TW201422067A - Copper clad laminate and method for manufacturing the same - Google Patents

Abstract

A copper clad laminate is provided. Cyclic olefin copolymer fabrics function as one material of the laminated fabrics for manufacturing the copper clad laminate to reduce permittivity (Dk) and loss tangent (Df) of the copper clad laminate. The flame-retarded curing agent included in the resin for use in manufacturing the copper clad laminate is halogen-free and does not cause environmental pollution. The cyclic phosphate structure of the flame-retarded curing agent enhances thermal stability and chemical stability of the copper clad laminate thus manufactured. During the manufacturing process of the copper clad laminate, an annealing process is performed while thermal curing and lamination is taking place to prevent bending otherwise resulting from a difference in thermal expansion coefficient between cyclic olefin copolymer fabric and glass fiber fabric.

Description

Copper foil substrate and method of manufacturing same

The present invention relates to a copper foil substrate for a printed circuit board, and more particularly to a copper foil substrate having a cyclic olefin polymer fiber cloth and a method of manufacturing the same.

The new generation of consumer electronics will move toward light, thin, short, small and versatile. The printed circuit board (PCB) used in electronic products is also moving toward high density and high aggregation, and the requirements for electrical properties and flame retardancy of printed circuit boards are increasing.

The low dielectric constant is required for the electrical properties of printed circuit board materials. The main purpose is to shorten the transmission time of electronic signals in the material medium and to reduce mutual interference and loss of energy when electronic signals are transmitted.

Copper clad laminate (CCL) is the most important substrate for manufacturing printed circuit boards (PCBs). Substrate fabrication techniques vary depending on the material. At present, the world's highest market share is FR4 (DICY Cured) substrate, but the dielectric constant value of such substrates is between 4.3 and 4.8, and the dielectric constant value is too high, so the material characteristics are more Room for improvement.

Further, the resin materials applied to the substrate of the high-frequency printed circuit board are mainly PTFE (polytetrafluoroethylene) series resin and PPO (Poly phenyl oxide) series resin. Although the PTFE series resin has a very low dielectric constant value, the raw material price is extremely expensive and it is difficult to process and form, which results in a special and expensive substrate process. Therefore, the PTFE series substrate is basically applied to a special demand field of frequencies above 3 GHz, and utilizes PTFE. The printed circuit boards are used in precision instruments or high-priced electronic products, so they are not commonly used. GE, on the other hand, uses the printed circuit board substrate GETEK ^® manufactured by PPO, which has a dielectric constant of about 4.0 and relatively poor material properties.

Based on the shortcomings of the dielectric constant of the above-mentioned copper foil substrate, most of the conventional techniques improve the dielectric constant of the resin material, but most of the results are not satisfactory, and the dielectric constant of the copper foil substrate is not significantly reduced.

In addition, in the copper foil substrate of the prior art, the flame retardant contained in the resin is generally a bromide which is a halogen compound which pollutes the environment, and international organizations have strictly regulated the halogen content in the copper foil substrate, so There is an increasing demand for halogen-free flame retardants in the industry. Furthermore, alternative flame retardants are generally generally poor in thermal stability and chemical stability, making it difficult to effectively replace halogen flame retardants in the industry.

In view of the above-mentioned deficiencies of the prior art, it is an object of the present invention to disclose a copper foil substrate having an improved base fabric to solve the problem of excessive dielectric constant. In addition, the present invention also discloses a derivative of a phosphorus-containing flame retardant to avoid contamination of the halide, and at the same time utilize the cyclic phosphate structure in the derivative of the phosphorus-containing flame retardant to improve the thermal stability of the flame retardant. Sexual and chemical stability.

In order to achieve the above object, the present invention provides a copper foil substrate, which comprises And comprising: a plurality of films, wherein each of the plurality of films is stacked in a layered manner from bottom to top, and each of the films is formed by coating a base fabric with a resin, and the base fabric may be a cyclic olefin polymer ( COC) a fiber cloth or a glass fiber cloth, and the base fabric of at least one of the plurality of films is a COC fiber cloth; and a copper foil pressed onto the plurality of films.

