JP2006315391A - Laminated plate and printed circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a (multilayer) printed circuit board excellent in connection reliability hardly causing cracks such as corner cracks in through-holes and solder cracks after the heat cycle test, and to provide a (metal-clad) laminate for use in manufacturing the printed circuit board. <P>SOLUTION: The laminate comprises an insulating substrate having a flexural modulus at room temperature of ≥24.0 GPa and a thermal expansion coefficient at ≤150°C of ≤20 ppm/°C in the horizontal direction and ≤60 ppm/°C in the vertical direction, and insulating resin composition layers formed on both surfaces of the insulating substrate each having 10-200 μm thickness and ≤3.0 GPa elastic modulus and ≥8.0% tensile elongation at room temperature. The printed circuit board uses this laminate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed wiring board that is inexpensive and has high connection reliability, and a laminated board therefor.

  Conventionally, wiring boards using ceramic substrates with high heat resistance have been mainly used for wiring boards used in high-temperature environments such as automobile engine rooms. Alternatives to printed wiring boards are being considered. However, if the thermal expansion coefficient difference between the copper wiring or mounting component and the organic substrate on the organic printed wiring board is large, after the heat cycle test, due to the difference, cracks in the through-hole, solder crack, organic substrate Cracks such as surface layer cracks are likely to occur, resulting in a decrease in connection reliability.

  Thus, there is an increasing demand for organic printed wiring boards that are inexpensive and less susceptible to defects such as cracks after heat cycle testing and have high connection reliability.

As a method for preventing the occurrence of cracks in the organic printed wiring board, for example, a large amount of an inorganic filler is blended in the resin composition of the organic substrate, and the thermal expansion coefficient of the organic substrate is determined as a mounted component such as a copper wiring or an IC chip. However, the resin composition containing a large amount of the inorganic filler has the advantage that the coefficient of thermal expansion is small, but has the disadvantage of becoming brittle. Corner cracks are likely to occur at the surface corner portions where stress is particularly high in the hole. In addition, since the resin composition containing a large amount of inorganic filler has a high elastic modulus, it applies more stress to the solder part due to the difference in thermal expansion coefficient between the component and the organic substrate, resulting in solder cracks. Is likely to occur. In other words, the method of adding a large amount of inorganic filler to the resin composition of the organic substrate cannot sufficiently meet the demand for the connection reliability of the organic printed wiring board that is increasing year by year.
Japanese Patent Publication No. 2-45348

  In view of the above, the present invention produces a (multilayer) organic printed wiring board that is unlikely to generate cracks such as through-hole corner cracks and solder cracks after a heat cycle test, and has excellent connection reliability, and the organic printed wiring board It is an object of the present invention to provide a (metal-clad) laminated board.

  As a result of diligent studies to solve the above problems, a laminate in which a resin composition layer having a low elastic modulus and a high tensile elongation is formed on both surfaces of an insulating substrate having a low thermal expansion coefficient and a high elastic modulus. The organic printed wiring board manufactured using the board has been found to be less susceptible to cracking even after the heat cycle test and exhibits excellent connection reliability, and has led to the present invention.

  That is, the present invention is characterized by the following (1) to (5).

(1) An insulating substrate having a flexural modulus at room temperature of 24.0 GPa or more and a thermal expansion coefficient at 150 ° C. or less of 20 ppm / ° C. or less in the horizontal direction and 60 ppm / ° C. or less in the vertical direction, and the insulating substrate An insulating resin composition layer having a thickness of 10 to 200 μm on both surfaces, an elastic modulus at room temperature of 3.0 GPa or less, and a tensile elongation of 8.0% or more,
Having a laminate.

  (2) The laminated board according to (1), wherein the insulating substrate has an inner layer circuit.

  (3) A metal-clad laminate, wherein a metal layer is formed on one side or both sides of the laminate according to (1) or (2).

  (4) A printed wiring board formed by etching a metal layer in the metal-clad laminate according to (3) to form a circuit.

  (5) (A) a step of forming a circuit by etching a metal layer of the metal-clad laminate as described in (3) above; (B) a step described in (1) or (2) above on the circuit; After laminating the laminate and metal foil sequentially or after laminating the metal-clad laminate as described in (3) above, (C) forming a circuit by etching the outermost metal layer A process for producing a multilayer printed wiring board, wherein the steps (B) and (C) are repeated according to the required number of layers.

  According to the present invention, a (multilayer) organic printed wiring board that is unlikely to generate cracks such as through-hole corner cracks and solder cracks after a heat cycle test, and has excellent connection reliability (metal for producing the printed wiring board) Zhang) can be provided.

