阅读说明：本技术 耐热脱模片和热压接方法 (Heat-resistant release sheet and thermocompression bonding method ) 是由 秋叶府统 吉松王彦 于 2019-10-01 设计创作，主要内容包括：本申请的耐热脱模片在利用热加压头进行压接对象物的热压接时配置在压接对象物与热加压头之间,用于防止压接对象物与热加压头的固着,所述耐热脱模片在300℃下的表面硬度用通过式子A-(300)(％)＝(d-(300)/t-0)×100而求出的压痕度A-(300)来表示,且为15％以下。其中,t-0为常温(20℃)下的耐热脱模片的厚度。d-(300)为通过基于以下的测定条件的热机械分析(TMA)而评价的、300℃下的贯穿探针对耐热脱模片的压痕量。[测定条件]·测定模式：贯穿模式、升温测定；·贯穿探针的形状和前端直径：圆柱状和1mmφ；·施加压力：1MPa；·升温开始温度和升温速度：20℃和10℃/分钟。根据本申请的耐热脱模片,能够更可靠地应对可预料到的热压接温度的进一步上升。(The heat-resistant release sheet is arranged between an object to be pressure-bonded and a hot pressing head when the object to be pressure-bonded is thermally pressure-bonded by the hot pressing head, and is used for preventing the object to be pressure-bonded and the hot pressing head from being fixed, and the surface hardness of the heat-resistant release sheet at 300 ℃ is represented by the formula A 300 (％)＝(d 300 /t 0 ) Degree of indentation A determined by X100 300 Expressed by (A), and is 15% or less. Wherein, t 0 Is a thickness of the heat-resistant release sheet at normal temperature (20 ℃ C.)And (4) degree. d 300 The trace amount of pressure of the penetrating probe against the heat-resistant release sheet at 300 ℃ was evaluated by thermomechanical analysis (TMA) based on the following measurement conditions. [ measurement conditions]Measurement mode: penetration mode, temperature rise measurement; shape and tip diameter of the penetrating probe: cylindrical and 1mm phi; application of pressure: 1 MPa; temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min. According to the heat-resistant release sheet of the present application, it is possible to more reliably cope with an expected further increase in the thermocompression bonding temperature.)

1. A heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressed by the heat pressing head, and which prevents the object to be pressure-bonded and the heat pressing head from being fixed to each other,

the surface hardness of the heat-resistant release sheet at 300 ℃ is represented by the general formula A₃₀₀(％)＝(d₃₀₀/t₀) Degree of indentation A determined by X100₃₀₀Expressed by (b), and is 15% or less,

wherein, t₀The thickness of the heat-resistant release sheet at normal temperature, i.e., 20 ℃; d₃₀₀The indentation amount of the heat-resistant release sheet by the penetration probe at 300 ℃ was evaluated by thermomechanical analysis (TMA) based on the following measurement conditions,

the measurement conditions were as follows:

measurement mode: penetration mode and temperature measurement

Shape and tip diameter of the penetrating probe: cylindrical and 1mm phi

Application of pressure: 1MPa of

Temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min.

2. The heat-resistant release sheet according to claim 1, wherein the heat-resistant release sheet comprises a sheet of Polytetrafluoroethylene (PTFE) or modified PTFE,

the modified PTFE has a Tetrafluoroethylene (TFE) unit content of 99 mass% or more.

3. The heat-resistant release sheet according to claim 1 or 2, wherein at least one main surface of the heat-resistant release sheet is subjected to a modification treatment for increasing the surface hardness.

4. The heat-resistant release sheet according to any one of claims 1 to 3, wherein a resin contained in the heat-resistant release sheet has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher.

5. A thermal compression bonding method for bonding an object by a thermal compression head, wherein,

performing thermocompression bonding of the object to be pressure-bonded by the heat pressing head in a state where the heat-resistant release sheet is arranged between the heat pressing head and the object to be pressure-bonded,

the heat-resistant release sheet according to any one of claims 1 to 4.

Technical Field

The present invention relates to a heat-resistant release sheet and a thermal compression bonding method using the same.

