KR20060074321A - A back up board for manufacturing a printed circuit board - Google Patents

Abstract

Disclosed is a low cost high quality printed circuit board backing board having high surface hardness and low hardness of an inner core layer and excellent thermal conductivity.

Such a backing board includes a sheet-like glass fiber base layer having excellent durability and tensile strength, a laminate for surface and back layers formed by impregnating and drying a thermosetting resin and a metallic material on the base layer, and a high density soft material or thermoplastic material. Either one of the resin and the thermosetting resin comprises an impregnated glass fiber inner core layer.

Printed Circuit Board, Backup Board, Friction Heat, Burr, Thermosetting Fiber

Description

Back up board for manufacturing a printed circuit board

1 is a side cross-sectional view of a backup board for manufacturing a printed circuit board according to the present invention.

Figure 2 is a side cross-sectional view of a stack layer for a surface layer in accordance with the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back up board for printed circuit board manufacturing, and more particularly, to a low cost high quality back up board for manufacturing high quality printed circuit board with high surface hardness and low hardness of an inner core layer.

As technology is developed in various industries and the demand for printed circuit boards is exploding rapidly, it is necessary to precisely process and reduce defect rate of printed circuit boards in order to improve product quality and be competitive in terms of manufacturing cost.

In recent years, printed circuit boards have been directed to produce substrates of electric and electronic products having small size and multifunction, and according to this trend, demand for high functional substrates such as multi-chip module boards, rigid boards, and flexible boards is increasing.

In order to manufacture such a high performance printed circuit board, the elements mounted on the circuit board are also miniaturized, so that the holes for mounting the elements are smaller in the circuit board than in the related art.

The holes for mounting the elements on the printed circuit board are drilled by the drill bit. To make the inner diameter of the hole drilled in the board constant, the drill bit must be completely penetrated through the board.

In order to perform the drilling work of such a drill bit, a so-called backup board is supported on the lower side of the printed circuit board.

As the diameter of the drill bit decreases and the rotational speed of the drill increases, frictional force between the drill bit, the circuit board, and the backup board is increased, and friction heat is generated between them.

Friction heat generated at this time causes the printed circuit board to melt the chips generated during the drilling operation and stick them to the drill bit.

Therefore, in order to solve such a problem, a backing board capable of quickly releasing frictional heat is required in the operation of drilling a printed circuit board with a drill bit.

Background Art [0002] In general, a structure in which a backup board for manufacturing a printed circuit board is laminated with a plurality of phenol resin-impregnated papers made by impregnating a phenol resin into a particle board or kraft paper.

Particle boards of this kind have a problem in that the backing board is not only heavy in weight but also has low surface hardness due to weak particle bonding strength of the cellulose component.

As described above, a backup board having a low surface hardness has a problem in that a burr or a smear phenomenon occurs during drilling.

In the case of phenolic resin boards, the surface hardness is low due to the properties of phenolic resins, so that the punishment due to the copper film attached to the surface of the printed circuit board is severe and the smear phenomenon occurs due to the local melting of the phenolic resin.

As described above, when the punishment or smear phenomenon occurs, the printed circuit board is not manufactured, and the drill bit is often broken due to the melt that adheres to the drill bit.

In order to solve these problems, a conventional backup board for manufacturing a circuit board is a phenolic prepreg that is cured and pressed for 1 hour or more in a state of high temperature and high pressure on both sides of a soft material such as a particle board or a medium density fiber board. The board is known.

However, such a backup board has a case where peeling phenomenon appears between the medium density fiber board, and it cannot fully function as a backup board.

The back-up board for printed circuit board proposed by Korean Patent Publication No. 2001-0038074 is impregnated with melamine resin impregnated liquid having 50% solids content in the paper with a lot of pulp content and then dried at 150 ° for 2 minutes. After the preparation, it is disclosed to manufacture a board by using a known phenolic resin impregnated kraft paper as an inner core, laminating the melamine resin impregnated paper prepared in advance on both sides thereof, and molding and cooling under a constant pressure and temperature.

 This method of manufacturing a backup board of the patent, while suppressing the bee phenomenon occurring in the copper foil formed on the printed circuit board during the drilling operation, dust dust and the like can be easily removed, but due to the limitation of the paper material with a high pulp content Not only are there limits to increasing the hardness of the surface, but they are also not particularly suitable for releasing frictional heat generated during drilling.

The present invention has been invented to solve the problems of the prior art, an object of the present invention is to provide a low cost high quality printed circuit board backup board having a high surface hardness, low hardness of the inner core layer and excellent thermal conductivity. .

