JPS60200991A - Method for preventing corrosion of aluminum - Google Patents

Abstract

PURPOSE:To prevent the corrosion of Al due to impurities in electronic parts each using Al as an electrode material or a wiring material by incorporating an inorg. ion exchanger into the electronic parts. CONSTITUTION:An inorg. ion exchanger is incorporated into proper constituent elements of electronic parts (elements) each using Al as the material of an element of an electrolytic capacitor, a lead wire or the like to capture ionic impurities. The constituent elements include a sealing material of electrolytic capacitor, an electrolyte and electrolytic paper part. The inorg. ion exchanger is required to have selectivity on alkali and halogen ions, and it is used by about 0.1-10wt% of the amount of each of the constituent elements.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of aluminum in electronic components used as electrode materials or wiring materials. The number one failure of electronic equipment that occurs in high temperature and humid environments
The cause is said to be corrosion. A particular problem with failures due to corrosion is corrosion of the wiring (lead wires) and electrodes in the components. Aluminum is used as an electrode material for electronic components such as aluminum electrolytic capacitor elements, and as a wiring material for IC1 semiconductors and the like.

It is well known that aluminum corrosion is accelerated by the presence of ionic impurities, especially sodium,
Alkali ions such as potassium and halogen ions such as chlorine and fluorine are considered to be problematic. These ionic impurities are, for example, those derived from resins used in packaging materials, raw materials for inorganic fillers, those that are contaminated from the air, and those that adhere to aluminum electrolytic capacitors. To remove the halogen-based solvents used, such as trichlorethane, trichloroethylene, and 7-leon, that have penetrated into electronic components (elements) and remained and decomposed into halogen ions. In addition, methods of pre-purifying raw materials and methods of creating a structure that prevents the infiltration of cleaning agents are being considered.

For example, raw materials such as IC encapsulant are washed with hot water,
In order to prevent the infiltration of organic chlorine solvents, such as aluminum electrolytic capacitors, various measures have been taken to prevent the infiltration of organic chlorine solvents, such as placing a resin disc on the capacitor's sealing part or attaching a sheet plate (for example, Japanese Patent Laid-Open No. 57-59316). , 57
-73928, 57-13233, 58-15
No. 1013 and No. 58-151014).

However, these methods complicate the manufacturing process of electronic components (elements), which is disadvantageous in terms of energy, increases the burden on personnel, and increases costs, so they are not necessarily good methods. Ta.

The corrosion mechanism of aluminum is explained as follows (
References W, M, Paulson, R0P, Logigan
, Rel.

pbys, Proc, 14.42 (1976).

0 Halogen ions and moisture (as anode reaction) A-C3+
3 C4-→A stone C,,e, +36-AeC133+
H2O-+AA (OH)3+6HCAAA (0)1
)3-)Ci-+ A,, g (OH),, (J+
OH-○ Alkaline ion and water z A4+Ha OH+Duck0-+Ha AlO2+-H2 or as a cathode reaction 3H++3g --+ '! -H.

2 ″ In view of the problems of the prior art described above, the present inventors have investigated a method for preventing corrosion of aluminum even if the ionic impurities are present in electronic components without removing the ionic impurities in advance. As a result, the present invention was completed.

That is, the present invention is a method for preventing corrosion of aluminum, which is characterized by coexisting an inorganic ion exchanger in an electronic component using aluminum as an electrode material or wiring material.

An object of the present invention is to provide a method for preventing corrosion of aluminum even when ionic impurities are present in electronic components. Corrosion of aluminum is caused by the diffusion, migration, etc. of ionic impurities that originally exist within electronic components (elements), ionic impurities that enter during the manufacturing process, or that enter due to contamination in the usage environment. By coming into contact with aluminum and causing a corrosive reaction. Therefore, it is considered that corrosion will not occur if the movement of ionic impurities can be prevented in the components (paths) through which ionic impurities are thought to move in electronic parts (elements).