In an embodiment of the invention, the base fabric of the top layer of the plurality of films of the copper foil substrate and the base fabric of the bottom layer are COC fiber cloth.

Furthermore, in another embodiment of the present invention, the base fabric of each of the plurality of film layers of the copper foil substrate is a COC fiber cloth.

In an embodiment of the present invention, the resin of the copper foil substrate may comprise a group consisting of a flame resistant hardener selected from the following formulas (1) to (3):

In addition, another object of the present invention is to provide a method for manufacturing a copper foil substrate, comprising the steps of: providing a resin and a plurality of base fabrics, wherein each of the plurality of base fabrics can be a COC fiber cloth or a glass fiber cloth. And the plurality of base fabrics comprise at least one COC fiber cloth; the plurality of base fabrics are impregnated in the resin; the plurality of base fabrics impregnated with the resin are dried to form a plurality of prepreg films; and the plurality of prepregs are prepreg Each of the film's prepreg is from bottom to top The layers are stacked in layers, and a copper foil is stacked on the plurality of prepreg films and then thermohardened and pressed to form a copper foil substrate.

In an embodiment of the invention, the base fabric of the top layer of the plurality of films of the copper foil substrate and the base fabric of the bottom layer are COC fiber cloth.

Furthermore, in another embodiment of the present invention, the base fabric of each of the plurality of film layers of the copper foil substrate is a COC fiber cloth.

Furthermore, in the embodiment of the present invention, when the copper foil and the plurality of prepreg films are subjected to thermosetting and pressing, an annealing process is further performed.

According to the annealing procedure described above, the copper foil substrate using the COC fiber cloth and the glass fiber cloth as the base fabric can be prevented from being thermally expanded, thereby maintaining the horizontal height of the substrate center point and the edge.

Further, in the annealing process described above, the annealing temperature may be between 90 ° C and 150 ° C, and the annealing process is performed for at least 30 minutes.

Further, in the embodiment of the present invention, the press curing temperature of the above thermosetting press may be from 175 ° C to 200 ° C.

In summary, the copper foil substrate produced by the above manufacturing method replaces the base fabric of the glass fiber by the base fabric made of the COC fiber cloth to reduce the dielectric constant and the electron escape rate of the copper foil substrate. The value of the property, where the dielectric constant value is as low as 2.5, and the electronic tangent loss value is as low as 0.0004. At the same time, since the dielectric constant value is obtained by testing the surface resistance value, and the electronic tangential loss value is obtained by testing the overall electron emission rate, the COC fiber is disposed on the top and bottom layers of the copper foil substrate. The aspect can significantly reduce the dielectric constant value, and the higher the content of the COC fiber cloth on the overall copper foil substrate, the more the electronic tangent loss value can be low.

In addition, since the flame-retardant hardeners of the formulas (1) to (3) synthesized by the present invention are phosphide and do not contain halogen, it is possible to avoid environmental pollution during use or recycling, and at the same time, with such flame resistance The cyclic molecular structure of the hardener makes it more stable and chemically stable than the generally uncyclic phosphate. In addition, it has been found that the flame resistant hardener can achieve a UL-94 V0 flame resistance standard by adding an appropriate ratio to the resin.

To fully clarify the objects, features, and advantages of the present invention, those of ordinary skill in the art of the invention can understand the invention and practice the invention. Schematic, a detailed description of the present invention, illustrated as follows:

definition

In this document, "a" is used to describe the elements and components of the invention. This usage is provided for convenience only, and is intended to be inclusive of the generality of the invention.

Where a quantity, a concentration, or other value or parameter is expressed by a range, a preferred range, or a series of upper and lower limits, it is understood to be a specific disclosure of the upper or lower value of any range or the lower limit of any range or All ranges of preferred values are constructed regardless of whether such ranges are disclosed separately. In addition, when the range of values is mentioned in this document, unless otherwise stated, It should include its endpoints and all integers and fractions within the range.

