JP2005187547A - Resin composition, carrier material with resin, and multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition, a carrier material with a resin, and a multilayer printed wiring board that can easily and reliably melt solder bumps and perform electrical bonding between circuit board layers. .
SOLUTION: A compound having a carboxyl group and a phenolic hydroxyl group, an inorganic filler having an average particle size of 0.1 to 1 μm, and a synthetic rubber modified with a carboxyl group, and the carboxyl group and the phenolic hydroxyl group. The compound having a group is a polyhydric phenol, the compound having a carboxyl group and a phenolic hydroxyl group is 5 to 25% by weight of the resin solid content, and further a resin composition containing an epoxy resin.
[Selection] Figure 4

Description

  The present invention relates to a resin composition, a carrier material with a resin, and a multilayer printed wiring board.

  Along with the recent increase in the density of electronic devices, the multilayered printed wiring board is being used, and a flexible printed wiring board having a multilayer structure is often used. This printed wiring board is a rigid flex printed wiring board that is a composite substrate of a flexible printed wiring board and a rigid printed wiring board, and its application is expanding.

A conventional method for producing a multilayer flexible printed wiring board or a rigid flex printed wiring board is obtained by alternately laminating a plurality of single-sided circuit boards and adhesive layers, and then forming through-holes for interlayer connection. After applying through-hole plating for interlayer connection, a method of processing the outermost layer circuit, etc., or making a hole that does not penetrate copper foil on the insulating material side of a single-sided circuit board, and forming a conductor post with metal or alloy Then, a method has been proposed in which the entire surface is coated, the adhesive layer and the wiring board are pressed, and the layers are repeatedly formed as many times as necessary. (For example, Patent Document 1)
In the former manufacturing method, as a generally used electrical connection method between layers, a method of electrically connecting each layer by forming a through hole penetrating all the layers and through-hole plating there is used. However, in this electrical connection method, although the processing method is simple, there are many restrictions on circuit design. Also, the most inferior point is that all layers are electrically connected by through-hole plating, and the outermost layer has more through-hole plating connection lands and the area ratio increases, which is critical for component mounting and circuit wiring. The circuit packaging density can not be increased. In addition, high-density packaging and high-density wiring will be difficult to produce, which will increase market demand in the future.

  In order to manufacture the flexible printed wiring board at a low cost, the flexible printed wiring board is produced by a multi-cavity pattern arranged in a single sheet. Therefore, a multilayer flexible printed wiring board can also be manufactured inexpensively through the same manufacturing method. However, in this manufacturing method, if there is a patterning defect in the sheet, the multilayer flexible printed wiring board in which the patterning defect part is laminated becomes defective, and the process yield in the lamination process is lowered.

  Further, the greatest difference between a multilayer flexible printed wiring board or a rigid flex printed wiring board and a multilayer rigid printed wiring board is the presence or absence of a flexible portion. In the production of this flexible part, the outer layer must be removed so that the flexible part is not laminated, or the outer layer must be removed after lamination, and when the sheets are laminated, the number of wiring boards per sheet is reduced. It gets worse. Furthermore, in the case of pattern design with different size of each layer, the number of wiring boards per sheet is limited to the smallest number of circuit boards obtained from each layer circuit board, resulting in poor number of wiring boards per sheet. End up.

In the latter manufacturing method, there is a special process in which the receiving base material of the conductor post is drilled by laser processing, desmearing, and a surface coating opening is produced, and there is a problem of establishment of these techniques and yield. In addition, as the number of layers increases, there are problems in that manufacturing takes time and costs, and the material cost of the surface coating increases.
JP 11-54934 A

  An object of the present invention is to provide a resin composition, a carrier material with a resin, and a multilayer printed wiring board that can easily and reliably melt a solder bump and perform electrical bonding between layers of a circuit board.

