JP2015084394A - Printed circuit board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed circuit board capable of preventing impairments such as warpage and distortion, and a manufacturing method thereof.SOLUTION: A printed circuit board 10 comprises: a composite material layer 105 having one face and another face corresponding thereto; a first insulator layer 110 formed on the one face of the composite material layer 105; and a second insulator layer 220 formed on the another face of the composite material layer 105. The thermal expansion coefficients of the first insulator layer 110, the second insulator layer 220 and the composite material layer 105 are different from each other.

Description

  The present invention relates to a printed circuit board and a method for manufacturing the same.

  In recent years, with the development of electronic devices, printed circuit boards have been reduced in weight, thickness, size, and integration. In order to meet such a demand, the structure of the printed circuit is further complicated, densified, and multilayered.

  In addition, due to the shortening of the product cycle, it is required to respond quickly to customer requests and shorten the development period. Under such circumstances, due to the trend toward thinner printed circuit boards, warpage of the substrates delivered to customers has become a core technical problem to be solved.

  In the process of mounting electronic components on such a printed circuit board, thermal expansion and warpage are generated due to heat in the printed circuit board that is thinned and multilayered. Here, each element constituting the printed circuit board has a different coefficient of thermal expansion (CTE), and the form, thickness, and area of the component are different from each other. Thermal expansion and warping inevitably occur due to high temperature heat during the manufacturing process.

  For example, the coefficient of thermal expansion (CTE) of copper is 10 to 20 ppm / ° C., and the coefficient of thermal expansion (CTE) of a normal polymer composite insulating material used for a printed circuit board (PCB) is 50-80 ppm / ° C.

  In particular, a polymer has a large coefficient of thermal expansion (CTE) at a temperature equal to or higher than the glass transition temperature (Tg) due to its viscoelasticity. The high temperature coefficient of thermal expansion (CTE) reaches 150 to 180 ppm / ° C., and the glass transition temperature (Tg) has a value of 150 to 200 ° C.

  When mounting a component such as a semiconductor on a printed circuit board (PCB), heat inside and outside of 250 to 280 ° C. is rapidly supplied to the printed circuit board (PCB) for 3 to 5 seconds. At this time, if the difference in coefficient of thermal expansion (CTE) between the circuit and the insulating layer is large, cracks may occur in the circuit formed by plating or the shape of the substrate may be distorted. However, due to the difference in coefficient of thermal expansion (CTE), there is a risk that a crack may occur in the solder between the mounted component and the printed circuit board, or the form of the board may be distorted.

  Thus, a substrate on which a structural problem such as warpage has occurred ultimately reduces the mountability of the electronic component. Thus, the electrical, thermal, mechanical and dimensional stability required for the substrate acts as a further important factor. Among these, dimensional deformation due to heat in particular is one of the important factors that influence the reliability when manufacturing a substrate.

  Conventionally used multilayer printed circuit boards have copper layers for wiring on the top and bottom centering on the insulating layer, and the copper layers and insulating layers made of resin are alternately stacked. It is composed of multiple layers.

  In spite of having such an upper / lower symmetrical structure, the printed circuit board warps either one, that is, a so-called warpage phenomenon occurs. This is due to the difference in thermal expansion between the upper part and the lower part with reference to the center line of the printed circuit board.

  However, in spite of various methods for lowering the coefficient of thermal expansion (CTE) of the polymer material constituting the insulating layer, a difference in coefficient of thermal expansion (CTE) from copper constituting the wiring eventually occurs.

  Therefore, even if the insulating layer of the printed circuit board has an up / down symmetrical structure, the volume and area of the copper layer are different from each other, and the thermal expansion surface cannot actually have a symmetrical structure. There is a problem that a phenomenon occurs in which the printed circuit board is warped in any one of them.

  Various methods have been tried to solve the above problems.

  As an example, a plurality of bars having a smaller thermal contraction rate than the copper wiring layer and the solder resist layer are vertically inserted into the warp portion of one side and the other side of the printed circuit board main body and having a large thermal contraction rate. A method for preventing this is used.

  Further, as another example, a warp canceling means in which a material having a low thermal expansion coefficient and a material having a large thermal expansion coefficient are vertically stacked is incorporated inside the printed circuit board so as to be vertically symmetrical, It adhered symmetrically to the upper and lower outer surfaces.

  As a result, even if a phenomenon of warping upward or downward occurs, the warp canceling means arranged in the upper part warps downward, and the warp canceling means arranged in the lower part warps upward, and printing is performed by the canceling action. The effect of reducing the warping phenomenon of the circuit board could be achieved.

  However, since such a conventional method is a method in which a portion for preventing warpage of the printed circuit board is added in the end, it is necessary to realize an integrated circuit pattern that is thinned and densified. There was a limit.

  By adjusting the filler content according to the amount of copper remaining in the insulating layer of the printed circuit board, the present inventors can prevent warping by forming insulating layers having different coefficients of thermal expansion. It confirmed and came to make this invention.

  Accordingly, it is an object of the present invention to provide a printed circuit board having a dimensional stability by preventing a warp phenomenon occurring in the printed circuit board without using another means for preventing warpage.

  Another object of the present invention is to provide a printed circuit board which is not only light and thin but also has an improved degree of integration because there is no other warp prevention means.

  Still another object of the present invention is to provide a method of manufacturing a printed circuit board in which warpage is prevented by adjusting the filler content of an insulating layer.

  In order to achieve the above object, a printed circuit board (hereinafter referred to as “first invention”) according to a specific example of the present invention includes a composite material layer having one surface and another surface corresponding thereto, A first insulating layer formed on one surface and a second insulating layer formed on the other surface of the composite material layer, wherein the first insulating layer, the second insulating layer, and the composite material layer It forms so that a thermal expansion coefficient may mutually differ.

  In the first invention, a first circuit layer formed between the first insulating layer and the composite material layer; a second circuit layer formed between the second insulating layer and the composite material layer; The first circuit layer and the second circuit layer have different formation areas.

