JPH08324649A - Method for storing bare chip - Google Patents

Abstract

PURPOSE: To prevent the deterioration of bare chips while they are stored temporarily in a manufacturing process and while they are kept on a shelf as stocks to maintain the quality of the chips in a good condition by tightly sealing the bare chips in a container having gas barrier properties from which oxygen and moisture has been substantially removed. CONSTITUTION: It is necessary to simultaneously create such a condition that the inside of a system is substantially free from oxygen and at a low humitity. A condition in which oxygen has been removed means that concentration of oxygen is 5% or less, preferably 1% or less, more preferably 0.1% or less. And a condition in which moisture has been substantially removed means that relative humidity is 10% or less, preferably 5% or less, more preferably 1% or less. Bare chips are tightly sealed in a container having gas-barrier properties together with oxygen absorbent which requires no moisture to absorb oxygen and dehumidifying agent. The oxygen absorbent is composed of, as principal agent of oxygen absorbing reaction, unsaturated fatty acid compounds and/or straight-chain hydrocarbon polymer having unsaturated groups, accelerator for accelerating oxygen absorbing reaction of the principal agent, and carriers, and preferably further composed of acid gas absorbent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bare chip storage method for mounting bare chips. INDUSTRIAL APPLICABILITY The method of the present invention is effective for high-density mounting of electronic device parts, for example, for preventing deterioration of bare chips used for mounting bare chips on hybrid IC boards or printed boards.

[0002]

2. Description of the Related Art With the rapid advancement of functions of electronic devices, it is indispensable to make them lighter, thinner and smaller. However, as the functionality becomes higher, the chip size and the number of electrodes increase, and the size of the IC package becomes larger, so that the area occupancy of the IC on the substrate increases, causing a problem of high-density mounting. Therefore, introduction of a method of directly mounting a bare chip (bare IC, LSI chip, etc.) on a substrate has been advanced. Since the bare chip is handled in a state where the chip itself is not sealed with resin, metal or the like, there is a problem that the electrode portion and the solder bump portion are deteriorated due to oxidation, contamination and the like due to oxygen, moisture and dust. In particular, moisture during chip dicing processing after bump formation promotes oxidation of the chip surface, spreads contamination, and deteriorates yield.

When storing chips, the initial oxygen in the container
It is necessary to remove water, etc., and to prevent oxygen, water, etc. from entering the container. As a storage measure, for example, a moisture-proof case disclosed in JP-A-59-17234 and JP-A-4-45333.
The storage room of the is considered. These methods are methods of suppressing the intrusion of moisture and dust during storage and preventing the deterioration of the chip by replacement with dry nitrogen gas. However, it requires a special precision container and a gas filling / replacement device, which makes it difficult to reduce costs and simplify the process.

For the purpose of preventing such deterioration of the bare chip, even if moisture is removed by using a desiccant such as silica gel as a moisture-proof measure for the bare chip, oxygen in the system also deteriorates the physical properties, and the appearance is deteriorated. The product value was often significantly impaired. Therefore, even if a desiccant is used in combination with a deoxidizer to try to store bare chips, a conventionally known deoxidizer such as iron powder, sulfite, catechol, or ascorbic acid is used as a base deoxidizer. However, the oxygen absorption capacity was lowered on the way and the oxygen could not be sufficiently deoxidized, or even if the oxygen was sufficiently removed, discoloration and deterioration of the physical properties still occurred, and it was not always possible to keep the oxygen content well.
As described above, the reality is that there is no simple method for storing bare chips so far.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and prevent deterioration of bare chips during primary storage and inventory storage during the manufacturing process, and maintain good quality of bare chips. It is to provide a bare chip storage method.

[0006]

In order to prevent the deterioration of bare chips and achieve the above object, the present inventors have found that an atmosphere in which only one of oxygen and moisture in the storage atmosphere is removed is not sufficient. They have found that it is necessary to cut off both oxygen and water at the same time, and have reached the present invention.

That is, the bare chip storage method of the present invention is characterized by hermetically sealing the bare chip in a gas barrier container from which oxygen and water have been substantially removed. Furthermore, the method of the present invention is characterized in that, in the above method, the bare chip is sealed in a gas barrier container together with an oxygen absorbent that does not require water for absorbing oxygen. Further, in the above method, the oxygen absorbent includes an acid gas absorbent. Furthermore, it is preferable that the oxygen absorbent preferably contains an unsaturated fatty acid compound and / or a chain hydrocarbon polymer having an unsaturated group as a main component and an oxygen absorption promoter. Hereinafter, the gas barrier container may be simply referred to as a container.