Such an object is achieved by the present invention described in the following (1) to (11).
(1) a compound having a carboxyl group and a phenolic hydroxyl group;
An inorganic filler having an average particle size of 0.1 to 1 μm;
A resin composition comprising a carboxyl group-modified synthetic rubber.
(2) The resin composition according to (1), wherein the compound having a carboxyl group and a phenolic hydroxyl group is a polyhydric phenol.
(3) The resin composition according to the above (1) or (2), wherein the compound having a carboxyl group and a phenolic hydroxyl group is 5 to 25% by weight of the resin solid content.
(4) The resin composition according to any one of (1) to (3), which further contains an epoxy resin.
(5) The resin composition as described in (4) above, wherein the epoxy resin has a dicyclopentadiene skeleton.
(6) The resin composition according to any one of the above (1) to (5), which further contains a novolac type phenol resin.
(7) The resin composition according to the above (6), wherein the novolak type phenolic resin contains 10% or less of dinuclear substance and 0.1% or less of free phenol.
(8) The resin composition according to any one of (1) to (7), wherein the inorganic filler is spherical silica.
(9) A carrier material with a resin, comprising a resin layer composed of the resin composition according to any one of (1) to (8) above and a carrier material.
(10) The carrier material with a resin according to (9), wherein the carrier material is a metal foil or a resin film.
(11) A multilayer printed wiring board obtained by superposing and heating and pressurizing the carrier material with resin according to (9) or (10) above on one or both sides of an inner layer circuit board.

  According to the present invention, it is possible to provide a resin composition, a resin-coated carrier material, and a multilayer printed wiring board that can easily and reliably melt solder bumps and perform electrical bonding between circuit board layers.

  Hereinafter, the resin composition, the carrier material with resin, and the multilayer printed wiring board of the present invention will be described in detail.

  The resin composition of the present invention enables good bonding with high strength by melting solder bumps and reducing the oxide film on the solder surface and the oxide film on the copper foil surface, which is the connected surface, during electrical bonding between layers. . Furthermore, the resin composition of the present invention does not need to be removed by washing or the like after soldering, and is heated as it is to form a three-dimensionally cross-linked resin, which has excellent adhesion, and is an interlayer between circuit boards and multilayer flexible printed wiring boards. Become a material.

  The resin composition of the present invention comprises a compound having a carboxyl group and a phenolic hydroxyl group, an inorganic filler having an average particle size of 0.1 to 1 μm, and a synthetic rubber modified with a carboxyl group. is there.

  The resin composition of the present invention uses a compound having a carboxyl group and a phenolic hydroxyl group.

  The compound having a carboxyl group and a phenolic hydroxyl group has at least one carboxyl group and at least one phenolic hydroxyl group in the molecule and may be liquid or solid.

  Although it does not limit, the following are mentioned as a compound which can be used by this invention. For example, one or more of salicylic acid, shikimic acid, vanillic acid, phenolphthalin, sender-chromium AL, 1,2-dicarboxy-cis-4,5-dihydroxycyclohexa-2,6-diene, etc. Can be used in combination. Among them, an epoxy resin whose base resin is one having two or more phenolic hydroxyl groups, such as shikimic acid, phenolphthalene, 1,2-dicarboxy-cis-4,5-dihydroxycyclohexa-2,6-diene, and the like This is preferable because it is incorporated three-dimensionally into the reaction.

  Further, the blending amount is preferably 5 to 25% by weight of the resin solid content in the blending components. If the amount is less than 5% by weight, the oxide film on the surface of the copper foil is reduced, resulting in insufficient strength and good bonding. If the amount exceeds 25% by weight, handling as film performance is deteriorated.

  The resin composition of the present invention preferably contains an epoxy resin.

  The epoxy resin is not particularly limited. For example, bisphenol A, bisphenol F, phenol novolac, cresol novolac, biphenyl skeleton, naphthalene skeleton, alkylphenol-based epoxy having dicyclopentadiene skeleton, etc. Resin is used by 1 type (s) or 2 or more types. Among them, an epoxy resin having a dicyclopentadiene skeleton characterized by low water absorption is preferable.

  The resin composition of the present invention preferably contains a novolac type phenol resin.

  The novolac type phenol resin preferably contains 10% or less of dinuclear substance and 0.1% or less of free phenol. Thereby, foaming can be suppressed even at a high temperature in the joining process by solder melting.

  The resin composition of this invention uses the inorganic filler whose average particle diameter is 0.1-1 micrometer.

  The inorganic filler is preferably spherical silica having an average particle size of 0.1 to 1 μm. If the average particle diameter is less than 0.1 μm, the thixotropy of the resin is increased, and it is difficult to form a solder fillet when solder bumps are joined. Also, during lamination, the solder bumps push the resin and come into contact with the lands, but the inorganic filler average particle size of the present invention is excluded from the bottom of the solder bumps together with the resin. There is a risk that the connection reliability will be reduced by biting between the two.

  The resin composition of the present invention uses a carboxyl group-modified synthetic rubber.

