KR20010106951A - Silver-copper paste composition for filling through hole of printed circuit board - Google Patents

Abstract

The present invention relates to a silver paste composition comprising a mixture of silver and copper as conductors and which can be used to form through electrodes filled in the through holes of a printed circuit board. The through-hole filling silver copper paste composition of the present invention comprises 35 to 75% by weight of a metal mixture of silver powder and copper powder as a conductor, 5 to 20% by weight of a thermosetting resin as a binder, and 0.1 to 3% by weight of a dispersant. And an organic solvent as a residual amount. Therefore, compared with the conventional silver paste composition which used only silver powder as a conductor, the metal mixture which mixed copper powder with silver powder was used as a conductor, and it has the outstanding electrical conductivity and spreadability, and the copper which can expect resource saving and cost reduction. There is an effect of providing a paste composition.

Description

Silver-copper paste composition for filling through hole of printed circuit board}

The present invention relates to a silver paste composition for filling through holes in a printed circuit board. More particularly, the present invention relates to a silver paste composition comprising a mixture of silver and copper as a conductor, and which can be used to form a through electrode by filling a through hole of a printed circuit board.

A printed circuit board is fixed to a plurality of electrical appliances on a single substrate to be electrically connected to each other in a conductive pattern formed on the substrate to form a circuit as a whole, is used in almost all electronic products.

In particular, the double-sided printed circuit board having the through-hole is filled with a conductive paste composition for filling the through-hole to serve to electrically connect both sides of the conductive pattern formed by printing on the double-sided substrate.

The conventional paste-filling silver paste composition of a printed circuit board is composed of silver powder as a conductor and a composition of a thermosetting resin which binds the silver powder. The thermosetting resin maintains a liquid state at room temperature and is cured when heat is applied. The thermosetting resin is mainly an epoxy resin, a polyester resin, an acrylic resin, a xylene resin, a polyurethane resin, a urea resin, an amino resin, an alkyd resin, or the like. Thermosetting resins have been mainly used, preferably epoxy resins, acrylic resins, phenol resins are mainly used.

On the other hand, the silver paste composition configured as described above is applied to the through-holes of the double-sided printed circuit board by a printing method such as screen printing, and then left at room temperature for at least 6 hours for leveling, and then undergoes a heat curing process. The paste composition filled in the through hole is cured to have conductivity, thereby making an electrical connection between the circuit formed on the substrate and the circuit. However, the conventional silver paste composition as described above has a problem of reducing productivity because it takes a lot of time for leveling when applied to the through-hole base wall of the double-sided printed circuit board.

In addition, a method of adding a curing accelerator to the thermosetting resin has been sought in order to shorten the leveling time, but the use of the curing accelerator reduces the electrical properties of the paste composition and causes a failure of the curing state, which cannot be a fundamental solution. .

Korean Unexamined Patent Publication No. 1997-58447 includes 50 to 65 wt% silver powder, 25 to 49.8 wt% urethane epoxy resin, 0.1 to 3 wt% dispersant and 0.1 to 7 wt% diluent, and only silver is used as a conductor. In addition, the present invention describes a conductive silver paste composition for a through hole of a double-sided printed circuit board capable of providing excellent electrical properties and a good curing state while reducing the leveling time by using only a urethane epoxy resin. However, such a conventional silver paste composition has a limitation in cost reduction because the raw material is still expensive because only silver is used as a conductor, and in particular, silver powder is used more than 50 to 65% by weight, and the amount of silver powder used is relatively high. In order to reduce the urethane epoxy resin also must be used as a solid component a lot, in this case there is a problem that the physical properties of the paste composition itself.

SUMMARY OF THE INVENTION An object of the present invention is to provide a silver paste composition capable of achieving good conductivity and reducing manufacturing costs by using a mixture of silver powder and copper powder as a conductor.

Another object of the present invention is to provide a silver paste composition having excellent reliability by using a thermosetting resin as a binder.

Still another object of the present invention is to provide a silver paste composition capable of shortening the curing time of the paste composition itself by using a solvent such as esters, alcohols, ketones or the like.

The through-hole filling silver copper paste composition of the present invention comprises 35 to 75% by weight of a metal mixture of silver powder and copper powder as a conductor, 5 to 20% by weight of a thermosetting resin as a binder, and 0.1 to 3% by weight of a dispersant. It consists of organic solvent as% and remainder.