Background

Thermocompression bonding is used in the manufacture and flip chip mounting of semiconductor chips and the manufacture of Printed Circuit Boards (PCBs) using an underfill such as NCF (Non-Conductive Film) and NCP (Non-Conductive Paste). The thermocompression bonding method is also used for connection between a PCB and an electronic component using an Anisotropic Conductive Film (ACF). In thermocompression bonding of a bonding object, a thermal pressing head is generally used as a heat source and a pressure source. In order to prevent the fixation between the object to be pressure-bonded and the thermal pressing head during the thermal compression bonding, a heat-resistant release sheet is generally disposed between the object to be pressure-bonded and the thermal pressing head.

Patent document 1 discloses a tetrafluoroethylene-hexafluoropropylene copolymer (FEP) film which is not a heat-resistant release sheet but can be used for curved surface molding of a fiber-reinforced prepreg.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2002-321238

Disclosure of Invention

Problems to be solved by the invention

The thermocompression bonding temperature at the time of thermocompression bonding of the object to be bonded is expected to further increase. By further increasing the thermocompression bonding temperature, for example, thermocompression bonding of the object to be bonded in which more layers are stacked than in the past can be achieved, and the manufacturing efficiency and mounting efficiency of the semiconductor chip can be improved.

An object of the present invention is to provide a heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressed by the heat pressing head, prevents the object to be pressure-bonded and the heat pressing head from being fixed, and can more reliably cope with an expected further increase in thermal pressing temperature.

Means for solving the problems

The invention provides a heat-resistant release sheet which is arranged between an object to be pressure-bonded and a heat pressing head when the object to be pressure-bonded is thermally pressed by the heat pressing head, and is used for preventing the object to be pressure-bonded and the heat pressing head from being fixed,

the surface hardness of the heat-resistant release sheet at 300 ℃ is represented by the general formula A₃₀₀(％)＝(d₃₀₀/t₀) Degree of indentation A determined by X100₃₀₀Expressed by (A), and is 15% or less.

Wherein, t₀The thickness of the heat-resistant release sheet was measured at room temperature (20 ℃). d₃₀₀The amount of pressing of the heat-resistant release sheet by the penetrating probe at 300 ℃ was evaluated by thermomechanical analysis (hereinafter referred to as "TMA") under the following measurement conditions.

[ measurement conditions ]

Measurement mode: penetration mode and temperature measurement

Shape and tip diameter of the penetrating probe: cylindrical and 1mm phi

Application of pressure: 1MPa of

Temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min

From other aspects, the present invention provides a thermocompression bonding method,

the hot press bonding method of the object to be bonded by using a hot press head, wherein,

the heat-resistant release sheet is arranged between the heat pressing head and the object to be pressure-bonded, and the object to be pressure-bonded is subjected to thermocompression bonding by the heat pressing head,

the heat-resistant release sheet is the heat-resistant release sheet of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

The surface hardness of the heat-resistant release sheet of the present invention at 300 ℃ is in a specific range. Therefore, even when the thermocompression bonding temperature is further raised, for example, when the heating set temperature of the thermal pressing head is raised to about 330 ℃, the bonding of the heat-resistant release sheet to the surface of the thermal pressing head is less likely to occur, and high releasability as a heat-resistant release sheet can be maintained. In addition, even when the heat-resistant release sheet supplied by conveyance is partially bonded to the thermal pressing head, the heat-resistant release sheet can be prevented from following the thermal pressing head due to surface stretching, and high releasability can be ensured. Therefore, the heat-resistant release sheet of the present invention can more reliably cope with a further increase in the thermocompression bonding temperature that can be expected.

Drawings

Fig. 1 is a cross-sectional view schematically showing an example of the heat-resistant release sheet of the present invention.

Fig. 2 is a schematic view for explaining an example of a thermal compression bonding method using the heat-resistant release sheet of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[ Heat-resistant Release sheet ]

Fig. 1 shows an example of the heat-resistant release sheet of the present invention. The heat-resistant release sheet 1 shown in fig. 1 is composed of a polytetrafluoroethylene (hereinafter referred to as "PTFE") sheet 2. The heat-resistant release sheet 1 of fig. 1 has a single-layer structure of a PTFE sheet 2. The heat-resistant release sheet 1 has high heat resistance and releasability from PTFE contained in the sheet 2.