  The type of the carboxyl group-modified synthetic rubber is not particularly limited, and examples thereof include commercially available carboxyl group-modified NBR. If no carboxyl group is present, the adhesive strength with the polyimide film surface to be adhered to the adhesive may be poor and may not pass moisture-absorbing solder heat resistance.

  Next, the carrier material with resin will be described.

  The carrier material with a resin of the present invention is a carrier material with a resin composed of a layer composed of the resin composition and a carrier material.

  The carrier material is not particularly limited, and is composed of a metal foil made of copper or a copper alloy, aluminum or an aluminum alloy, a fluorine resin, a polyimide resin, a polybutylene terephthalate, a polyester resin such as polyethylene terephthalate, or the like. Resin film and the like.

  The carrier material with resin is not particularly limited, but is usually performed by a method of applying varnish to the carrier material. The solvent used for preparing the varnish desirably exhibits good solubility in the resin composition, but a poor solvent may be used as long as it does not adversely affect the varnish. Examples of the good solvent include DMF, MEK, and cyclohexanone.

  Moreover, when preparing a varnish, although solid content of a resin composition is not specifically limited, 20 to 80 weight% is preferable and 30 to 60 weight% is especially preferable.

  Moreover, the carrier material with a resin can be obtained by applying the above-mentioned varnish to a carrier material and drying at 80 to 200 ° C.

  The resin thickness after coating and drying is not particularly limited, but is preferably adjusted to within ± 20% of the height of the solder bump. If it is less than -20%, formability is difficult and voids are likely to be generated around the solder bump. If it exceeds + 20%, the solder bump may not reach the surface to be joined.

  Next, a multilayer printed wiring board will be described.

  The multilayer printed wiring board of the present invention has a resin layer of the above-mentioned carrier material with resin superimposed on one or both sides of an inner circuit board with solder bumps, melts the solder bumps, It is a multilayer printed wiring board formed by reducing the oxide film on the surface of the copper foil, which is the connected surface, and having good strength and good bonding. Furthermore, the resin composition of the present invention is a multilayer printed wiring board that does not need to be removed by washing or the like after solder bonding, and is heated as it is to become a three-dimensionally crosslinked resin and has excellent adhesion.

  Although the temperature to heat is not specifically limited, 100-160 degreeC is preferable as 1st temperature which an adhesive agent softens, and 220-260 degreeC is preferable as 2nd temperature after which a solder is fuse | melted after that. The three-dimensional crosslinking of the adhesive is performed at the same time as melting the solder, and if necessary, the adhesion can be further improved by after-baking. Although the temperature in that case is not specifically limited, 160-200 degreeC is preferable.

  Although the pressure to pressurize is not particularly limited, 0.01 to 1 MPa is preferable and 0.1 to 0.5 MPa is more preferable at the first temperature. The second temperature is preferably 0.001 to 0.01 MPa.

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

In order to confirm the effectiveness of the resin composition of the present invention, the carrier material with resin, and the multilayer printed wiring board, the following multilayer wiring board was prepared and evaluated as follows. The results are shown in Table 1.
Solder joint: A cross section of the solder joint was visually observed using a microscope.
-Moisture absorption reflow: After treatment at 30 ° C / 60% / 168 hours, a solder reflow with a maximum temperature of 260 ° C was passed 3 times, and the product without peeling or delamination was regarded as acceptable.
-Temperature cycle test: -65 ° C / 30 minutes 125 ° C / 30 minutes, conduction resistance before and after 1000 cycle treatment was confirmed, and the rate of change was 10% or less.
Insulation resistance: The case where the insulation resistance after treatment at 30 ° C./85%/DC50V/240 hours was 10 ⁸ Ω or more was regarded as acceptable.
(Production of multilayer flexible wiring board)
1. Production of outer-layer single-sided wiring board A flexible copper-clad laminate 110 (Upicel N manufactured by Ube Industries) with a 12 μm-thick copper foil 101 on a support substrate 102 made of a polyimide film with a thickness of 25 μm Then, a supporting substrate opening 103 having a diameter of 100 μm is formed by UV laser, and desmearing with an aqueous potassium permanganate solution is performed. Electrolytic copper plating is performed in the support base material opening 103 so as to have a height of 15 μm from the surface of the insulating base on the opposite side of the copper foil, and then solder plating is applied to a thickness of 15 μm to form a conductor post 1045. To do. Next, the copper foil 101 of the single area layer plate 110 is etched to form a wiring pattern 106, a liquid resist (SR9000W manufactured by Hitachi Chemical Co., Ltd.) is printed, and a surface film 107 is applied. Subsequently, it formed by laminating | stacking the 25-micrometer-thick sheet | seat carrier material with a resin with a reduction | restoration function (in-house developed product DBF) 111 of this invention with a vacuum laminator. Finally, an outer shape was processed to the size of the laminated portion to obtain an outer layer single-sided wiring board 120.