  The present invention relates to an insulating substrate having a flexural modulus at room temperature of 24.0 GPa or more and a thermal expansion coefficient at 150 ° C. or less of 20 ppm / ° C. or less in the horizontal direction and 60 ppm / ° C. or less in the vertical direction. A laminated board having an insulating resin composition layer formed on both surfaces of a substrate with a thickness of 10 to 200 μm, an elastic modulus at room temperature of 3.0 GPa or less, and a tensile elongation of 8.0% or more, and To do. The horizontal direction and the vertical direction are directions with respect to the insulating substrate.

  As the insulating substrate, known substrates can be used as long as they satisfy the bending elastic modulus and the thermal expansion coefficient, and are not particularly limited. For example, MCL-E- which is a glass epoxy copper-clad laminate. 679 and MCL-E-679F (both manufactured by Hitachi Chemical Co., Ltd., trade name) and the like, and a resin composition containing an insulating resin such as an epoxy resin on an organic substrate such as an aramid nonwoven fabric What was obtained by impregnation and drying can be used. Moreover, you may have an inner layer circuit. The thickness of the insulating substrate may be a general thickness and is not particularly limited, but is preferably in the range of 0.2 to 3.2 mm.

  Further, when the insulating substrate has a flexural modulus of less than 24.0 GPa, when a low-elasticity insulating resin composition layer is provided on both sides, the thermal expansion coefficient in the horizontal direction as a composite material (laminate) is large. This is not preferable. Further, if the thermal expansion coefficient of the insulating substrate at 150 ° C. or lower exceeds 20 ppm / ° C. in the horizontal direction or exceeds 60 ppm / ° C. in the vertical direction, the thermal expansion coefficient of mounted components such as copper wiring and electronic components This is not preferable because the difference between the two increases and causes cracks.

  As described above, the insulating resin composition layer needs to have an elastic modulus at room temperature of 3.0 GPa or less and a tensile elongation of 8.0% or more. If this elastic modulus exceeds 3.0 GPa, the stress generated in a high temperature environment cannot be sufficiently relaxed, and if the tensile elongation is less than 8.0%, through-hole corner cracks and the like are generated. It becomes difficult to prevent enough.

  Further, the insulating resin composition layer is, for example, coated and dried on the support, the insulating resin composition is laminated on the insulating substrate so that the insulating resin composition coating layer is in contact with the insulating substrate, It may be formed by removing the support and heating and pressurizing. A resin-impregnated base material (prepreg) formed by impregnating an organic resin base material such as aramid non-woven fabric, glass cloth, glass non-woven fabric with an insulating resin composition and drying. It may be formed by laminating on the insulating substrate and heating and pressing, and is not particularly limited. In addition, when the said support body is metal foils, such as copper foil, it can be set as the metal-clad laminated board of this invention by leaving this as a metal layer, without removing this. The heating and pressurization is preferably performed under conditions of a temperature of 150 to 180 ° C. and a pressure of about 9 to 20 MPa. However, the characteristics of the laminate, the reactivity of the insulating resin composition, the ability of the press, and the desired laminate The thickness can be appropriately determined in consideration of the thickness of the material, and is not particularly limited.

  The insulating resin composition is not particularly limited. For example, an insulating resin such as an epoxy resin, a rubber such as acrylonitrile butadiene rubber, a curing agent such as a phenol resin, and a curing accelerator such as 2-ethyl-4-methylimidazole. It is possible to use those containing flame retardants, plasticizers, fillers, solvents, etc., and by appropriately adjusting the amount of each composition and the amount of solvent, the elastic modulus and tensile elongation of the insulating resin composition layer can be adjusted. Can be adjusted.

  Examples of the filler include, but are not limited to, silica, fused silica, talc, alumina, aluminum hydroxide, barium sulfate, calcium hydroxide, calcium carbonate, glass fiber, and quartz fiber. It can be used alone or in combination.

  Moreover, it is preferable that the thickness of the said insulating resin composition layer is 10-200 micrometers. If the thickness is less than 10 μm, the stress generated in a high temperature environment cannot be sufficiently relaxed, and if it exceeds 200 μm, the thermal expansion coefficient in the vertical direction tends to be too large.

  The metal-clad laminate of the present invention is characterized in that a metal layer is formed on one or both sides of the laminate of the present invention, and the metal layer is made of, for example, a metal foil such as a copper foil. It can be formed by placing on one or both sides of the laminate and heating and pressing. Further, as described above, the metal-clad laminate of the present invention is obtained by placing an insulating resin composition on a metal foil and drying it (insulating resin film with metal foil) on an insulating substrate and heating and pressing. It can also be. The heating and pressurization is preferably performed under conditions of a temperature of 150 to 180 ° C. and a pressure of about 9 to 20 MPa. However, the characteristics of the laminated board, the reactivity of the insulating resin composition, the ability of the press, and the desired laminated board The thickness can be appropriately determined in consideration of the thickness of the material, and is not particularly limited.

