JPH03287680A - Paste composition for organic thick film - Google Patents

Abstract

PURPOSE:To obtain a paste for an organic thick-film circuit having both high reliability and low-temperature curability by mixing a filler powder and a bismaleimidetriazine resin with an organophosphorus compound and/or a specified alkoxide. CONSTITUTION:The title composition is made by mixing at least one kind of filler powder selected from a carbon powder, a metal powder, and a non- conductive powder; a bismaleimidetriazine resin; and an organophosphous compound and/or a group III or IV element alkoxide having unsaturated bonds in the molecule. Examples of the organophosphorus compound include trivalent phosphorus compounds, such as a phosphine, a phosphite, a phosphorous ester, and a phosphinous ester, and pentavalent phosphorus compounds, such as a phosphine oxide, a phosphoric ester, a phosphonic ester, and a phosphinic ester, among which a phosphite is preferably used in particular from the viewpoints of the stability of the composition after mixing and the cure accelerating effect. As the alkoxide, especially a silicon-containing alkoxide is preferably used from the viewpoint of the cure accelerating effect.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Industrial Application Field 1 The present invention relates to an organic thick film paste composition for electronic components used in hybrid integrated circuit elements, printed wiring circuit boards, various devices, etc. It is something.

[Prior art] Hybrid integrated circuit elements (
Hybrid IC1 and below are abbreviated as rHIC. ) is known.

HIC is a high-density modular circuit that includes integrated circuit elements (ICs), active elements such as transistors, passive elements such as resistors and capacitors, and other electronic components and is housed in a single package. If mounted on a wiring board or the like, the entire circuit can be made compact.

HIC is often used as a module for high-power analog circuits, and its typical configuration is a cermet thick film circuit paste (metal and/or metal oxide and glass) on a ceramic insulating substrate such as alumina. It is equipped with circuits made of printed conductors, printed resistors, and various electronic components designed to be heat-resistant, and is sealed with ceramic or metal packages, heat-resistant resin, etc. Conventional HICs were highly reliable and heat resistant.

On the other hand, in recent years, with the development of digital circuits and improvements in insulating substrate technology, cheaper, higher density, and size-free HICs using metal core substrates or organic substrates have begun to become popular.

However, CTF paste requires a baking process at around 1000°C, which is much higher than the heat resistance temperature of metal core substrates and organic substrates, making it difficult to form printed circuits mounted on these substrates using CTF paste. .

Therefore, the paste for organic thick film circuits (hardened type or dry type paste consisting of conductive particles and an organic binder; hereinafter referred to as rPTF paste) can be baked at a relatively low temperature.

) has been studied and used extensively.

[Problems to be Solved by the Invention] However, when PTF paste is applied to HIC, there are the following problems.

■ If PTF paste, which is usually reprinted, is applied, the durability and reliability of HIC will be significantly inferior to conventional ones, and the product's applications will be narrowed down.

■ When a PTF paste using a highly heat-resistant binder such as polyimide, which has high durability and reliability, is applied, its drying and curing conditions are severe, causing thermal damage to organic substrates and some metal core substrates.

That is, for example, in an insulated metal substrate with an aluminum core (IMST substrate), which is the most common metal core substrate, the hardness of aluminum changes, and even in a polyimide substrate, deformation such as warping occurs.

■ Even with plated terminals for bonding on the board, metal diffusion and surface contamination occur, making metal wire bonding difficult.

HrC using metal core substrate or organic substrate and PTF paste
(hereinafter referred to as "organic HiCJ") has excellent features as low cost, high density, and size-free, but solutions to these problems have been required in order for it to become more widespread.

(B) Structure of the invention [Means for solving the problem] As a result of intensive study on this problem, the present inventors have found a P of a specific composition that can achieve both high reliability and low-temperature curability.
After discovering TF paste, we completed further studies and completed the present invention.

That is, the present invention is an organic thick film paste composition comprising the following components.

(A) One or more filler powders selected from carbon powder, metal powder, and non-conductive powder (B) Bismaleimide triazine resin (C) Organic phosphorus compound and/or unsaturated bond in the molecule The present invention will be described in detail below.

