JP3264443B2 - Printed circuit board manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a prepreg for a unidirectional printed circuit board reinforced with glass fiber and a printed circuit board, and more particularly to a printed board excellent in heat shock resistance.

(Prior Art) Printed circuit boards are frequently used in various fields, but in recent years their importance has been increasing in computer-related and communication-related fields. Among printed circuit boards, those using glass fiber as a reinforcing material are becoming mainstream from the viewpoint of their performance, and among them, those using glass fiber woven fabric as a reinforcing material are mainly used. This is because, by using a glass fiber fabric as a reinforcing material, a substrate having a high content of the reinforcing material can be obtained, and since the reinforcing material is a continuous fiber,
This is because a substrate having excellent mechanical properties, electrical properties, heat resistance, chemical resistance, and the like can be obtained.

In the case of using a glass fiber fabric as a reinforcing material, the printed circuit board is made by impregnating the glass fiber fabric with a resin varnish such as an epoxy resin or a polyimide resin to prepare a prepreg, laminating the prepreg, further laminating a copper foil, and hot pressing. It is manufactured by.

The printed circuit board manufactured in this manner becomes a printed wiring board on which a copper foil circuit is formed, and is further mounted with chip components such as ICs and LSIs, and is used in computers and communication devices.

Conventionally, when mounting a chip component on a printed wiring board, a leg of the chip is inserted into a through hole portion, dipped in molten solder, and the chip is fixed by soldering. However, when the surface mounting technology is performed with the increase in the degree of integration of chips, the method of fixing chips is changing from a method of dipping to molten solder to a method of spotting with solder paste. In the case of the solder paste method, since it is necessary to instantaneously melt the solder paste and bond and fix the chip, heating at a higher temperature is performed by far-infrared irradiation than in the method of dipping in molten solder. It has been confirmed that a thermal shock is applied to the printed circuit board itself by this heating, and as a result, a small peeling phenomenon may occur at the intersection of the warp and the weft of the base fabric.
When such a peeling phenomenon occurs, a plating solution infiltrates into the peeled portion at the time of through-hole plating, and as a result, circuit conduction occurs in an unnecessary portion. It also affects the roughness of the inner wall of the through hole.

(Problems to be Solved by the Invention) The glass fiber woven fabric has an intersection of a warp and a weft, and a printed wiring board made of this glass fiber woven fabric receives a thermal shock due to high-temperature heating performed during a mounting process, and the intersection is formed. Therefore, small peeling easily occurs, which is a major problem.

(Means for Solving the Problems) The present invention provides: (1) a glass fiber yarn arranged in a sheet shape in one direction;
And a synthetic resin, and the glass fiber yarn is impregnated with a synthetic resin, and the synthetic resin is in a semi-cured state. A prepreg for a printed circuit board, and (2) glass fiber yarns arranged in a sheet shape in one direction,
And a synthetic resin, and the glass fiber yarn is impregnated with a synthetic resin, and the synthetic resin is in a semi-cured state. The present invention relates to a laminate of a prepreg for a printed circuit board and a printed circuit board made of a metal foil which is laminated and pressed on one or both surfaces thereof.

The prepreg for a printed circuit board of the present invention is a method for producing a resin fiber varnish by arranging and aligning glass fiber yarns at a constant density in a state where there is a gap between the yarns, and arranging the glass fiber yarns in a sheet form; , And dried to produce a unidirectional sheet-like prepreg composed of glass fiber yarns in which the resin is in a semi-cured state.

Further, a unidirectional sheet-like prepreg made of the glass fiber yarn is laminated, and a foil-forming metal, for example, an aluminum foil or a copper foil is laminated on one or both sides, and is heated and pressed to form a unidirectional prepreg as a base material. Can be obtained.

The term "one-way" in the present specification means a state in which glass fiber yarns are arranged side by side in a sheet shape at a constant density with a gap between the yarns.

As the glass fiber yarn used in the present invention, generally used fiber yarns such as E-glass, S-glass (high-strength glass), and D-glass (low-dielectric glass) can be used, and Any of ply-twisted yarn, aligned yarn, single yarn (single-twisted yarn) and the like can be used. However, in view of the impregnating property of the resin, a sweet twisted single yarn having a twist number of about 0.3 t / 25 mm to 2 t / 25 mm or a non-twisted single yarn is desirable. Particularly, in the case of a non-twisted single yarn, there is an advantage that a printed board with less warpage and twist can be obtained.

Further, as the glass fiber yarn used in the present invention, any glass fiber yarn used for glass fiber fabrics for ordinary printed circuit boards can be used, and the monofilament diameter is 5 μm to 13 μm, and the count is 10 Tex to 140 Tex. Can be used, and the effect is particularly large in the case of a glass fiber yarn having a high count in the range of 67 Tex to 140 Tex.

