Polyamic acid, polyamic acid composition, polyamic acid film, polyimide, polyimide film, wiring circuit board, semiconductor package and electronic apparatus

Abstract

To provide a polyamic acid, a polyamic acid composition and a polyamic acid film capable of improving surface smoothness of an insulator layer, a polyimide and a polyimide film produced from the polyamic acid, a wiring circuit board equipped with an insulator layer produced from the polyamic acid, and a semiconductor package and an electronic apparatus equipped with the wiring circuit board.SOLUTION: A polyamic acid is a precursor of a polyimide to be used as an insulator layer of a wiring circuit board. The polyamic acid is a reaction product of 3,4'-oxydiphthalic acid dianhydride and a diamine component containing ether diamine.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to polyamic acid, polyamic acid composition, polyamic acid film, polyimide, polyimide film, wiring circuit board, semiconductor package, and electronic device.

Background Art

[0002] Conventionally, as a precursor of a polyimide film that can be used as an interlayer insulating film, a polyamic acid obtained by the reaction of pyromellitic dianhydride and a diamine component (2,2'-bis(trifluoromethyl)benzidine and 3,5-diaminobenzamide) is known (for example, see Patent Document 1 below).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the varnish of polyamic acid as described in Patent Document 1, when the varnish of polyamic acid is applied to a substrate having irregularities on the surface, depending on the irregularities of the applied surface, irregularities may occur on the surface of the dry film of the polyamic acid varnish.

[0005] If the dry film thermosets in a state where irregularities exist on the surface of the dry film, irregularities will remain on the surface of the cured insulating layer, and it may become difficult to form a conductor pattern on the insulating layer.

[0006] The present invention provides a polyamic acid, a polyamic acid composition, and a polyamic acid film capable of improving the flatness of an insulating layer, a polyimide and a polyimide film made from the polyamic acid, a wiring circuit board including an insulating layer made from the polyamic acid, and a semiconductor package and an electronic device including the wiring circuit board.

Means for Solving the Problems

[0007] The present invention [1] includes a polyamic acid which is a precursor of polyimide used as an insulating layer of a wiring circuit board and is a reaction product of 3,4'-oxydiphthalic dianhydride and a diamine component containing an ether diamine.

[0008] The present invention [2] includes the polyamic acid of the above [1], wherein the ratio of the ether diamine in the diamine component is 0.5 mol or more per 1 mol of 3,4'-oxydiphthalic dianhydride.

[0009] The present invention [3] includes the polyamic acid of the above [1] or [2], wherein the diamine component contains only the ether diamine.

[0010] The present invention [4] includes the polyamic acid of any one of the above [1] to [3], wherein the ether diamine is 1,3-bis(4-aminophenoxy)benzene.

[0011] The present invention [5] is a polyamic acid composition containing any one of the polyamic acids of the above [1] to [4] and a solvent.

[0012] The present invention [6] includes a polyamic acid film which is a dried product of the polyamic acid composition of the above [5].

[0013] The present invention [7] includes a polyimide which is an imidized product of any one of the polyamic acids of the above [1] to [4].

[0014] The present invention [8] includes a polyimide film which is a film made of the polyimide of the above [7].

[0015] The present invention [9] includes a wiring circuit board which includes an insulating layer made of the polyimide of the above [7] and a conductor pattern.

[0016] The present invention

[10] includes a semiconductor package which includes the wiring circuit board of the above [9] and a semiconductor chip mounted on the wiring circuit board.

[0017] The present invention

[11] includes an electronic device which includes the semiconductor package of the above

[10] .

Advantages of the Invention

[0018] The polyamic acid of the present invention is a reaction product of 3,4'-oxydiphthalic dianhydride and a diamine component containing ether diamine. 3,4'-oxydiphthalic dianhydride is an asymmetric tetracarboxylic dianhydride having a molecular structure in which two phthalic anhydrides are bonded by an ether bond.

[0019] Therefore, a dry film (polyamic acid film) made from the polyamic acid can be easily formed by hot pressing.