In the present invention, before the object can be attained, the numerical value should be understood as having the accuracy of the number of significant digits. For example, the number 40 should be understood to cover the range from 35.0 to 44.9, while the number 40.0 should be understood to cover the range from 39.50 to 40.49.

raw material

Changchun epoxy resin (Epoxy Resin, product model: CNE-200ELF and BE501, purchased from CHANG CHUN PLASTICS O., LTD.), hardener is dicyandiamide (Dicy, dicyandiamide), flame retardant is 9,10-two Hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and the solvent is dimethylformamide (DMF, dimethylformamide) ). The above-mentioned raw materials can be directly purchased from commercially available products, and can be directly used without purification.

Flame retardant

In an embodiment of the present invention, a halogen-free flame retardant hardener is provided which has better thermal stability and chemical stability and which simultaneously provides flame resistance and hardening function.

The flame-resistant hardener was stirred and reacted with DOPO and Dicy at 100 ° C to 140 ° C for 6 hours, followed by cooling to room temperature, and finally a translucent brownish yellow solid was obtained.

The chemical structure of the compound contained in the flame resistant cured product (DOPO-Dicy) obtained by the reaction is as shown in the following formulas (1) to (3):

Since the guanamine group in the flame retardant (DOPO-Dicy) has high water absorption, it is easy to absorb water when placed in an atmosphere, and the higher the moisture content of the flame retardant (DOPO-Dicy) causes the subsequent pressed copper foil substrate. When the flame-retardant (DOPO-Dicy) and the epoxy resin are not hardly reacted, the flame-resistant hardener (DOPO-Dicy) needs to be dried to have a water content of 800 ppm or less.

Fiber cloth

In an embodiment of the present invention, the base fabric used for the copper foil substrate comprises a cyclic olefin copolymer (COC) fiber cloth which is entangled with COC fibers by using polyvinyl alcohol (PVA) fibers. To form a core-spun yarn, and then to make a plain weave fabric by warping and wefting, the warp and weft density is 50×37/in., and the cloth thickness is 0.2 mm, and then the hot water is 80°C. After the water washing treatment for 30 minutes, the PVA fiber was removed to obtain a COC fiber cloth.

The warp yarn and the weft yarn of the COC fiber cloth are composed of COC fibers, and the COC fiber cloth also has a low dielectric constant due to the low dielectric constant property of the COC fiber.

Copper foil substrate and its process [copper foil substrate]

Referring to FIG. 1, a copper foil substrate 1 of the present invention comprises a plurality of films 12 and a copper foil 11 disposed on the films 12, wherein the films 12 are stacked in layers, and each of the films 12 is composed of Resin and base fabric are formed. In the base fabric used in the film 12, it may comprise both COC fiber cloth and glass fiber cloth, or all of them are COC fiber cloth. Furthermore, the number of the above films may be, but not limited to, 4 to 12 pieces.

Referring to FIGS. 2 to 6 , each of the drawings sequentially shows a stacking manner of the copper foil substrates of Embodiments 1 to 5 of the present invention, and each of the copper foil substrates includes seven sheets of film. In Fig. 2, the top and bottom layers of the copper foil substrate 2 are film 221 formed of COC fiber cloth, and the middle five layers are films 222 formed of glass fiber cloth. In Fig. 3, the top and bottom layers of the copper foil substrate 3 are films 322 formed of glass fiber cloth, and the middle five layers are films 321 formed of COC fiber cloth. In Figures 4 and 5, the film formed by the COC fiber cloth is alternately stacked with the film system formed of the glass fiber cloth, wherein the top and bottom layers of Figure 4 are films formed by COC fiber cloth 421. The top and bottom layers of Figure 5 are films 522 formed of fiberglass cloth. In Fig. 6, the film of the copper foil substrate 6 is a film 621 formed of a COC fiber cloth.

In addition, in comparison with the copper foil substrate of the embodiment, the present invention further provides a copper foil substrate of a comparative example, wherein the base fabric is a glass fiber cloth, and other materials and stacked structures are the same as the embodiment, and the glass fiber cloth is Commercially available electronic grade product (product number 7628), warp and weft density is 44×33 roots/in., cloth thickness is 0.18 Mm.

