KR100359679B1 - Laminated paper - Google Patents

Abstract

The present invention provides a laminate base material excellent in Ag migration inhibitory and dimensional stability. It is claimed herein a laminate base material using hardwood kraft pulp having a cation absorption capacity of 5.0 meq or less per 100 g of pulp, a residual chlorine ion concentration of 100 ppm or less, and a fiber bending degree of 15 or less, if necessary.

Description

Laminated paper

The present invention relates to a laminate base stock which provides a laminate having excellent electrical properties, in particular Ag mobility (silver resistance) and excellent dimensional stability.

Laminate base paper is processed with phenol resin, polyester resin, etc. and is mainly used for printed circuit board. In recent years, as the multifunctionality and densification of electronic machines have increased, holes through copper plating and holes through silver paste have increased, so that high reliability is required even for laminated boards using paper substrates. In particular, there is a need for laminate base paper that is excellent in terms of silver mobility and dimensional stability.

As a method of manufacturing a laminate for solving the above problems, a method of reducing the residual ion concentration in the laminate [Japanese Patent Application Laid-Open Nos. Hei 3-164242 and Hei 3-138151] and a lamination base paper Although a method of reducing residual ion concentration in the genus (Japanese Patent Laid-Open No. 62-191597) is known, a sufficiently satisfactory result has not been achieved. In particular, even when the cation is sufficiently removed by washing or the like in the papermaking process, as long as the adsorption site exists, there is a fear of attracting metal ions in the manufacturing and converting process of the laminate.

In addition, in the improved paper substrate, Ag mobility resistance has been improved by using softwood in which sulfite pulp, linter and the like are dissolved. However, the fiber length of these pulp is long and the bending of the fiber is severe, which causes a problem that adversely affects the dimensional stability of the laminate.

The problem to be solved by the present invention is to determine the allowable range of the cation adsorption capacity of the laminate base paper, and, if necessary, the allowable range of the chlorine ion concentration, both of which are considered to be particularly related to Ag mobility in the electrical properties of the laminate. It also includes defining the acceptable range of morphological features of the pulp fibers that do not impair the dimensional stability of the laminate when the above conditions are met.

The present invention provides a laminated sheet paper and a method of manufacturing the same for providing a laminated sheet excellent in electrical properties and dimensional stability by clearly defining the above acceptable range.

Of the electrical properties of the laminate, in particular, the fact that Ag mobility is closely related to the cation adsorption capacity and the residual chlorine ion concentration indicates that, according to the present invention, the cation adsorption capacity is set to 5.0 meq or less per 100 g of pulp. It has been found that the objective can be effectively achieved by suppressing the chloride ion concentration to 100 ppm or less.

The ion bonding capacity mentioned above indicates the ability to adsorb metal ions such as sodium, potassium, calhum, magnesium and iron to cation adsorption groups such as carboxyl groups and sulfonyl groups in the pulp. Therefore, it is desirable that the cation adsorption capacity be as close as possible to 100 eq per 100 g of pulp. The lower limit is not particularly limited but is practically about 0.01 meq per 100 g of pulp.

Moreover, even when the cation content can be suppressed low in the papermaking process, as long as the cation adsorption capacity is present, there is a possibility that the cations are resorbed in the manufacturing process and the conversion process of the laminate. In particular, in the case of the Ag-resistant laminated plate, the base paper is mainly treated with a water-soluble phenol resin (Japanese Patent Application Laid-Open No. Hei 4-168043), and therefore, the characteristics regarding the cation adsorption capacity are important.

When Na ⁺ in the adsorption group is adsorbed in an amount of 5.0 meq per 100 g of pulp, it corresponds to 120 ppm in content per pulp, and by smaller than this, the Ag mobility is significantly improved. In addition, when the value exceeds 5.0 meq per 100 g of pulp, Ag mobility is significantly reduced, and excellent electrical properties cannot be obtained.

As a method for measuring the cation adsorption capacity, a method for measuring a carboxyl residue and a method for measuring a sulfonyl residue are known.However, almost all cation adsorption capacity can be comprehensively measured using a method for measuring a carboxyl residue proposed in the Tappi standard method. It is believed to be present.

Ionic adsorption groups tend to increase with increasing residual lignin due to increased sulfonyl groups. In the present invention, unbleached pulp having a K value of 10 or less, which can be obtained by cooking for a longer time, is used. In addition, in the preparation of such pulp, if the cooking temperature is too high, amorphous cellulose increases, which increases the possibility that carboxyl groups are produced in the bleaching process. In the present invention, it is possible to prepare the desired pulp by performing cooking by adding a larger amount of chemical at a lower temperature.

