was read from the measurement results.

3) Attach the mask sheets of Examples and Comparative Examples to a CDA194 frame with adhesive residue (lead frame, manufactured by Shinko Electric Industry Co., Ltd.) with the adhesive layer in contact with the lead frame at room temperature (24 ° C.) and a load of 20 N. rice field. The lead frame and the mask sheet were heated in an oven in an air atmosphere while changing the conditions in the order of 180° C. for 60 minutes and 200° C. for 60 minutes. Plasma treatment was performed on the surface of the lead frame opposite to the mask sheet under the conditions of 150 W and 15 seconds in an argon gas atmosphere (flow rate: 20 sccm).

Using a molding machine (manufactured by Apic Yamada Co., Ltd.), sealing is performed under the conditions of 175 ° C., 6.8 MPa, and 2 minutes, and a sealing material (trade name: GE-7470L-A (manufactured by Hitachi Chemical) was used to form a sealing layer.

After that, each mask sheet was peeled off at a speed of 50 mm/min in a direction of 180°, and the state of adhesive residue on the sealing layer and the lead frame after peeling off was confirmed. Based on the ratio of the area of the adhesive residue to the total area of the surfaces of the sealing layer and the lead frame, the presence or absence of the adhesive residue was evaluated in 6 grades according to the following criteria.

5: 60-100% (the remaining adhesive layer is generally relatively thick)
4: 60-100% (the remaining adhesive layer is generally relatively thin)
3: 30% or more and less than 60% 2: 10% or more and less than 30% 1: more than 0% and less than 10% X: 0%

4) Adhesive strength to lead frame The mask sheet of each example was cut into 100 mm (length) x 25 mm (width) and pressed with a lead frame made of copper material at a temperature of 230°C to 250°C to evaluate the adhesive strength. A test piece was manufactured for After that, the peel strength was measured when the mask sheet was peeled off from the lead frame at a peel strength of 180°C, a peeling temperature of 25°C, and a peeling speed of 300 mm/min using an adhesive strength measuring device (CHEMI LAB SurTA).

5. Comparative Evaluation of Slip Friction Forces of Examples and Comparative Examples The slip friction forces of Examples and Comparative Examples were evaluated. The evaluation results are shown in Table 5 below.

The slip friction force was measured by preparing a pair of each of the mask sheets used in the examples and the comparative examples, placing the adhesive layer of one of the mask sheets against the reinforcing layer of the other mask sheet, and then placing the A weight of 1 kg was lifted to apply a horizontal force to the reinforcement layer, and the slip force of the reinforcement layer from the adhesive layer was measured.

Windability is determined by whether wrinkles or folds occur when the mask sheets of Examples and Comparative Examples are wound at a constant speed of 3 m/min.

As shown in Table 5 above, the mask sheet according to the present invention has a slip frictional force of 700 gf/50 mm or less, so that air bubbles and wrinkles do not occur during long-term winding and storage. However, since the mask sheet according to the comparative example has a very high slip frictional force of 1450 gf/50 mm, the adhesive layer and the reinforcing layer stick to each other, which may cause problems during winding and storage.

As described above, the present invention has been described, but the present invention is not limited by the embodiments disclosed herein, and various modifications can be made by ordinary engineers within the scope of the technical idea of the present invention. It is self-evident that Furthermore, even if the operation and effect of the configuration of the present invention are not explicitly described and explained in the above-described embodiments of the present invention, it should be appreciated that the predictable effect of the configuration should also be recognized.

Claims (12)

supporting film,
an adhesive layer located on one side of the support film;
a reinforcing layer located on the surface of the support film opposite to the surface on which the adhesive layer is located,
The slip friction force of the reinforcing layer with respect to the adhesive layer is 700 gf/50 mm or less,
Mask sheet for QFN semiconductor package.
[Slip friction force]
The slip friction force is obtained by placing the reinforcing layer on the adhesive layer, placing a weight of 1 kg on the reinforcing layer, and applying a horizontal force to the reinforcing layer. It is defined as the force that the reinforcing layer slips. The reinforcing layer contains 0.1 to 5% by weight of inorganic particles,
A mask sheet for a QFN semiconductor package according to claim 1. The adhesive layer is
Including a thermoplastic resin having an imide group,
A mask sheet for a QFN semiconductor package according to claim 1. The reinforcing layer is
Including a thermoplastic resin having an imide group,
A mask sheet for a QFN semiconductor package according to claim 1. The support film is
is a polyimide film,
A mask sheet for a QFN semiconductor package according to claim 1. The adhesive layer is
After pressing at 230 ° C to 250 ° C, the adhesive strength is 5 gf / 25 mm to 600 gf / 25 mm,
A mask sheet for a QFN semiconductor package according to claim 1. The adhesive layer is
a glass transition temperature of 100 to 250° C.;
A mask sheet for a QFN semiconductor package according to claim 1. The elastic modulus at 230 ° C. is 5 MPa or more,
A mask sheet for a QFN semiconductor package according to claim 1. 5% weight loss temperature is 400 ° C. or higher,
A mask sheet for a QFN semiconductor package according to claim 1. A protective film is provided on the surface of the adhesive layer opposite to the surface on which the support film is located,
A mask sheet for a QFN semiconductor package according to claim 1. a lead frame including a die pad and inner leads;
A mask sheet according to any one of claims 1 to 10,
The mask sheet is attached to the lead frame so that the adhesive layer is in contact with one side of the lead frame.
Lead frame. a lead frame including a die pad and inner leads;
a semiconductor element mounted on the die pad;
a wire connecting the semiconductor element and the inner lead;
an encapsulation layer encapsulating the semiconductor element and the wires;
A mask sheet according to any one of claims 1 to 10,
In the mask sheet, the adhesive layer is attached to the surface of the lead frame opposite to the surface on which the semiconductor element is mounted.
QFN semiconductor package.

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