[Process Description]

In the process of the copper foil substrate, the resin used in the examples and the comparative examples of the present invention is a mixture of a plurality of components, and the ratio of the composition of the different resins is used to control the degree of hardening by using a suitable ratio of components. Table 1 shows the blending ratio of the resin. In the test, the platen conditions of the copper foil substrate were fixed at a hot pressing pressure: 20 kg/cm ² , a hot pressing temperature: 185 ° C, and a hot pressing time: 2 hours to find the optimum number of greases. formula.

Among them, CNE-200 is a product type of epoxy resin, which is soluble in acetone, 70% solid content, which can be purchased from general commercial sources; 2-MI stands for 2-methyl imidazole, which is The hardening accelerator is used in an amount of 0.05 PHR; DOPO-Dicy represents the flame retardant of the present invention; and DMF represents dimethylformamide.

According to the copper foil substrate pressing process, the optimum hardening time is 180 seconds. It is known from Table 1 that the gelation time of the formulation 1 is closest to 180 seconds, so the resin formulation for pressing the copper foil substrate is Formulation 1.

Next, the process of the copper foil substrate is performed, and the flame retardant (DOPO-Dicy) is dissolved in the DMF according to the composition ratio of the formula 1, and then mixed with the epoxy resin and the filler, and then adjusted to the appropriate with acetone. Viscosity, forming a raw glue (Varnish), confirm the gelation time on a hot plate at 170 ° C, and set 2/3 of the gelation time as the impregnation time. The raw glue was impregnated at room temperature with a base cloth, and then dried at 165 ° C in a hot air circulating bellows to prepare a prepreg. Finally, 7 pieces of prepreg were laminated with 1 oz of copper foil, and heat-hardened at 185 ° C. The hot pressing pressure was 20 kg/cm ² , and the temperature rising process was carried out in stages, firstly by 35 ° C. The temperature was raised for 11 minutes, maintained at 85 ° C for 20 minutes, and then after 45 minutes of temperature separation, reached 185 ° C for 120 minutes to complete the thermosetting press-fitting procedure.

It should be understood that in other equivalent embodiments of the invention, the temperature of the thermosetting press can be between 175 ° C and 200 ° C.

After the thermosetting press-fitting process is completed, since the COC fiber cloth and the glass fiber cloth have different thermal expansion rates, the copper foil substrates of Examples 1 to 4 including the two base cloths are subjected to thermosetting and pressing. The copper foil substrate is warped, and the horizontal difference between the center point and the edge of the substrate exceeds 3 mm. On the other hand, in the copper foil substrate of Example 5, since the base fabric was a COC fiber cloth, no warping occurred.

Therefore, with respect to the copper foil substrates of Examples 1 to 4, after the temperature of the thermosetting press-bonding reaches 185 ° C, an annealing procedure is further performed, that is, after the above-described temperature rising process, the temperature is lowered. Thermal hardening press-fit procedure. The following Table 2 series shows the difference in level between the center point and the edge of the substrate of Examples 1 to 4 after 30 minutes at different annealing temperatures.

The data in Table 2 shows that when the annealing temperature is heated above 100 ° C, only the copper foil substrate of Example 1 reaches the flat standard, and the copper foil substrate of the other embodiments still has a rocker, when the tempering temperature reaches 120 ° C. The copper foil substrates of Examples 1 to 4 were all flat, and the difference in level between the center point and the edge of the substrate was 0 mm. Observing the results of Table 2, it is known that the copper foil substrate including the COC fiber cloth and the glass fiber cloth preferably needs to increase the annealing temperature of 120 ° C for 30 minutes, and the level difference of the copper foil substrate can reach the level of flatness.

It should be noted that the annealing temperature varies depending on the number and manner of stacking the film of the copper foil substrate. Therefore, in other equivalent embodiments of the present invention, the annealing temperature may be between 90 ° C and 150 ° C. The time required for annealing can be adjusted corresponding to the annealing temperature.