  In the first invention, the composite material layer or the first and second insulating layers are alternately and repeatedly laminated with the first and second circuit layers.

  In the first invention, the composite material layer includes an organic fiber or an inorganic fiber, a liquid crystal oligomer, an epoxy resin, and a filler.

  In the first invention, the first insulating layer and the second insulating layer include a liquid crystal oligomer, an epoxy resin, and a filler.

  In the first invention, the liquid crystal oligomer is represented by the following chemical formula 1.

  Here, a is an integer of 13 to 26, b is an integer of 13 to 26, c is an integer of 9 to 21, d is an integer of 10 to 30, and e is an integer of 10 to 30.

  1st invention WHEREIN: The said organic fiber or inorganic fiber, and a filler are contained by 20-80 weight% with respect to 100 weight% of said composite material layers.

  1st invention WHEREIN: The content of the said inorganic fiber or organic fiber is 5-25 weight% with respect to the total weight of the said composite material layer, and the content of the said filler is 5-75 weight%.

  In the first invention, the inorganic fiber or organic fiber includes glass fiber, carbon fiber, polyparaphenylene benzobisoxazole fiber, thermotropic liquid crystal polymer fiber, lyotropic liquid crystal polymer fiber, aramid fiber, polypyridobisimidazole fiber, One or more selected from polybenzothiazole fibers and polyarylate fibers.

  In the first invention, the glass fiber is any one selected from T-glass fiber, E-glass fiber, S-glass fiber, ceramic fiber, and a mixture thereof.

  In the first invention, the filler is included in an amount of 20 to 80% by weight with respect to 100% by weight of the first insulating layer or the second insulating layer.

  In the first invention, the filler is any one selected from the group consisting of an organic filler, an inorganic filler, and a combination thereof.

In the first invention, the inorganic filler is silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), barium sulfate (BaSO ₄ ), talc, mica powder, aluminum hydroxide (AlOH ₃ ), magnesium hydroxide (Mg _(OH) 2), calcium carbonate (CaCO _3), magnesium carbonate (MgCO _3), magnesium oxide (MgO), boron nitride (BN), aluminum borate (alBO _3), barium titanate (BaTiO ₃ ), calcium zirconate (CaZrO ₃ ), and combinations thereof.

  In the first invention, the organic filler is any one selected from the group consisting of epoxy resin powder, melamine resin powder, urea resin powder, benzoguanamine resin powder, styrene resin, and combinations thereof.

  In the first invention, when the remaining copper ratio of the first circuit layer and the second circuit layer increases in the range of 10 to 20%, the filler of the first insulating layer, the second insulating layer, and the composite material layer The content is adjusted in the range of 1 to 10% by weight.

  According to another aspect of the present invention, there is provided a method of manufacturing a printed circuit board (hereinafter referred to as a “second invention”) comprising providing a composite material layer having one surface and another surface, and one surface of the composite material layer. Forming a first circuit layer, a second circuit layer on the other surface of the composite material layer, a third circuit layer on the first circuit layer, and the first circuit layer and the third circuit layer. Forming a first insulating layer between the circuit layer, forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer; Forming a filler content of the first insulating layer and a filler content of the second insulating layer different from each other, and a residual copper ratio of the first insulating layer is different from that of the second insulating layer. When the percentage of remaining copper is higher, the filler content of the first insulating layer is formed to be greater than the filler content of the second insulating layer.

  In the second invention, when the remaining copper ratio of the first circuit layer and the second circuit layer is increased in the range of 10 to 20%, the filler of the first insulating layer, the second insulating layer, and the composite material layer The content is adjusted to a range of 1 to 10% by weight.

  In the second invention, the filler is contained in an amount of 20 to 80% by weight with respect to 100% by weight of the first insulating layer or the second insulating layer.

  According to another aspect of the present invention, there is provided a method of manufacturing a printed circuit board (hereinafter referred to as a “third invention”) comprising: providing a composite material layer having one surface and another surface; Forming a first circuit layer on one surface and a second circuit layer on the other surface of the composite material layer; forming a third circuit layer on the first circuit layer; and Forming a first insulating layer between the three circuit layers, forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer; Forming a filler content of the first insulating layer and a filler content of the second insulating layer different from each other, and a remaining copper ratio of the first insulating layer is different from that of the second insulating layer. When the remaining copper ratio is higher, the filler content of the second insulating layer is less than the filler content of the first insulating layer. To.

  In the third invention, when the remaining copper ratio of the first circuit layer and the second circuit layer is increased in the range of 10 to 20%, the filler of the first insulating layer, the second insulating layer, and the composite material layer The content is adjusted in the range of 1 to 10% by weight.

  In the third invention, the filler is contained in an amount of 20 to 80% by weight with respect to 100% by weight of the first insulating layer or the second insulating layer.

  According to embodiments of the present invention, a printed circuit board and a method of manufacturing the printed circuit board may selectively adjust the filler content of the insulating layer disposed between the circuit layers to form insulating layers having different coefficients of thermal expansion. Thus, it is possible to prevent defects such as warpage and distortion.

  Further, by relaxing the stress due to thermal expansion, it is possible to prevent damage to the circuit and the chip mounted on the circuit.

  Further, since the filler is added in a necessary amount, the material is saved and the manufacturing cost can be reduced.

  Further, since another warp prevention means is unnecessary, not only is it light and thin, but also the degree of integration can be improved.

1 is a cross-sectional view of a printed circuit board according to an exemplary embodiment of the present invention. 1 is an enlarged cross-sectional view of a printed circuit board according to an exemplary embodiment of the present invention. FIG. 5 is a process diagram illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention. FIG. 5 is a process diagram illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention. FIG. 5 is a process diagram illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention. FIG. 5 is a process diagram illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention. FIG. 5 is a process diagram illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention.

  Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings. In this specification, it should be noted that when adding reference numerals to the components of each drawing, the same components are given the same number as much as possible even if they are shown in different drawings. I must. The terms “one side”, “other side”, “first”, “second” and the like are used to distinguish one component from another component, and the component is the term It is not limited by. Hereinafter, in describing the present invention, detailed descriptions of known techniques that may obscure the subject matter of the present invention are omitted.

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

  First, a printed circuit board according to an exemplary embodiment of the present invention and a manufacturing method thereof will be described with reference to FIGS.

  In an exemplary embodiment of the present invention, a printed circuit board including a liquid crystal oligomer and an insulating layer having a controlled filler content will be described, but the present invention is not limited thereto, and various insulating layers are used. be able to.

  FIG. 1 is a cross-sectional view of a printed circuit board according to an exemplary embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a printed circuit board according to an exemplary embodiment of the present invention.

  Referring to FIGS. 1 and 2, a printed circuit board 10 according to an exemplary embodiment of the present invention is formed on one surface of a composite material layer 105 having one surface and the other surface corresponding thereto, and on one surface of the composite material layer 105. The first insulating layer 110, the second insulating layer 220 formed on the other surface of the composite material layer 105, and the first insulating layer 110, the second insulating layer 220, and the composite material layer. The thermal expansion coefficients of 105 are different from each other.

  Here, the first circuit layer 1100 is interposed between the one surface of the composite material layer 105 and the first insulating layer 110, and the third circuit layer 1300 is interposed between the first insulating layer 110 and the third insulating layer 130. Let Further, the second circuit layer 2200 is formed between the other surface of the composite material layer 105 and the second insulating layer 220, and the fourth circuit layer 2400 is formed between the second insulating layer 220 and the fourth insulating layer 240. can do. As described above, the printed circuit board 10 is formed by alternately laminating a large number of insulating layers and circuit layers, and at this time, the thickness and formation area of the circuit layers can be different from each other.

  In addition, an insulating layer can be formed on the outermost side of the printed circuit board 10 on which a large number of insulating layers and circuit layers are stacked. A part of the outermost insulating layers 150 and 260 is opened, and a pad connected to an electronic component can be formed.

  Such circuit layers 1100, 1300, 2200, and 2400 are arranged on the composite material layer 105 or the insulating layers 110, 130, 150, 220, 240, and 260, and form wiring to form a circuit. Can do.

  The composite material layer 105 or the insulating layers 110, 130, 150, 220, 240, and 260 are stacked in the thickness direction of the circuit layers 1100, 1300, 2200, and 2400, and the internal circuit layer 1100, 1300, 2200, and 2400 can be insulated from each other.

  Here, the structure of the conventional printed circuit board is a structure in which insulating layers 110, 130, 150, 220, 240, and 260 are alternately stacked in the thickness direction with respect to the composite material layer 105 to form an upper / lower symmetry. And comprising an insulating layer and a composite layer formed with the same filler content.

  However, in a product that is actually applied, the circuit layers 1100, 1300, 2200, and 2400 that have relatively low thermal expansion constitute a circuit (signal layer and ground layer), and therefore, the upper part is based on the center of the printed circuit board 10. In addition, the volume and area of copper constituting the lower circuit layers 1100, 1300, 2200, and 2400 may be different. Hereinafter, the circuit layers 1100, 1300, 2200, and 2400 formed in contact with the composite material layer 105 or the insulating layers 110, 130, 150, 220, 240, and 260, respectively, will be referred to as the remaining copper ratio.

  Since the circuit layers 1100, 1300, 2200, and 2400 receive and transmit electrical signals through the circuit wiring, heat can be generated in the copper wiring due to such electrical energy. The generated heat becomes different thermal energy depending on the volume and area of the copper wiring, and the thermal energy is transmitted to the adjacent composite material layer 105 and insulating layers 110, 130, 150, 220, 240, and 260.

  Furthermore, a semiconductor chip or the like is mounted on the circuit wiring during the process (surface mounted technology: SMT). At this time, a preheating process is added before the mounting, and the heat inside and outside of 280 ° C. is applied in the mounting process. Provided to layer 105 or insulating layer 110, 130, 150, 220, 240, 260. Therefore, the composite material layer 105 or the insulating layers 110, 130, 150, 220, 240, and 260 may thermally expand, which may cause the printed circuit board 10 to warp.

  Further, in the circuit layers 1100, 1300, 2200, and 2400, more heat can be generated depending on the remaining copper ratio in a region where the area where the copper wiring is exposed is large. Furthermore, the insulating layers 110, 130, 150, 220, 240, and 260 have viscosity and elasticity characteristics, and the rate of thermal expansion due to heat can increase exponentially due to such viscoelasticity. As described above, since the copper wiring, the composite material layer 105, and the insulating layers 110, 130, 150, 220, 240, and 260 have different thermal expansion coefficients, there is a risk of warping due to the transmitted thermal energy.

  In addition, in order to adjust the thermal expansion due to the transmission of the thermal energy, the insulating layers 110, 130, 150, 220, 240, and 260 may be formed by including a filler 180 in a polymer. Compared to copper forming the circuit layers 1100, 1300, 2200, and 2400, the thermal expansion coefficient of the polymer that forms the insulating layers 110, 130, 150, 220, 240, and 260 is relatively high.

  Accordingly, by injecting the filler 180 or the like into the insulating layers 110, 130, 150, 220, 240, and 260 and adjusting the thermal expansion coefficient, it is possible to prevent a warp phenomenon due to thermal expansion.

  The insulating layers 110, 130, 150, 220, 240, and 260 may be build-up films in which a filler 180 is added to a polymer. The build-up film can be provided with via holes to increase the wiring density, thereby increasing the density and thickness of the printed circuit board 10.

  The content of the filler 180 mixed with the insulating layers 110, 130, 150, 220, 240, and 260 is 20 to 80% by weight with respect to the total weight of the insulating layers 110, 130, 150, 220, 240, and 260. Can be filled.

