KR950012100B1 - Process for forming a coating on a substrate using a silses quiozane resin - Google Patents

Abstract

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Description

Method of forming protective film of silsesquioxane resin using silane hydrolyzate solution

The present invention relates to metastable silane hydrolyzate solutions and methods for their preparation, and more particularly to the use of such metastable solutions for coating substrates with protective films of insoluble silsesquioxane resins. Such a paint can then be ceramicized by heating to form a flattening film on the substrate.

The present invention provides a relatively simple synthesis process for forming silane hydrolyzate which forms insoluble hydrogen or hydrogen and methylcopolymer silsesquioxane resin upon solvent removal. The hydrolyzate composition is metastable in solvent solution but becomes insoluble after coating on the substrate. Hydrolyzate compositions are described as metastable because they cause relatively small changes in the solvent solution resulting in gelation of the hydrolyzate. Resins are useful as planarizing paints for substrates such as electronic devices and can be ceramicized by heating to form ceramic or ceramic coatings on such substrates.

According to one embodiment of the invention, the general formula wherein the silanol content in the final product is about 1 to 10% by weight A method of preparing a metastable silane hydrolyzate wherein R is hydrogen or a methyl group, n is an integer of at least about 8 and x is a number from 0 to 2 is provided. For practical purposes of the present invention, x will be a number less than one. For example, when x is 0.06, the silanol content of the silane hydrolyzate is about 2%. When X is 0.26, the silane content of the silane hydrolyzate is about 8%. Preferably, the hydrogen constitutes at least 50% of the R group relative to the silane hydrolyzate.

The method includes adding chlorosilane of the general formula RsiCl ₃ , wherein R is hydrogen or methyl group, to form a reaction mixture with water or hydrochloric acid-containing polar organic solvent. Substantially more stoichiometric metal oxides are added to the reaction mixture. The metal oxide acts as a scavenger for hydrogen chloride and as a source of continuous water formation during the reaction.

The reaction is initiated by adding an effective amount of water or hydrochloric acid to the reaction mixture. An effective amount of water or hydrochloric acid is substantially less than the stoichiometric amount (based on the water of the chlorosilane reactant) and may be less than 10% of the stoichiometric amount. In addition, the amount of water or hydrochloric acid present is insufficient to form a separate aqueous phase in the reaction mixture.

It has been found that a small amount of hydrochloric acid initiates a hydrolysis reaction because the reaction of the acid with the metal oxide forms water and metal chlorides. Preferably, the metal oxide is selected to form an insoluble metal chloride precipitate so that it can be easily removed from the hydrolyzate in solution. By washing the hydrolyzate the chloride residual of the composition is very low (ie less than 500 ppm residual chloride). If an effective amount of water is present, chlorosilanes are reacted and hydrolyzed in the reaction mixture and then condensed to form metastable silane hydrolysates.

In a preferred embodiment, the metal oxide is selected from CuO, ZnO, MgO, CaO, Cu ₂ O and mixtures thereof. The organic polar solvent selects the silane remaining in the hydrolyzate as being capable of bonding a group and hydrogen. The solvent does not contain sulfur and is preferably an aprotic oxidized solvent selected from ketones, esters and mixtures thereof. Specific examples of solvents useful for practicing the present invention include ethyl acetate, methyl isobutyl ketone, tert-butyl acetate, diethyl ether and mixtures thereof. The concentration of hydrolyzate produced in the solvent is maintained at a lower concentration with the longest stability in solution, from about 1 to about 25 weight percent, ie less than about 5 weight percent.

The process of the present invention produces a composition wherein the silane of the dissolved hydrolyzate has a content of about 1 to 10 weight percent, preferably about 4 to 8 weight percent. It is believed that the groups of these silanes in the hydrolyzate will hydrogen bond with the solvent to reveal their stability in solution. Subsequent addition of a solvent without hydrogen bonding capability and / or evaporation of the solvent for hydrogen bonding causes the hydrolyzate composition to condense the silane into an insoluble product with only 0.2 to 0.9% residual content.