Heat-resistant release sheet 1 having surface hardness at 300 ℃ represented by the general formula A₃₀₀(％)＝(d₃₀₀/t₀) Degree of indentation A determined by X100₃₀₀Expressed by (A), and is 15% or less. Here, t₀Is at normal temperature (20 deg.C)Thickness of the heat-resistant release sheet 1. d₃₀₀The trace amount of pressure of the penetrating probe at 300 ℃ against the heat-resistant release sheet 1 was evaluated by TMA based on the following measurement conditions.

[ measurement conditions ]

Measurement mode: penetration mode and temperature measurement

Shape and tip diameter of the penetrating probe: cylindrical and 1mm phi

Application of pressure: 1MPa of

Temperature increase start temperature and temperature increase rate: 20 ℃ and 10 ℃/min

Degree of indentation A₃₀₀The content may be 14.5% or less, 14% or less, 13.5% or less, 13% or less, 12.5% or less, 12% or less, 11.5% or less, 11% or less, 10.5% or less, 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7% or less, 6.5% or less, 5% or less, 4.5% or less, and further may be 4% or less. Degree of indentation A₃₀₀The lower limit of (B) is, for example, at least-5%, may be at least-4%, -at least-3%, -at least-2%, and may be at least-1%. The indentation degree A is₃₀₀The heat-resistant release sheet 1 may have a negative value due to thermal expansion.

The heat-resistant release sheet 1 of fig. 1 is composed of a PTFE sheet 2. Wherein the indentation degree A is used as long as the surface hardness is 300 DEG C₃₀₀In the case of the resin, the resin content is 15% or less, and the resin contained in the heat-resistant release sheet 1 of the present invention is not limited to PTFE. In view of the heat resistance of the heat-resistant release sheet 1, the resin contained in the heat-resistant release sheet 1 preferably has a melting point of 310 ℃ or higher and/or a glass transition temperature of 210 ℃ or higher. The melting point may be more than 310 ℃, 315 ℃ or more, 320 ℃ or more, and further 325 ℃ or more. The upper limit of the melting point is, for example, 400 ℃ or lower. The glass transition temperature may be 220 ℃ or higher, 230 ℃ or higher, 240 ℃ or higher, and may be 250 ℃ or higher. The glass transition temperature is, for example, 300 ℃ or lower. In the present specification, the "melting point of the resin" means: a peak of "endothermic peak by crystal melting" measured when the resin is heated at a constant temperature rise rate, for example, 10 ℃ per minute in differential scanning calorimetry (hereinafter referred to as "DSC")And (3) temperature. In addition, the "glass transition temperature of the resin" in the present specification means: the peak temperature of the "endothermic peak by glass transition" measured when the resin is heated at a constant temperature-raising rate in DSC, for example, 10 ℃ per minute.

The heat-resistant release sheet 1 of the present invention may contain a resin of, for example, at least 1 selected from PTFE, modified PTFE, polyimide, polyamideimide, and Polyetheretherketone (PEEK), at least 1 selected from PTFE, modified PTFE, polyamideimide, and PEEK, or PTFE and/or modified PTFE. The heat-resistant release sheet 1 may contain a PTFE sheet, a modified PTFE sheet, a polyimide sheet, a polyamideimide sheet, or a PEEK sheet, may contain a PTFE sheet, a modified PTFE sheet, a polyamideimide sheet, or a PEEK sheet, and may contain a PTFE sheet or a modified PTFE sheet.

The modified PTFE is a copolymer of TFE and a modifying comonomer. In order to be classified as modified PTFE, the content of Tetrafluoroethylene (TFE) units in the copolymer must be 99 mass% or more. The modified PTFE is, for example, a copolymer of TFE with at least 1 modifying comonomer selected from the group consisting of ethylene, perfluoroalkyl vinyl ether, and hexafluoropropylene.

At least one main surface (main surface 3A and/or main surface 3B) of the heat-resistant release sheet 1 may be subjected to a modification treatment for increasing the surface hardness of the main surface, in other words, to a degree of indentation a₃₀₀A reduced upgrading process. The heat-resistant release sheet 1 subjected to the reforming treatment can more reliably cope with a further increase in the thermocompression bonding temperature. The modification treatment is preferably a treatment that does not form a new layer and/or coating film made of a resin and/or a compound different from the substance contained in the heat-resistant release sheet on the at least one main surface. An example of this treatment is a treatment of modifying at least one of the main surfaces. This treatment can maintain the thermal conductivity of the heat-resistant release sheet 1, for example. Further, the formed new layer and/or coating film can be prevented from being contaminated by the thermal pressing head and/or the object to be pressed due to decomposition products generated by decomposition at high temperature in the thermal pressing.