Flame resistance measurement

In the flame resistance measurement of the copper foil substrate of the present invention, the flame resistance rating of the copper foil substrate is determined by the UL-94 standard.

The invention introduces the DOPO derivative (DOPO-Dicy) as a hardener into the epoxy resin, can simultaneously improve the flame retardancy and thermal stability of the epoxy resin, and more importantly, avoids the use of the brominated epoxy resin. And recycled The process pollutes the environment.

Due to the reduced crosslink density of the cured oxygen resin after the addition of the phosphorus ring-containing fuel, the Td is reduced, but both are much higher than 300 ° C, which can meet the demand for the heat stability of the copper foil substrate (>288 °C). The phosphorus-containing group in the resin during heating generates a phosphorus-containing residue, which contributes to improving the flame resistance of the substrate.

Table 4 below shows the flame retardant data measured by the copper foil substrates of the respective examples made of different phosphorus-containing resins, so that those skilled in the art to which the present invention pertains can understand the flame-retardant hardeners of the present invention. Flame retardant properties and support for achieving the desired flame retardant effect on copper foil substrates.

As can be seen from the data in Table 4, when the phosphorus content exceeds 13,000 ppm, the substrate made of pure COC fiber cloth (Example 5) has a flame retardancy level of UL-94 V0. Please cooperate with the structure of Fig. 2 to Fig. 5, from the stacking method of glass fiber cloth and COC fiber cloth in the figure and the data of Table 4, it can be found that when the COC fiber cloth is coated on the outer layer of the substrate, the required phosphorus is required. The amount is much higher than the amount of phosphorus contained in the outer layer of the glass fiber cloth, even when the proportion of the COC fiber cloth in the copper foil substrate is more than 50%. The reason is that the phosphorus-containing group in the phosphorus-containing epoxy resin helps to improve the degradation temperature after degradation. The carbonized material is coated on the outside of the substrate to form a flame-retardant layer, thereby providing a flame retardant effect.

Measurement and comparison of electrical properties of copper foil substrates

In the physical property measurement of the present invention, the electrical characteristics of the copper foil substrate were measured using a dielectric meter for the copper foil substrate property test.

Since COC fiber cloth has a low dielectric constant (D _k, dielectric constant) values of about 2.3 and lower electron loss tangent (D _f, loss tangent) value of about 0.00007, the present invention is directed to glass fiber based fabrics and COC Different stacking combinations of fiber cloths were used to measure electrical properties.

Table 3 below shows the electrical property analysis data of the copper foil substrates of the above-described Examples 1 to 5 and Comparative Examples.

The dielectric constant of Table 3 was measured according to the test standard method of IPC-TM-650, and the dielectric constant of the copper foil substrate of Example 5 was lower than that of the copper foil substrate of the comparative example from 1 MHz to 5 GHz. Constant, whose data differs by a maximum of 2.1. It can also be found in the data in Table 3 that the COC fiber cloth has a lower dielectric constant as the base fabric of the top and bottom layers of the copper foil substrate, as in Example 1 (as shown in Figure 2) and Example 3 (e.g. The structure shown in Fig. 4, so as long as the base fabric of the top and bottom layers of the substrate is COC fiber cloth, the copper foil substrate can be effectively reduced. The dielectric constant, that is, the dielectric constant of the copper foil substrate is correlated with the distribution position of the base fabric using the COC fiber cloth on the copper foil substrate, and the dielectric constant of the copper foil substrate and the COC fiber are disposed in the copper foil substrate. There is no absolute relationship between the proportion.

Furthermore, according to the electronic tangential loss data of the copper foil substrate of Table 3, it is also known that the copper etched substrate of Example 5 has the lowest electron tangential loss value and is more pronounced at a high frequency portion, and the lowest value is 0.0004. Significantly lower than the electronic tangent loss value (0.035) of the comparative example; it should be noted that the electronic tangential loss of the copper foil substrate has a greater influence on the proportion of the COC fiber cloth in the substrate, and the data of Table 3 can be It was observed that at a frequency of 5 GHz, the copper foil substrate made of pure COC fiber cloth (Example 5) had the lowest electron tangential loss (0.0004), followed by the structure of Example 2 (as shown in Fig. 3). Next, the structure of Example 3 (as shown in Fig. 4), the worst case of a copper foil substrate made of pure glass fiber cloth (comparative example), has an electron tangent loss of up to 0.035.