Further, it is desirable that the glass fiber yarn used in the present invention is subjected to a surface treatment using a synthetic resin-based sizing agent, and that the sizing agent contains a silane coupling agent. As synthetic resin-based sizing agents, epoxy resin, polyester resin,
There is no particular limitation as long as it has compatibility and affinity with the polyimide resin or the like, but a sizing agent having a film-forming component such as an epoxy resin modified with an amine or polyethylene glycol, a urethane resin to which polyethylene glycol is added, or the like is preferable. As the silane coupling agent contained in the sizing agent, aminosilane [A-110 of Nippon Unicar Co., Ltd.]
0, A-1120] methacryl silane [Nihon Unicar Co., Ltd.
A-174], epoxy silane [A-187 of Nippon Unicar Co., Ltd.], cationic silane [SZ-6032 of Toray Dow Corning Silicone Co., Ltd.] and the like can be used.

In addition, the alignment density of glass fiber yarn is 30 yarns / 25mm-70
It is appropriately selected from the range of book / 25 mm from the type of yarn to be used and the required weight per unit area of the sheet material.

Further, as the resin component of the unidirectional prepreg material of the present invention, a thermosetting resin, for example, an epoxy resin, a polyester resin, a polyimide resin, a phenol resin, or the like can be used. These resins are selected as needed from the range of 30% to 50% by weight.

In producing the unidirectional sheet-shaped prepreg material of the present invention, it is also possible to laminate a thin resin film as a carrier film in a dried state. As the carrier film, a polyethylene film, a polyester film, a nylon film and the like can be used.
Preferably, the polyethylene film (thickness: 50 μm) is suitable because it has solvent resistance and is inexpensive. The carrier film is peeled off when the prepreg material is laminated.

The unidirectional sheet-like prepreg material of the glass fiber yarn obtained as described above is laminated, and a copper foil is laminated on one or both sides thereof, and then heated and pressed to form a printed board. When laminating unidirectional prepreg materials, there is a method of laminating in the same direction, and a method of alternately laminating a direction in which the yarns are arranged and a direction perpendicular to the direction.In the present invention, any of those methods is used. However, it is preferable that the printed circuit boards be alternately laminated in that there is little difference between the X-direction and the Y-direction in the various characteristics of the obtained printed circuit boards. The thermocompression bonding method can be performed by a commonly used pressing method, but a method of thermocompression bonding under vacuum and reduced pressure is more preferable.

(Function) As a glass fiber yarn constituting a glass fiber fabric for a printed circuit board, several hundred monofilaments having a filament diameter of 5 μm to 13 μm are aligned and lightly twisted. In order to demonstrate the reinforcing effect of glass fiber,
Most desirably, the glass fibers and the matrix resin in the printed circuit board are uniformly mixed. In the case of a glass fiber woven fabric, it is not easy for the resin to penetrate into the yarn because the glass fiber yarn filaments are in a bundle. In particular, in the case of a woven fabric, there is a portion of only a warp or a weft, a portion where a warp and a weft intersect, and the impregnating property of the resin is different between a portion of the warp or the weft only and a portion where the warp and the weft intersect. . In a portion where the yarn intersects, the resin is harder to enter the inside of the yarn than in other portions, and in some cases, a portion that is not impregnated with the resin remains inside the yarn.

In the case of a glass fiber woven fabric, the yarn is distorted at the time of weaving, and is present as a reinforcing material in a printed circuit board in a state in which stress for the distortion remains. When subjected to instantaneous high-temperature heating during the chip mounting process, small peeling occurs at a portion where the adhesive force between filaments or yarns is weak due to the effect of residual stress remaining in the fabric. That is, a peeling phenomenon occurs in a portion where the resin is small around the glass filament.

In the prepreg for a printed circuit board of the present invention, since the glass fiber yarns are arranged in one direction and are in a sheet shape, the impregnation of the resin during the production of the prepreg does not vary depending on the case and is substantially uniform. In addition, unlike a woven fabric, there is no intersection of yarns, so that there is less likely to be a portion where resin impregnation is insufficient. In a printed board obtained by laminating such prepregs, the impregnation of the glass fiber yarns with the resin in the prepreg state is relatively uniform. Therefore, the glass fiber yarn is not distorted because the fiber yarn with less resin is arranged in one direction in parallel with the filament around the filament seen when using the glass fiber woven fabric. No unevenness exists. Therefore, even when a thermal shock is applied, the peeling phenomenon between filaments does not occur, and a printed board having excellent heat resistance can be obtained.

Example 1 A glass filament having a diameter of 9 μm was subjected to a surface treatment using the following sizing agent components.

