JPH07300792A - Substratum for laminate - Google Patents

Abstract

PURPOSE:To obtain a substratum for a laminate, a having excellent silver migration-resistant suitability and excellent dimensional stability, by laminating a bleached kraft pulp of broad-leaf tree having cation adsorption ability and residual chloride ion concentration prescribed in specific ranges. CONSTITUTION:Chips of broad-leaf tree are digested at a low temperature, then subjected to multistage bleaching treatment by low-chlorine bleaching with oxygen, an alkali/H2O2 and chlorine dioxide to give a kraft pulp having functions of 0.01-8.0meq/100g cation adsorption ability, and 0.01-50ppm residual chloride ion concentration and >=0.1 and <=10 flex degree. The pulp is made into a substratum for a laminate, which is thermally pressed and formed to give a substratum for a laminate having silver migration-resistant suitability and excellent dimensional stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is concerned with electrical characteristics, especially Ag resistance.
The present invention relates to a laminated board base paper which provides a laminated board having good migration suitability and excellent dimensional stability.

[0002]

2. Description of the Related Art A base paper for a laminated board 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, as electronic devices have become multifunctional and have higher density, copper plated through holes and silver paste through holes have been advanced, and high reliability is also required for a laminated board using a paper base material. In particular, a laminated base paper having excellent silver migration resistance and dimensional stability is required.

As a method of manufacturing a laminated plate for solving the above problems, a method of reducing the residual ion concentration in the laminated plate (Japanese Patent Laid-Open Nos. 3-164242 and 3-138151), Method for reducing residual ion concentration in a
No. 7) is known, but the result is not sufficiently satisfactory. In particular, with regard to cations, even if they are sufficiently removed by washing or the like in the papermaking process, as long as there are adsorption sites, there is a concern that metal ions will be incorporated in subsequent processing steps.

Further, as an improvement of the paper base material, NDSP,
By using a linter or the like, the suitability for Ag migration resistance is improved. However, since the fibers of these pulps have a long fiber length and are extremely bent, there arises a problem that the dimensional stability of the laminated plate is adversely affected.

[0005]

The problem to be solved by the present invention is that the cations of the base paper for the laminate, which are considered to be involved in the suitability for Ag migration resistance, among the electrical properties of the laminate, are considered. It is to determine each allowable range of adsorption capacity and chlorine ion concentration. Also, when this condition is met,
It is to define the allowable range of the morphological characteristics of pulp fiber without impairing the dimensional stability of the laminate.

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

[0007]

The present invention has focused on the fact that, among the electrical characteristics of the laminate, the suitability for Ag migration is particularly closely related to the cation adsorption capacity and the residual chlorine ion concentration. , Cation adsorption capacity is 8.0meq / 100g
It was found that the objective can be effectively achieved by keeping the residual chlorine ion concentration below 15 ppm below pulp.

The above-mentioned ion adsorption ability indicates the ability of metal ions such as sodium, potassium, calcium, magnesium and iron to be adsorbed on cation adsorption groups such as carboxyl group and sulfonyl group in pulp. Therefore, in order to improve the electrical properties of the laminate, it is important that the cation adsorption capacity be as close as possible to 0 meq / 100 g pulp. The lower limit is not particularly limited, but in reality it is about 0.01 meq / 100 gpulp. Further, by suppressing the cation adsorption capacity to be low, not only the adsorption of cations in the paper making process but also the adsorption in the manufacturing and processing steps of the laminated plate can be prevented. In particular, in the case of an Ag migration-resistant laminated plate, it is often impregnated with a water-soluble phenol resin (Japanese Patent Laid-Open No. 4-168043), and these characteristics are particularly important.

When Na ⁺ is adsorbed on all the adsorbing groups of 8.0 meq / 100 g pulp, the content of the pulp with respect to pulp corresponds to 188 ppm, and when the content is less than this, the Ag migration resistance is greatly improved. In addition, this value is 8.0meq / 100
If it exceeds g pulp, the suitability for Ag migration resistance is significantly reduced, and good electrical characteristics cannot be obtained.

As a method of measuring the cation adsorption capacity, TAPP
It is considered that the adsorption capacity of almost all cations can be comprehensively measured by using the method for measuring the carboxyl residue proposed in the standard method of I.