  The printed wiring board of the present invention can be obtained, for example, by forming a circuit by etching the metal layer in the metal-clad laminate of the present invention with a known etching means. In addition, the multilayer printed wiring board of the present invention includes, for example, (A) a step of forming a circuit by etching a metal layer of the metal-clad laminate of the present invention, and (B) a laminate of the present invention on the circuit. And a metal foil sequentially laminated, or after laminating the metal-clad laminate of the present invention, and heating and pressurizing, and (C) forming a circuit by etching the metal layer as the outermost layer. By repeating the steps (B) and (C), a multilayer printed wiring board having a desired number of layers can be obtained. Of course, in addition to the above steps, known processing steps such as a through-hole forming step and a plating step can be performed as necessary in manufacturing the multilayer printed wiring board.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
<Preparation of copper-clad laminate>
A varnish-like insulating resin composition having the following composition was prepared, and this resin composition was coated and dried on a copper foil (GTS-12: Furukawa Circuit Foil, trade name) so that the resin film thickness was 25 μm ( 150 ° C., 10 minutes) to produce an insulating resin composition film with a copper foil. In addition, after drying the said insulating resin composition film with a copper foil at 180 degreeC for 2 hours, all the copper foil is etched away and it cuts out to predetermined length (length 80mm, width 10mm), and about the resin composition film obtained When the tensile modulus was measured by the tensile test until the elastic modulus at room temperature and the tensile elongation until ruptured (autograph tensile tester (distance between chucks 60 mm, pulling speed 5 mm / min)), they were 2.1 GPa and 12%, respectively. It was.
・ 100 parts by weight of biphenyl epoxy resin (trade name: NC-3000H, manufactured by Nippon Kayaku Co., Ltd.) ・ 10 parts by weight of carboxylic acid-modified acrylonitrile butadiene rubber (trade name: PNR-1H, manufactured by JSR Corporation) : Phenol novolac type resin (trade name: HP-850, manufactured by Hitachi Chemical Co., Ltd.) 50 parts by weight / curing accelerator: 2-ethyl-4-methylimidazole (trade name: 2E4MZ, manufactured by Shikoku Chemical Industry Co., Ltd.) 0 .3 parts by weight-Flame retardant: Phosphate ester (trade name: PX-200, manufactured by Daihachi Chemical Industry) 25 parts by weight-Solvent: 55 parts by weight of methyl ethyl ketone

  Next, a glass epoxy copper clad laminate having a thickness of 1.0 mm, a flexural modulus of 29 GPa at room temperature, and a thermal expansion coefficient of 150 ° C. or less at 13 ppm / ° C. in the horizontal direction and 24 ppm / ° C. in the vertical direction (Hitachi All the copper foils manufactured by Kasei Kogyo Co., Ltd., trade name: MCL-E-679F) were removed by etching and dried, and then the insulating resin composition film with copper foil obtained above on the laminate was used as the resin composition. The laminated film was heated and pressed at 185 ° C. for 70 minutes under vacuum at a product pressure of 3.0 MPa so that the physical film surface and the laminate were in contact with each other, to prepare a copper clad laminate for evaluation. The flexural modulus was measured in accordance with JIS-C-6481 using a sample obtained by removing the copper foil of the glass epoxy copper clad laminate by etching. Moreover, the said thermal expansion coefficient calculated | required by calculating the average linear expansion coefficient in the conditions to 30-100 degreeC in the tension mode of a thermomechanical analyzer (TMA) about the sample similar to a bending elastic modulus.

(Example 2)
A copper clad laminate for evaluation was produced in the same manner as in Example 1 except that the thickness (resin film thickness after drying) of the insulating resin composition film with copper foil was 165 μm.

(Example 3)
The film layer thickness of the insulating resin composition film with copper foil (resin film thickness after drying) is 65 μm, and MCL-E-679 (trade name, thickness 1.0 mm, manufactured by Hitachi Chemical Co., Ltd. In the same manner as in Example 1 except that a glass epoxy copper-clad laminate having a flexural modulus of 25 GPa and a thermal expansion coefficient of 150 ppm or lower in the horizontal direction of 16 ppm / ° C. in the horizontal direction and 55 ppm / ° C. in the vertical direction is used. A copper clad laminate for evaluation was produced.

Example 4
A glass cloth (IPC standard, equivalent to product number 1080 type) is impregnated with the same insulating resin composition varnish as in Example 1, dried in a dryer at 150 ° C. for 10 to 15 minutes, and a B-stage state having a resin content of 62% A prepreg was prepared.

Next, a glass epoxy copper clad laminate having a thickness of 1.0 mm, a flexural modulus of 29 GPa at room temperature, and a thermal expansion coefficient of 150 ° C. or less at 13 ppm / ° C. in the horizontal direction and 24 ppm / ° C. in the vertical direction (Hitachi All the copper foil of Kasei Kogyo Co., Ltd., trade name: MCL-E-679F) is removed by etching and dried, and then between the laminate and the copper foil (GTS-12: trade name made by Furukawa Circuit Foil) A copper-clad laminate for evaluation was prepared by sandwiching the prepreg sandwiched by heating and pressing at 185 ° C. for 70 minutes at a product pressure of 3.0 MPa under vacuum.