As binders for PTF paste, thermoplastic resins, thermosetting resins, photocuring resins, and radiation are the most reliable and widely used.

The thermosetting resin referred to in 22 is a monomer and/or prepolymer having a reactive functional group, which is blended as a PTF paste and then crosslinked and cured by heating.

Printed circuits with high durability and reliability can be obtained by using thermosetting resins with high heat resistance as binders, but such binders usually require strict curing conditions, such as polyamin resin. Acid-type condensed polyimides, polyimides that polymerize through Michael addition reactions, and polyimides that polymerize through the reaction of polyfunctional cyanate esters, bismaleimides, and other substances, called bismaleimide triazine resins (hereinafter referred to as r).
BT resin. ) etc., it is necessary to react at a temperature of 200° C. or higher for several hours to several tens of hours.

It has long been known that if these polyimides are used as a binder for PTF paste, printed resistors and printed conductors (hereinafter collectively referred to as "printed circuits") that are stable even under high heat and high humidity conditions can be obtained. However, as mentioned above, under these curing conditions, the metal core substrate and the organic substrate suffer thermal damage.

As a result of the study, it was found that the curing conditions under which such thermal damage etc. are not observed are approximately 250° C. or less and 30 minutes or less.

As a result of examining the possibility of low-temperature curing in the above temperature range for PTF paste based on BT resin, the present inventors found that when the two types of compounds described below are added as accelerators, specific We have found that a stable printed circuit can be formed that satisfies this requirement.

The BT resin is composed of (a) a polyfunctional cyanate ester, a cyanate ester prepolymer, or a prepolymer of the cyanate ester and an amine, and (b) a bismaleimide, a bismaleimide prepolymer, or a prepolymer of the bismaleimide and an amine. It is a curable resin composition characterized by consisting of a polymer, and its details are disclosed in, for example, Japanese Patent Publication No. 52-31279.
As described in the above publication, in many cases, the BT resin further contains (C) an epoxy compound.

The cured product of BT resin exhibits heat resistance by using the reaction product of the above (a) and (b) as its skeleton, and the above (C) is used to modify the physical properties of the cured product. Both BT resins with and without (C) can be used in the present invention.

Preferred as (a) are those containing 2,2-bis(4-sanatophenyl)propane (i.e., bisphel A dicyanate ester), and preferred as (°C) are those containing bis(4-maleimide) as the main component. The main component is (phenyl)methane.

In addition, (C) which may be optionally blended includes, for example, a bisphenol A type epoxy resin, and its blending improves the flexibility, adhesion, etc. of the cured product.

These components may be used as a mixture as they are, or may be partially or completely prepolymerized (prepolymerized) beforehand. The BT resin in the present invention is a bismaleimide triazine resin monomer and/or prepolymer as described above.

The binder of the organic thick film paste composition of the present invention has a BT resin as its main component, and preferably accounts for 50% by weight or more of the resin component constituting the binder. Other resins that can be used in combination include monomers and/or prepolymers such as phenolic resins and xylene-modified phenolic resins. In addition to these, for the purpose of improving the adhesion of the cured product, 1 part of glycidyl methacrylate monomer is added to 100 parts by weight of BT resin (hereinafter simply referred to as "parts").
It is preferable to mix 50 parts or less to form the resin component.

Alkoxides of Group 3 or Group 4 elements of the periodic table (hereinafter simply referred to as "alkoxides") having an unsaturated bond in the molecule include B, AI, and Ga.

Alkoxide containing Si, Ge, Ti or Zr, specific compounds include 2-chlorovinyldimethoxyboron, 2-(2-chlorovinyl)-1,3,2-dioxaboron, allyldimethoxyboron, acrylic Diisopropoxyaluminum, tris(acetylacetone)aluminum, tris(ethylacetoacetate)aluminum, acetylacetonebis(ethylacetoacetate)aluminum, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, vinyltriacetyl Silane, T-methacryloxypropyltrimethoxysilane, isopropoxymethacrylictitanium dilaurate, isopropoxydimethacrylictitanium laurate, isopropoxydimethacrylictitanium isostearate, isopropoxytrimethacrylictitanium, isopropoxytriacrylictitanium, dipropoxybis( acetylacetone) titanium, tri-n-
Examples include butoxyacetylacetone zircon and isopropoxytriacryl zircon.