[0020] Therefore, in the step of forming the insulating layer, the surface of the dry film made from the polyamic acid can be easily formed into a flat shape by hot pressing.

[0021] As a result, the flatness of the insulating layer can be improved.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0023] 1. Polyamic acid The polyamic acid of the present invention is used in the manufacture of wiring circuit boards. Specifically, the polyamic acid of the present invention is a precursor of polyimide used as an insulating layer of a wiring circuit board. Preferably, the polyamic acid of the present invention is a precursor of polyimide used as the interlayer insulating layer 22 (see Fig. 2) of the semiconductor package substrate 2 (see Fig. 1). The semiconductor package substrate 2 will be described later. [[ID=z12]]

[0024] The polyamic acid is a reaction product of 3,4'-oxydiphthalic dianhydride (α-ODPA) and a diamine component.

[0025] α-ODPA has a molecular structure in which two phthalic anhydrides are bonded by an ether bond. The ether bond bonds the carbon at the 3-position of one phthalic anhydride and the carbon at the 4-position of the other phthalic anhydride. Therefore, the molecular structure of α-ODPA is asymmetric when the oxygen atom of the ether bond is the center of symmetry. That is, α-ODPA is an asymmetric tetracarboxylic dianhydride.

[0026] Note that 4,4'-oxydiphthalic dianhydride (s-ODPA), which is a structural isomer of α-ODPA, is symmetric when the oxygen atom of the ether bond is the center of symmetry. That is, s-ODPA is a symmetric tetracarboxylic dianhydride.

[0027] The diamine component contains at least one kind of diamine. The diamine component contains only diamine. The diamine component contains, for example, ether diamine. Ether diamine is a diamine having an ether bond.

[0028] Examples of the ether diamine include aromatic diamines having an ether bond (aromatic ether diamines) and aliphatic diamines having an ether bond (aliphatic ether diamines).

[0029] Examples of the aromatic ether diamine include 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB), 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB), 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 3,3'-oxydianiline, and 3,4'-diaminodiphenyl ether.

[0030] Examples of the aliphatic ether diamine include poly(propylene glycol)diamine, 1,4-butanediol bis(3-aminopropyl)ether, 1,2-bis(2-aminoethoxy)ethane, diethylene glycol bis(3-aminopropyl)ether, 2,2'-oxybis(ethylamine), 1,14-diamino-3,6,9,12-tetraoxatetradecane, polyethylene glycol bis(3-aminopropyl)ether, and polyethylene glycol diamine.

[0031] The ether diamine is preferably an aromatic ether diamine, more preferably 1,3,4-APB.

[0032] When the ether diamine is 1,3,4-APB, the heat resistance of the insulating layer can be improved.

[0033] The proportion of the ether diamine in the diamine component is, for example, 0.5 mol or more, preferably 0.7 mol or more, relative to 1 mol of α-ODPA.

[0034] When the proportion of the ether diamine in the diamine component is at the above lower limit or more, the flatness of the insulating layer can be improved.

[0035] The upper limit of the proportion of the ether diamine in the diamine component is not limited. The proportion of the ether diamine in the diamine component may be equimolar to α-ODPA. The diamine component may contain only the ether diamine.

[0036] In addition to the ether diamine, the diamine component may contain a diamine having no ether bond.

[0037] Examples of the diamine having no ether bond include an aromatic diamine having no ether bond and an aliphatic diamine having no ether bond.

[0038] Examples of aromatic diamines having no ether bond include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 1,4-diaminobenzene, 2,5-diaminotoluene, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 1,5-diaminonaphthalene, α,α'-bis(4-aminophenyl)-1,4-diisopropylbenzene, m-xylylenediamine, p-xylylenediamine, 3-aminobenzylamine, 4-aminobenzylamine, bis(3-aminophenyl)sulfone, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,3-bis[2-(4-aminophenyl)-3-propyl]benzene, 1,8-diaminonaphthalene, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diamino-p-terphenyl, 4,4'-diaminodiphenylmethane, 4,4'-methylenebis(2-ethyl-6-methylaniline), 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2,6-dimethylaniline), 1,4-phenylenediamine, 1,3-phenylenediamine, 1,3-phenylenediamine, o-tolidine, bis(4-aminophenyl)sulfide, 3,3',5,5'-tetramethylbenzidine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 4,4'-ethylenedianiline, and 4,4'-diamino-2,2'-dimethylbibenzyl.