Hereinafter, the present invention will be described in detail with reference to specific examples.

The through-hole filling silver copper paste composition of the present invention comprises 35 to 75% by weight of a metal mixture of silver powder and copper powder as a conductor, 5 to 20% by weight of a thermosetting resin as a binder, and 0.1 to 3% by weight of a dispersant. It is characterized by comprising an organic solvent as a% and the remaining amount.

The content of silver powder in the metal mixture may include 50 to 90% by weight, preferably 70 to 90% by weight based on the total weight of the metal mixture. Therefore, the content of the copper powder may be 50 to 10% by weight, preferably 30 to 10% by weight. Since silver and copper are both good conductors as conductors, the metal mixture of these powders is also an excellent conductor. The silver powder or copper powder constituting the metal mixture may be in any shape of piece, resin, spherical or irregular shape, and the particle size of the powder may be 50 μm or less, preferably 1 to 30 μm. have. The content of the metal mixture with respect to the whole silver paste composition may be 35 to 75% by weight. When the content of the metal mixture is included in less than 35% by weight may have a problem that the resulting paste composition affects the conductivity, on the contrary, when the content of the metal mixture exceeds 75% by weight, it affects the properties such as viscosity and spreadability of the paste composition. There may be a problem that leveling is not done properly. Preferably the content of the metal mixture with respect to the whole silver paste composition may be 60 to 71% by weight.

The thermosetting resin used as the binder may be preferably selected from the group consisting of bisphenol A type epoxy resin, novolac type epoxy resin, resol type phenol resin, novolac type phenol resin, phenoxy resin or a mixture of two or more thereof. However, in addition to this, commercially available thermosetting resins cured by heating may be used without limitation. The thermosetting resin may be used 5 to 20% by weight, preferably 9 to 12% by weight. If the thermosetting resin is contained in less than 5% by weight may have a problem that the metal mixture as the conductor is not sufficiently bound, if the amount exceeds 20% by weight, the content of other active ingredients, such as a metal mixture is relatively insufficient. There may also be a problem that leads to degradation of the physical properties of the resulting paste composition.

As the dispersant used to homogeneously disperse the metal mixture in a thermosetting resin as a paste, in particular, a binder selected from the group consisting of polyamine salts, carboxylic acid salts, silicone acryls and the like may be used. Dispersant may be used 0.1 to 3% by weight, preferably 0.5 to 2% by weight, there may be a problem that the dispersing effect is insufficient when using less than 0.1% by weight, more than 3% by weight is obtained There may be a problem of lowering the physical properties of the paste composition.

The organic solvent is used for controlling the viscosity and spreading properties of the obtained silver paste composition, and improves thixotropy so as to be filled in the through-hole of the printed circuit board. Preferred organic solvents that can be used include most commercially available organic solvents such as esters, alcohols, ketones, and the like, and particularly preferably butyl cellusolve acetate, benzyl alcohol, cyclohexanol, and isophorone. Or a group selected from the group consisting of two or more of these may be used.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described.

The following examples are intended to illustrate the invention and should not be understood as limiting the scope of the invention.

Example 1

69 wt% of a metal mixture in which silver powder and copper powder were mixed in a ratio of 90:10 by weight, 10 wt% of epoxy resin as thermosetting resin, 1 wt% of silicone acrylic as a dispersant, and 20 wt% of butyl cellulsolve acetate as an organic solvent. The% was mixed homogeneously using a conventional mixer to obtain a silver copper paste composition according to the present invention.

The obtained paste composition was printed by the screen printing method on the through-hole of the test printed circuit board having 100 through-holes on which conductive patterns were formed on both sides, and was thermally cured at 150 ° C. immediately after printing without standing at room temperature. After thermal curing, the contact resistance and the curing state of the through-electrode cured composition formed in the through-hole were measured, and the results are shown in Table 1 below.

Measurement of contact resistance is good when the resistance value of the through electrodes formed in the 100 through holes is measured by an ordinary resistance measuring instrument, and the measured 100 resistance values are 1/100 average values of 100 mPa or less. In the case of 200 mPa, it was evaluated as normal (△), and in case of 200 mPa or more, it was evaluated as bad (x).

