JPH075862B2 - Coating material for IC or hybrid IC - Google Patents

Description

The present invention relates to a coating material for forming a protective coating on an IC or hybrid IC, which is a solvent-based coating material with high reliability and excellent coating workability. It is related to.

[Prior art]

IC or hybrid IC packaging methods include hermetic sealing and resin sealing. Airtight sealing is highly reliable, but high costs in materials and processes are unavoidable, so resin sealing is becoming the mainstream.

The resin encapsulation differs depending on the mold type IC and the bare chip type IC, but the main structure of the bare chip IC is roughly divided into a chip coating material that partially covers the semiconductor chip and the like and an exterior material that covers the entire circuit board.

(1) Chip coating material In a bare chip IC, a semiconductor chip or the like is attached to a circuit board with an adhesive and wire-bonded. Next, for mechanical protection and moisture-proof treatment, a silicon resin is usually mainly used as a chip coating material.

However, although the silicone resin has relatively few problems in the drop coating operation, it has the following drawbacks, and development of a material to replace this is desired.

It has poor adhesion to other materials (exterior materials, etc.) and has moisture permeability, so it does not prevent water from entering.

Since the elastomeric coating film is flexible, there is a risk that the bonding film such as a gold wire may be cut through the coating film by handling in the manufacturing process of IC or hybrid IC.

(3) Since the solvent resistance is generally poor, characteristic deterioration and circuit short-circuiting are likely to occur due to the post-cleaning process (flux removing process).

Further, since the chip coat material is in direct contact with the IC element and mounted parts, the material must be selected in consideration of stress, thermal expansion coefficient, adhesiveness, amount of ionic impurities, hygroscopicity, etc. of the material. Therefore, as a result of earnestly advancing the development of such materials, the present inventors say that these problems can be solved all at once by dropping and coating a solvent-based coating material containing a large amount of filler instead of the silicone resin. I have knowledge.

However, there are the following items to be improved for this coating material.

Recently, high-density mounting has advanced and reliability of encapsulation materials has become more and more severe, and the amount of ionic impurities related to aluminum pattern corrosion and short circuits has been reduced.

To improve the defect that the needle part (nozzle part) is likely to be clogged during drop coating with a dispenser and to cope with automation of drop coating work.

The chip coating material requires partial coating on the IC element, improving the precision of the drop coating area.

Improves the effect of preventing sagging so that the coating shape does not spread too much after dropping.

 Prevents settling of filler during storage and storage.

(2) Exterior materials IC or hybrid IC exterior materials include powder coating,
Casting materials and dip coating materials are used.

In particular, a solvent-based dip coating material containing a large amount of filler has a thermal expansion coefficient as low as that of a ceramic and has a small internal stress, and thus has excellent thermal shock resistance. Therefore, recently, its application has been spreading especially to hybrid ICs using a large circuit board. Similar to the chip coat material, the dip coating material is required to have a reduced amount of ionic impurities and an improved sag property at the time of dip work as the circuit board becomes larger.

[Object of the Invention]

The present invention uses a solvent-based coating material containing a large amount of a filler, instead of the conventional protective coating with a silicone resin, and can not only improve the above-mentioned disadvantages but also has excellent adhesion to a circuit board. A coating material is provided. For that purpose, by using a resole-type phenol resin that uses a nitrogen-containing compound catalyst as the thermosetting resin component as the main component and an organic thixotropic agent as the thixotropic component, it is strictly required as a chip coating material. Satisfying various characteristics,
It has been found that various problems can be solved, and it has been found that the demand for exterior materials can be satisfied, and the present invention has been completed.

An object of the invention is to provide a coating material for IC or hybrid IC which is highly reliable and has excellent coating workability and partial coating system.

[Structure of Invention]

The present invention relates to a solvent-based coating material in which essential components are a thermosetting resin, a thixotropic agent, a filler, an additive, and a solvent. (1) Resol-type phenol using a nitrogen-containing compound catalyst as a thermosetting resin component A coating material for an IC or a hybrid IC, characterized by comprising a resin and (2) an organic-based thixotropic agent as a thixotropic agent component.

The resol type phenol resin used in the present invention is usually 1 mol or more of formaldehyde, preferably 1.1 to 1.8 mol, per 1 mol of phenol, and a nitrogen-containing compound catalyst as a catalyst, or a nitrogen-containing compound and an alkaline earth metal catalyst. Is a resin that has been condensed and dehydrated by a conventional method by using together.

The phenols mentioned here are alkylphenols such as phenol, cresol, xylenol, resorcin, and paratertiarybutylphenol, paraoctylphenol, paranonylphenol, and paraphenylphenol.

The formaldehyde may be paraformaldehyde in addition to the formalin aqueous solution.