[0039] Examples of aliphatic diamines having no ether bond include 1,12-dodecanediamine, 1,6-diaminohexane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 1,2-cyclohexanediamine, ethylenediamine, 3,3'-diamino-N-methyldipropylamine, N,N'-bis(3-aminopropyl)ethylenediamine, 1,10-diaminodecane, 1,12-diaminododecane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,5-diaminopentane, 1,3-diaminopropane, 1,4-diaminobutane, 1,11-diamino-undecane, 2-methyl-1,5-diaminopentane, 2,2'-diamino-N-methyldiethylamine, 2-methyl-1,3-propanediamine, 4,4'-methylenebis(cyclohexylamine), and 1,3-diaminopentane.

[0040] The proportion of the "diamine having no ether bond" in the diamine component is, for example, less than 0.5 mol, preferably 0.3 mol or less, relative to 1 mol of α-ODPA1.

[0041] 2. Polyamic acid composition The polyamic acid composition is in a liquid state (varnish). The polyamic acid composition contains the above-described polyamic acid and a solvent.

[0042] The solvent is not limited as long as it can dissolve the polyamic acid. Examples of the solvent include aprotic polar solvents.

[0043] Examples of the aprotic polar solvent include N-methyl-2-pyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethylformamide, and hexamethylphosphoramide.

[0044] The proportion of the polyamic acid in the polyamic acid composition is, for example, 5% by mass or more, preferably 7.5% by mass or more, more preferably 10% by mass or more.

[0045] The proportion of polyamic acid in the polyamic acid composition is, for example, 20% by mass or less, preferably 16% by mass or less, more preferably 14% by mass or less.

[0046] The proportion of polyamic acid in the polyamic acid composition may be 5% by mass to 20% by mass, 7.5% by mass to 16% by mass, or 10% by mass to 14% by mass.

[0047] The viscosity of the polyamic acid composition at 25°C is, for example, 5 Pa·s or more, preferably 8 Pa·s or more.

[0048] The viscosity of the polyamic acid composition at 25°C is, for example, 15 Pa·s or less, preferably 14 Pa·s or less.

[0049] The viscosity of the polyamic acid composition at 25°C may be 5 Pa·s to 15 Pa·s, or 8 Pa·s to 14 Pa·s.

[0050] The polyamic acid composition is obtained, for example, by reacting α-ODPA and a diamine component in a solvent.

[0051] When patterning the insulating layer of a wiring circuit board by photolithography, the polyamic acid composition may contain a photosensitizer and a development accelerator in addition to the polyamic acid and the solvent.

[0052] The photosensitizer promotes the imidization of the polyamic acid in the exposed portion during the exposure step of the photolithography method. The exposed portion is the exposed portion of the dry film of the polyamic acid composition.

[0053] The development accelerator promotes the dissolution of the unexposed portion during the development step of the photolithography method. The unexposed portion is the portion of the dry film of the polyamic acid composition that was not exposed during the exposure step.

[0054] 3. Polyamic Acid Film, Polyimide, and Polyimide Film The polyamic acid film of the present invention is a dried product of the above-described polyamic acid composition. The polyamic acid film can be obtained, for example, by applying the polyamic acid composition to a substrate and drying it. The polyamic acid film contains the above-described polyamic acid, and optionally, a photosensitizer and a development accelerator.

[0055] The glass transition temperature (Tg) of the polyamic acid film is, for example, 135°C or lower, preferably 120°C or lower. The glass transition temperature (Tg) of the polyamic acid film is, for example, 60°C or higher. The glass transition temperature (Tg) of the polyamic acid film may be 60°C to 135°C, or 60°C to 120°C.