In the thermocompression bonding by the thermal pressing head, the main surface of the heat-resistant release sheet 1 which is in contact with the thermal pressing head is exposed to a higher temperature than the main surface which is in contact with the object to be pressure bonded. Therefore, the heat-resistant release sheet 1 having one main surface subjected to the above-described modification treatment is preferably used so that the one main surface contacts the hot pressing head.

When the heat-resistant release sheet 1 includes a PTFE sheet or a modified PTFE sheet, the modification treatment is, for example, a chemical treatment performed on the one main surface. An example of a chemical treatment is a sodium metal treatment. However, the modification process is not limited to this example. It can be presumed that: in the sodium metal treatment of the PTFE sheet and the modified PTFE sheet, fluorine atom desorption and carbonization (carbonization) are performed on the treated surface of the sheet, whereby the surface hardness of the treated surface is increased. The metal sodium treatment can be performed, for example, by applying a treatment liquid containing metal sodium to at least one of the main surfaces of the PTFE sheet or modified PTFE sheet to be treated, or by immersing the PTFE sheet or modified PTFE sheet to be treated in the treatment liquid. Depending on the impregnation method, both main surfaces of the PTFE sheet or the modified PTFE sheet may be subjected to modification treatment.

The treatment liquid used for the treatment of metal sodium is, for example, an ammonia solution of metal sodium or a tetrahydrofuran solution of a metal sodium-naphthalene complex. As the treatment liquid, a commercially available treatment liquid (for example, fluorobinder (registered trademark) manufactured by TECHMOS) can be used.

It is known that the adhesiveness of the treated surface is improved by treating the PTFE sheet with sodium metal. The present inventors have found for the first time that the effect of improving the releasability when used as a heat-resistant release sheet, particularly when the thermocompression bonding temperature is further raised.

The PTFE sheet 2 is preferably a sintered PTFE sheet comprising PTFE subjected to sintering. The term "sintering" of PTFE as used herein means heating PTFE obtained by polymerization to a temperature not lower than its melting point (327 ℃ C.), for example, 340 to 380 ℃.

The thickness of the heat-resistant release sheet 1 is, for example, 1 to 50 μm, and may be 5 to 40 μm, 10 to 35 μm, 20 to 35 μm, and further 25 to 35 μm.

The tensile strength of the heat-resistant release sheet 1 varies depending on the kind of the resin contained in the heat-resistant release sheet 1, and may be, for example, 30MPa or more, 33MPa or more, 35MPa or more, 40MPa or more, 45MPa or more, 50MPa or more, 55MPa or more, 60MPa or more, 80MPa or more, 100MPa or more, 150MPa or more, 200MPa or more, 220MPa or more, 240MPa or more, and further 260MPa or more. The upper limit of the tensile strength is, for example, 500MPa or less. According to the heat-resistant release sheet 1 having a tensile strength in these ranges, the supply by the conveyance between the heat pressing head and the object to be pressure-bonded can be performed more reliably and stably.

The maximum tensile elongation of the heat-resistant release sheet 1 varies depending on the kind of the resin contained in the heat-resistant release sheet 1, and may be, for example, 380% or less, 360% or less, 340% or less, 300% or less, 280% or less, 250% or less, 200% or less, 180% or less, 150% or less, 130% or less, 120% or less, 100% or less, 50% or less, 40% or less, and further 35% or less. The lower limit of the maximum tensile elongation is, for example, 5% or more. According to the heat-resistant release sheet 1 having the maximum tensile elongation in these ranges, particularly the heat-resistant release sheet 1 having the maximum tensile elongation of 300% or less, when the heat-resistant release sheet 1 is supplied by conveyance between the heat pressing head and the object to be pressure-bonded, even when the heat pressing head and/or the object to be pressure-bonded and the heat-resistant release sheet 1 are partially bonded, the sheet 1 can be suppressed from following these members due to elongation. In other words, the releasability of the heat-resistant release sheet 1 from the thermal pressing head and/or the object to be pressure-bonded can be further improved.