  If the content of the filler 180 is less than 20% by weight, the heat transfer force may be weakened. If the content of the filler 180 exceeds 80% by weight, the adhesion with the circuit layers 1100, 1300, 2200, and 2400 is reduced. Problems may occur.

  As the filler 180, any one of an inorganic filler, an organic filler, and a combination thereof can be used.

Here, as the inorganic filler, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), barium sulfate (BaSO ₄ ), talc, clay, mica powder, aluminum hydroxide (AlOH ₃ ), magnesium hydroxide (Mg ( _OH) 2), calcium carbonate (CaCO _3), magnesium carbonate (MgCO _3), magnesium oxide (MgO), boron nitride (BN), aluminum borate (alBO _3), barium titanate (BaTiO _3), and zirconate One or more selected from calcium (CaZrO ₃ ) can be used.

  Further, as the organic filler, any one selected from the group consisting of epoxy resin powder, melamine resin powder, urea resin powder, benzoguanamine resin powder, styrene resin, and combinations thereof can be used.

  The insulating layers 110, 130, 150, 220, 240, and 260 are made of a polymer and include an epoxy resin and a liquid crystal oligomer represented by the following chemical formula 1.

  Here, a is an integer of 13 to 26, b is an integer of 13 to 26, c is an integer of 9 to 21, d is an integer of 10 to 30, and e is an integer of 10 to 30.

  The liquid crystal oligomer has both a structure embodying liquid crystal characteristics and a soluble structure that is soluble in a solvent. In addition, the liquid crystal oligomer may have the same or different curable groups introduced into one or more of both ends of the main chain. In other words, there are portions at both ends that can have a cured structure of an epoxy and a curing agent.

  As such a curable group, a photocurable group or a thermosetting group can be introduced. The liquid crystal oligomer will be described with reference to, for example, a thermosetting or photocurable liquid crystal oligomer, but is not particularly limited as long as the material can improve mechanical properties.

  When the thermosetting group undergoes high-temperature curing when the printed circuit board 10 or the like is produced using the substrate forming composition, these cross-linking functional groups are cross-linked with each other to form a stable structure in a strong network form. Therefore, the mechanical properties of the printed circuit board 10 can be improved.

  In addition, when photo energy is provided by ultraviolet light, the photocurable group can have a stable cured structure having a strong net form by cross-linking functional groups.

  On the other hand, although the composite material layer 105 is illustrated as a single layer in the drawing, it may be formed in multiple layers in order to improve the modulus of the printed circuit board 10, and the insulating layers 110, 130, 150, 220, 240, 260 may also be formed. It may be formed in multiple layers as shown.

  Here, the composite material layer 105 may be a prepreg (PPG) in which a polymer including the filler 180 further includes organic / inorganic fibers 170.

  The composite material layer 105 may use the same polymer, filler, and filler content as the insulating layers 110, 130, 150, 220, 240, and 260.

  On the other hand, the content of the organic / inorganic fibers 170 and the filler 180 mixed in the composite material layer 105 can be filled so as to be 20 to 80% by weight with respect to the total weight of the composite material layer 105. In addition, the organic / inorganic fiber 170 may be included in an amount of 5 wt% to 25 wt%.

  Depending on the amount of the organic / inorganic fiber 170 added, the filler 180 can be included in an amount of 5 wt% to 75 wt% with respect to the total weight of the composite material layer 105.

  At this time, the filler 180 must be added by at least 5% by weight in order to reduce the thermal expansion coefficient.

  When the added amount of the filler 180 exceeds 75% by weight, the dispersibility of the filler 180 is lowered, the aggregation phenomenon of the filler 180 occurs, and the surface roughness of the substrate may increase. In addition, the viscosity of the polymer may increase, making it difficult to mold the product. Furthermore, in the laminated structure formed in multiple layers, the interlayer adhesion may be reduced.

  The organic / inorganic fiber 170 includes glass fiber, carbon fiber, polyparaphenylene benzobisoxazole fiber, thermotropic liquid crystal polymer fiber, lyotropic liquid crystal polymer fiber, aramid fiber, polypyridobisimidazole fiber, polybenzothiazole. One or more selected from fibers and polyarylate fibers.

  Among these, as said glass fiber, T-glass fiber, E-glass fiber, S-glass fiber, ceramic fiber, etc. can be used. Moreover, as the organic / inorganic fiber 170, inorganic fiber, organic fiber, and a combination thereof may be used.

  Thus, by adjusting the amount of the organic / inorganic fibers and filler added to the composite material layer 105 or the insulating layers 110, 130, 150, 220, 240, and 260 according to the remaining copper ratio, the insulating layer and The coefficient of thermal expansion of the composite material layer can be adjusted. Thereby, the curvature which generate | occur | produces by a thermal expansion coefficient difference can be prevented. Further, by relaxing the stress due to thermal expansion, it is possible to prevent damage to the circuit and the chip mounted on the circuit.

  Meanwhile, FIG. 2 is an enlarged cross-sectional view of a printed circuit board according to an exemplary embodiment of the present invention. Here, for easy explanation of the printed circuit board according to the exemplary embodiment of the present invention, a circuit layer is illustrated. The pattern shape is arbitrarily illustrated.

  Referring to FIG. 2, circuit layers 1100, 1300, 2200, and 2400 are disposed on insulating layers 110, 130, 150, 220, 240, and 260 to form wirings that form a circuit. Circuit layers 1100, 1300, 2200, and 2400 are disposed on the upper and lower surfaces of the insulating layers 110, 130, 150, 220, 240, and 260, respectively. In other words, the circuit layers 1100, 1300, 2200, and 2400 are interposed between the insulating layers 110, 130, 150, 220, 240, and 260, respectively.

  Here, since the circuit layers 1100, 1300, 2200, and 2400 are formed in a pattern, they are formed on the upper and lower surfaces of the insulating layers 110, 130, 150, 220, 240, and 260 so as to have different volumes and areas. obtain.