In the present invention, an inorganic ion exchange (adsorption) body having selectivity for alkali ions and halogen ions is used as a material for preventing the movement of ionic impurities.
The ionic impurities are trapped in the inorganic ion exchange (adsorption) body. A suitable component of an electronic component (device) usually refers to a part where ionic impurities enter or are present and then migrate.

Examples of such components include protective packaging materials for semiconductors, sealing materials for aluminum electrolytic capacitors, electrolytic value materials, electrolytic paper parts, and the like.

In the present invention, the proportion of the inorganic ion exchanger used in the constituent elements of the electronic component (element) is not particularly limited, but is preferably 0.1 to 10% by weight in the constituent elements of the electronic component. The trapping effect is exhibited in the presence of 0.1 weight candy or more, and the upper limit is determined within a range that does not impair the original function of the constituent elements, but in general use, it is sufficient to contain as much as 10%. . If the proportion used is less than 0.1% by weight, the effect of trapping ionic impurities will not be sufficiently exhibited, and if the proportion exceeds 10% by weight, there is a risk that the insulation properties of electronic components may be impaired.

Furthermore, when the constituent elements of an electronic component are liquid than when they are solid, the proportion used can be smaller.

For reference, the structure of an aluminum capacitor is shown in FIGS. 1 and 2 as an example of an electronic component.

The inorganic ion exchanger referred to in the present invention undergoes the following ion exchange (adsorption) reaction (here, the cation exchanger is
0-)(, anion exchanger is temporarily indicated as N-OH.

In addition, alkali ions are temporarily expressed as AOH as hydroxide, and halogen ions as acids as HX).

MO-H+AOH-+MOA +H,,ON-OH+
HX-+H-X+H20 Here, M and N represent multivalent elements.

Preferred inorganic cation exchangers in the present invention include:
For example, antimonic acid (S b20.-nH2O),
Niobic acid (Nb20.-nH2O), tantalic acid (Ta
20. Hydrous oxides such as -n H, O), zirconium phosphate (Zr(HPO4)2-nH2O), tita phosphate:
Examples include phosphates such as y ('I' i (HPO, ), -nH2O), tin phosphate (S n (HPO, ), -nH2O), and of course other compounds that have exchangeability for alkali ions. Inorganic cation exchangers can also be used in the present invention. These inorganic cation exchangers are mixtures,
It may be used as a composite (the above n is O or more to 5
is a real number up to 0).

Further, as a preferable inorganic anion exchanger in the present invention, hydrous oxidized bis-q,x, (Bi,, 03-nl
(20), hydrated titanium oxide (1' i 02・nH2O
), hydrous I zirconium oxide (Zr02-nH2O)
, hydrated tin oxide (S1102・nH2O), hydrated a/I/minium oxide (A-g203-nl-L, O), hydrated magnesium oxide (M, 9O-nH2O), etc. Phosphates and carbonates such as hydroxyapatite and hydrotalcite can also be used in the present invention. These may be used as mixtures or composites.

The proper use of the inorganic cation exchanger and the inorganic anion exchanger is determined by the target ion, but they may be used alone or in combination.

When used in combination, particularly when the ionic impurity is present in the electronic component (device) as a neutral salt of an alkali ion such as sodium chloride and a halogen ion, an excellent effect is exhibited.

The reason for this is that in general, inorganic anion exchangers exhibit ion exchange ability in acidic conditions and have almost no ion exchange ability in alkaline or neutral conditions (on the contrary, inorganic cation exchangers have ion exchange ability in strongly acidic conditions. This is because it exhibits high ion exchange ability in slightly acidic, neutral, and especially alkaline conditions.This is explained using a reaction formula.

A + 10 to 40-H → MOA-1-H (proceeds under alkaline conditions) (1) X +N-01 (→NX+OH- (proceeds under acidic conditions) (2)
H-4-01-1-+H20 In other words, A of the neutral salt AX reacts with the cation exchanger to produce H, and X- reacts with the anion exchanger to produce OH-, so the above (1) This is because H+ released in formula (2) promotes the reaction of formula (2), and OH- released in formula (2) has the effect of promoting the reaction of formula (11), which does not occur when used alone. Even difficult exchange reactions can proceed with the combined use of a cation exchanger and an anion exchanger.