Sizing agent component: (a) film forming component: Epicoat 828 [registered trademark,
Addition of 1 mol of diethanolamine to an epoxy resin manufactured by Shell Chemical Co., Ltd. (3% of active ingredient) (b) Coupling agent: epoxy silane A-187
(Nippon Unicar Co., Ltd.) (0.3%) (c) Lubricant: butyl stearate (effective ingredient: 0.1%)
(5%) Tetraethylenepentamine distearate (0.05% of active ingredient) (d) Water residue Sizing agent pH: adjusted to about 5 with acetic acid.

Sizing treatment of sizing agent: Filaments of glass fiber spun from the bushing are sizing-processed with a sizing agent by an apron-type sizing agent application device, bundled by a sizing roller into a strand, wound by a winding machine, and twisted. And twisted into yarn.

Sizing agent adhesion rate: 0.35% Glass fiber yarn ECG75 1/0 0.7Z consisting of 400 glass filaments surface-treated as described above [Nitto Boseki Co., Ltd.
Made) were adjusted to 37 lines / 25mm. The obtained aligned glass fiber yarn was immersed in an epoxy resin varnish of the following composition, air-dried, and dried at 140 ° C. for 10 minutes.Using a polyethylene film as a carrier film, winding the film together with the film, the resin amount was 40.5%. A prepreg consisting of 59.5 parts by weight of glass fiber yarn was obtained.

Epoxy resin varnish Epoxy resin [Epicoat 1001 manufactured by Shell Chemical Co., Ltd.] 100 parts by weight Dicyandiamide 2 parts by weight Benzyl dimethylamine 0.2 parts by weight About 100 parts by weight Methyl oxitol Approximately 100 parts by weight , 35μm thick copper foil on both surfaces, 720mmHg
Under a reduced pressure of 170 ° C., compression molding was performed at 170 ° C., 20 kg / cm ² for 90 minutes to obtain a printed wiring board made of a copper-clad laminate.

Furthermore, after removing the copper foil by etching the entire surface, washing with water,
After air-drying, a test piece having a size of 50 mm × 50 mm was prepared.

Next, the test piece of the obtained laminate was measured for boiling water absorption, solder heat resistance time and heat shock resistance. The results are shown in Table 1.

Comparative Example 1 A glass fiber woven fabric using glass cloth WEA-18W [manufactured by Nitto Boseki Co., Ltd.] and deoiled by heat cleaning was prepared using 0.5% of epoxysilane A-187, 1.0% of acetic acid,
Surface treatment using a treatment liquid consisting of 98.5% of water and
It was squeezed with a squeeze roll until the pickup amount reached 30%. This was dried at a temperature of 110 ° C. for 5 minutes. A prepreg was prepared and molded in the same manner as in Example 1 to produce a sample piece. The test pieces were measured for boiling water absorption, solder heat resistance time and heat shock resistance, and the results are shown in Table 1.

Test Method of Laminated Plate Specimen (1) Boiling Water Absorption According to the test method of JIS C-6481, the water absorption of the laminated plate sample after boiling for 5 to 20 hours was measured.

(2) Solder heat test After laminating the test piece in a pressure cooker at 133 ° C, immersing it in a solder bath at 280 ° C for 20 seconds, removing the test piece from the test piece for blistering or peeling, and then generating these defects The boiling time was taken as the solder heat resistance time.

(3) Heat shock resistance Immediately after immersing the laminate test piece in liquid nitrogen for about 1 minute,
Floating damage was observed on a 0 ° C. solder bath, the surface condition was examined, and the evaluation was made according to the following criteria.

 A: No abnormality is observed in the appearance of the test piece.

X: A cross-shaped white pattern emerges over the entire surface of the test piece at the intersection of the fabric.

(Effects of the Invention) As is clear from the results in Table 1, a printed circuit board excellent in heat shock resistance can be manufactured by using the prepreg for a printed circuit board of the present invention. Also, by using a non-twisted yarn, a printed circuit board without warpage or twist can be manufactured.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-137733 (JP, A) JP-A-64-45841 (JP, A) JP-A-62-140836 (JP, A) JP-A-1- 112792 (JP, A) Shokai Sho 60-178122 (JP, U) Shoko Sho 59-21001 (JP, Y2)

Claims (1)

(57) [Claims] A) a sizing agent comprising a synthetic resin as a film-forming component and a glass thread having a silane coupling agent arranged in one direction in parallel to form a unidirectional sheet; b) a thermosetting resin varnish on the unidirectional sheet. C) a method of manufacturing a printed circuit board by laminating a plurality of prepreg sheets, laminating a metal foil on at least one surface thereof, and hot pressing.