  For example, the first circuit layer 1100 is formed on one surface of the composite material layer 105, and the first insulating layer 110 is formed on the first circuit layer 1100. A third circuit layer 1300 is formed on the first insulating layer 110. Therefore, the first insulating layer 110 is in contact with the first circuit layer 1100 and the third circuit layer 1300. The second insulating layer 220 formed on the other surface of the composite material layer 105 is also formed so as to be in contact with the second circuit layer 2200 and the fourth circuit layer 2400.

  Here, the structure of the printed circuit board 10 has a structure in which the first and second insulating layers 110 and 220 are vertically symmetrical with respect to the composite material layer 105. Since the circuit layers 1100, 1300, 2200, and 2400 that have relatively little expansion form a circuit, the copper layers and circuit areas that form the circuit layers can be formed differently on the top and bottom with respect to the center of the printed circuit board 10. That is, the copper layers formed on the first and second insulating layers 110 and 220, that is, the remaining copper ratios are different from each other.

  As described above, since the circuit layers 1100, 1300, 2200, and 2400 formed on the first and second insulating layers 110 and 220 have different areas and volumes, they are formed in contact with the circuit layers 1100, 1300, 2200, and 2400. Different thermal energy is transmitted to the composite material layer 105 or the first and second insulating layers 110 and 220.

  As shown in FIG. 2, the second and fourth circuit layers 2200 and 2400 formed in contact with the second insulating layer 220 are formed with a low residual copper ratio and are in contact with the first insulating layer 110. The first and third circuit layers 1100 and 1300 thus formed are formed with a higher residual copper ratio than the second and fourth circuit layers 2200 and 2400.

  At this time, the first insulating layer 110 having a high residual copper ratio receives a larger amount of thermal energy than the second insulating layer 220 having a low residual copper ratio, and has a high coefficient of thermal expansion.

  Here, the filler amount of the first insulating layer 110 or the second insulating layer 220 can be adjusted according to the remaining copper ratio. In other words, the coefficient of thermal expansion due to the transmitted thermal energy can be adjusted by adjusting the amount of filler added to the insulating layer according to the remaining copper ratio. Thereby, the curvature by thermal expansion can be prevented by mixing so that the filler content of the 1st insulating layer 110 with a high residual copper ratio and the 2nd insulating layer 220 with a low residual copper ratio may mutually differ.

  For example, the remaining copper ratio is defined as a total percentage of 200% as a percentage calculated from the area of the circuit layer formed on one surface (100%) and the other surface (100%) of the insulating layer.

  In addition, it is assumed that the first and second insulating layers 110 and 220 are formed using the same polymer and the same type of filler and have the same filler content. At this time, assuming that the first insulating layer 110 has a remaining copper ratio of 80% and the second insulating layer 220 has a remaining copper ratio of 60%, the printed circuit board 10 receives a large amount of thermal energy. That is, it is warped convexly in the direction of the first insulating layer 110 having a high residual copper ratio.

  Here, warpage can be prevented by further mixing a filler with the first insulating layer 110 where much thermal expansion has occurred to reduce the thermal expansion of the first insulating layer 110. Alternatively, by reducing the amount of filler in the second insulating layer 220 to increase thermal expansion, the rate of thermal expansion between the first insulating layer 110 and the second insulating layer 220 can be adjusted to prevent warping.

  That is, the filler contents of the first insulating layer 110 and the second insulating layer 220 having different copper ratios are increased or decreased so that the thermal expansion coefficients of the first insulating layer 110 and the second insulating layer 220 are different from each other. By making it, it can prevent warping in one direction.

  At this time, when a difference in the remaining copper ratio of 10 to 20% occurs, the filler content can be increased or decreased within the range of 1 to 10%. Thereby, the thermal expansion coefficient of an insulating layer can be adjusted and curvature can be prevented.

  In this way, since the filler is added only in a necessary amount, the material can be saved, the manufacturing cost can be reduced, and another warping prevention means is unnecessary, so that it is light and thin, and the degree of integration. Can be improved.

  3 to 7 are process diagrams illustrating a method of manufacturing a printed circuit board according to an exemplary embodiment of the present invention. Here, in order to avoid redundant description, description will be made with reference to FIGS.

  A method of manufacturing a printed circuit board according to an embodiment of the present invention includes providing a composite material layer having one surface and another surface, a first circuit layer on one surface of the composite material layer, and the other surface of the composite material layer. Forming a second circuit layer on the first circuit layer, forming a third circuit layer on the first circuit layer, and forming a first insulating layer between the first circuit layer and the third circuit layer. Forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer.

  Here, when the filler content of the first insulating layer and the filler content of the second insulating layer are different from each other, and the remaining copper ratio of the first insulating layer is higher than the second insulating layer, The first insulating layer is formed to have a filler content greater than that of the second insulating layer.

  According to another aspect of the present invention, there is provided a method of manufacturing a printed circuit board, the step of providing a composite material layer having one surface and another surface, a first circuit layer on one surface of the composite material layer, and the composite material layer. Forming a second circuit layer on each of the other surfaces; forming a third circuit layer on the first circuit layer; and providing a first insulating layer between the first circuit layer and the third circuit layer. Forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer.

  Here, when the filler content of the first insulating layer and the filler content of the second insulating layer are different from each other, and the residual copper ratio of the first insulating layer is higher than the second insulating layer, The second insulating layer is formed so that the filler content is less than the filler content of the first insulating layer.

  More specifically, first, as shown in FIG. 3, the composite material layer 105 is provided. The composite material layer 105 may include a liquid crystal oligomer, organic / inorganic fibers 170, and a filler 180, and may be a single layer or a multilayer. With this composite material layer 105, the modulus of the printed circuit board 10 can be improved. The liquid crystal oligomer, the organic / inorganic fiber 170, and the filler 180 of the composite material layer 105 are the same as described above, and thus are omitted.