[0056] The glass transition temperature (Tg) is the temperature at which the loss tangent (tanδ) is maximized when the dynamic viscoelasticity is measured under the following measurement conditions using a dynamic viscoelasticity measuring device (trade name: RSA-G2, manufactured by TA Instruments Japan).

[0057] <Measurement Conditions> Sample size: Width 10 mm, length 20 mm Measurement mode: Tensile mode Measurement temperature range: 0°C to 200°C Heating rate: 5°C / min Frequency: 1 Hz Load (axial direction): 0.01 N The polyimide of the present invention is an imidized product of the above-described polyamic acid. The polyimide film of the present invention is a film made of polyimide. The polyimide film can be obtained, for example, by heating the above-described polyamic acid film to imidize the polyamic acid.

[0058] The glass transition temperature (Tg) of the polyimide film is, for example, 140°C or higher. The upper limit value of the glass transition temperature (Tg) of the polyimide film is not limited.

[0059] The heat resistance temperature of the polyimide film is, for example, 130°C or higher, preferably 200°C or higher, more preferably 300°C or higher, and even more preferably 400°C or higher. The upper limit value of the heat resistance temperature of the polyimide film is not limited.

[0060] The heat resistance temperature of the polyimide film is measured by the method described in the examples below.

[0061] The dielectric constant of the polyimide film at 10 GHz is, for example, 3.0 to 4.0, preferably 3.2 to 3.5.

[0062] The dielectric tangent of the polyimide film at 10 GHz is, for example, 0.00500 to 0.00800, preferably 0.00550 to 0.00700.

[0063] The dielectric constant and the dielectric tangent are measured by the method described in the examples below.

[0064] 4. Semiconductor Package and Wiring Circuit Board The semiconductor package 1 is a component that constitutes a circuit board of an electronic device. That is, the electronic device includes the semiconductor package 1.

[0065] As shown in FIG. 1, the semiconductor package 1 includes a semiconductor package substrate 2 as an example of a wiring circuit board, a semiconductor chip 3, and a sealing resin 4.

[0066] (1) Semiconductor Package Substrate As shown in FIG. 2, the semiconductor package substrate 2 includes a core layer 21, a plurality of insulating layers 22A, 22B, 22C, and a plurality of conductor patterns 23A, 23B, 23C.

[0067] The core layer 21 is made of, for example, metal. Examples of the metal include aluminum, stainless steel, and copper. The core layer 21 is preferably made of stainless steel. The thickness of the core layer 21 is not limited.

[0068] The plurality of insulating layers 22A, 22B, 22C are laminated on one side of the core layer 21 in the thickness direction of the semiconductor package substrate 2. Each of the plurality of insulating layers 22A, 22B, 22C is made of polyimide. That is, each of the plurality of insulating layers 22A, 22B, 22C is an example of the above-described polyimide film. The insulating layer 22A is disposed between the conductor pattern 23A and the core layer 21 in the thickness direction. The insulating layer 22B is disposed between the conductor pattern 23B and the conductor pattern 23A in the thickness direction. The insulating layer 22C is disposed between the conductor pattern 23C and the conductor pattern 23B in the thickness direction.

[0069] The thickness of each of the plurality of insulating layers 22A, 22B, 22C is, for example, 5 μm to 20 μm, preferably 5 μm to 15 μm.

[0070] The conductor pattern 23A is disposed on one surface of the insulating layer 22A in the thickness direction. The semiconductor package substrate 2 also has a plurality of insulating layers 24 (see FIG. 1) and a plurality of conductor patterns on the other side of the core layer 21 in the thickness direction. The conductor pattern 23A is connected to the conductor pattern on the other side in the thickness direction via a via (not shown) that penetrates the insulating layer 22A and the core layer 21. The conductor pattern 23B is disposed on one surface of the insulating layer 22B in the thickness direction. The conductor pattern 23B is connected to the conductor pattern 23A via the via 25A. The conductor pattern 23C is disposed on one surface of the insulating layer 22C in the thickness direction. The conductor pattern 23C is connected to the conductor pattern 23B via the via 25B. As the material of each of the conductor patterns, for example, copper can be mentioned.

