JP2764536B2 - Base paper for laminated board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a base paper for a laminate for providing a laminate having good migration suitability and excellent dimensional stability.

[0002]

2. Description of the Related Art A base paper for a laminate is processed with a phenol resin, a polyester resin or the like, and is mainly used as a printed circuit wiring board. In recent years, with the increase in functions and densification of electronic devices, the use of copper plated through-holes and silver paste through-holes has advanced, and high reliability is also required for laminated boards using paper base materials. In particular, a laminate base paper excellent in silver migration resistance and dimensional stability is required.

[0003] As a method of manufacturing a laminated board to solve the above problems, a method of reducing the residual ion concentration in the laminated board (JP-A-3-164242 and JP-A-3-138151), For reducing the residual ion concentration of methane (JP-A-62-19159)
No. 7) is known, but no satisfactory results have been obtained. In particular, even if cations are sufficiently removed by washing or the like in the paper making process, there is a concern that metal ions may be taken in the production and processing steps of the laminate as long as there are adsorption sites.

[0004] In addition, NDSP,
By using a linter or the like, the Ag migration resistance suitability is improved. However, since the fibers of these pulp have a long fiber length and are extremely bent, there is a problem that the dimensional stability of the laminate is adversely affected.

[0005]

The problem to be solved by the present invention is that the electrical properties of the laminate, especially the cations of the cations of the laminate base paper, which are considered to be related to the suitability for Ag migration resistance. The purpose is to determine the allowable range of the adsorption capacity and, if necessary, the allowable range of the chloride ion concentration. Another object of the present invention is to determine the allowable range of the morphological characteristics of the pulp fiber so as not to impair the dimensional stability of the laminate when satisfying this condition.

[0006] The present invention is a base paper for laminated sheets and a method for producing the same, which aims to provide a laminated sheet having excellent electrical characteristics and dimensional stability by clarifying the above-mentioned allowable limits.

[0007]

SUMMARY OF THE INVENTION The present invention focuses on the fact that, among the electrical properties of a laminated plate, the suitability for Ag migration resistance is closely related to the cation adsorption capacity and the residual chlorine ion concentration. , Cation adsorption capacity is 5.0meq / 100g
pulp or less, and if necessary, residual chlorine ion concentration of 10
It has been found that the object can be effectively achieved by suppressing the content to 0 ppm or less.

The above-mentioned ion-adsorbing ability indicates the ability of metal ions such as sodium, potassium, calcium, magnesium and iron to be adsorbed to cation-adsorbing groups such as carboxyl group and sulfonyl group in pulp. Therefore, it is desirable that the cation adsorption capacity be as close as possible to 0.0 meq / 100 g pulp, and the lower limit is not particularly limited, but is about 0.01 meq / 100 g pulp from a practical viewpoint.
Further, even when the cation content is suppressed low in the papermaking process, there is a possibility that cations may be re-adsorbed in the production process and the processing process of the laminated board as long as the cation adsorption ability is provided. In particular, in the case of a laminated board for Ag migration resistance, since the base paper is often subjected to primary treatment with a water-soluble phenol resin (Japanese Patent Laid-Open No. 4-168043), characteristics relating to the cation adsorption ability are important.

When Na ⁺ is adsorbed to all the adsorbed groups of 5.0 meq / 100 g pulp, the content of pulp is equivalent to 120 ppm, and by setting the content to less than 120 ppm, the resistance to Ag migration is greatly improved. This value is 5.0meq / 100
When the value exceeds g pulp, the suitability for Ag migration resistance is remarkably reduced, and good electrical properties cannot be obtained.

As a method for measuring the cation adsorption ability, a method for measuring a carboxyl residue and a method for measuring a sulfonyl residue are known, and the method for measuring a carboxyl residue proposed by the Tappi standard method is known. It is thought that the measurement can be performed comprehensively by using almost all of the cation adsorption ability.

When the amount of residual lignin is large, the number of ion-adsorbing groups tends to increase because the number of sulfonyl groups increases. In the present invention, unbleached pulp having a K value of 10 or less is used by proceeding the cooking.
In addition, when producing these pulp, if the cooking temperature is too high, the amount of non-crystalline cellulose increases, and the possibility of generating carboxyl groups in the bleaching step increases. Therefore,
By performing high-medicine digestion at a low temperature, it becomes possible to produce the target pulp.

The generation of carboxyl groups in the bleaching step occurs in an oxygen stage, a hydrogen peroxide stage, a sodium hypochlorite stage, etc., and is particularly effectively suppressed by controlling the sodium hypochlorite stage. .