In order to realize the object of the present invention, a backup board for manufacturing a printed circuit board provided by the present invention includes a front layer, an inner core layer, and a back layer.

The surface layer and the back layer include a glass fiber-based thermosetting resin layer and a metallic material, and the inner core layer includes a high-density soft wood layer or a glass fiber layer impregnated with any one of a thermoplastic resin and a thermosetting resin.

The backing board for manufacturing a printed circuit board manufactured by the present invention includes a metal material having excellent thermal conductivity such as glass fiber, thermosetting resin, aluminum paste, copper powder, mixed powder of copper and zinc, and gold powder and a high density soft wood layer. While increasing the hardness of the has excellent thermal conductivity properties.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the backing board according to the present invention is any one of a surface layer laminate 2 including a base layer, a high density soft wood layer adhered to one side of the laminate 2, or a thermoplastic resin and a thermosetting resin. A glass fiber inner core layer 4 impregnated with a resin, and a back layer stack 6 stacked in a symmetrical manner with the stack layer 2 interposed therebetween with the inner core layer 4 interposed therebetween. .

As shown in FIG. 2, the surface layer laminate 2 is impregnated with a glass fiber layer 8 used as a substrate to form a surface impregnation layer 10.

The glass fiber layer 8 used as the substrate may be used in the form of a woven or nonwoven fabric. Preferably, the higher the density of the glass fiber is, the better.

The density of the glass fiber suitable for this embodiment is preferably in the range of 30 g / cm 2-120 g / cm 2. When the density structure is less than this range, the structure becomes coarse, the tensile strength is weakened, and the rupture phenomenon appears, and the impregnated amount of the thermosetting resin becomes small and the surface hardness cannot be increased.

On the contrary, when the density is greater than the above range, the impregnated coating amount is too large, resulting in a long drying and curing time and deformation of the laminate.

As the thermosetting resin, melamine resin, amino resin, acrylic resin, epoxy resin, urethane resin, or the like may be used.

Among these resins, the most preferable one is a melamine resin or an epoxy resin having a high hardness, and preferably a solid content of 30% to 60% is used.

If the solid content of the resin is less than the above range, there is a problem that the adhesive strength is lowered, if more than the above range, the adhesion is easy but the curing time is long and the toughness is weak.

After impregnating the glass fiber layer 8 which is the base material layer with a melamine or an epoxy resin mixed with a metallic material, Dry at 120 ° to store the surface impregnation layer 10 in a prepreg state.

The metallic material is any one or at least one of aluminum paste, copper powder, copper zinc compound, and gold powder is mixed with the thermosetting resin and impregnated with a well-known roll-containing chip method.

The metallic material may be used in an amount of 1% by weight to 10% by weight based on the thermosetting resin.

The aluminum paste has a thermal conductivity of 196 kcal / ??, 320 kcal / ?? for copper powder, 300 kcal / ?? for copper zinc compound, and 254 kcal / ?? for gold powder. The above can satisfy the thermal conductivity of the surface layer to be obtained.

The metallic material is not used in the case of a printed circuit board having less influence of frictional heat during drilling, and a surface impregnation layer may be made of a thermosetting resin.

On the other hand, the inner core layer 4 may be a glass fiber or the like impregnated with any one of a thermoplastic resin and a thermosetting resin in a medium density fiber board or a high density fiber board.

The medium density fiber refers to a density of 800 kg / cm 2 or more and a bending strength of 500 kg / cm 2 or more, and the high density fiber refers to a density of 900 kg / cm 2 or more and a bending strength of 600 kg / cm 2 or more.

The glass fiber used for this inner core layer also has a density structure of 30 g / cm 2-120 g / cm 2, and the glass fiber is thermoplastic such as acrylic resin, fluorine resin, polyvinyl chloride resin, polyethylene resin, and polypropylene resin. Impregnated or coated with these resins.

And when this glass fiber is contained in a thermosetting resin, a melamine resin, an amino resin, an acrylic resin, an epoxy resin, and a urethane resin is used as an impregnation liquid.

The solids content of the resins is preferably 30% to 60%. If the content of resin below this range is used, there is a problem that the adhesive strength is lowered. If the content of the resin above this range is used, the adhesion is excellent, but the flowability of the resin is not good, the balance of thickness, contamination of the cut surface may occur. .

On the other hand, the back layer stack 6 may have the same or similar structure as the stack layer 2 for the front layer, and thus a detailed description thereof will be omitted.

The backup board having such a structure is manufactured in various structures as follows.