For example, in packaging materials and sealing parts of aluminum electrolytic capacitors, inorganic ion exchangers can be present in each component of electronic parts (elements) using conventionally used thermoplastic resins, synthetic rubbers, and thermosetting resins. ,light,
A method similar to that used for mixing an electromagnetic beam-cured resin such as an electron beam and an inorganic filler, such as white carbon or fused silica, may be used. When dispersing in an electrolyte solution such as an electrolyte solution for an aluminum electrolytic capacitor, in which the electrolyte is dissolved in an organic solvent such as N,N-dimethylformamide or ethylene glycol, the inorganic ion exchanger must be uniformly dispersed, and a dispersing agent may be used together. Also, when mixing aluminum electrolytic capacitors into paper-like materials such as electrolytic paper, it may be mixed during the process of making the electrolytic paper into paper, or it may be done by dissolving raw materials for the non-material ion exchanger in the finished electrolytic paper. rear,
For example, electrolytic paper is impregnated with a hydrochloric acid solution of antimony pentachloride (a raw material for antimonic acid), and then subjected to an appropriate chemical treatment (
The desired inorganic ion exchanger may be generated within the electrolytic paper by hydrolysis, etc.).

According to the present invention, there is no need to refine each element in an electronic component in advance, there is no need for a structure to prevent the infiltration of cleaning agents, and corrosion of aluminum used as an electrode material or wiring material can be easily prevented. It can be efficiently prevented and is industrially useful.

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that the parts on each side represent parts by weight.

Example 1 and Comparative Example 1 Bismuth nitrate hydrate 10I and Mannilla) 8F were kneaded at the same temperature for 15 minutes. This was dissolved in water 50F and thickened, then poured into a 20% aqueous sodium chloride solution 50II, and then the total volume was made up to 5001 Ll with water. Next, 4N sulfuric acid was added to this solution to adjust the pH to 10. After aging at room temperature day and night in the presence of the precipitate, the resulting crude crystals of hydrous bismuth oxide were separated using 5A quantitative F paper. The obtained crude crystals were dispersed in acetone and ground with a polyethylene ball mill # (balls coated with resin) to obtain powdered hydrated bismuth oxide with a size of 1 to 10 microns.

Next, as a sealing material, 60 parts of a cresol novolak type epoxy resin, 65 parts of fused silica, 5 parts of the above-mentioned hydrous bismuth oxide, and a small amount of an amine curing agent were added and mixed. The test model for the occurrence of corrosion on aluminum electrodes uses a printed circuit board on which aluminum pins (AA99, 99 qb or more) are set (not connected) at equal intervals (5y+m), and the above-mentioned sealing is applied to fill half of the aluminum bottle. I used something that was covered with. The sealing material was cured according to a conventional method.

In the corrosion test, each pin (21 pieces) was alternately used as the ■ and ○ electrodes. Before entering the corrosion test, this model was immersed in trichlorethylene and subjected to 30 KHz ultrasonic waves.
I washed my hair for a minute.

After this, the model was taken out and air-dried at room temperature for a day and night, and then heated at 121°C and 2 atm with an applied voltage of 20V between the electrodes (Bre, Scher, Kutzker-Tess) (PCT).
The occurrence of corrosion on the 'electrode was examined after 500 hours. In addition, a similar test was conducted on a product that did not use an inorganic ion exchanger (Comparative Example 1). As a result, there was a large difference between the presence and absence of an inorganic ion exchanger (hydrous bismuth oxide).

Example 2 and Comparative Example 2 Instead of the hydrous bismuth oxide of Example 1, quaternary titanium, zirconium oxychloride, and aluminum chloride were used as raw materials,
Each of these hydrochloric acid solutions was mixed with aqueous ammonia and hydrolyzed using a conventional method. The resulting precipitate was aged under certain conditions, filtered, washed with water, and then dried at 105°C for 2 hours. Aluminum oxide (all anion exchangers) was obtained. Each of these was mixed with isobutylene tadiene rubber by a roll mixing method.