In the case of the hardened state and the hole state, the shape of the penetrating electrode itself is observed by an optical microscope, and thus the cutting of the penetrating electrode is not observed. Good (◎), no abnormal state such as lifting or peeling is observed between the penetrating electrode and the substrate, but when the electrode thickness is uneven, it is normal (△), and it is bad when lifting or peeling between the penetrating electrode and the substrate is observed. (X) was evaluated.

Example 2

Except for using a metal mixture of silver powder and copper powder in a ratio of 70: 30 by weight as a conductor was carried out in the same manner as in Example 1, and the test for the paste composition obtained was the same, The results are shown in Table 1 below.

Example 3

Except for using a metal mixture of silver powder and copper powder in a ratio of 60: 40 by weight as a conductor was carried out in the same manner as in Example 1, and the test for the paste composition obtained was the same, The results are shown in Table 1 below.

Example 4

Except for using a metal mixture of silver powder and copper powder in a ratio of 50: 50 by weight as a conductor, it was carried out in the same manner as in Example 1, and the test for the paste composition obtained was the same, The results are shown in Table 1 below.

Example 5

Except for using the novolak modified type phenolic resin as a binder was carried out in the same manner as in Example 1, and the test for the paste composition obtained was performed in the same manner, the results are shown in Table 1 below.

Example 6

The same procedure was followed as in Example 1, except that butyl celusolve acetate and benzyl alcohol were mixed at 50:50 as the organic solvent, and the test for the obtained paste composition was performed in the same manner. Shown in

Comparative example

Except for using only the copper powder as the conductor was carried out in the same manner as in Example 1, the test for the paste composition obtained was performed in the same manner, the results are shown in Table 1 below.

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example Contact resistance ^* (mΩ) ◎ ◎ △ △ ◎ ◎ × Hardening state and hole state ^** ◎ ◎ △ △ ◎ ◎ △ * Contact resistance; ◎: Good, △: Normal, ×: Poor ** Hardening state and hole state; ◎: Good, △: Normal, ×: Poor

As a result of the synthesis of the above embodiments, it was confirmed that even when a metal mixture of silver powder and copper powder was used as the conductor, it exhibited good electrical conductivity. Therefore, the amount of the expensive silver powder can be greatly reduced. It was confirmed that the conventional silver paste composition can be replaced without deteriorating physical properties such as conductivity and spreadability.

Therefore, according to the present invention, compared to the conventional silver paste composition which used only silver powder as a conductor, a metal mixture of copper powder mixed with silver powder has excellent electrical conductivity and spreadability, etc. Compared to the composition of the curing state and the shape inside the hole is excellent, and the spreadability important for print workability is excellent, there is no need for time to level after printing immediately

Curing is effective in shortening the production time. In addition, there is an effect of providing a silver paste composition that can be expected to save resources and cost.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (6)

A printed circuit board comprising 35 to 75% by weight of a metal mixture of silver powder and copper powder as a conductor, 5 to 20% by weight of a thermosetting resin, 0.1 to 3% by weight of a dispersant, and an organic solvent as a balance. Silver paste composition for filling through holes The method of claim 1, The silver paste composition for filling the through-holes of the printed circuit board, characterized in that the content of the silver powder in the metal mixture is 50 to 90% by weight based on the total weight of the metal mixture. The method of claim 1, The silver paste composition for filling the through-holes of the printed circuit board, characterized in that the content of the metal mixture with respect to the entire silver paste composition. The method of claim 1, The thermosetting resin used as the binder is a bisphenol A type epoxy resin, a novolak type epoxy resin, a resol type phenol resin, a novolak type phenol resin, and other modified copolymers. A type phenolic resin, a phenoxy resin or a mixture of two or more thereof, the paste composition for filling the through-holes of the printed circuit board, characterized in that the selected. The method of claim 1, The dispersant is a silver paste composition for filling the through-holes of the printed circuit board, characterized in that the dispersant is selected from the group consisting of polyamine salts, carboxylic acid salts, silicone acryl. The method of claim 1, The silver paste composition for filling the through-holes of the printed circuit board, wherein the organic solvent is selected from the group consisting of butyl celusolve acetate, benzyl alcohol, cyclohexanol, isophorone, or a mixture of two or more thereof.