In summary, the dielectric constant of the copper foil substrate is determined by the relative position of the COC fiber cloth using the base fabric; however, the electronic tangential loss of the copper foil substrate is determined by the proportion of the COC fiber cloth in the substrate. .

Accordingly, the invention has been described herein in terms of the preferred embodiments of the present invention, and it should be understood that this invention is not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of protection of the present invention is defined by the scope of the patent application.

1, 2, 3, 4, 5, 6‧‧‧ copper foil substrates

11, 21, 31, 41, 51, 61‧‧‧ copper foil

12‧‧‧ Film

Film formed by 221, 321, 421, 521, 621‧‧‧COC fiber cloth

Film formed by 222, 322, 422, 522‧‧ ‧ glass fiber cloth

Fig. 1 is a schematic view showing the stacking structure of a copper foil substrate of the present invention.

2 is a schematic view showing a stacked structure of a copper foil substrate according to Embodiment 1 of the present invention.

3 is a schematic view showing a stacking structure of a copper foil substrate according to Embodiment 2 of the present invention.

4 is a schematic view showing a stacking structure of a copper foil substrate according to Embodiment 3 of the present invention.

Fig. 5 is a schematic view showing the stacking structure of a copper foil substrate according to Embodiment 4 of the present invention.

Fig. 6 is a schematic view showing the stacking structure of a copper foil substrate according to Embodiment 5 of the present invention.

1‧‧‧ copper foil substrate

11‧‧‧ copper foil

12‧‧‧ Film

Claims (10)

A copper foil substrate comprising: a plurality of films, wherein each of the plurality of films is stacked in a layered manner from bottom to top, and each of the films is formed by coating a base fabric with a resin, and the base fabric can be a ring An olefin polymer (COC) fiber cloth or a glass fiber cloth, and the base fabric of at least one of the plurality of films is a COC fiber cloth; and a copper foil pressed onto the plurality of films. The copper foil substrate according to claim 1, wherein the base fabric of the top layer of the plurality of films and the base fabric of the bottom layer are COC fiber cloth. The copper foil substrate according to claim 1, wherein the base fabric of each of the plurality of film layers is a COC fiber cloth. The copper foil substrate according to any one of claims 1 to 3, wherein the resin comprises a group consisting of a flame retardant hardener selected from the following formulas (1) to (3): A method for manufacturing a copper foil substrate, comprising the steps of: providing a resin and a plurality of base fabrics, wherein each of the plurality of base fabrics is Is a COC fiber cloth or a glass fiber cloth, and the plurality of base cloths comprise at least one COC fiber cloth; the plurality of base cloths are impregnated in the resin; and the plurality of base cloths impregnated with the resin are dried to form a plurality of prepregs a film; and stacking the prepreg films of the plurality of prepreg films in a layered manner from bottom to top, and then stacking a copper foil on the plurality of prepreg films, followed by thermosetting and pressing to form a copper foil substrate . The copper foil substrate according to claim 5, wherein the base fabric of the top layer of the plurality of prepreg films and the base fabric of the bottom layer are COC fiber cloth. The copper foil substrate according to claim 5, wherein the base fabric of each of the plurality of prepreg films is a COC fiber cloth. The manufacturing method according to claim 5, wherein when the copper foil and the plurality of prepreg films are thermohardened and pressed, an annealing process is further performed. The manufacturing method of claim 8, wherein the annealing process has an annealing temperature of from 90 ° C to 150 ° C, and the annealing process is performed for at least 30 minutes. The manufacturing method according to any one of claims 5 to 9, wherein the press-cure temperature of the thermosetting press is between 175 ° C and 200 ° C.