The tensile strength and the maximum tensile elongation of the heat-resistant release sheet 1 can be determined by a tensile test using a tensile tester. The stretching direction in the tensile test is, for example, the longitudinal direction (MD direction) of the heat-resistant release sheet 1. The shape of the test piece is, for example, Japanese Industrial Standard (JIS) K6251: dumbbell No. 1 as defined in 1993. The measurement conditions when the test piece is used are, for example: the distance between the standard lines of the test piece was 40mm, the distance between the grips was 70mm, and the drawing speed was 200 mm/min. The maximum tensile elongation can be calculated from the above-mentioned distance between the marks before the test and the distance between the marks at the time of breaking. The measurement temperature is, for example, 25. + -. 10 ℃.

In the heat-resistant release sheet 1, another layer may be disposed on the main surface 3A and/or the main surface 3B. However, in order to ensure good thermal conductivity as the heat-resistant release sheet 1, it is preferable not to dispose another layer on the main surface of the heat-resistant release sheet 1. In other words, the heat-resistant release sheet 1 is preferably a single layer.

The heat-resistant release sheet 1 is preferably a non-porous sheet. The heat-resistant release sheet 1 may be an impermeable sheet that does not allow a fluid (fluid) such as water to pass through in the thickness direction, based on the high liquid repellency (water repellency and oil repellency) of the material contained in the sheet 1, for example, PTFE. The heat-resistant release sheet 1 may be an insulating sheet (non-conductive sheet) based on the high insulating property of the material contained in the sheet 1, for example, PTFE.

The shape of the heat-resistant release sheet 1 is, for example, a polygon including a square and a rectangle, a circle, an ellipse, and a belt. The corners of the polygon may have a curvature. However, the shape of the heat-resistant release sheet 1 is not limited to these examples. The polygonal, circular, and elliptical heat-resistant release sheet 1 can be distributed in a single piece, and the strip-shaped heat-resistant release sheet 1 can be distributed in a wound body (roll) formed by winding around a core. The width of the strip-shaped heat-resistant release sheet 1 and the width of a roll body formed by winding the strip-shaped heat-resistant release sheet 1 can be freely set.

[ method for producing Heat-resistant Release sheet ]

Hereinafter, an example of a method for producing the heat-resistant release sheet 1 will be described with reference to the heat-resistant release sheet 1 made of the PTFE sheet 2 or the modified PTFE sheet as an example. However, the method for producing the heat-resistant release sheet 1 is not limited to the following examples.

First, a PTFE powder (molding powder) is introduced into a mold, and the powder in the mold is preshaped by applying a predetermined pressure for a predetermined time. The preforming may be carried out at normal temperature. The shape of the internal space of the die is preferably cylindrical so as to enable cutting by a cutting lathe described later. In this case, a cylindrical preform and a PTFE preform (block) can be obtained. Next, the obtained preform was taken out of the mold and sintered at a temperature not lower than the melting point (327 ℃) of PTFE for a predetermined time to obtain a PTFE preform. Next, the obtained PTFE preform is cut to a predetermined thickness to obtain a PTFE sheet 2 as a cut sheet (cut sheet). The obtained PTFE sheet 2 may be used as it is as the heat-resistant release sheet 1, or may be used as the heat-resistant release sheet 1 after undergoing a predetermined treatment, lamination of other layers, or the like. An example of the treatment is a modification treatment for increasing the surface hardness. An example of the reforming treatment is a sodium metal treatment. The PTFE sheet 2 may be stretched and/or rolled in order to increase the tensile strength of the heat-resistant release sheet 1 or suppress the maximum tensile elongation. When the PTFE preform is cylindrical, the PTFE sheet 2 and the heat-resistant release sheet 1 can be efficiently formed by using a cutting lathe that continuously cuts the surface while rotating the preform. Further, the thicknesses of the PTFE sheet 2 and the heat-resistant release sheet 1 to be formed can be relatively easily controlled by a cutting lathe, and the PTFE sheet 2 and the heat-resistant release sheet 1 can be formed in a band shape. Further, by using a modified PTFE powder instead of a PTFE powder, a modified PTFE sheet can be formed by the above-described method.

