JPS61171192A - Formation of conductive circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application] The present invention relates to a method for forming a conductive circuit, which includes conducting electricity on a substrate, mounting components on a substrate, and making connections between conductors. The present invention relates to a method for forming a circuit, an electrode portion, and a terminal portion (hereinafter abbreviated as a circuit).

[Prior art]

BACKGROUND OF THE INVENTION Forming a conductive circuit on an insulating substrate made of resin, ceramics, or the like is widely required for printed circuit boards, electronic components, and the like. Chemical plating, PVD methods such as vapor deposition, and brazing methods such as soldering are performed.

In the most popular chemical plating method, X=, CU, etc. are reduced and precipitated on a surface catalyzed by Pd, etc. These methods allow sufficient Pd to adhere, and the surface is etched by special etching. It is necessary to take measures such as roughening, activating, and sensitizing with Sn+1 or the like.

Etching of resin requires a strong oxidizing agent such as strong acid or chromic acid, and hydrofluoric acid is required for ceramics. These methods are complicated, and at the same time are not safe or
This poses a huge burden on pollution control measures.

However, even with these methods, it is often difficult to obtain a plating layer of sufficient strength on a general substrate. Using a special board consisting of
Methods such as applying a special rubber adhesive containing A powder to the entire surface were used.

However, these measures not only consume a large amount of expensive Pd, but also cause chemical plating to occur over the entire surface, so that after plating, the desired pattern must be modified by resist etching.

(Problems to be Solved) In many electronic and electrical applications, there is a strong demand to directly form conductor circuits in desired patterns, that is, to avoid the conventional multi-stage and complicated process described above. The circuits formed are firmly attached to the substrate, have sufficient electrical conductivity, and are often indispensable for component connection characteristics such as soldering and wire bonding.Also, these circuits are The condition is that it can be formed economically in a short period of time.

The present invention solves these conventional problems, and provides a method for forming a conductive circuit that is relatively simple, can be firmly fixed, has sufficient conductivity, and can provide a circuit with good connectivity between components. This is what we are trying to provide.

[Means for elaborating the solution]

Main departure 1! I11 is Ou or CU alloy powder and Pd or P
A conductive paste made by mixing D alloy powder in a viscous medium is adhered and solidified in a desired pattern on the surface of an insulating substrate, and then a continuous metal layer is formed on the surface layer by chemical plating. Features.

The conductive paste used in the method of the present invention has a Pd content of 5 to 50% by weight based on the total amount of metal powder.
If it is less than 50%, the catalytic ability will be weak, and if it exceeds 50%, the catalytic ability will not increase and it will not only be uneconomical but also cause a decrease in conductivity, which is preferable. If the blending ratio of the metal powder with the resin binder is less than 60%, not only the electric J conductivity is low, but also the bonding strength of the plating layer, which is difficult to stably obtain a continuous plating layer by chemical plating, is reduced. On the other hand, if it exceeds 95%, the strength of the paste part decreases and the viscosity increases, making screen printability unsuitable, whereas resinous pastes containing metal powder of 6G or 95% do not have this problem. Particularly preferred for these reasons.

As the Cu powder in the conductive paste used in the present invention, in addition to pure Ou, Ou-Ay (3u-an) is used.

It also envelops alloys such as cu-MtQu-Ti, and these metal powders are manufactured by electrolysis, atomization, chemical precipitation, etc. In addition, as Pa powder, pure Pd (Q
In addition, Pd-Ni, Pd-Co, Pa-0u, P
(1-mu U.

It also includes alloys such as Pd-me and Pd-Pt, and these metal powders are also produced in the same manner. Therefore, it is preferable that the particle size of these metal powders be in the range of Q,l-20μ or less, since accurate circuits can be obtained by screen printing.

It is desirable to use Pd for 5 to 50% of the total amount of metal powders to be mixed in the first stage because a suitable catalytic ability can be obtained and the Pd ratio does not decrease.

In addition, these Jinteng powders can be used for glass frit, epoxy, polyimide, polyester, phenol, melamine,
Mixed with resins such as silicone and modified phenoxy.

The mixing ratio of both is 60 to 95% metal. In addition, paste vI4J1! In this process, viscosity modifiers, stabilizers, etc. are added to the solvent, if necessary.

The conductive paste obtained by kneading the above-mentioned ingredients is applied onto a substrate in a predetermined pattern by screen printing or the like, and is heated and solidified. The heating conditions are determined by the melting temperature of the glass and the solidification temperature of the resin. After the paste is solidified, it is pretreated with acid, alkali, etc. as necessary, and then chemical plating is applied thereon. This chemical plating uses a solution whose essential components are metal components such as Ou and N1, and reducing agents such as formalin, NaH2PO, and dimethylamine borane. I
Complexing agents such as JTA, ethylenediaminetetraacetic acid, Rochelle's salt, and additives for adjusting the reduction reaction are also used. all
−? The reduction precipitation of N1 is Pd −? Since this occurs preferentially on Cu grains, a desired circuit can be easily formed.

[Effect]

In the present invention as described above, the Cu paste portion moves twice together with the circuit conductor as a catalyst for the subsequent chemical plating.