The production of carboxyl groups in the bleaching process occurs in the oxygen stage, the hydrogen peroxide stage, the sodium hypochlorite stage and the like, and is particularly effectively inhibited by controlling the sodium hypochlorite stage.

Chlorine ions are thought to adversely affect Ag mobility by promoting the ionization of Ag. Therefore, it is desirable that the concentration of chlorine ions be as close as possible to 0 ppm. The lower limit is not particularly limited, but is about 0.01 ppm in practical terms.

In the present invention, by using a chlorine-free bleaching such as oxygen bleaching, ozone bleaching, alkali / hydrogen peroxide bleaching and microbial bleaching or low chlorine bleaching slightly mixed, the concentration of residual chlorine ions in the base plate of the laminate is reduced to 100 ppm or less. Significantly improves mobility. In addition, when the value exceeds 100 ppm, Ag mobility is significantly reduced and excellent electrical properties cannot be obtained.

Laminates with excellent Ag mobility are usually used to provide high density printed circuits, and thus the laminate base used here must also have a high degree of dimensional stability. It is known that when the degree of curvature of the pulp fibers is 15 or more, the dimensional stability of the laminate is severely impaired (Japanese Patent Laid-Open No. 2-175996). Therefore, in the present invention, the object was achieved by improving the cooking conditions and the bleaching conditions to produce a laminate paper having excellent dimensional stability having a degree of bending of 15 or less. In addition, although the lower limit of the degree of curvature is not particularly limited, it is about 0.1 in reality.

This time, wood raw materials were examined to easily produce the above pulp. Comparing various wood species such as acacia, mangrove, apitong and eucalyptus wood in Japan, Eucalyptus wood was effective in providing laminates with excellent electrical properties and dimensional stability. In particular, when using eucalyptus grandis, eucalyptus camdulensis and eucalyptus salini (E. saligna), their lower lignin content and also lower molecular weight can easily increase cooking. And the lower hemicellulose content, it is possible to produce laminate paper with reduced cation adsorption capacity.

According to the present invention, Ag mobility and dimensional stability of the laminate are improved. Since the cation exchange group is reduced and, if necessary, residual chlorine ions are also reduced, no movement of ions occurs even when an applied voltage is applied under warm heating conditions. Moreover, since the straight fiber which has a bending degree of 15 or less is used, it is also excellent in dimensional stability.

Example

Next, the effect of this invention is shown based on an Example. However, the present invention is not limited to these examples.

Example 1

Using a South African eucalyptus chip, as shown in Table 1, kraft cooking was carried out under a temperature condition lower than that of Comparative Example 1 and a condition in which a large amount of chemical was added, so that unbleached pulp having a K value of 8 ( UKP) is obtained. The UKP is low chlorine bleached with oxygen, alkali / hydrogen peroxide and chlorine dioxide to give bleached kraft pulp (BKP). Using this BKP, a handsheet of laminated sheet paper having a basis weight of 135 g / m ² and a density of 0.5 g / cm ³ is obtained. Alcohol-soluble phenolic resins marketed in the handsheet of the base paper [trade name: BLS-3122, manufacturer; Showa Highpolymer Co., Ltd.] is impregnated and dried to prepare a prepreg. Then, the adhesive-added copper foil is placed on both sides of the eight laminated prepregs, which are heated under pressure at 155 ° C., 100 kg / cm ² and 60 minutes. After cooling for 30 minutes as it is under pressure, a double-sided copper plated laminate having a resin content of 50% and a plate thickness of 1.6 mm is obtained.

Table 1 shows the properties of the laminate and the laminate obtained in this way. As demonstrated in Table 1, Ag mobility is improved while maintaining dimensional stability.

Example 2

Using Hokkaido hardwood chips, as shown in Table 1, kraft cooking was carried out at a temperature lower than the conditions of Comparative Example 3 to obtain unbleached pulp (UKP) having a K value of 10. The UKP is multistage bleached with oxygen, alkali / hydrogen peroxide and chlorine dioxide to give bleached kraft pulp (BKP). The BKP was used to obtain a laminate similar to Example 1.

Table 1 shows the properties of the laminate and the laminate obtained by the above method. As demonstrated in Table 1, Ag mobility is improved while maintaining dimensional stability.