  Next, as illustrated in FIG. 4, a circuit layer is formed on at least one surface of the composite material layer 105. At this time, the first circuit layer 1100 can be formed on one surface of the composite material layer 105 and the second circuit layer 2200 can be formed on the other surface of the composite material layer 105. The first circuit layer 1100 and the second circuit layer 2200 may be formed to have different formation areas.

  The first and second circuit layers 1100 and 2200 may be formed of circuit wiring formed by forming a pattern. Therefore, such circuit wiring can be formed in a predetermined pattern. At this time, the first and second circuit layers 1100 and 2200 may be formed by a plating method, or a pattern may be formed by a development and etching process. The first and second circuit layers 1100 and 2200 may be made of copper or a conductive metal.

  Next, as illustrated in FIG. 5, the first insulating layer 110 is formed on the first circuit layer 1100, and the second insulating layer 220 is formed on the second circuit layer 2200. The first and second insulating layers 110 and 220 can be formed by laminating a copper clad laminate 500 on the first circuit layer 1100 or the second circuit layer 2200 (see FIG. 6).

  Here, the copper clad laminate 500 includes an insulating film 510 and a copper foil layer 550 formed on the insulating film 510. Here, the insulating film 510 includes a polymer and a filler mixed with the polymer. At this time, a circuit layer can be formed by performing a plating process on the copper foil layer 550 and patterning. In the circuit layer, a circuit is formed by patterning, but circuit layers having different formation areas, volumes, and the like are formed according to the design of the circuit. Therefore, by comparing the areas where the circuit layers are formed, copper clad laminates having different filler contents of the insulating film 510 can be disposed on one side and the other side of the composite material layer, respectively.

  Next, as illustrated in FIG. 6, the third circuit layer 1300 can be formed on the first insulating layer 110 by etching and patterning the copper foil layer 550 (see FIG. 5). In addition, a process for processing a via for electrically connecting the first circuit layer and the third circuit layer and filling the via with copper can be performed.

  Further, the fourth circuit layer 2400 can be formed on the second insulating layer 220 by stacking the copper-clad laminate 500 (see FIG. 5) also on the second circuit layer 2200. Thus, by laminating the copper-clad laminate a plurality of times, it is possible to form a printed circuit board composed of an insulating layer and a circuit layer that are symmetric or asymmetric with respect to the composite material layer.

  For example, the first and second circuit layers 1100 and 2200 are covered with first and second insulating layers 110 and 220. The first and second circuit layers 1100 and 2200 are connected to an electronic component or the like to transmit a signal, and predetermined heat is generated in the signal transmission process. The thermal energy is transmitted to the first insulating layer 110 and the second insulating layer 220. At this time, the thermal expansion coefficient and the heat transfer coefficient of copper used for the circuit layer may be different from the thermal expansion coefficient and the heat transfer coefficient of the insulating material used for the first and second insulating layers 110 and 220. Furthermore, since the circuit layer has a different volume and area, different thermal energy is generated, and the thermal energy is transmitted to the insulating layer.

  Conventionally, an insulating layer having the same thermal expansion coefficient is laminated around a composite material layer. Further, different thermal energy is transmitted to the insulating layer by the circuit layers having different formation areas. At this time, a phenomenon occurs in which the printed circuit board in which the insulating layers formed of the insulating material having the same coefficient of thermal expansion are stacked as described above is warped in either direction.

  Therefore, an insulating material having a large thermal expansion coefficient is used for an insulating layer that receives a large amount of thermal energy, and an insulating material having a small thermal expansion coefficient is used for an insulating layer that receives a small amount of thermal energy. It is possible to prevent the thermal expansion from being concentrated in any one direction around the layer 105, thereby preventing the warp of the printed circuit board.

  In order to adjust such thermal expansion, the thermal expansion coefficient can be adjusted by adjusting the amount of filler or organic / inorganic fiber according to the formation area of the circuit layer. For example, the formation area of the first circuit layer 1100 and the third circuit layer 1300, that is, the remaining copper ratio of the first insulating layer 110 is the remaining copper ratio of the second insulating layer (the second circuit layer 2200 and the fourth circuit layer 2400 In the case of being formed smaller than the formation area, the amount of filler in the first insulating layer 110 is adjusted, or the amount of filler in the second insulating layer 220 in contact with the second circuit layer 2200 and the fourth circuit layer 2400 is adjusted. can do.

  In other words, by adjusting the amount of filler in the first insulating layer 110 and the second insulating layer 220, the first insulating layer 110 and the second insulating layer 220 can have different thermal expansion coefficients.

  For example, when the first insulating layer 110 and the second insulating layer 220 have the same thermal expansion coefficient, that is, the filler amount, the formation area of the second circuit layer 2200 and the fourth circuit layer 2400 is the first and third circuits. When larger than the layers 1100 and 1300, a convex warpage may occur in the direction of the second insulating layer 220.

  At this time, the warpage of the printed circuit board 10 can be reduced by increasing the filler amount of the second insulating layer 220 or decreasing the filler amount of the first insulating layer 110. On the other hand, even when warping occurs, the warping of the printed circuit board 10 can be reduced by the method described above.

  Alternatively, since the first circuit layer 1100 and the second circuit layer 2200 can be formed with a predetermined circuit pattern, the amount of filler or organic / inorganic fiber can be adjusted accordingly.

  At this time, the filler content of the first and second insulating layers 110 and 220 may be 20 to 80% by weight, and by adjusting the content, the first insulating layer 110 and the second insulating layer 220 may be mutually connected. They can be formed to have different coefficients of thermal expansion. Moreover, the curvature of a printed circuit board can be reduced by adjusting the content of the organic / inorganic fiber 170 in the composite material layer 105.

  Next, as illustrated in FIG. 7, the copper clad laminate 500 (see FIG. 5) is repeatedly laminated on the first insulating layer 110 or the second insulating layer 220. By repeatedly laminating the copper-clad laminate in this way, a printed circuit board having a plurality of insulating layers and circuit layers can be formed.