The state in which oxygen is substantially removed in the present invention means an oxygen concentration of 5% or less, preferably 1% or less, more preferably 0.1% or less. Further, a state in which water is substantially removed means that the relative humidity is 10% or less, preferably 5%.
Hereafter, 1% or less is more preferable. In the method of the present invention, an atmosphere in which only one of oxygen and water is removed is insufficient, and it is essential to create a state of substantially oxygen-free and low humidity in the system at the same time. If either the oxygen concentration or the relative humidity is higher than the above concentration range, oxidation proceeds during storage, and the physical properties required for bare chips cannot be sufficiently satisfied.

In the present invention, the above-mentioned atmosphere can be created by sealing the bare chip in a gas barrier container together with an oxygen absorbent and a dehumidifying agent that do not require moisture for oxygen absorption. An oxygen absorber containing an unsaturated fatty acid compound and / or a chain hydrocarbon polymer having an unsaturated group as a main component and an oxygen absorption promoter is preferably used. As oxygen absorbers, for example, those containing a sulfite salt, a metal / metal salt typified by iron powder / iron salt, catechol, an organic compound typified by ascorbic acid, etc. as main agents are known. The absorbent requires water to absorb oxygen, and the oxygen absorbent must retain water for use under dry conditions. However, when an oxygen absorbent that requires water for absorbing oxygen is used in the present invention, oxygen absorption stops halfway, and it also interferes with dehumidification of the dehumidifying agent, resulting in substantially no oxygen. The water-removed state is not achieved and cannot be used in the present invention.

The oxygen absorbent used in the present invention is an unsaturated fatty acid compound and / or a chain hydrocarbon polymer having an unsaturated group, which is the main agent of the oxygen absorption reaction, and a accelerating substance for promoting the oxygen absorption reaction of the main agent. It comprises a carrier material, preferably an acid gas absorbent. Since the deterioration of the bare chip is promoted in the presence of the acidic gas, the combined use of the acidic gas absorbent is effective.

The unsaturated fatty acid compound used for the oxygen absorbent is an unsaturated fatty acid having 10 or more carbon atoms and a double bond between carbons, or a salt or ester of the unsaturated fatty acid. The unsaturated fatty acid and the salt or ester of the fatty acid may have a substituent such as a hydroxyl group and a formyl group. Further, the unsaturated fatty acid compound does not necessarily have to be a pure substance.

Examples of unsaturated fatty acid compounds include unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, arachidonic acid, parinaric acid, dimer acid and ricinoleic acid, and oils, esters, metals containing these esters. Examples include salt. Further, as the unsaturated fatty acid, vegetable oil, fatty acid obtained from animal oil, that is, linseed oil fatty acid, soybean oil fatty acid, tung oil fatty acid, bran oil fatty acid, sesame oil fatty acid, cottonseed oil fatty acid, rapeseed oil fatty acid, tall oil fatty acid and the like are also used.

The chain hydrocarbon polymer having an unsaturated group is a polymer having 10 or more carbon atoms and one or more double bonds between carbon atoms and its derivatives. The derivative may have, for example, a hydroxyl group, an amino group, a formyl group or a carboxyl group as a substituent. Examples of chain hydrocarbon polymers having unsaturated groups include oligomers and polymers such as butadiene, isoprene and 1,3 pentadiene. The chain hydrocarbon polymer having an unsaturated group does not necessarily have to be a pure substance, and a small amount of impurities such as a solvent mixed in at the time of its production is allowed within a common sense range.

Examples of the oxygen absorption promoting substance include metal salts and radical initiators that promote autoxidation of organic compounds. As the metal salt, Cu, Fe, Co, N
Transition metal salts such as i, Cr and Mn are preferable, and as the transition metal salt, for example, unsaturated fatty acid transition metal salt is suitably used.

Examples of the carrier substance include paper made of natural pulp and synthetic pulp, synthetic paper, silica gel, alumina, activated carbon, zeolite, perlite, activated clay and the like. Further, when the main ingredient or the like is a liquid substance, it is preferable to use an adsorptive substance as the carrier substance. Further, it is also a practical use method that the carrier substance selected is a dehumidifying agent and the carrier has a dehumidifying ability.