Among these, silicon compounds containing Si as an element are preferred because they exhibit particularly excellent hardening accelerating effects.

In the present invention, various organic phosphorus compounds can be used. Among them, trivalent phosphorus compounds include phosphines (triphenylphosphine is actually the most suitable in terms of stability against oxidation and stability of the composition after blending), phosphite esters, and phosphorus acids. There are esters and phosphinate esters, and trivalent phosphorus compounds include phosphine oxytos, phosphate esters,
Examples include phosphinates, phosphinates, and thioate type compounds thereof.

Among these, phosphite esters are particularly preferred in view of the stability of the composition after blending and the effect of accelerating curing.

When an alkoxide and/or an organic phosphorus compound is blended into a BT resin to form an organic thick film paste, the paste has good stability, is sufficiently cured even under mild curing conditions, and has excellent durability and reliability of printed circuits. It becomes something.

The preferred blending amount of the alkoxide and/or organic phosphorus compound is 2 to 10 parts per 100 parts of the resin. If the amount is too small, the effect will not be exhibited, and even if more than 10 parts is added, no further effect can be expected.

The powder filler in the PTF paste of the present invention may be either electrically conductive or non-conductive.
More than a species.

For printed resistors, (1) and (3) are usually used together, for printed conductor circuits, (2) is usually used, and for protective coats used for both purposes, (3) is usually used.

The carbon powder is preferably so-called carbon black obtained by incomplete combustion of various organic substances, or so-called graphite, which is naturally produced or artificially obtained as a layered structure with high crystallinity, and among them, those with good conductivity, That is, generally speaking (although the names are classified according to raw materials, manufacturing methods, and characteristics), furnace black, acetylene black, lamp black, Ketschen black, and graphite are most preferred.

Although these may be used alone or in combination, they are usually used in combination in view of the various characteristics of the printed resistor.

Preferred metal powders are powders of various metals that are relatively stable against oxidation and have good conductivity. Examples include platinum, gold, silver, copper, nickel, titanium, and palladium, but silver and copper are usually used because of their cost and performance.

The non-conductive powder is a fine powder of an inorganic substance or an organic substance. Examples of the inorganic substance include colloidal silica, fused silica,
Alumina, talc, mica, iron oxide, calcium carbonate,
Magnesium carbonate, bentonite, dolomite, kaolin, etc. are used, and organic substances include thermosetting resins such as hardened powders of phenol resins and benzoguanamine resins, and thermoplastic resins such as polymethyl methacrylate, polyethylene, and polystyrene powders. be.

These non-conductive powders are used alone or in combination as appropriate.

The blending amount of the powder filler in the organic thick film paste of the present invention varies depending on whether the paste is intended to be conductive or non-conductive, or what resistance value is intended.

For printed resistors and protective coats, binder 10
It is preferable to mix 80 parts or less of the powder filler with respect to 0 parts. If the amount exceeds 80 parts, the viscosity of the paste will become too high, resulting in poor coating properties.

On the other hand, since the metal powder used for printed conductor circuits has a high specific gravity, it is preferable to mix it in an amount of 1900 parts or less per 100 parts of the binder.

The organic thick film paste of the present invention can also contain a ketone, ester, ether, or alcohol solvent, but when considering screen printing, a high boiling point solvent is preferred. For example, butyl cellosolve acetate, butyl carpitol acetate, isophorone, terpineol, etc. are preferably used.

The solvent is preferably mixed in an amount of about 2 to 50 parts per 100 parts of other solid components (resin and powder filler) constituting the organic thick film paste.

Other additives, such as various ink property improvers such as leveling improvers, dispersibility improvers, adhesion improvers, etc., and various pigments, dyes, etc. as coloring agents are appropriately blended as desired, and the present invention It can also be an organic thick film paste composition.