Another aspect of the invention is the general formula (I) Wherein R is hydrogen or methyl group, n is an integer of at least about 8, x is a number from 0 to 2, and comprises a sulfur-free polar organic solvent containing a composition of About 1 to 10% by weight, preferably about 4 to 8% by weight, of a metastable silane hydrolyzate solution. Preferably, the concentration of hydrolyzate in the solution is about 1 to about 25 weight percent. Again, sulfur-free organic polar solvents are selected based on their ability to hydrogen bond silanes with groups in the hydrolyzate, preferably ethyl, acetate, methyl isobutyl ketone, tert-butyl acetate, diethyl ether and its Choose from mixtures.

The present invention can be used to form a protective film of silsesquioxane resin on a substrate. This method is the general formula (Ⅰ) A silane in the composition comprising a sulfur-free polar organic solvent containing a hydrolyzate composition wherein R is hydrogen or a methyl group, n is an integer of at least about 8 and x is a number from 0 to 2. A substrate having a content of about 1 to 10% by weight, preferably about 4 to 8% by weight, coated on the substrate, followed by evaporation of the solvent to condense the silanol and then a substrate containing about 0.2 to 0.9% residual silane And depositing an insoluble silsesquioxane resin paint on it. The insoluble silsesquioxane resin paint can then be converted to a ceramic or ceramic coating by applying the insoluble silsesquioxane resin paint to an oxidizing atmosphere at a temperature of about 100 to about 1000 ° C.

The metastable silane-containing hydrolyzate of the present invention can be applied onto a substrate by a variety of known processes. For example, the solution containing the hydrolyzate may be coated onto the substrate by spray coating, dip coating, flow coating or spin coating. The use of the metastable hydrolyzate of the present invention is particularly advantageous for applying a planarizing paint on a substrate, such as an electronic device, as the first layer in a multilayer coating. Since the resin dries the coating film, many thin coating layers can be easily formed.

It is therefore an object of the present invention to provide a relatively simple synthesis process which is metastable in solvent solution but forms a silane-containing hydrolyzate composition of insoluble hydrogen or hydrogen and methyl copolymer silsesquioxane resin after coating on a substrate. . These and other advantages of the present invention will become apparent from the following detailed description and the appended claims.

The present invention provides a method useful for forming a methyl copolymer silsesquioxane resin film with insoluble hydrogen and hydrogen on a substrate, and an article resulting from the method. The present invention is particularly useful for coated substrates that are susceptible to moisture and other environmental conditions such as electronic components and electronic circuits. Resins with a low chloride residual content (eg, less than 550 ppm residual chloride) are also advantageous. Insoluble silsesquioxane resin paints prepared by the process of the present invention convert the good precursors into silica films and provide continuous application of additional coatings such as passivation and barrier layers to provide complete welding to electronic components and electronic circuits. It is prepared by a method for providing an adhesive base film for.

The process of the invention uses chlorosilanes of the general formula RSiCl ₃ , wherein R is hydrogen or a methyl group, as starting material. It is believed that the chlorosilane starting material is placed in a polar organic solvent containing water and hydrochloric acid and also containing a substantial stoichiometric amount of metal oxide and then added to the reaction mixture to react as follows:

The hydrolyzate formed is represented by the general formula (Ⅰ) Where R is hydrogen or a methyl group, n is an integer greater than or equal to 8 and x is a number from 0 to 2. If the chlorosilane starting material comprises a mixture of hydrogen and methyl moieties, the resulting hydrolyzate is a copolymer. The ratio of hydrogen to methyl in the copolymer can vary over a very wide range. Preferably, however, the molar ratio of hydrogen to methyl in the copolymer is at least one.

As can be seen from Scheme 2, the metal oxide is believed to react with hydrochloric acid to form the corresponding metal chloride and water. Therefore, even if only a small amount of effective amount of water or hydrochloric acid is present, the reaction will be initiated. The metal oxides used may be CuO, ZnO, MgO, CaO, Cu ₂ O and mixtures thereof. The process of the present invention involves the direct reaction of metal oxides with chlorosilanes. Metal oxides are believed to act only as regenerators of hydrochloric acid scavengers and controlled water. It is believed that the presence of more than an effective amount of water or hydrochloric acid is necessary to proceed with the reaction.

Sulfur-free organic polar solvents are selected based on their ability to hydrogen bond residual silanes in the hydrolyzate with the group. The solvent is preferably selected from ketones, esters, ethyrs and mixtures thereof. Specific examples of suitable solvents include ethyl acetate, methyl, isobutyl ketone, tert-butyl acetate, diethyl ether and mixtures thereof. The concentration of hydrolyzate produced in the solvent is preferably maintained at about 1 to about 25 weight percent to have a lower concentration with the longest stability in solution, ie, less than about 5 weight percent. In general, solutions with concentrations below 5% by weight can remain stable for months, while solutions containing increased concentrations of hydrolyzate can remain stable for hours to days.