The content of inorganic ion exchanger in each sample was 5% by weight. These rubber compositions were processed so that about half of the aluminum of the substrate with the aluminum bottle used in Example 1 was filled.

Afterwards, these models were immersed in trichlorethylene, and
Cleaning was performed for 60 minutes by applying ultrasonic waves at 0 K and H4Z. Similar to Example 1, each pin was used as the electrodes of ■ and ○ alternately, and with an applied voltage of 10V applied, a high temperature and high humidity bias test was carried out under the conditions of 85°C and 85% LH. The occurrence of corrosion on the aluminum bottle electrode was investigated after 500 hours and 1000 hours. A similar test was also conducted on a sample that did not use an inorganic ion exchanger (Comparative Example 2).

The results are shown in Table 2.

Example 6 The sodium and chloride ions of commercially available N,N-dimethylformamide and ethylene glycol used as electrolyte solvents were analyzed and the results were as follows.

(Na was analyzed by Zeeman atomic absorption spectrometry, and C was analyzed by burning the solvent in a closed container in an oxygen stream, pouring the ash into water, and using the Rodan mercury method.) As a result, the values of Na and C4 were as follows. Ta.

N, N-dimethylformamide, ethylene glycol N
a 180pT) b 230ppb C! 260ppb 350ppb Separately, as an inorganic cation exchanger, crystalline antimonic acid,
Zirconium phosphate was used as an anion-exchanging inorganic ion exchanger, such as hydrous bismuth oxide of Example 1, and a composite hydrated oxide (Ti-
Zr (1:1)) was prepared.

These cation exchangers and anion exchangers were uniformly mixed in the following combinations to prepare test samples.

A: Crystalline antimonic acid + hydrous bismuth oxide = 2:1 (
Weight ratio) B Zirconium diphosphate-4-'I'1-Zr (1:
1) Hydrous oxide = 1: 1 (weight ratio) When natrilam and halogen, which exist as impurities in the electrolyte solvent, cause a complex (mixture) of these A and H to coexist in the electrolyte, these A and H To confirm the fixation, add 0.0% of A and B to 100ml of each of the above solvents.
After adding No. 11 and leaving it for one night without stirring, the sodium and chloride ions in the p solution were separated.

As a result, Na is less than 1 oppb and C1 is 30p.
It was found that the sodium and chloride ions were fixed to the inorganic ion exchanger, and corrosion of aluminum electric appliances was prevented.

Example 4 and Comparative Example 3 A mixture of 60 parts of base low-melting glass powder bed, 65 parts of melt 1Δ1 quartz powder, and 5 parts of cation exchanger (crystalline antimonic acid powder) was mixed and pulverized at 460 to 470°C. ? A test board was prepared by attaching 1±'.

A test substrate was similarly produced without using an inorganic ion exchanger (Comparative Example 6).

The test board thus prepared was subjected to P C'I' at 121°C and 12 atm with an applied voltage of 20V applied.
was carried out.

As a result, when an inorganic ion exchanger was present, the corrosion rate of aluminum was significantly higher.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams of an aluminum capacitor, and FIG. 6 is a schematic diagram of a printed circuit board used in each example and comparative example. 1... Element body 2... Aluminum oxide film (anode) 6... Conductive metal foil (cathode) 4... Electrolytic paper 5A, 5B... Electrode lead wire 6... Main body protective container 7 ... Sealing material 8 ... Rubber ring (sometimes absent) 9 ... Substrate 10 ... Aluminum electrode 11 ... Resin (for sealing and sealing) q! J-revised application Applicant E Synthetic Chemical Industry Co., Ltd. Ki 1p Paperback 27m

Claims (1)

[Claims] 1. A method for preventing corrosion of aluminum, which comprises coexisting an inorganic ion exchanger in an electronic component using aluminum as an electrode material or wiring material.