(Comparative Example 1)
A copper clad laminate for evaluation was produced in the same manner as in Example 1 except that the thickness (resin film thickness after drying) of the insulating resin composition film with copper foil was 8 μm.

(Comparative Example 2)
A copper clad laminate for evaluation was produced in the same manner as in Example 1 except that the thickness (resin film thickness after drying) of the insulating resin composition film with copper foil was 215 μm.

(Comparative Example 3)
As an insulating resin composition film with copper foil, an inorganic filler (spherical silica, manufactured by Admatechs) was further added to the insulating resin composition varnish similar to that in Example 1 to 35 vol. With copper foil obtained by applying and drying (150 ° C., 10 minutes) to a resin film thickness of 65 μm after drying on copper foil (GTS-12: Furukawa Circuit Foil, trade name) A copper clad laminate for evaluation was produced in the same manner as in Example 1 except that the insulating resin composition film was used. The resin composition film obtained by drying the insulating resin composition film with copper foil at 180 ° C. for 2 hours and then removing all the copper foil by etching was subjected to a tensile test until the modulus of elasticity at room temperature and breaking. When the elongation rate was measured, they were 3.3 GPa and 5%, respectively.

(Comparative Example 4)
As a laminate, MCL-E-67 (manufactured by Hitachi Chemical Co., Ltd., trade name, thickness 1.0 mm, bending elastic modulus 20 GPa at room temperature, thermal expansion coefficient of 150 ° C. or less in the horizontal direction is 25 ppm / ° C., in the vertical direction A copper clad laminate for evaluation was prepared in the same manner as in Example 1 except that 60 ppm / ° C. glass epoxy copper clad laminate) was used.

<Evaluation of copper clad laminate>
(Through hole corner crack)
A 0.5 mm hole is drilled in each evaluation copper clad laminate, and a through hole is formed in the hole and on the surface of the copper clad laminate by plating with a thickness of about 20 μm. A daisy chain pattern sample was produced by etching the surface copper of unnecessary portions so that the holes 100 could be electrically connected.

  Next, each sample obtained above was put into a temperature cycle tester, and the connection resistance value of the daisy chain pattern was measured every 500 cycles with -65 ° C, 30 minutes and 125 ° C, 30 minutes repeated as one cycle. When the connection resistance value exceeded ± 20% with respect to the initial resistance value before the introduction of the test machine by 4000 cycles, the presence or absence of through-hole corner cracks was confirmed by cross-sectional observation. Table 1 shows the number of cycles when the connection resistance value exceeds ± 20% with respect to the initial resistance value, and the presence or absence of through-hole corner cracks in that case.

(Solder crack)
An unnecessary portion of the copper foil for each evaluation copper clad laminate was removed by etching to form an external electrode for chip mounting, and a solder paste was applied on the external electrode. Next, a chip of 3.2 × 2.5 mm size was mounted on the external electrode, put into a reflow furnace, and the chip was soldered to a copper clad laminate. Thereafter, the copper-clad laminate sample for evaluation on which the chip was mounted was put into a temperature cycle tester, and the sample was taken out every 500 cycles, with -65 ° C, 30 minutes and 125 ° C, 30 minutes repeated as one cycle. The presence or absence of solder cracks was confirmed visually (maximum 4000 cycles). Table 1 shows the number of cycles when a solder crack occurs.

Claims (5)

An insulating substrate having a flexural modulus at room temperature of 24.0 GPa or more and a thermal expansion coefficient at 150 ° C. or less of 20 ppm / ° C. or less in the horizontal direction and 60 ppm / ° C. or less in the vertical direction; An insulating resin composition layer having a thickness of 10 to 200 μm, an elastic modulus at room temperature of 3.0 GPa or less, and a tensile elongation of 8.0% or more;
Having a laminate.   The laminated board according to claim 1, wherein the insulating substrate has an inner layer circuit.   A metal-clad laminate, wherein a metal layer is formed on one side or both sides of the laminate according to claim 1 or 2.   A printed wiring board formed by etching a metal layer in the metal-clad laminate according to claim 3 to form a circuit. (A) a step of etching the metal layer of the metal-clad laminate according to claim 3 to form a circuit;
(B) a step of heating and pressurizing after further laminating the laminate and the metal foil according to claim 1 or 2 on the circuit, or after laminating the metal-clad laminate according to claim 3, and (C) forming a circuit by etching a metal layer as the outermost layer;
And the steps (B) and (C) are repeated according to the required number of laminated layers.