Methods for printing organic thick film pastes include screen printing, gravure printing, offset printing, and nozzle drawing methods, and the most common method is screen printing.

Drying and curing methods include methods using a hot air oven, a far-infrared oven, a near-infrared oven, a microwave heating oven, etc., and any of them can be used.

[Effect]

It is not clear why alkoxides and organic phosphorus compounds act effectively as curing accelerators for BT resins, but in the case of alkoxides, the unsaturated bonds and the nitrile bonds of the cyanate ester compound undergo an addition reaction. Produced by transesterification with a cyanate ester compound and hydrolysis from an alkoxide (
It is presumed that this is due to an addition reaction of the semi-metal hydroxide to the nitrile bond of the cyanate ester compound.

On the other hand, in the case of organic phosphorus compounds, it is presumed that in addition to the phosphorus atom coordinating with the cyanate ester compound and acting as a catalyst, it also undergoes a transesterification reaction with the cyanate ester compound as in the case of alkoxides. .

〔Example〕

Hereinafter, the present invention will be explained in detail using Examples and Comparative Examples.

Example 1 BT resin BT2300( 100 parts of a mixture of 50 parts of glycidyl methacrylate and 5 parts of tris(ethyl acetoacetate) aluminum; 8 parts of furnace black MS-500 (manufactured by Asahi Carbon) as a filler; 40 parts of talcum powder Micro Ace (manufactured by Nippon Talc ■) and 30 parts of butyl carbitol acetate as a solvent were blended and kneaded with a three-roller to obtain a resistance paste.

PTF silver paste C-100 (manufactured by Toagosei Chemical Industry Co., Ltd.)
Use a polyimide insulating substrate on which 10 sets of terminals are printed, and apply the resistor paste on it with a width of 2 mm and a distance of 2 mm between the terminals.
(Wrap width with the terminal is 1 mm each), screen printed so that the solid content thickness is 20 parts 2 μm, and
It was dried for 30 minutes and cured at 250°C for 30 minutes.

Furthermore, P-100 (manufactured by Toagosei Chemical Industry Co., Ltd.) was applied thereon as an overcoat to a solid content thickness of 20 μm, similarly dried at 150° C. for 5 minutes, and cured at 180° C. for 30 minutes. The test piece obtained as a result showed no abnormalities such as warping.

In this way, a total of 10 test pieces were created, giving a total of 100 printed resistors.

These printed resistors have an average resistance value of 8.52 KΩ/hole when converted to a 20 μm thickness (all resistance values listed below represent average sheet resistance values converted to a 20 μm thickness);
The standard deviation was 0.61 Ω/mouth.

The resistance change rate of the printed resistor after a 1000 hour humidity test (hereinafter simply referred to as "humidity test") at 60°C, 295% Rh was 2.5%, 121"C, 12 atmospheres, 100% Rh.
, 48-hour pressure test (rP)
It is written as CTJ. ) The resistance value change rate after 2.1%, 260
After being immersed in a solder bath of "C" for 10 seconds, the resistance change rate was 2.2%, indicating excellent durability.

Examples 2 to 8, Comparative Examples 1 to 4 Organic thick film pastes (for resistors, conductor circuits, and protective coats) shown in Table 1 were manufactured using combinations of various binders and fillers.

By combining these and under the conditions shown in Table 2, printed resistors,
A printed circuit including printed conductor terminals was prepared according to Example 1 and evaluated. The results are shown in Table 2.

(c) Effects of the Invention Since the circuit made of the organic thick film paste composition of the present invention has extremely excellent durability and reliability, it can be used to create metal core substrates and other circuits. Organic HICs based on substrates can be manufactured. This greatly contributes to high-density packaging and cost reduction of electronic components.

Claims (1)

[Claims] 1. An organic thick film paste composition comprising the following components. (A) One or more filler powders selected from carbon powder, metal powder, and non-conductive powder (B) Bismaleimide triazine resin (C) Organic phosphorus compound and/or unsaturated bond in the molecule Alkoxide of Group 3 or Group 4 element of the periodic table with