The heat-resistant release sheet 1 can also be produced by the following method.

First, a substrate sheet to be coated with a PTFE dispersion liquid on the surface is prepared. The substrate sheet is composed of, for example, resin, metal, paper, and a composite material thereof. The surface of the substrate sheet to which the PTFE dispersion is applied may be subjected to a peeling treatment for facilitating the peeling of the PTFE sheet 2 from the substrate sheet. The peeling treatment may be performed by a known method. Next, a coating film of the PTFE dispersion was formed on the surface of the substrate sheet. Various known coaters can be used for coating the PTFE dispersion. The PTFE dispersion may be applied to the surface of the substrate sheet by immersing the substrate sheet in the PTFE dispersion. Next, a PTFE sheet is formed from the coating film of the PTFE dispersion formed on the surface of the substrate sheet by drying and sintering. Subsequently, the formed PTFE sheet was peeled from the base sheet to obtain a PTFE sheet 2 as a casting sheet. The obtained PTFE sheet 2 may be used as it is as the heat-resistant release sheet 1, or may be used as the heat-resistant release sheet 1 after being subjected to a predetermined treatment, lamination of other layers, or the like. Examples of processing are described above. In order to improve the tensile strength or suppress the maximum tensile elongation of the heat-resistant release sheet 1, the PTTFE sheet 2 may be stretched and/or rolled. In this method, the thicknesses of the formed PTFE sheet 2 and the heat-resistant release sheet 1 can be controlled according to the coating thickness and/or the number of times of coating of the PTFE dispersion to the substrate sheet. Further, by using the modified PTFE dispersion instead of the PTFE dispersion, the modified PTFE sheet can be formed by the above-described method.

[ use of Heat-resistant Release sheet ]

As shown in fig. 2, the heat-resistant release sheet 1 can be used as a heat-resistant release sheet that is disposed between the hot pressing head 21 and the object 22 to be pressed when the object 22 to be pressed is thermocompressed by the hot pressing head 21, and prevents the fixation of both. The heat-resistant release sheet 1 is excellent in releasability. According to the heat-resistant release sheet 1, it is possible to prevent fixation (heat fixation) of the sheet 1 to the thermal pressing head 21 and/or the object 22 to be pressure-bonded, which is caused by heat at the time of thermocompression bonding.

The heat-resistant release sheet 1 can be supplied and arranged between the hot pressing head 21 and the object 22 to be pressure-bonded by conveyance. The heat-resistant release sheet 1 supplied and arranged by conveyance is, for example, in a belt shape.

The object 22 to be pressure-bonded is, for example, a semiconductor chip, a PCB, or an electronic component. The heat-resistant release sheet 1 can be used for, for example, the manufacture and flip chip mounting of semiconductor chips by thermocompression bonding, the manufacture of PCBs, and the connection of electronic components, and the like.

The heating set temperature of the hot pressing head 21 at the time of thermocompression bonding, in other words, the use temperature of the heat-resistant release sheet 1 may be, for example, 300 ℃. The use temperature may be 310 ℃ or higher, 320 ℃ or higher, 330 ℃ or higher, and may be 340 ℃ or higher. However, the use temperature of the heat-resistant release sheet 1 is not limited to these ranges. The heat-resistant release sheet 1 can also be used at a lower use temperature than the above examples.

[ Hot Press bonding method ]

The object 22 to be pressure-bonded can be subjected to thermocompression bonding using the heat-resistant release sheet 1 of the present invention. This thermocompression bonding method is a thermocompression bonding method for the object 22 to be bonded by the thermal pressing head 21, and the object 22 to be bonded is thermocompression bonded by the thermal pressing head 21 in a state where the heat-resistant release sheet 1 is arranged between the thermal pressing head 21 and the object 22 to be bonded. The heat-resistant release sheet 1 can be supplied and arranged between the hot pressing head 21 and the object 22 to be pressure-bonded, for example, by conveying.