[0013] Chlorine ions promote Ag ionization and are resistant to A.
It is considered that the g migration characteristics are adversely affected. Therefore, it is desirable that the chlorine ion concentration be as close to 0 ppm as possible. The lower limit is not particularly limited, but is practically about 0.01 ppm. In the present invention, chlorine-free bleaching such as oxygen bleaching, ozone bleaching, alkali / hydrogen peroxide bleaching, and microbial bleaching;
By using low chlorine-based bleaching incorporating some chlorine-based bleaching to reduce the residual chlorine ion concentration in the laminate base paper to 100 ppm or less, the resistance to Ag migration is greatly improved. On the other hand, if this value exceeds 100 ppm, the suitability for Ag migration resistance is remarkably reduced, and good electrical properties cannot be obtained.

A laminate excellent in Ag migration resistance is often provided with high-density wiring and the like, and the laminate base paper used for the same must also have high dimensional stability. It is known that the dimensional stability of a laminate is significantly impaired when the degree of bending of the pulp fiber is 15 or more (Japanese Patent Application Laid-Open No. 2-175996). Therefore, in the present invention, the object has been achieved by improving the digestion conditions and the bleaching conditions to produce a laminated base paper having extremely good dimensional stability having a degree of bending of 15 or less. Although the lower limit of the degree of bending is not particularly limited, it is practically about 0.1.

At this time, a study was made on wood raw materials for producing the pulp by a simple means. As a result of comparing various Japanese domestic materials, acacia, mangrove, apiton, and eucalyptus, eucalyptus was effective in obtaining a laminate having good electrical characteristics and good dimensional stability.
In particular, E. grandis , E. camld 3 to 10 years after planting
When ulensis and E. saligna are used, the lignin content is low and the molecular weight is small, so that it is easily digestible,
Since the content of hemicellulose is also small, it has become possible to produce a laminated base paper having a low cation adsorption capacity.

[0016]

According to the present invention, the Ag migration resistance and the dimensional stability of the laminate are improved. The reason is that if the number of cation-exchange groups in the base paper of the laminated board is still small, the remaining chlorine ions are further reduced, so that even if an applied voltage is applied under a heated and humidified condition, the ions do not move. Also, since straight fibers having a degree of bending of 10 or less are used, dimensional stability is also good.

[0017]

EXAMPLES The effects of the present invention will be described below with reference to examples.
However, the present invention is not limited by this embodiment.

(Example 1) Using eucalyptus chips produced in South Africa , kraft digestion was carried out under the conditions shown in Table 1 at a lower temperature and higher medicament than in Comparative Example 1, and the K value was not exposed to 8. Pulp (UKP) was obtained. The UKP was bleached by low chlorine bleaching of oxygen, alkali / hydrogen peroxide and chlorine dioxide to obtain bleached kraft pulp (BKP). Using this BKP, a laminated base paper having a basis weight of 135 g / m ² and a density of 0.5 g / cm ³ was obtained by hand-making. This base paper was impregnated with a commercially available alcohol-soluble phenol resin (trade name: BLS-3122, manufactured by Showa Polymer Co., Ltd.) and dried to prepare a prepreg. Next, eight prepregs and copper foil with an adhesive were laminated on both sides, and were hot-pressed at 155 ° C., 100 kg / cm ² for 60 minutes. %, A double-sided copper-clad laminate having a thickness of 1.6 mm was obtained.

Table 1 shows the properties of the laminate base paper and the laminate obtained by this method. As is clear from Table 1, the Ag migration resistance suitability was improved while maintaining the dimensional stability.

Example 2 Kraft cooking was performed at a lower temperature than in Comparative Example 3 using Hokkaido hardwood chips under the conditions shown in Table 1 to obtain unbleached pulp (UKP) having a K value of 10. The UKP was bleached by multistage bleaching of oxygen, chlorine, alkali / hydrogen peroxide and chlorine dioxide to obtain bleached kraft pulp (BKP). Using this BKP, a laminate was obtained in the same manner as in Example 1.

Table 1 shows the properties of the laminate base paper and the laminate obtained by this method. As is clear from Table 1, the Ag migration resistance suitability was improved while maintaining the dimensional stability.

(Comparative Example 1) Using eucalyptus chips produced in South Africa under the conditions shown in Table 1, kraft cooking was performed at a higher temperature and a lower rate than in Example 1 to obtain unbleached pulp (K value: 8). UK
P) was obtained. The UKP was bleached by low chlorine bleaching of oxygen, alkali / hydrogen peroxide and chlorine dioxide to obtain bleached kraft pulp (BKP). Using this BKP, a laminate was obtained in the same manner as in Example 1.