The process of the present invention produces a composition wherein the silane content of the hydrolyzate is from about 1 to 10 weight percent, preferably from about 4 to 8 weight percent. This process is in stark contrast to the previous process to produce a nearly completely condensed, soluble hydrogen silsesquioxane resin having a silane content of only about 140-330 ppm (eg, about 0.01-0.03 wt% silanol). Do it. It is believed that these silanol groups in the hydrolyzate of the present invention are hydrogen bonded to the solvent to provide their metastable products in solution. Successive addition of non-hydrogenated solvents and / or evaporation of the hydrogenated solvents condenses the hydrolyzate composition into an insoluble product having a residual silanol content of about 2000-9000 ppm.

The present invention can be used to form a protective film of an insoluble silsesquioxane resin on a substrate such as an electronic component or an electronic circuit. This process includes coating the substrate with a solution containing a sulfur-free polar organic solvent containing the metastable hydrolyzate composition of the present invention and then evaporating the solvent to deposit an insoluble silsesquioxane paint on the substrate. do. The insoluble silsesquioxane paint can then be converted to a ceramic or ceramic coating by applying it to an oxidizing atmosphere at a temperature of about 100 to about 1000 ° C.

The metastable silane-containing hydrolyzate of the present invention can be applied onto a substrate by a number of known processes. For example, a solution containing hydrolyzate can be coated onto the substrate by spray coating, dip coating, flow coating or spin coating. The use of the metastable hydrolyzate of the present invention is particularly advantageous for applying a planarization coating on a substrate such as an electronic device as the first layer in a multilayer coating. Since the resin dries the insoluble paint, a large number of thin coating layers can be easily formed. In addition, the silsesquioxane resin layer provides an adhesive substrate for additional coatings such as passivation layers and barrier layers.

In order that the present invention may be more readily understood, the following examples have been cited in describing the present invention, and are not cited as suggesting the scope of the present invention.

Example 1

In order to assess the effect of water initially present in the reaction mixture, ethyl acetate solvent and copper (II) oxide are dried before use. Ethyl acetate is distilled off over phosphorus pentoxide. Copper (II) oxide is placed in a vial under vacuum and heated for several hours. 2.70 g of trichlorosilane is added to the rapidly stirred mixture of 2.36 g of 'anhydrous' CuO in 25 ml of 'anhydrous' ethyl acetate for 1 minute. No exothermic and color change is observed before adding water. After about 30 minutes, a small amount of water (about 0.51 ml) is added to the reaction medium. Within 30 minutes of the reaction proceeding, a dark brown solution is formed. The clear solution is decanted from the dark brown CuO / CuCl ₂ mixture and washed with distilled water. Place the clear solution on an evaporating dish. 0.54 g (50% yield) of insoluble hydrogen silsesquioxane is collected after evaporation of the solvent. Experiments show that more than an effective amount of water is required to facilitate the formation of silane hydrolyzate.

Example 2

1.35 g (0.01 mol) of trichlorosilane are added to a rapidly stirred reaction mixture of 1.18 g (0.015 mol) CuO (stoichiometric) in 25 ml of ethyl acetate containing an effective amount of water to initiate the reaction. Exothermic reactions are not observed. However, it is slowly observed that the black cupric oxide (II) changes color to greenish-brown, indicating the formation of copper (II) chloride. The solution is then filtered and washed several times with distilled water. The solvent is evaporated continuously to yield 0.14 g (26% yield) of insoluble resin. Analysis of this resin by infrared spectroscopy shows that insoluble hydrogen silsesquioxanes containing some silanol functional groups are formed.

Slowly add trichlorosilane to the reaction medium and study different stoichiometry. 20.2 g (0.15 mole) of trichlorosilane in 100 ml of ethyl acetate are added over 5.0 hours to a rapidly stirred reaction mixture of 12.0 g (0.15 mole) of CuO in 380 ml of ethyl acetate. The clear solution is then decanted from brown copper (II) chloride and washed several times with distilled water. 400 ml of solution is stored for future paint studies. 80 ml of the residue is placed in an evaporating dish. A total of 0.57 g (43% yield) of insoluble resin is collected after solvent evaporation. Infrared spectroscopic analysis of the resin is characterized by the formation of an insoluble hydrogen silsesquioxane containing some silanol functionality.