[ method for producing thermocompression bonded article ]

The heat-resistant release sheet 1 of the present invention can be used to produce a thermocompression bonded product. The manufacturing method of the thermal compression bonding object comprises the following steps: the heat-resistant release sheet 1 is arranged between the hot pressing head 21 and the object 22 to be pressure-bonded, and the object 22 to be pressure-bonded is subjected to thermocompression bonding using the hot pressing head 21, thereby obtaining a thermocompression bonded body of the object 22 to be pressure-bonded, that is, a thermocompression bonded body. Examples of thermocompression bonds are PCBs and electronic components.

Examples

The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

First, a method for evaluating the heat-resistant release sheet produced in this example is shown.

[ surface hardness (indentation degree A)₃₀₀)]

The indentation degree A was evaluated as the surface hardness at 300 ℃ by the above-mentioned method₃₀₀. Specifically, the following is shown. First, a heat-resistant release sheet to be evaluated was cut into a square of 7mm × 7mm to obtain a test piece. Then, as the thickness t₀The thickness of the test piece was measured by a micrometer (manufactured by MITUTOYO corporation). Next, a test piece was placed on an evaluation table of a TMA measuring apparatus (manufactured by BRUKER, TMA4000S), and the indentation amount d of the test piece by the penetration probe at 300 ℃ was measured using a cylindrical penetration probe having a diameter of 1mm₃₀₀. The measurement mode includes a penetration mode and a temperature rise measurement. The applied pressure to the test piece was a constant pressure of 1MPa, the temperature increase start temperature was 20 ℃, and the temperature increase rate was 10 ℃/min. According to the measured thickness t₀And the amount of indentation d₃₀₀Through the formula A₃₀₀(％)＝(d₃₀₀/t₀) X 100 to determine the degree of indentation A₃₀₀。

[ releasability at the time of thermocompression bonding ]

The releasability (releasability from the hot press head) at the time of thermocompression bonding was evaluated as follows.

A heat-resistant release sheet cut into a rectangular shape having dimensions of 20mm X100 mm and serving as an evaluation object was placed on a base of a thermocompression bonding apparatus (Flip chip bonder FC-3000W, manufactured by Toray engineering Co.) having a thermal pressure head and a base. The heat-resistant release sheet was fixed to a base by bonding using an adhesive tape (No. 360UL, 60 μm thick, 19mm wide, having a polyimide base) having heat resistance to withstand only a thermal compression test. Specifically, the adhesive tape is bonded and fixed to each short side of the heat-resistant release sheet placed on the base so that the bonding width to the heat-resistant release sheet is 10mm and the bonding width to the base is 9 mm. The length of the adhesive tape used was set to 50mm, and the central portion in the longitudinal direction of the adhesive tape was brought into contact with the heat-resistant release sheet. The set temperature of the susceptor was set to 120 ℃. Next, after the hot pressing head was lowered so that the pressing pressure reached 20N, the hot pressing head was heated to 330 ℃ to perform a thermocompression bonding test for a pressing time of 10 seconds, and whether or not thermal fixing of the heat-resistant release sheet to the hot pressing head occurred was evaluated. When the hot press head was raised after the thermocompression bonding test, the case where the adhesive tape was not peeled from the base and the heat-resistant release sheet was peeled from the hot press head was judged to be good in releasability (o), and the case where the heat-resistant release sheet was not peeled or the case where the heat-resistant release sheet was peeled but the adhesive tape was peeled from the base was judged to be unsatisfactory in releasability (x).

[ tensile Strength and maximum tensile elongation ]

The tensile strength (tensile breaking strength) and the maximum tensile elongation were determined by a tensile test using a tensile tester (AG-I, Shimadzu corporation). The stretching direction is the longitudinal direction (MD direction) of the heat-resistant release sheet. The shape of the test piece was a dumbbell No. 1 as defined in JIS K6251: 1993. The measurement conditions were: the measurement temperature was 25 ℃, the distance between the standards of the test piece was 40mm, the distance between the jigs was 70mm, and the drawing speed was 200 mm/min. The maximum tensile elongation is calculated from the distance between the above-mentioned marks before the test and the distance between the marks at the time of breaking.