  Therefore, the insulating layer includes a circuit layer on at least one surface, and can receive heat energy. Therefore, the degree of thermal expansion of the insulating layer differs depending on the exposed area and volume of the circuit layer, and the insulating layers have different thermal expansion coefficients.

  As described above, warping of the printed circuit board can be prevented by adjusting the filler content of the insulating layer to form insulating layers having different coefficients of thermal expansion.

(Experimental example)
In this experimental example, the warpage phenomenon was observed while adjusting the amount of the filler in order to observe the warpage occurrence characteristics due to the coefficient of thermal expansion of the composite material layer which is a polymer material used for the printed circuit board.

  First, with respect to the configuration of the printed circuit board, FIGS. 1 and 2 are cited in order to avoid redundant description.

  A composite material layer 105 is formed in the center of the printed circuit board 10. Here, the composite material layer 105 is for improving the modulus of the printed circuit board 10 and is a prepreg containing glass fibers. Such a composite material layer 105 may be a single layer or a multilayer. In addition, circuit layers are formed on both surfaces of the composite material layer 105, and an insulating layer is formed on the circuit layer. In this way, the circuit layers and the insulating layers are alternately stacked in order.

  As described above, the printed circuit board 10 can have a mirror-symmetric structure with the composite material layer 105 as the center.

  On the other hand, since each circuit layer is formed with a circuit pattern, it may be formed with different exposed areas and different exposed volumes.

  Table 1 shows the thickness of each layer of the printed circuit board 10 and the remaining copper ratio of the circuit layer. Here, the thickness is obtained by converting the ratio of the thickness of each layer to the total thickness of the printed circuit board 10 as a percentage. The amount (remaining copper ratio) is expressed as a percentage.

  Thus, since each circuit layer is comprised by a circuit pattern, a circuit layer can be formed in a mutually different exposure ratio (remaining copper ratio). Accordingly, different thermal energy is transmitted to the composite material layer and the insulating layer depending on the remaining copper ratio of the circuit layer.

(Comparative example)
In the comparative example, as in the experimental example, a printed circuit board is formed, the composite material layer and the insulating layer contain the same epoxy resin, the same content of liquid crystal oligomer, and the same content of organic / inorganic fiber or filler. Were mixed. At this time, regardless of the remaining copper ratio of the insulating layer, the amount of organic / inorganic fiber and filler was added in the same amount as 40% by weight to form a printed circuit board. Moreover, the same kind was used for the filler mixed with a composite material layer and an insulating layer.

Example 1
In Example 1, unlike the comparative example, the remaining copper ratio formed in the composite material layer and the insulating layer, that is, the amount of filler mixed in the composite material layer and the insulating layer according to the volume and area of copper. Was added after adjusting.

  As shown in Table 1, the remaining copper ratio of the first circuit layer is 39.8%, the remaining copper ratio of the third circuit layer is 43.4%, and it is between the first circuit layer and the third circuit layer. The intervening first insulating layer has a remaining copper ratio of 83.2%. The remaining copper ratio of the second circuit layer is 53.0%, the remaining copper ratio of the fourth circuit layer is 46.9%, and the second insulation interposed between the second circuit layer and the fourth circuit layer. The residual copper ratio of the layer is formed at 99.9%.

  Here, the first insulating layer with a low residual copper ratio was mixed with a filler content reduced by 20%, and the second insulating layer with a high residual copper ratio was mixed with a filler content increased by 30%. . In this way, different amounts of fillers were added to the first insulating layer and the second insulating layer formed with different residual copper ratios, and warpage due to thermal expansion was observed.

(Example 2)
In Example 2, unlike Example 1, the polymer of the composite material layer was impregnated with glass fiber, and the thermal expansion coefficient of the composite material layer was measured while adjusting the content of the glass fiber. Here, the composite material layer was formed into a single layer and two layers while adjusting the glass fiber content while maintaining the same polymer component and content and the same filler content and component. .

(Physical properties and analysis)
The warpage of the printed circuit board due to the coefficient of thermal expansion of the composite material layer and the insulating layer formed in Example 1, Example 2, and Comparative Example was measured. In order to measure the deformation rate of the printed circuit board due to warpage, an ASAME (Target Model & 2D Model) and GPA products are used, and the warp is calculated using the difference between the substrate position information before deformation and the substrate position information after deformation as deformation rate information. Observed.

  Table 2 is a table summarizing the presence or absence of warpage in Comparative Example, Example 1, and Example 2.

  As shown in Table 2, since the heat generation amount differs depending on the volume and area of the circuit layer, the heat transferred to the composite material layer disposed between the copper foil layers also differs, and the thermal expansion of the composite material layer Occur differently from each other.

  Therefore, as in the comparative example, although the same resin and the same filler are used for the volume and area of the circuit layer, the warpage caused by thermal expansion is different from each other, and the warpage of the printed circuit board may occur. .

  On the other hand, when the amount of filler and the amount of glass fiber are adjusted according to the volume and area of the circuit layer as in Example 1 and Example 2, the extent to which the filler discharges the heat transferred to the composite material layer. Since they are different, the upper and lower thermal expansions are symmetrical with each other, and warpage can be prevented.

  On the other hand, warpage can be prevented by adjusting the amount of organic / inorganic fibers added to the composite material layer to adjust the coefficient of thermal expansion to form composite material layers having different thermal expansion coefficients. Further, since a separate structure for preventing warpage is not necessary, it is possible to realize thinning and integration.

  As described above, the present invention has been described in detail based on the specific embodiments. However, the present invention is only for explaining the present invention, and the present invention is not limited thereto. It will be apparent to those skilled in the art that modifications and improvements within the technical idea of the present invention are possible.

  All simple variations and modifications of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be apparent from the appended claims.

  The present invention is applicable to a printed circuit board and a manufacturing method thereof.