The nitrogen-containing compound is ammonia, triethylamine, triethanolamine, diethyleneamine, aniline, hexamethylenetetramine and the like. The alkaline earth metal is an oxide or hydroxide of an alkaline earth metal such as calcium, magnesium or barium.

The resole-type phenol resin obtained from the nitrogen-containing compound and the catalyst containing the nitrogen-containing compound and the alkaline earth metal in combination has a small amount of ionic impurities which is one cause of aluminum pattern corrosion. Furthermore, since the cured product of this resin has good moisture resistance, it is an essential resin for improving reliability.

On the other hand, in the case of a resol using only an alkali metal catalyst such as an alkali metal or an alkaline earth metal, the moisture resistance of the resin is poor and a factor causing aluminum pattern corrosion when used as a coating material is included. In fact, when these resins are used, a reliable coating material cannot be obtained.

This is considered to be because the nitrogen-containing group of the catalyst incorporated into the resin structure has a good effect on the moisture resistance and high reliability.

The resol type phenolic resin used in the present invention is more preferably an ammonia resol using ammonia and hexamethylenetetramine as a reaction catalyst. A preferable catalyst amount is ₃ as NH _{3 with} respect to 100 parts of phenol.
~ 15 copies.

Further, the addition amount of the thermosetting resin component is 5 to the filler.
It is preferably 20% by weight.

The thixotropic agent can be roughly divided into an inorganic type and an organic type. Inorganic thixotropic materials include metal soaps such as aluminum stearate, amine-modified bentonite, anhydrous fine powder silica, surface-treated calcium carbonate, kaolin, and clay. On the other hand, as the organic thixotropic agent, a polymerized vegetable oil type, a hydrogenated castor oil type, an oxidized polyethylene type obtained by oxidizing polyethylene to introduce a carboxyl group, and an amide wax type (a higher fatty acid nitrogen compound) which is a condensate of a higher fatty acid and an amine. Derivatives), benzylidene sorbitol, etc.

Most of the inorganic thixotropic agents are used to improve the sagging property, but they contain a large amount of ionic impurities, which causes corrosion of the aluminum pattern of the IC and deteriorates reliability. Also,
It was found that improvement of nozzle clogging during drop coating work with a dispenser cannot be expected. Furthermore, since it is a fine powder, it has a drawback of promoting crack generation as a coating film defect.

The organic thixotropic agent used in the present invention has less ionic impurities than the inorganic thixotropic agent and does not impair the reliability. It was also found that the nozzle clogging during the drop coating operation with a dispenser can be greatly improved and that it also has a sufficient sagging prevention effect. Among the organic substance thixotropic agents, polyethylene oxide type and amide wax type are more preferable, and these may be used in combination. The addition amount of the thixotropic agent is preferably 0.2 to 2.0% by weight in terms of solid content with respect to the filler.

The filler used in the present invention is an inorganic filler such as calcium carbonate, alumina, talc, crystalline silica, fused silica, and sintered aluminum silicate, but is not limited thereto. Further, one or more of these fillers can be used in combination. Among these fillers, it is preferable to use crystalline silica or fused silica containing few ionic impurities.

Solvents used in the present invention include hydrocarbon solvents such as toluene and xylene, alcohol solvents such as ethyl alcohol, ketone solvents such as acetone and methyl ethyl ketone, and others, ester-based, ether-based, ether alcohol-based, ether ester-based solvents. One or more solvents such as

A solvent that dissolves the resol-type phenol resin and has a dielectric constant as small as possible is preferable. Further, regarding the additive, in order to further improve the adhesiveness, a silane coupling agent or a titanium coupling agent is added in an amount of 0.1 to 2.0 with respect to the filler.
It is preferable to contain it by weight%.

As other additives, curing accelerators such as imidazoles and aromatic amines, defoaming agents, pigments, dyes and the like can be added in appropriate amounts.

〔The invention's effect〕

As described above, as a coating material for IC or hybrid IC, the solvent-based coating material of the present invention has excellent thermal shock resistance, and also has excellent reliability and workability.

This high reliability is due to the effect of imparting moisture resistance to the cured product by the resol type phenol resin, and the effect of using a resin component having less ionic impurities and an organic thixotropic agent having less ionic impurities.

On the other hand, regarding workability such as dispenser workability and sag property, the effect is mainly due to the organic-based thixotropic agent.

The present invention, combined with the achievement of automation in terms of work, makes it possible to reliably and easily manufacture highly reliable ICs or hybrid ICs, which is extremely effective in industry.

〔Example〕

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.
Moreover, all "parts" and "%" described herein mean "parts by weight" and "% by weight".