(example 1)

PTFE powder (Polyflon PTFE M-18 manufactured by Daikin Industries, Ltd.) was introduced into a cylindrical mold and preformed at a temperature of 23 ℃ and a pressure of 8.5MPa for a pressure application time of 1 hour. Next, the preform thus formed was taken out of the mold and sintered at 370 ℃ for 24 hours to obtain a cylindrical preform having a height of 300mm and an outer diameter of 470mmThe PTFE preform of (1). Then, the obtained PTFE preform was cut by a cutting lathe to obtain a PTFE cut film having a thickness of 50 μm. Next, the obtained cut film was rolled by a roll rolling device equipped with a pair of metal rolls maintained at 170 ℃, to obtain the heat-resistant release sheet of example 1 as a PTFE sheet having a thickness of 30 μm. Degree of indentation A of the heat-resistant release sheet of example 1₃₀₀0.3%, tensile strength 66.2MPa, maximum tensile elongation 120%, and good results of mold release property (. smallcircle.). The melting point of PTFE constituting the heat-resistant release sheet of example 1 was 327 ℃ or higher.

(example 2)

The heat-resistant release sheet produced in example 1 was immersed in a treatment solution containing sodium metal (fluorobinder (registered trademark) manufactured by TECHMOS corporation), then pulled up, and washed with acetone. Next, the heat-resistant release sheet of example 2 was immersed in pure water, washed, and then dried at 100 ℃ for 1 minute, whereby both main surfaces were treated with sodium metal. The immersion time in the treatment solution was set to 30 seconds. Indentation degree a of the heat-resistant release sheet of example 2₃₀₀0.1%, tensile strength 59.9MPa, maximum tensile elongation 118%, and good results of mold release property (. smallcircle.). The melting point of PTFE constituting the heat-resistant release sheet of example 2 was 327 ℃ or higher.

(example 3)

The PTFE preform produced in example 1 was cut with a cutting lathe to obtain a PTFE cut film having a thickness of 30 μm. This was used as the heat-resistant release sheet of example 3. Indentation degree a of the heat-resistant release sheet of example 3₃₀₀11%, tensile strength 34.6MPa, maximum tensile elongation 177%, and good results of evaluation of releasability (good quality). The melting point of PTFE constituting the heat-resistant release sheet of example 3 was 327 ℃ or higher.

(example 4)

The heat-resistant release sheet produced in example 3 was subjected to the same sodium metal treatment as in example 2. The treated sheet was used as the heat-resistant release sheet of example 4. Indentation degree a of the heat-resistant release sheet of example 4₃₀₀0.1% and tensile strengthThe degree was 33.1MPa, the maximum tensile elongation was 180%, and the results of the mold release properties evaluation were good (. largecircle.). The melting point of PTFE constituting the heat-resistant release sheet of example 4 was 327 ℃ or higher.

(example 5)

A modified PTFE preform was obtained in the same manner as in example 1, except that a modified PTFE powder (Dyneon TFM modified PTFE TFM1700, manufactured by 3M corporation, having a TFE unit content of 99 mass% or more) was used instead of the PTFE powder. The obtained modified PTFE preform was cut by a cutting lathe to obtain a modified PTFE cut film having a thickness of 30 μm. This was used as the heat-resistant release sheet of example 5. Indentation degree a of the heat-resistant release sheet of example 5₃₀₀10%, tensile strength of 42.1MPa, maximum tensile elongation of 278%, and good results of evaluation of releasability (good quality). The melting point of the modified PTFE constituting the heat-resistant release sheet of example 5 was 327 ℃ or higher.

(example 6)

The heat-resistant release sheet produced in example 5 was subjected to the same sodium metal treatment as in example 2. The treated sheet was used as the heat-resistant release sheet of example 6. Indentation degree a of the heat-resistant release sheet of example 6₃₀₀0.2%, tensile strength 43.1MPa, maximum tensile elongation 270%, and good results of mold release property (. smallcircle.). The melting point of PTFE constituting the heat-resistant release sheet of example 6 was 327 ℃ or higher.

The evaluation results are summarized in table 1 below.

[ Table 1]

Industrial applicability

The heat-resistant release sheet of the present invention can be disposed between a thermal pressing head and an object to be pressure-bonded when the object to be pressure-bonded is thermally pressed by the thermal pressing head, and prevents the fixation of the both. Thermocompression bonding using the heat-resistant release sheet of the present invention can be applied to, for example, manufacturing and flip chip mounting of semiconductor chips, manufacturing of PCBs, and connection of electronic components.