2. Production of Inner Layer Flexible Wiring Board Two-layer double-sided board 210 (Mitsui Chemicals NEX23FE (25T)) having a copper foil 201 of 12 μm and a supporting base material 202 of polyimide film thickness of 25 μm is directly plated after drilling and electrolytic copper After the through hole 203 is formed by plating and electrical conduction between the front and back sides is formed, a pad 204 that can receive the wiring pattern and the conductor two-layer post 105 is formed by etching. After that, a surface coating 206 is formed on the wiring pattern 205 corresponding to the flexible portion 330 by using a thermosetting adhesive (in-house developed material) having a thickness of 25 μm on a polyimide having a thickness of 12.5 μm (Apical NPI manufactured by Kaneka Chemical Industry). did. Finally, it cut | judged to the external size and the inner-layer flexible wiring board 220 was obtained.
3. Production of Multilayer Flexible Wiring Board The outer-layer single-sided wiring board 120 was laid up on the inner-layer flexible wiring board 220 using a jig with a pin guide for alignment. Thereafter, it was temporarily bonded for positioning with a spot heater at 250 ° C. Next, lamination was performed at 100 ° C. and 0.1 MPa for 60 seconds using a vacuum press, and the conductor post was molded until it contacted the conductor pad, and the circuit of the inner-layer flexible wiring board 220 with the conductor pad was molded and embedded. Next, the conductor post 1045 is pressed on the inner layer through a hydraulic carrier press at 260 ° C. and 0.005 MPa for 60 seconds, and through a 25 μm thick sheet-like carrier material with a reducing function (in-house developed DBF) 111 of the present invention. Solder fusion bonding was performed with the pad 204 of the flexible wiring board 220 to form solder bonding and a solder fillet, and the layers were bonded. Subsequently, in order to cure the adhesive, the temperature was heated at 180 ° C. for 60 minutes to obtain a multilayer flexible wiring board 310 in which the layers were laminated.

  A cross-sectional photograph of the interlayer junction is shown in FIG.

(Example 1)
40 parts by weight of bisphenol A type epoxy resin (Epiclon 840-S manufactured by Dainippon Ink & Chemicals, Inc.), 20 parts by weight of novolac type phenolic resin (PR-53647 manufactured by Sumitomo Bakelite Co., Ltd.), carboxyl group-modified synthesis 20 parts by weight of rubber (Nippol 1072J manufactured by Nippon Zeon Co., Ltd.), 20 parts by weight of salicylic acid (reagent manufactured by Kanto Chemical Co., Inc.), and spherical silica having an average particle size of 0.5 μm (SE2050 manufactured by Admatechs Co., Ltd.) 30 Both heavy parts and 100 parts by weight of acetone were measured, mixed, stirred and dissolved to obtain a varnish.

  As a releasable base material, an antistatic PET film having a thickness of 25 μm is coated with a comma knife coater so that the thickness after drying is 25 μm, and dried, with a resin having a sheet-like reducing function Carrier material (DBF) was prepared. This was used as an adhesive layer as described above to prepare a multilayer flexible wiring board. Subsequently, the above-described evaluation was performed.

(Example 2)
30 parts by weight of bisphenol F-type epoxy resin (Epicron 830-S, manufactured by Dainippon Ink and Chemicals), 30 parts by weight of dicyclopentadiene type epoxy resin (HP-7200, manufactured by Dainippon Ink and Chemicals), novolak Type phenolic resin (NMD-101 manufactured by Sumitomo Bakelite Co., Ltd.), 25 parts by weight, synthetic rubber modified with carboxyl group (Nippol 1072J manufactured by Nippon Zeon Co., Ltd.), Shikimic acid (manufactured by Kanto Chemical Co., Ltd.) 5 parts by weight and 100 parts by weight of acetone were measured, mixed, stirred and dissolved to obtain a varnish. It was coated and dried with a comma coater so that the adhesive thickness was 25 μm as in Example 1, and then a multilayer flexible wiring board was prepared and evaluated.

(Example 3)
A multilayer flexible wiring board was prepared in the same manner except that salicylic acid of Example 1 was changed to phenolphthaline (a reagent manufactured by Kanto Chemical Co., Inc.). Next, the evaluation described above was performed.