Comparative Example 1

Using a South African eucalyptus chip, as shown in Table 1, kraft cooking was carried out at a temperature higher than the conditions of Example 1 and under the condition of adding a small amount of chemical, and the unbleached pulp (UKP) having a K value of 8 was used. To obtain. The UKP is low chlorine bleached with oxygen, alkali / hydrogen peroxide and chlorine dioxide to obtain bleached kraft pulp (BKP). The BKP was used to obtain a laminate similar to Example 1.

Table 1 shows the properties of the laminate and the laminate obtained by the above method. As demonstrated in Table 1, Ag mobility is insufficient compared to Examples 1 and 2 due to the increased cation adsorption capacity.

Comparative Example 2

Using a Fukkaido hardwood chip, as shown in Table 1, kraft cooking was carried out under the condition of adding a smaller amount of chemical than the condition of Example 2 to obtain unbleached pulp (UKP) having a K value of 13. The UKP is multistage bleached with oxygen, chlorine, alkali, sodium hypochlorite and chlorine dioxide to give bleached kraft pulp (BKP). The BKP was used to obtain a laminate similar to Example 1.

Table 1 shows the properties of the laminate and the laminate obtained by the above method. As demonstrated in Table 1, Ag mobility is insufficient due to increased cation exchange capacity and residual chlorine ion concentration compared to Examples 1 and 2.

Comparative Example 3

Using Fukkaido hardwood chips, as shown in Table 1, kraft cooking was carried out under similar conditions as in Example 1, except that the heavy sea temperature was higher than that in Example 1. Bleached pulp (UKP) is obtained. The UKP is low chlorine bleached with oxygen, alkali / hydrogen peroxide and chlorine oxide to give bleached graft pulp (BKP). The BKP was used to obtain a laminate similar to Example 1.

Table 1 shows the properties of the laminate and the laminate obtained by the above method. As demonstrated in Table 1, Ag mobility and dimensional stability are insufficient due to increased cation exchange capacity and curved fibers compared to Examples 1 and 2.

Table 1

* 1 Effective alkali addition rate: Alkaline addition rate based on the pulp converted into NaOH + 1 / 2Na ₂ S

* 2 O ₂ step: Oxygen bleaching is performed for 60 minutes at 100 ° C and 10% pulp concentration.

* 3 C step: Chlorine bleaching is carried out for 30 minutes at 50 ° C and 3% pulp concentration.

* 4 E / P step: Alkaline / hydrogen peroxide bleaching is carried out at 60 ° C. and 10% pulp concentration for 60 minutes.

* 5 H step: Sodium hypochlorite bleaching is performed for 60 minutes at 45 ° C and 10% pulp concentration.

Step 6 D: Chlorine dioxide bleaching is performed at 75 ° C. and 10% pulp concentration for 120 minutes.

* 7 Cation adsorption capacity: The cation adsorption capacity is measured according to the carboxyl residue measuring method (Tapi standard method T237om-83).

* 8 The degree of bending of the fiber: Defibering the base paper and then expanding the randomly sampled fiber to obtain the straight length (L _s ) pulled between the actual length of the fiber (L _t ) and both ends of the long axis of the fiber. All fibers appearing are measured and calculated according to the following equation.

* 9 Thermal expansion coefficient and thermal contraction coefficient: using a tensile load type thermal expansion system, the expansion from 50 ° C to 150 ° C, the contraction at 150 ° C and the contraction from 150 ° C to 50 ° C at 10 g load and 5 ° C / min It is measured by cooling at room temperature.

* 10 Ag mobility: A comb-shaped test pattern (circuit width: 1.0mm) is printed on the surface of the laminate using silver paste, and the applied voltage of 50V is positive in 50 ° C and 95% humidity environment. It is applied to the electrode and the time (hr) until a short circuit occurs is measured.

As demonstrated from Table 1, the Ag mobility of the double-sided copper plated laminated sheet using the base paper according to the present invention shown in Examples 1 and 2 in which specific cooking and bleaching conditions were set is excellent. Moreover, the dimensional stability of the base paper is also excellent. Therefore, it has an important industrial significance.

Claims (3)

Laminate base stock using hardwood kraft pulp having a cation adsorption capacity of 0.01 to 5.0 meq per 100 g of pulp. The laminated sheet paper according to claim 1, wherein the concentration range of residual chlorine ions in the bleached hardwood kraft pulp is 0.01 to 100 ppm. The laminate paper according to claim 1 or 2, wherein the curvature range of hardwood kraft pulp fibers is 0.1 to 15.