When the 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 with cooking.
In addition, if the cooking temperature is too high during the production of these pulps, the amount of non-crystalline cellulose increases, and the possibility that carboxyl groups will be generated in the bleaching step increases. Therefore,
By cooking under relatively low temperature and high chemical addition conditions,
It is possible to produce the intended pulp. If the bleaching conditions are made severe to further increase the whiteness, the cation adsorption capacity becomes high, which is not preferable.

Chloride ion promotes dissociation of Ag ion,
It promotes the occurrence of Ag migration. Therefore, it is desirable that the chlorine ion concentration be as close to 0 ppm as possible, but in reality, the lower limit is about 0.01 ppm. In the present invention, by using chlorine-free bleaching or low-chlorine bleaching, the residual chlorine ion concentration in the laminated base paper is set to 50 ppm or less, whereby Ag migration resistance is greatly improved. Also, if this value exceeds 50ppm, A resistance
The suitability for g-migration is significantly reduced, and good electrical characteristics cannot be obtained.

A laminated board excellent in Ag migration resistance is often provided with high-density wiring and the like, and the laminated board base paper used for this must also have a high degree of dimensional stability. It is known that when the degree of bending of pulp fibers is 15 or more, the dimensional stability of the laminated plate is significantly 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 laminated board base paper having a flexibility of 10 or less and excellent dimensional stability. The lower limit of the degree of bending is not particularly limited, but is practically about 0.1.

[0014]

The present invention improves the suitability for Ag migration resistance and dimensional stability of the laminate. The reason is that the cation exchange groups of the laminated base paper are small and the residual chlorine ions are small, so that ion migration does not occur even when an applied voltage is applied under heating and humidifying conditions. Also, if necessary, the degree of bending is 10
Since the following straight fibers are used, the dimensional stability is also good.

[0015]

EXAMPLES The effects of the present invention are shown below by examples.
However, the present invention is not limited to this embodiment.

(Example 1) Using hardwood chips produced in Hokkaido, under the conditions shown in Table 1, kraft cooking was carried out at a lower temperature than in Comparative Example 3 under conditions of high chemical addition, and unbleached pulp with a K value of 10 (UK) was used.
P) was obtained. This UKP was bleached by chlorine-free bleaching of oxygen and alkali / hydrogen peroxide to obtain a bleached kraft pulp (BKP). Using this BKP, the basis weight is 135 g / m ² ,
A laminated base paper having a density of 0.5 g / cm ³ was obtained by handmaking. Commercially available alcohol-soluble phenolic resin (trade name B
LS-3122: Showa High Polymer Co., Ltd. was impregnated and dried to prepare a prepreg. Next, 8 pieces of prepreg and copper foil with adhesive are laminated on both sides, 155 ℃, 100kg / cm ² ,
After thermocompression molding under the condition of 60 minutes and cooling for 30 minutes in a pressurized state, a double-sided copper-clad laminate having a resin content of 50% and a plate thickness of 1.6 mm was obtained.

The properties of the laminated base paper and laminated plate obtained by this method are shown in Table 1. As is clear from Table 1, the suitability for Ag migration was improved while maintaining the dimensional stability.

(Example 2) Using hardwood chips produced in Hokkaido, under the conditions shown in Table 1, kraft cooking was carried out at a lower temperature than in Comparative Example 3 under conditions of high chemical addition, and unbleached pulp with a K value of 10 (UK) was used.
P) was obtained. The UKP was bleached by low chlorine bleaching with oxygen, alkali / hydrogen peroxide and chlorine dioxide to obtain a bleached kraft pulp (BKP). A laminated board was obtained in the same manner as in Example 1 by using this BKP.

The characteristics of the laminated board base paper and laminated board obtained by this method are shown in Table 1. As is apparent from Table 1, the suitability for Ag migration was improved while maintaining the dimensional stability.

(Comparative Example 1) Using hardwood chips produced in Hokkaido, under the conditions shown in Table 1, kraft cooking was carried out at a lower temperature than in Comparative Example 3 under conditions of higher chemical addition, and unbleached pulp with a K value of 10 (UK) was used.
P) was obtained. This UKP was bleached by multi-stage bleaching with oxygen, chlorine, alkali, sodium hypochlorite, and chlorine dioxide to obtain a bleached kraft pulp (BKP). This BKP
A laminated board was obtained in the same manner as in Example 1 using.