[0071] The thickness of each of the conductor patterns 23A, 23B, 23C is, for example, 5 μm to 40 μm.

[0072] (2) Semiconductor chip As shown in FIG. 1, the semiconductor chip 3 is mounted on the semiconductor package substrate 2. The semiconductor chip 3 is disposed on one surface of the semiconductor package substrate 2 in the thickness direction. In the present embodiment, the semiconductor chip 3 is electrically connected to the terminal 231 of the conductor pattern 23C via, for example, a wire 5.

[0073] (3) Encapsulating resin The encapsulating resin 4 is disposed on one surface of the semiconductor package substrate 2 in the thickness direction. The encapsulating resin 4 encapsulates the semiconductor chip 3.

[0074] 5. Manufacture of semiconductor package substrate In the manufacture of the semiconductor package substrate 2 described above, for example, starting from the core layer 21, the insulating layer 22 and the conductor pattern 23 are alternately formed. That is, the manufacturing method of the semiconductor package substrate 2 includes a step of forming the insulating layer 22 (see FIGS. 3A and 3B) and a step of forming the conductor pattern 23 (see FIG. 3C).

[0075] Specifically, as shown in FIG. 3A, in the step of forming the insulating layer 22, first, the above-described polyamic acid composition is applied to the surface of the core layer 21 or the insulating layer 22.

[0076] Next, the coating film of the polyamic acid composition is dried by heating. The drying temperature is not limited as long as the solvent can be volatilized. When the solvent is N-methyl-2-pyrrolidone, the drying temperature is, for example, 120°C to 140°C, preferably 125°C to 135°C. By drying the coating film of the polyamic acid composition, a dry film F of the polyamic acid composition is formed. The dry film F is an example of the above-described polyamic acid film.

[0077] At this time, due to the volatilization of the solvent and the shrinkage during drying (the shrinkage of the polyamic acid film due to the imidization of the polyamic acid), unevenness may occur on the surface of the dry film F according to the unevenness of the surface on which the polyamic acid composition is applied. If the dry film F is thermoset in a state where unevenness exists on the surface of the dry film F, unevenness may remain on the surface of the insulating layer 22, making it difficult to form the conductor pattern 23.

[0078] In this regard, the above-mentioned polyamic acid is a reaction product of α-ODPA and a diamine component containing ether diamine.

[0079] Therefore, as shown in FIG. 3B, the surface of the dry film F can be easily formed into a flat shape by hot pressing.

[0080] The heating temperature in the hot pressing is, for example, 140°C to 200°C, preferably 180°C to 190°C.

[0081] The pressure in the hot pressing is, for example, 0.1 MPa to 3 MPa, preferably 1 MPa to 2 MPa.

[0082] After hot pressing, the insulating layer 22 is formed by curing if necessary.

[0083] Next, as shown in FIG. 3C, through-holes 221 for passing vias 25 are formed in the insulating layer 22, for example, by laser processing.

[0084] Next, the conductor pattern 23 and the via 25 are formed, for example, by electrolytic plating.

[0085] In this way, by alternately forming the insulating layer 22 and the conductor pattern 23 with the core layer 21 as the starting material to form the conductor pattern 23 with the desired number of layers, the semiconductor package substrate 2 is completed.

[0086] 6. Function and effect The polyamic acid of the present invention is a reaction product of α-ODPA and a diamine component containing ether diamine. α-ODPA is an asymmetric tetracarboxylic dianhydride having a molecular structure in which two phthalic anhydrides are bonded by an ether bond.

[0087] Therefore, the dry film F (polyamic acid film) made from the polyamic acid can be easily formed by hot pressing.