The acidic gas absorbent may be any substance capable of absorbing or adsorbing an acidic substance produced by the reaction of the main component or an acidic substance brought into the storage atmosphere, for example, an oxide of an alkali metal or an alkaline earth metal, Hydroxides, carbonates, organic acid salts and organic amines are used. It is also possible to select a basic substance as the above-mentioned carrier substance or dehumidifying agent so as to give it a function, and in this case, it is not necessary to add an acidic gas absorbent again.

The proportion of each component in the oxygen absorbent is in the range of 0.01 to 40 parts by weight and the carrier material is in the range of 1 to 1000 parts by weight with respect to 100 parts by weight of the main agent. If necessary, the acid gas absorbent is 1 to 100.
Used in the range of 0 parts by weight.

In the above-mentioned components, the oxygen absorbent is preferably a liquid substance supported on a carrier substance, and the above-mentioned components are mixed and appropriately used in the form of granules, tablets, sheets or the like. These oxygen absorbents are usually further used as a package by wrapping them in a known breathable wrapping material based on, for example, paper or nonwoven fabric. The form of the package is not necessarily limited, and may be, for example, a pouch, a sheet, a blister container, or the like depending on the purpose. As a dustproof measure,
It is desirable to further cover the above-mentioned package with a dust-free packaging material that does not hinder the permeability of oxygen and water. However, if the known package itself is dust-free, it is not necessary to cover it again with a dust-free packaging material.

The dehumidifying agent used in the present invention includes paper made of natural pulp and synthetic pulp, synthetic paper, silica gel,
Alumina, activated carbon, zeolite, perlite, activated clay, quicklime, barium oxide, calcium chloride, barium bromide, calcium hydride, calcium sulfate, magnesium chloride, magnesium oxide, magnesium sulfate, aluminum sulfate, sodium sulfate, sodium carbonate, potassium carbonate , Zinc chloride and the like. The dehumidifying agent may be usually used as a mixture with the oxygen absorbent, or may be provided as an individual package.

The oxygen absorbent and the dehumidifying agent are used in such an amount that the oxygen absorbent can absorb at least oxygen in the space volume in the hermetically sealed container, preferably 1.1 to 10 of the amount. In addition, the dehumidifying agent is in an amount capable of absorbing at least the water content of the space volume in the sealed container, and is preferably in the range of 1.1 to 500 times that amount, and has gas barrier properties. It is appropriately selected according to the barrier performance of the container.

The gas barrier container used in the present invention is
Depending on the purpose, for example, a container made of a gas barrier material such as a plastic container, a film bag, a metal container or a glass container is selected. Gas barrier property The gas barrier property of the container is that the oxygen permeability at 25 ° C and 60% RH is 1
0 ml / m ² · Day · atm or less and 40 ° C, 9
The water vapor permeability at 0% RH is preferably 1 g / m ² · Day or less. It is advantageous in terms of cost to select the barrier performance so that it does not become excessive performance depending on the purpose. Further, when the bare chip is sealed in the container, the inside of the container may be replaced with a dry inert gas such as dry nitrogen gas, and gas replacement is performed by reducing the amount of oxygen absorbent, dehumidifying agent, particularly oxygen absorbent used. Leads to.

[0022]

EXAMPLES Examples of the present invention will be shown below and will be described more specifically. The present invention is not limited to these examples.

Example 1 Production of Gas Absorbent Package: Soybean oil was selected as the main component unsaturated organic compound, and cobalt naphthenate was selected as the oxygen absorption promoting substance. 100 parts by weight of soybean oil and 20 parts by weight of cobalt naphthenate were selected. 350 parts by weight of zeolite was added to the mixture of 1 part, mixed with a blender, and then allowed to stand at 25 ° C. for 10 minutes to obtain a fluid granular material. 5 g of the obtained granules and quicklime 2.5
a small pouch made of paper mixed with g and laminated with a polyethylene film with holes on the inner surface (internal size, 5 cm x 7.5
cm) and covered with a dust-free packaging material that does not impair the permeability of oxygen and water to produce a gas absorbent package (hereinafter, simply referred to as gas absorbent).