Table 1 shows the properties of the laminated base paper and the laminated board obtained by this method. As is clear from Table 1, the cation adsorption ability was large, and the Ag migration resistance suitability was insufficient compared to Examples 1 and 2.

(Comparative Example 2) Using hardwood chips from Hokkaido under the conditions shown in Table 1, kraft digestion was carried out at a lower medicinal condition than in Example 2, and unbleached kraft pulp having a K value of 13 (U
KP) was obtained. The UKP was bleached by multistage bleaching of oxygen, chlorine, alkali, sodium hypochlorite and chlorine dioxide to obtain bleached kraft pulp (BKP). This B
A laminate was obtained in the same manner as in Example 1 using KP.

Table 1 shows the properties of the laminate base paper and the laminate obtained by this method. As is clear from Table 1, the cation adsorption capacity and the residual chloride ion concentration were large as compared with Examples 1 and 2, and the Ag migration resistance was insufficient.

(Comparative Example 3) Kraft cooking was carried out using Hokkaido hardwood chips under the conditions shown in Table 1 under the same conditions as in Example 1 except that the cooking temperature was high.
Of unbleached pulp (UKP) was obtained. The UKP was bleached by low chlorine bleaching using oxygen, alkali / hydrogen peroxide and chlorine dioxide bleaching to obtain bleached kraft pulp (BKP). Using this BKP, a laminate was obtained in the same manner as in Example 1.

Table 1 shows the properties of the laminate base paper and the laminate obtained by this method. As is clear from Table 1, the cation-adsorbing ability was higher than those of Examples 1 and 2, and the fiber was bent, so that the Ag migration resistance and the dimensional stability were insufficient.

[0028]

[Table 1]

* 1 Effective alkali addition amount: NaOH + 1 /
2Na ₂ S-based pulp alkali addition rate. * 2 O ₂ stage: Oxygen bleaching at 10% pulp concentration, 100 ℃, 60
Performed in minutes. * 3 Stage C: Chlorine bleaching was performed at 50 ° C. for 30 minutes at a pulp concentration of 3%. * 4 E / P stage: alkali / hydrogen peroxide bleaching pulp concentration
Performed at 60% for 60 minutes at 10%. * 5 H stage: Pulp concentration of 10 for sodium hypochlorite bleaching
% At 45 ° C. for 60 minutes. * 6 D stage: chlorine dioxide bleaching is 75% at 10% pulp concentration.
C. for 120 minutes. * 7 Cation adsorption capacity: Cation adsorption capacity was measured by a method for measuring the amount of carboxyl residues (Tappi's standard method T237om-83). * 8 Fiber bend degree: Disintegration of base paper, enlarged projection of randomly collected fibers, and projection and projection of all fibers projected. The straight line distance (Lt) connecting the actual fiber length (Lt) and both ends of the fiber long axis.
s) was measured and calculated by the following equation. * 9 Thermal expansion and contraction coefficient: Using a tensile load type thermal dilatometer,
Load 10g, Temperature rise 5 ℃ / min, Cooling is allowed to cool, from 50 ℃ to 150
The expansion to 150 ° C and the shrinkage from 150 ° C to 50 ° C were measured. * 10 Ag migration resistance: Comb-shaped test pattern (circuit width: 1.0mm) is printed on the surface of the laminate with silver paste. Apply 50V applied voltage to both electrodes at 50 ° C and 95% humidity until short circuit occurs. Was measured for hours.

[0030]

As is clear from Table 1, Ag migration resistance of a double-sided copper-clad laminate based on the base paper according to the present invention shown in Examples 1 and 2 in which specific digestion and bleaching conditions were set. Suitability was good. The dimensional stability of these base papers was also good. Therefore, its industrial significance is great.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 11/00-11/22 D21H 27/00-27/42 H05K 1/03

Claims (3)

(57) [Claims] 1. A laminated base paper made from hardwood kraft pulp having a cation adsorption capacity of 0.01 to 5.0 meq / 100 g pulp. 2. The laminated base paper according to claim 1, wherein the residual chlorine ion concentration in the hardwood bleached kraft pulp is 0.01 ppm or more and 100 ppm or less. 3. The laminated board base paper according to claim 1, wherein the fiber of the hardwood kraft pulp has a degree of bending of 0.1 or more and 15 or less.