[0088] Therefore, as shown in FIGS. 3A and 3B, in the step of forming the insulating layer 22, the surface of the dry film F can be easily formed flat by hot pressing.

[0089] As a result, the flatness of the insulating layer 22 can be improved.

Examples

[0090] Examples and comparative examples are shown below to more specifically explain the present invention. Note that the present invention is not limited to any examples and comparative examples. Also, specific numerical values such as the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (numerical values defined as "below" and "less than") or lower limit (numerical values defined as "above" and "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Mode for Carrying Out the Invention".

[0091] 1. Production of polyamic acid composition (1) Example 1 3,4'-Oxydiphthalic dianhydride (α-ODPA) and 1,3-bis(4-aminophenoxy)benzene (1,3,4-APB) were dissolved in N-methylpyrrolidone (solvent) at a molar ratio (α-ODPA:1,3,4-APB) of 1:1. The obtained solution was stirred at 25°C to prepare a polyamic acid composition.

[0092] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0093] The viscosity (at 25°C) of the polyamic acid composition was measured at 25°C for 5 minutes at a rotational speed of 2.5 rpm after preheating at 25°C for 1 minute using an E-type viscometer (RE-85U, manufactured by Toki Sangyo Co., Ltd.).

[0094] (2) Example 2 A polyamic acid composition was prepared in the same manner as in Example 1, except that 1,3-bis(3-aminophenoxy)benzene (1,3,3-APB) was used instead of 1,3,4-APB as the diamine.

[0095] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0096] (3) Example 3 A polyamic acid composition was prepared in the same manner as in Example 1, except that 1,12-dodecanediamine was used in addition to 1,3,4-APB as the diamine, and α-ODPA, 1,3,4-APB, and 1,12-dodecanediamine were blended at a molar ratio (α-ODPA:1,3,4-APB:1,12-dodecanediamine) of 1:7:3.

[0097] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0098] (4) Comparative Example 1 A polyamic acid composition was prepared in the same manner as in Example 1, except that 4,4'-oxydiphthalic dianhydride (s-ODPA) was used instead of α-ODPA as the tetracarboxylic dianhydride.

[0099] In Comparative Example 1, since the viscosity (at 25°C) after stirring for 15 hours was 15 Pa·s or more, N-methylpyrrolidone was added to adjust the viscosity (at 25°C) from 8 Pa·s to 14 Pa·s.

[0100] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0101] (5) Comparative Example 2 A polyamic acid composition was prepared in the same manner as in Example 1, except that 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (BPADA) was used as the tetracarboxylic dianhydride instead of α-ODPA.

[0102] In Comparative Example 2, since the viscosity (at 25°C) after stirring for 15 hours was 15 Pa·s or more, N-methylpyrrolidone was added to adjust the viscosity (at 25°C) from 8 Pa·s to 14 Pa·s.

[0103] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0104] (6) Comparative Example 3 A polyamic acid composition was prepared in the same manner as in Example 1, except that pyromellitic dianhydride (PMDA) was used as the tetracarboxylic dianhydride instead of α-ODPA, and 4,4'-bis(3-aminophenoxy)biphenyl (4,3-BAPOBP) was used as the diamine instead of 1,3,4-APB.

[0105] In Comparative Example 1, since the viscosity (at 25°C) after stirring for 15 hours was 15 Pa·s or more, N-methylpyrrolidone was added to adjust the viscosity (at 25°C) from 8 Pa·s to 14 Pa·s.

[0106] The solid content and viscosity of the obtained polyamic acid composition are shown in Table 1.

[0107] 2. Evaluation (1) Flatness of the polyimide film A two-layer substrate composed of a polyimide layer (thickness: 10 μm) and a stainless steel layer (thickness: 25 μm) was prepared, and an opening with a diameter of 100 μm was formed in the stainless steel layer.

[0108] Next, the polyamic acid compositions of each example and each comparative example were applied to the stainless steel layer with an applicator (coating gap: 150 μm) and dried at 130°C for 5 minutes.