10 Printed Circuit Board 105 Composite Material Layer 110 First Insulating Layer (Insulating Layer)
130 3rd insulating layer (insulating layer)
150 5th insulating layer (insulating layer)
170 Organic / inorganic fiber 180 Filler 220 Second insulating layer (insulating layer)
240 4th insulating layer (insulating layer)
260 6th insulating layer (insulating layer)
500 Copper-clad laminate 510 Insulating film 550 Copper foil layer 1100 First circuit layer (circuit layer)
1300 Third circuit layer (circuit layer)
2200 Second circuit layer (circuit layer)
2400 Fourth circuit layer (circuit layer)

Claims (19)

A composite layer having one side and the other side corresponding thereto;
A first insulating layer formed on one surface of the composite material layer;
A second insulating layer formed on the other surface of the composite material layer,
The printed circuit board, wherein the first insulating layer, the second insulating layer, and the composite material layer are formed to have different coefficients of thermal expansion. A first circuit layer formed between the first insulating layer and the composite material layer;
A second circuit layer formed between the second insulating layer and the composite material layer,
The printed circuit board according to claim 1, wherein the first circuit layer and the second circuit layer have different formation areas.   The printed circuit board according to claim 2, wherein the composite material layer or the first and second insulating layers are alternately and repeatedly stacked with the first and second circuit layers.   The printed circuit board according to claim 1, wherein the composite material layer includes an organic fiber or an inorganic fiber, a liquid crystal oligomer, an epoxy resin, and a filler.   The printed circuit board according to claim 1, wherein the first insulating layer and the second insulating layer include a liquid crystal oligomer, an epoxy resin, and a filler. The printed circuit board according to claim 4, wherein the liquid crystal oligomer is represented by the following chemical formula 1.

Here, a is an integer of 13 to 26, b is an integer of 13 to 26, c is an integer of 9 to 21, d is an integer of 10 to 30, and e is an integer of 10 to 30.   The printed circuit board according to claim 4, wherein the organic fiber or the inorganic fiber and the filler are contained in an amount of 20 to 80% by weight with respect to 100% by weight of the composite material layer.   5. The printed circuit board according to claim 4, wherein the content of the inorganic fiber or organic fiber is 5 to 25 wt% and the content of the filler is 5 to 75 wt% with respect to the total weight of the composite material layer. .   The inorganic fiber or organic fiber includes glass fiber, carbon fiber, polyparaphenylene benzobisoxazole fiber, thermotropic liquid crystal polymer fiber, lyotropic liquid crystal polymer fiber, aramid fiber, polypyridobisimidazole fiber, polybenzothiazole fiber, The printed circuit board according to claim 4, wherein the printed circuit board is one or more selected from polyarylate fibers.   The printed circuit board according to claim 9, wherein the glass fiber is any one selected from T-glass fiber, E-glass fiber, S-glass fiber, ceramic fiber, and a mixture thereof.   The printed circuit board according to claim 5, wherein the filler is included at 20 to 80 wt% with respect to 100 wt% of the first insulating layer or the second insulating layer.   The printed circuit board according to claim 4, wherein the filler is any one selected from the group consisting of an organic filler, an inorganic filler, and a combination thereof. The inorganic filler is silica (SiO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), barium sulfate (BaSO ₄ ), talc, mica powder, aluminum hydroxide (AlOH ₃ ), magnesium hydroxide (Mg) _{(OH) 2),} calcium carbonate (CaCO _3), magnesium carbonate (MgCO _3), magnesium oxide (MgO), boron nitride (BN), aluminum borate (alBO _3), barium titanate (BaTiO _3), lead zirconate acid The printed circuit board according to claim 12, which is any one of calcium (CaZrO ₃ ) and a combination thereof.   The printed circuit according to claim 12, wherein the organic filler is any one selected from the group consisting of epoxy resin powder, melamine resin powder, urea resin powder, benzoguanamine resin powder, styrene resin, and combinations thereof. substrate.   When the remaining copper ratio of the first circuit layer and the second circuit layer is increased in the range of 10 to 20%, the filler content of the first insulating layer, the second insulating layer, and the composite material layer is set to 1 to 10%. The printed circuit board according to claim 11, wherein the printed circuit board is adjusted within a range of weight%. Providing a composite layer having one side and the other side;
Forming a first circuit layer on one surface of the composite material layer and a second circuit layer on the other surface of the composite material layer;
Forming a third circuit layer on the first circuit layer, forming a first insulating layer between the first circuit layer and the third circuit layer;
Forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer,
Forming a filler content of the first insulating layer and a filler content of the second insulating layer different from each other;
When the residual copper ratio of the first insulating layer is higher than the residual copper ratio of the second insulating layer, printing is performed such that the filler content of the first insulating layer is greater than the filler content of the second insulating layer. A method of manufacturing a circuit board. Providing a composite layer having one side and the other side;
Forming a first circuit layer on one surface of the composite material layer and a second circuit layer on the other surface of the composite material layer;
Forming a third circuit layer on the first circuit layer, forming a first insulating layer between the first circuit layer and the third circuit layer;
Forming a fourth circuit layer on the second circuit layer, and forming a second insulating layer between the second circuit layer and the fourth circuit layer,
Forming a filler content of the first insulating layer and a filler content of the second insulating layer different from each other;
When the remaining copper ratio of the first insulating layer is higher than the remaining copper ratio of the second insulating layer, the filler is formed so that the filler content of the second insulating layer is less than the filler content of the first insulating layer. A method of manufacturing a circuit board.   When the remaining copper ratio of the first circuit layer and the second circuit layer is increased in the range of 10 to 20%, the filler content of the first insulating layer, the second insulating layer, and the composite material layer is set to 1 to 10%. The method for manufacturing a printed circuit board according to claim 16, wherein the printed circuit board is adjusted in a range of% by weight.   18. The method of manufacturing a printed circuit board according to claim 16, wherein the filler is contained in an amount of 20 to 80 wt% with respect to 100 wt% of the first insulating layer or the second insulating layer.

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