The metal powder moves closely as an electrical conductor, and at the same time Pd
The component can contribute to rapid and strong precipitation as a catalyst. O
N1, which is a more base metal than u, precipitates on the O powder, whereas in the present invention, any chemical plating can proceed smoothly.

The above-mentioned effects can be practically achieved within the blending range described in the previous section. If the Pd content is excessive, it is uneconomical and at the same time causes a decrease in conductivity. Moreover, if the amount of metal powder is excessive, resin etc. will be insufficient and the degree of adhesion will be reduced.

When resin is used as a fixing agent, the amount of metal powder mixed is particularly 9
Level 5 or below is desirable.

The paste solidified body according to the present invention has a specific resistance of approximately l
O~lOμΩ-mouth, and when it is chemically plated, 1
．． It decreases to 0-100 μΩ-α.

〔Example〕

Example l Electrolyzed Qu powder with an average particle size of about 7.5μ and wet-reduced Pd powder with an average particle size of about 0.8μ are mixed in various proportions to obtain mixed powder, melamine-modified phenoxy resin, and a small amount of butyl carbinol acetate. are shown in Table 1, and crosstalk was dispersed using the following formulation. The thus obtained conductive resin paste was printed on a glass epoxy substrate with a thickness of approximately 80 μm and a thickness of 0.5 μm by screen printing.
Print it on a 0m5 wide circuit and heat it at 200℃ x 8G to solidify it.

Next, this was immersed in N1 plating solution (Top Nikolon 60 manufactured by Okuno Pharmaceutical Co., Ltd.) at 90°C for 80 minutes, and then Q
It was immersed in u plating solution (ELO-Is bath manufactured by Uezai Kogyo Co., Ltd.) at 65° C. for 2 hours.

Then, measure the plating thickness, sheet resistance, and beering strength for each circuit obtained. Furthermore, these circuits were immersed in a eutectic solder bath at 285° C. for 5 seconds, and the solder wetting area was measured.

In addition, Aum (25μ-) was bonded by ultrasonic thermocompression method (180℃,
50 KHz, 10G? ), then measure the pull strength with a pull tester. The above results are summarized in Table-1. In this table, sample A1
-6 show those of this example.

As is clear from the above table, in this example, the desired Ni
Since Ou plating can be formed strongly, the results are satisfactory in terms of conductivity, bonding strength, solderability, and bonding properties.

In comparison, Pd is insufficient (Al) or absent (A8
), the plating, especially the N1 plating, is insufficiently deposited, resulting in unsatisfactory results such as bonding strength.

In addition, in the case of an excess of 7 minutes (Y9), the plating precipitation was non-luminous and the various properties were unsatisfactory. On the other hand, in the case of insufficient resin content (/l610), the plating was not sufficient, but the paste layer was destroyed in the bonding strength test, resulting in unsatisfactory results.

Example 2 A mixed powder in which atomized Qu powder with an average particle size of 1 Gμ and reduced Pd powder with an average particle size of about 0.8μ was blended in various proportions, lead borosilicate glass, ethyl cellulose, and terpineol were blended in the proportions shown in Table 2. were uniformly mixed in a crusher to form a conductive paste. This paste is 95% AI! ,O,
After screen printing on a substrate of
To 0℃? Baked for θ minutes and solidified to a thickness of 20μ, $0
．． After the 85 mm circuit was assembled, this product was chemically plated by immersion in an all-Ni chemical plating bath (Nibok LP manufactured by Japan Metal Finishing Co., Ltd.) at pH 7 and 0.90° C. for 80 minutes.

The sheet resistance, soldering properties, and bonding strength of the resulting products were measured in the same manner as in Example 1 above. The results are summarized in Table-2. This table-2
Some examples are also shown in which N1 plating is not performed (Al a
). Even if chemical plating is omitted and the paste on the next side (/I616) is appropriate, soldering and bonding will be unsatisfactory. The next side lacking Pd (Muto 1 can be successfully plated with N1, but the result is similarly unsatisfactory.Also, in the case of excessive glass content (415), many metal powders are waxed with glass, so Not enough effect.

〔effect〕

As is clear from the above examples and the like, according to the present invention, a desired pattern can be formed on a substrate with high efficiency, and the resulting circuit is a continuous metal film that is strongly bonded, and is electrically - It is a good conductor of heat and can be used for soldering, wire bonding, etc. with high efficiency in the same way as ordinary metal circuits. For example, as exemplified above, this method can be applied to manufacturing printed circuit boards that are more economical than conventional additive methods.

Claims (1)

[Claims] 1. A conductive paste made by mixing Cu or Cu alloy powder and Pd or Pd alloy powder in a viscous medium is adhered and solidified in a desired pattern on the surface of an insulating substrate. A method for forming a conductive circuit, comprising forming a continuous metal layer on the surface thereof by chemical plating. 2. The method for forming a conductive circuit according to claim 1, wherein the amount of Pd in the conductive paste is 5 to 50% by weight based on the total amount of metal powder. 3. The first aspect of the present invention is characterized in that the conductive paste is a resinous paste containing 60 to 95% by weight of the metal powder and the resin binder.
A method for forming a conductive circuit as described in .