[0109] Thereby, a laminate of a polyimide layer (thickness: 10 μm) / a stainless steel layer (thickness: 25 μm) / a polyamic acid film (thickness: 5 μm) was produced.

[0110] Next, the obtained laminate was hot-pressed at 185 °C for 15 minutes under 2 MPa using a vacuum hot-pressing device (VS20-3430, manufactured by Mikado Technos).

[0111] Next, the depth of the indentation on the surface of the polyamic acid film (i.e., polyimide film) after hot pressing was measured using a laser microscope (VK-X1000-300, manufactured by Keyence).

[0112] The maximum value of the measured depth is shown in Table 1. The smaller the value, the better the flatness.

[0113] (2) Electrical properties of the polyimide film The polyamic acid compositions of each example and each comparative example were applied to a stainless steel substrate (thickness: 20 μm) using an applicator (coating gap: 150 μm) and dried at 130 °C for 5 minutes and then at 185 °C for 5 minutes.

[0114] Next, heat treatment was performed at 200 °C to 400 °C in an environment where the pressure was reduced to 10 Pa or less to produce a polyimide film on the substrate.

[0115] Next, the substrate was removed with a ferric chloride solution to obtain a polyimide film.

[0116] Using an electrical property device (10 GHz SPDR resonator, manufactured by QWED), the dielectric constant and dielectric loss tangent of the obtained polyimide film at 10 GHz were measured.

[0117] The results are shown in Table 1.

[0118] (3) Heat resistance temperature of the polyimide film The polyamic acid compositions of each example and each comparative example were applied to a release film using an applicator (coating gap: 200 μm) and dried at 130 °C for 5 minutes.

[0119] Next, the obtained polyamic acid film was peeled off from the release film, placed in a heating chamber of a high-temperature observation device (SK-5000, manufactured by Sanyo Seiko Co., Ltd.), and the shape change of the film was observed while raising the temperature to 400 °C at a rate of 12 °C / min.

[0120] The temperature at which the film melted was defined as the heat resistance temperature. The results are shown in Table 1.

[0121] (4) Flexibility of the polyimide film The polyamic acid compositions of each example and each comparative example were applied to a release film using an applicator (coating gap: 200 μm) and dried at 130 °C for 5 minutes, and then at 185 °C for 5 minutes.

[0122] Next, the obtained polyamic acid film was peeled off from the release film, and the loss elastic modulus at 185 °C was measured using a dynamic viscoelasticity measuring device (RSA-G2, manufactured by TA Instruments Japan). The results are shown in Table 1.

[0123]

Table 1

Explanation of symbols

[0124] 1 Semiconductor package 2 Semiconductor package substrate (an example of a wiring circuit board) 3 Semiconductor chip 22 Insulating layer 23 Conductor pattern

Claims

1. A polyamic acid which is a precursor of polyimide used as an insulating layer of a wiring circuit board, and is a reaction product of 3,4'-oxydiphthalic dianhydride and a diamine component containing ether diamine.

2. The ratio of the ether diamine in the diamine component is 0.5 mol or more with respect to 1 mol of 3,4'-oxydiphthalic dianhydride. The polyamic acid according to Claim 1.

3. The diamine component contains only the ether diamine. The polyamic acid according to Claim 1.

4. The ether diamine is 1,3-bis(4-aminophenoxy)benzene. The polyamic acid according to Claim 1.

5. A polyamic acid composition containing the polyamic acid according to any one of Claims 1 to 4, and a solvent.

6. A polyamic acid film which is a dried product of the polyamic acid composition according to Claim 5.

7. A polyimide which is an imidized product of the polyamic acid according to any one of Claims 1 to 4.

8. A polyimide film which is a film made of the polyimide according to Claim 7.

9. A wiring circuit board comprising an insulating layer made of the polyimide according to Claim 7, and a conductor pattern.

10. A semiconductor package comprising the wiring circuit board according to Claim 9, and a semiconductor chip mounted on the wiring circuit board.

11. An electronic device comprising the semiconductor package according to Claim 10.

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