(Example 1)

The surface layer laminate 2, the inner core layer 4, and the back layer laminate 6 are all made by laminating hot pressing a glass fiber of a nonwoven fabric impregnated with a thermosetting resin as a base layer.

(Example 2)

The surface layer laminate 2 and the back layer laminate 6 use a glass fiber in the form of a woven fabric impregnated with a thermosetting resin as the base layer, and the inner core layer 4 is a glass in the form of a nonwoven fabric impregnated with a thermosetting resin. A fiber base layer is used so that a plurality of laminates are hot pressed together.

(Example 3)

The surface layer laminate 2 and the back layer laminate 6 use a non-woven glass fiber impregnated with a thermosetting resin as a base layer, and the inner core layer 4 is a woven glass fiber impregnated with a thermosetting resin. By using as a base material layer, many are laminated | stacked and hot-pressed.

In the above embodiment, the inner core layer 4 may be a high density soft wood.

Products made in this way are 120 ?? It is pressurized at a pressure of 15kg / cm 2-30kg / cm 2 by pressing at 150 ° C for 30 minutes, and then cooled at room temperature for about 30 minutes.

As described above, in the back-up board according to the present invention, the surface layer and the back layer are based on the glass fiber, so that the hardness of the thermosetting resin is impregnated, so that the surface hardness is high. The heat transfer rate becomes excellent.

As such, the back-up board with high surface strength and excellent heat transfer can reduce the occurrence of burrs when drilling a printed circuit board, and the chips coming out as the board is drilled do not stick to the drill bit to facilitate the operation. have.                     

In addition, the work process is simple and the failure rate can be reduced, enabling the production of low cost backup boards.

In addition, the inner core layer provides an area where the tip portion of the bit penetrates the printed circuit board during drilling and has a smaller hardness than the surface layer, so that the internal core layer can absorb the impact applied to the surface layer or the back layer. Breakage can be prevented.

Claims (11)

A surface layer laminate having high surface hardness and excellent thermal conductivity; An inner core layer of a soft material that is pressure-attached to one side of the surface layer laminate and has a lower hardness than the surface layer laminate; And a back layer laminate provided at a position opposite the surface layer laminate with the inner core layer interposed therebetween, the back layer laminate having the same surface hardness and thermal conductivity as the stack layer for the surface layer. Inner core layer, A laminate for surface layers and a laminate for back layers, which are provided on both surfaces of the inner core layer, The inner core layer, the laminate for the surface layer, the laminate for the back layer is a backup board for manufacturing a printed circuit board using a glass fiber in the form of a nonwoven fabric impregnated with a thermosetting resin. Inner core layer, A laminate for surface layers and a laminate for back layers, which are provided on both surfaces of the inner core layer, The inner core layer is a glass fiber of a nonwoven fabric impregnated with a thermosetting resin as a base layer, The laminate for the surface layer and the laminate for the back layer is a backup board for manufacturing a printed circuit board using a glass fiber of a woven fabric impregnated with a thermosetting resin as a base layer. Inner core layer, A laminate for surface layers and a laminate for back layers, which are provided on both surfaces of the inner core layer, The inner core layer is made of glass fiber in the form of a woven fabric impregnated with a thermosetting resin, The laminate for the surface layer and the laminate for the back layer is a backup board for manufacturing a printed circuit board using a glass fiber of a nonwoven fabric impregnated with a thermosetting resin as a base layer. The backup board of claim 1, wherein the surface layer laminate and the back layer laminate are laminated with a plurality of glass fiber substrate layers having a density of 30 g / cm 2 to 120 g / cm 2. The backup board of claim 5, wherein the glass fiber base layer is formed of a nonwoven fabric or a woven fabric. The backup board of claim 5, wherein the glass fiber base layer is impregnated with any one of thermosetting resins such as melamine resin, amino resin, acrylic resin, epoxy resin, and urethane resin. The stacking layer for the surface layer and the stacking layer for the back layer is a mixture of at least one metallic material of aluminum paste, copper powder, copper and zinc compounds, and gold powder in a thermosetting resin. Backup board for manufacturing a printed circuit board, characterized in that impregnated. The backup board according to any one of claims 1 to 4, wherein the inner core layer is impregnated with a thermosetting resin or a thermoplastic resin in a glass fiber base layer. The backup board according to any one of claims 1 to 4, wherein the inner core layer is one of a high density fiber board and a medium density fiber board. The method of claim 9, wherein the thermoplastic resin is one of an acrylic resin, a fluorine resin, a polyvinyl chloride resin, a polyethylene resin, and a polypropylene resin. Back-up board for the manufacture of printed circuit board made by gong.

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