The characteristics of the laminated board base paper and laminated board obtained by this method are shown in Table 1. As is clear from Table 1, the suitability for Ag migration resistance and the dimensional stability were insufficient as compared with Examples 1 and 2.

(Comparative Example 2) Using hardwood chips produced in Hokkaido, under the conditions shown in Table 1, kraft cooking was carried out at a lower temperature than in Comparative Example 3 under conditions of high chemical addition, and unbleached pulp with a K value of 10 (UK) was used.
P) was obtained. The UKP was bleached by low chlorine bleaching with oxygen, alkali / hydrogen peroxide and chlorine dioxide to obtain a bleached kraft pulp (BKP). However, in order to obtain whiteness, the conditions of oxygen bleaching and hydrogen peroxide bleaching stronger than those in Example 2 were used. A laminated board was obtained in the same manner as in Example 1 by using this BKP.

The properties of the laminated base paper and laminated sheet obtained by this method are shown in Table 1. As is clear from Table 1, the dimensional stability was insufficient as compared with Examples 1 and 2.

(Comparative Example 3) Using hardwood chips from Hokkaido, kraft cooking was carried out under the conditions shown in Table 1 to obtain an unbleached pulp (UKP) having a K value of 10. This UKP was bleached by chlorine-free bleaching with oxygen and alkali / hydrogen peroxide to obtain a bleached kraft pulp (BKP). A laminated board was obtained in the same manner as in Example 1 by using this BKP.

The characteristics of the laminated board base paper and the laminated board obtained by this method are shown in Table 1. As is clear from Table 1, the suitability for Ag migration resistance was insufficient as compared with Examples 1 and 2.

[0026]

[Table 1]

* 1 Effective alkali addition amount: NaOH + 1 /
2Na ₂ S equivalent to pulp alkali addition rate. * 2 O ₂ stage: Oxygen bleaching is at a pulp concentration of 10%, 100 ℃, 60
I went in minutes. * 3 Stage C: Chlorine bleaching was performed at 50% for 30 minutes at a pulp concentration of 3%. * 4 E / P stage: Alkaline / hydrogen peroxide bleaching is pulp concentration
10%, 60 ° C., 60 minutes. * 5 H stage: Sodium hypochlorite bleaching has a pulp concentration of 10
% At 45 ° C. for 60 minutes. * 6 Stage D: Chlorine dioxide bleaching is 75% at a pulp concentration of 10%.
The test was performed at 120 ° C for 120 minutes. * 7 Cation adsorption capacity: Cation adsorption capacity was measured by the method for measuring the amount of carboxyl residues (Tappi standard method T237om-83). * 8 Fiber flexibility: For all fibers projected by magnifying and projecting randomly sampled fibers by disaggregating the base paper, the actual fiber length (Lt) and the straight line distance (L) connecting both ends of the fiber long axis
s) was measured and calculated by the following formula. * 9 Thermal expansion / shrinkage coefficient: Using a tensile load type thermal expansion meter,
Load 10g, temperature rise 5 ℃ / min, cooling is allowed to cool, 50 ℃ to 150 ℃
Swelling to ℃ and shrinking from 150 ℃ to 50 ℃ were measured. * 10 Ag migration resistance suitability: A comb-shaped test pattern (circuit width 1.0 mm) is printed on the surface of the laminated plate with silver paste, and a voltage of 50 V is applied to both electrodes under an environment of 50 ° C and 95% humidity until short circuit occurs. Was measured.

[0028]

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

Claims (2)

[Claims] 1. A laminated board base paper composed of hardwood kraft pulp having a cation adsorption capacity of 0.01 meq / 100 g pulp or more and 8.0 meq / 100 g pulp or less and a residual chlorine ion concentration of 0.01 ppm or more and 50 ppm or less. 2. The laminated board base paper according to claim 1, wherein the fibers of the hardwood kraft pulp have a degree of bending of 0.1 or more and 10 or less.