Example 4
A multilayer flexible wiring board was prepared in the same manner except that the inorganic filler of Example 1 was alumina having an average particle diameter of 1 μm. Next, the evaluation described above was performed.

(Comparative Example 1)
A multilayer flexible wiring board was prepared in the same manner as in Example 1 except that no salicylic acid was added as a compound having a phenolic hydroxyl group in Example 1, and the above-described evaluation was performed.

(Comparative Example 2)
A multilayer flexible wiring board was prepared in the same manner as described above except that the carboxyl group-modified synthetic rubber of Example 1 was a similar one containing no carboxyl group (Nippol DN1201 manufactured by Nippon Zeon Co., Ltd.), and the evaluation described above was performed.

(Comparative Example 3)
A multilayer flexible wiring board was prepared in the same manner except that the inorganic filler of Example 1 was silica having an average particle diameter of 5 μm. Next, the evaluation described above was performed.

Solder joint: A cross section of the solder joint was visually observed using a microscope.
-The thickness of each layer joined with the interlayer adhesive with a sheet-like reducing function was measured by cross-sectional observation, compared at the center of the substrate and the four locations at the end, and if the difference was within 20%, it was considered acceptable.
-Moisture absorption reflow: After treatment at 30 ° C / 60% / 168 hours, a solder reflow with a maximum temperature of 260 ° C was passed 3 times, and the product without peeling or delamination was regarded as acceptable.
-Temperature cycle test: -65 ° C / 30 minutes 125 ° C / 30 minutes, conduction resistance before and after 1000 cycle treatment was confirmed, and the rate of change was 10% or less.
Insulation resistance: The case where the insulation resistance after treatment at 30 ° C./85%/DC50V/240 hours was 10 ⁸ Ω or more was regarded as acceptable.

  Since a pad-on-via structure can be taken, it is possible to obtain a small and thin multilayer wiring board corresponding to higher density mounting. As a result, it is used in mobile devices that require high functionality and downsizing, such as mobile phones, digital video cameras, digital cameras, and small notebook personal computers.

The joint part by the solder bump joined using the adhesive agent of this invention. Sectional drawing for demonstrating the outer layer single-sided wiring board for multilayer wiring board preparation for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method. Sectional drawing for demonstrating the flexible wiring board for inner layers for multilayer wiring board preparation for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method. Sectional drawing for demonstrating the multilayer flexible wiring board of the 4 layer structure for confirming the effectiveness of the adhesive bond layer of this invention, and its manufacturing method.

Explanation of symbols

101, 201: Copper foil 102, 202: Support base material 106, 205: Wiring pattern 107, 206: Surface coating 108: Surface coating opening 103: Support base material opening 105: Metal coating layer 104: Copper post 1045: Conductor Post 110: Single area layer board 111: Adhesive layer 120: Outer layer single-sided wiring board 203: Through hole 204: Pad 210: Double-sided board 220: Inner layer flexible wiring board 310: Multilayer flexible wiring board (four layers)
320: Multilayer part 330: Flexible part

Claims (11)

A compound having a carboxyl group and a phenolic hydroxyl group;
An inorganic filler having an average particle size of 0.1 to 1 μm;
A resin composition comprising a carboxyl group-modified synthetic rubber. The resin composition according to claim 1, wherein the compound having a carboxyl group and a phenolic hydroxyl group is a polyhydric phenol. The resin composition according to claim 1 or 2, wherein the compound having a carboxyl group and a phenolic hydroxyl group is 5 to 25% by weight of the resin solid content. The resin composition according to any one of claims 1 to 3, further comprising an epoxy resin. The resin composition according to claim 4, wherein the epoxy resin has a dicyclopentadiene skeleton. The resin composition according to any one of claims 1 to 5, further comprising a novolac type phenol resin. The resin composition according to claim 6, wherein the novolac type phenolic resin contains 10% or less of dinuclear substance and 0.1% or less of free phenol. The resin composition according to any one of claims 1 to 7, wherein the inorganic filler is spherical silica. A carrier material with a resin, comprising a resin layer comprising the resin composition according to claim 1 and a carrier material. The carrier material with a resin according to claim 9, wherein the carrier material is a metal foil or a resin film. A multilayer printed wiring board obtained by superposing the carrier material with resin according to claim 9 or 10 on one side or both sides of an inner layer circuit board and heating and pressing.

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