Example 3

A total of 1.35 g (0.01 mole) of trichlorosilane is added to a rapidly stirred mixture of 1.21 g (0.015 mole) (stoichiometric amount) of zinc oxide in 25 ml of ethyl acetate containing an effective amount of water produced by immediate exothermic reaction. . It is observed that the initially cloudy solution is cleared by precipitation of ZnCl ₂ as the reaction proceeds. The solution is allowed to stand to determine the gel time. When gelling has not yet started, filter the solution. The insoluble resin is then collected after solvent evaporation. The insoluble material obtained after solvent evaporation or after solution gelation is characterized by an infrared spectrometer in the form of an insoluble hydrogen silsesquioxane containing some silanol functionality.

The reaction is repeated using ZnO 1.82, 0.61 and 0.24 g instead of zinc oxide and stoichiometric amounts of calcium oxide (0.83 g), copper oxide (2.13 g) or magnesium oxide (0.60 g). The resulting insoluble resin is collected and applied to an infrared spectrometer to characterize it as a form of insoluble hydrogen silsesquioxane containing some silanol functional groups. The test results are shown in Table 1.

TABLE 1

(s) Equivalent to stoichiometric ratio.

Example 4

Elemental analysis data obtained for insoluble hydrogen silsesquioxane resins isolated from the reactants comprising trichlorosilane and cupric oxide (II) in the above examples are summarized in Table II below.

TABLE 2

(S, br) -wide singlet; (a) Gel permeation chromatography data is obtained by leaching the soluble fraction of the resin with a chlorinated solvent.

A small loss of 3.8% by weight, observed in the thermogravimetric analysis in the absence of air, suggests that a high molecular weight hydrogen silsesquioxane resin is obtained. Gel permeation chromatography (GPC) data is obtained on soluble fraction leached from anhydrous resin by chlorinated solvent. Most hydrogen silsesquioxane resins suggest that small amounts of low molecular weight extrudable components are still present in the resin.

The silanol residues present in the separated hydrogen silsesquioxane resins are observed by infrared spectroscopy. Additional amounts of hydroxyl content of these resins are included before and after solvent removal. Prior to solvent removal, the hydrolyzate was found to contain about 4 to 8 weight percent silanol residues. The silanol content in the insoluble film obtained after solvent evaporation ranges from 2000 to 9000 ppm (0.2 to 0.9%) as determined by infrared spectroscopy. This silanol content is 140-330 ppm higher than the pre-measured content for a nearly completely condensed, soluble hydrogen silsesquioxane resin formed according to the method of Collins and Frye, US Pat. No. 3,615,272. .

All infrared data is obtained using a Perkin-Elmer infrared spectrometer, Model 783 or Nicolet FTIR spectrometer, Model 5 SXB. Elemental analysis of chlorine is obtained by neutron activation analysis performed by Dow Chemical Company. All GPC data is obtained using Hewlett-Packard Gas Chromatography, Model 5840A, Model 18835B and 30m DB-17 Phenylmethylsilicon molten quartz capillary column (0.32 diameter) equipped with a capillary inlet system.

Example 5

Hydrocarbon solvents are used to determine the reaction of trichlorosilane and their effect on the subsequent gelling reaction of silane hydrolysates when exposed to such hydrocarbon solvents. A total of 5.37 g of trichlorosilane is added to a rapidly stirred medium of 4.74 g of CuO in 50 ml of ethyl acetate containing an effective amount of water. The clear solution is decanted from the metal oxide and then washed with distilled water. Then 50 ml of toluene is added to the clear solution. It is observed that the solution becomes turbid immediately. The solution is washed again with distilled water, filtered and placed on an evaporating dish. After solvent evaporation, a total of 0.11 g (6% yield) of insoluble hydrogen silsesquioxane is obtained.

In another reaction, a total of 2.70 g of trichlorosilane is added to a rapidly stirred reaction medium consisting of 2.36 CuO in a mixture of 2 ml of ethyl acetate and 25 ml of toluene containing an effective amount of water. Hydrogen chloride vapor is observed during the washing process prior to gelation of the solution. Minimal reactions are expected to be performed prior to flushing. Similar results are obtained using cyclo hexane instead of toluene and zinc oxide / toluene / ethyl acetate reaction medium.