Storage test of bare chip: A bare chip for flip chip bonding, which is obtained by dicing and cutting after forming solder bumps, and the gas absorbent produced above are packed in an aluminum foil laminated material (stretched polypropylene / aluminum foil / polyethylene) packaging bag (size: 220 mm). × 300mm, below "A
500ml of air (25 ℃, 75% R)
H), and the bag opening was heat-sealed and sealed. This sealed Al bag was stored in an atmosphere of 25 ° C. and 60% RH for 3 months. After 3 months, the oxygen and water concentrations in the sealed Al bag were measured using a gas chromatograph, and it was confirmed that the storage system was maintained in an atmosphere in which oxygen and water were substantially removed. Then
The bare chip was taken out from the sealed Al bag and the appearance was observed. On the surface of the bare chip and solder bumps stored for 3 months, no change in surface condition or discoloration was observed as compared with that before storage. The results are shown in Table 1.

Examples 2 to 4 In Examples 2 to 4, the combination of the main agent and the oxygen absorption promoting substance in the gas absorbent of Example 1 was changed as follows, and the gas was prepared in the same manner as in Example 1. An absorbent was produced. Main agent (100 parts by weight) Oxygen absorption promoter (20 parts by weight) ──────────────────────────────────── Example 1 Soybean oil Cobalt naphthenate Example 2 Tall oil fatty acid Cobalt naphthenate Example 3 Soybean oil Tall oil fatty acid cobalt Example 4 Soybean oil + Liquid polyisoprene Note) Sodium oil Note: Soybean oil: Liquid polyisoprene (Japan) Synthetic rubber production, Dynacrine R113) = 6: 4 (weight ratio) mixture. Using the above gas absorbents having different combinations of the main agent and the oxygen absorption promoting substance, respectively, as in Example 1, respectively,
A bare chip storage test was conducted. Table 1 shows the storage test results of the bare chips of Examples 2 to 4.

[0026]

[Table 1]

Comparative Examples 1 to 3 As a comparative example of bare chip storage, when the bare chip prepared in Example 1 was used and hermetically stored in an Al bag, in Comparative Example 1, only the bare chip was air-sealed without enclosing the gas absorbent. Sealed with 500 ml, and Comparative Example 2
Fuji Silica gel type A (manufactured by Fuji Devison Chemical Co., Ltd., 1
(With 0g) 1 piece enclosed and sealed with 500ml air,
Further, in Comparative Example 3, one self-reacting iron powder-based oxygen absorber (Mitsubishi Gas Chemical Co., Ltd., Ageless Z-100PT) was enclosed and sealed together with 500 ml of air.
It was stored for 3 months in an atmosphere of 60 ° C and 60% RH. 3 above
Regarding the bare chip stored for a month, the oxygen and water concentrations in the sealed Al bag were measured, and then the bare chip was taken out from the sealed Al bag and the appearance was observed. Table 2 shows the bare chip storage test results of Comparative Examples 1 to 3.

In Examples 1 to 4, the bare chips stored for 3 months did not change in appearance from those before storage, whereas the bare chips of Comparative Examples 1 to 3 were as shown in Table 2.
Although there are some differences, the discoloration of the chip surface,
Roughness of bumps and generation of deposits were observed.

[0029]

[Table 2]

[0030]

EFFECTS OF THE INVENTION By storing bare chips in a gas barrier container in an atmosphere from which oxygen and water have been substantially removed by the method of the present invention, deterioration of bare chips can be prevented and good quality can be maintained. , Discoloration does not occur. Moreover, according to the present invention, bare chips can be favorably stored by a very simple method by simply sealing the bare chips in a gas barrier container together with an oxygen absorbent and a dehumidifying agent that do not require moisture for oxygen absorption. You can

Claims (4)

[Claims] 1. A bare chip storage method, characterized in that the bare chip is stored in a gas barrier container from which oxygen and water have been substantially removed. 2. The bare chip storage method according to claim 1, wherein the bare chip is sealed in a gas barrier container together with an oxygen absorbent and a dehumidifying agent that do not require moisture to absorb oxygen. 3. The bare chip storage method according to claim 2, wherein the oxygen absorbent contains an acidic gas absorbent. 4. The oxygen absorbing agent, which comprises an unsaturated fatty acid compound and / or a chain hydrocarbon polymer having an unsaturated group as a main agent and contains an oxygen absorption promoting substance. The method for storing bare chips according to item 3.