Production Example 1 94 parts phenol, 146 parts 37% formalin, 28 as catalyst
% 15% aqueous ammonia and 0.5 part calcium hydroxide were charged and reacted at a temperature of 100 ° C for 40 minutes, then dehydrated under vacuum to give a solvent (acetone / ethyl alcohol = 1/1).
To obtain a resol type phenol resin having a resin content of 50%.

Production Example 2 A resol type phenolic resin having a resin content of 50% was obtained in the same manner as in Production Example 1 except that 20 parts of 28% ammonia water was used as a catalyst.

Comparative Production Example 1 2 parts of sodium hydroxide and calcium hydroxide as a catalyst
Resin content is 50% in the same manner as in Production Example 1 except that 0.5 part is used.
To obtain a resol type phenol resin.

Comparative Production Example 2 A resol type phenolic resin having a resin content of 50% was obtained in the same manner as in Production Example 1 except that 7 parts of calcium hydroxide was used as a catalyst.

Production Example 3 94 parts of phenol, 60 parts of 37% formalin and 1 part of oxalic acid as a catalyst were charged, and the reaction was carried out at a temperature of 100 ° C. for 3 hours,
Then, dehydration was performed under vacuum to obtain a novolac type phenol resin having a melting point of 70 ° C.

Examples and Comparative Examples Solvent-based coating materials were prepared as follows.

The thermosetting resin component and the filler were mixed with the compounding parts shown in Tables 1 and 2, the thixotropic agent 0.4% (to the filler) silane coupling agent 0.85 part, and methyl ethyl ketone 35 parts in a mixer for 2 hours. A coating material was prepared and diluted with methyl ethyl ketone to adjust the viscosity at 25 ° C. to 30 poises.

The composition and the evaluation results are shown in Tables 1 to 3.

The evaluation method is as follows.

1. Measurement of ionic impurities The method of measuring ionic impurities by hot water extraction is as follows. The coating material is cured at 150 ° C. for 2 hours, and then the cured product is ground. A small amount of ethyl alcohol is added to the obtained powder sample to immerse it, and then pure water is added and treated at 125 ° C for 20 hours. The supernatant is used as a test solution, and chloride ion concentration (ppm) and sodium ion are measured by ion chromatography. The concentration (ppm) was calculated.

2. Workability of dispenser A pneumatic needle type dispenser is used to put a coating material in a 50cc syringe and a metal needle (0.86m / mφ nozzle)
Assuming an actual continuous drop coating operation, a pressure of 0.5 kg / cm ² was applied every 5 minutes and the dropping operation was repeated to determine the degree of nozzle clogging.

As a result, the nozzle clogged after 5 minutes (first time) was x,
Nozzle clogged in 10 to 20 minutes (2 to 4 times) △, 25
No clogging of the nozzle was shown as ◯ for more than 5 minutes (5 times or more).

3. Sagging property The slide glass was immersed in the covering material in the longitudinal direction for about half, and slowly pulled up to turn it upside down, and the degree of sagging was visually observed.

Those without sagging are marked with a circle.

4. Moisture resistance of the cured product Make a test piece of 30mm (width) x 100mm x 1mm (thickness) and
It is cured at 0 ° C. for 2 hours to obtain a cured test piece. Pressure cooker (condition: 125 ° C 2.
Bending strength after treatment for 2 hours was measured, and those with no strength change were indicated by ◯, and those with a decrease in strength were indicated by x.

5. Reliability Using a fine aluminum wiring comb pattern as an evaluation element, a coating material is dropped and applied on the pattern, and after 16 hours of air drying, the temperature is cured at 150 ° C for 2 hours, and the number of short circuit defects due to aluminum corrosion is tested by a tester. It was measured at.

The denominator represents the number of test samples, and the numerator represents the number of short circuits.

6. Speed of flexural strength A coating material is poured into a mold with a width of 30 mm and a length of 100 mm so that it has a thickness of about 1 mm, air-dried at room temperature for 24 hours, and then cured at a temperature of 150 ° C for 2 hours.

Take it out of the mold and use a bending strength tester to measure this test piece for 2 m.
Bending strength was measured at a load rate of m / min.

7. Adhesion Using a 10 mm x 0.6 mm x 40 mm alumina ceramic substrate as a test piece, apply a coating material to an adhesion area of 5 x 10 mm, bond the test pieces, and air-dry at room temperature for 16 hours, then at a temperature of 150 ° C. Two
Allow to harden for hours. 5m of this adhesion test piece with a tensile tester
The tensile shear bond strength was measured at a load rate of m / min, and this value was taken as the adhesion.

Claims (1)

[Claims] 1. A resol type phenolic resin comprising a thermosetting resin, a thixotropic agent, a filler, an additive and a solvent as an essential component, and a thermosetting resin component using a nitrogen-containing compound catalyst. A coating material for IC or hybrid IC, wherein the agent component is an organic thixotropic agent.