Finally, a total of 1.35 g of trichlorosilane is added to a rapidly stirred mixture of 1.21 g of zinc oxide in 25 ml of ethyl acetate containing an effective amount of water. After decanting the clear solution from the metal chloride, 100 ml of toluene are added. Removal of ethyl acetate under vacuum results in gelation of the solution. Similar results are obtained using xylene instead of toluene.

Example 6

The reaction is carried out using a methyl iso-butylketone (MIBK) solvent. A total of 2.70 g of trichlorosilane is added to a rapidly stirred mixture of 2.36 g of CuO in 30 ml of MIBK containing an effective amount of water. Within a few minutes the solution turns orange-brown and a green precipitate forms. Mild fever occurs. The solution is filtered and the filtrate is washed five times with 100 ml distilled water. The final wash of the solution is cleared. 9.5 ml of clear solution is placed in an evaporating dish. The solvent is collected after evaporation of 0.29 g (86% yield) of insoluble hydrogen silsesquioxane. Residual clear solution is stored for stability studies. It is observed that the solution gels within 24 hours. Experiments show the stability of MIBK as a solvent for the method of the present invention.

Example 7

The reaction is initiated using diethyl ether solvent. A total of 2.70 g of trichlorosilane is added to a rapidly stirred mixture of 2.36 g of CuO in 30 ml of diethyl ether containing an effective amount of water. Color change is inconspicuous. The clear solution is washed four times with 50 ml of distilled water. During the washing process the clear solution turns yellow, turns white and then becomes clear again. 25 ml of clear solution is placed in an evaporating dish. After evaporating the solvent, a total of 0.27 g (30% yield) of insoluble hydrogen silsesquioxane is collected.

Example 8

A total of 2.55 g of methyltrichlorosilane is added to a rapidly stirred mixture of 2.03 g of CuO in 30 ml of MIBK containing an effective amount of water. It is observed that the reaction solution mixture changes color from black to green over 30 minutes. The mixture is filtered and the filtrate is washed three times with 100 ml of distilled water. The clear solution is then placed in an evaporating dish. After solvent evaporation, a total of 0.47 g (52% yield) of insoluble methyl silsesquioxane resin was collected.

Example 9

A total of 1.35 g of trichlorosilane and 1.28 g of methyltrichlorosilane are added to a rapidly stirred mixture of 2.20 g of CuO in 30 ml of MIBK containing an effective amount of water. After filtration of the resulting solution. The clear solution is washed three times with 50 ml of distilled water. The clear solution is then placed in an evaporating dish. After evaporating the solvent, a total of 0.39 g (yield 40%) of an insoluble copolymer of HSiO ₃ /2-(H ₃ C) SiO _{3/2 having} a ratio of methyl-Si: H-Si of 1: 1 was collected. Proves to form aerial harveys.

Example 10

A mixture of trichlorosilane and methyltrichlorosilane in a rapidly stirred solution of MIBK (25 ml) containing an effective amount of water in a solution containing a total of 5% by weight (H ₃ C) and H-Si hydrolyzate at various ratios (See Table III) to prepare. The clear solution is filtered and washed three times with 30 ml of distilled water. Finally, the clear solution is stored and periodically checked for stability.

TABLE 3

Example 11

Potassium bromide disks are coated with several hydrolyzate solutions prepared in the above examples. Both methyl and hydrogen silane hydrolysates in ethyl acetate are used. In addition, 50 ppm tin 2-ethyl hexanoate, nickel iodide, or platinum acetylacetonate catalyst is added to a slight hydrolyzate solution. No other samples are added to the catalyst.

The coated disc is then oxidized for one hour at 150 ° C. in air. The presence of silanol (Si-OH) residues could not be detected by infrared spectroscopy in any sample heated after 1 hour. Thermal H-Si redistribution reactions are observed by infrared spectroscopy in both catalyzed and uncatalyzed reactions. The test is repeated for 1 hour on other coated discs at 300 ° C. However, no H-Si redistribution reactions are observed for samples containing platinum, nickel or tin catalysts. It is observed by infrared spectroscopy that oxidation of Si-H residues occurs within temperatures between 150 ° and 300 ° C.

Example 12

Several unprotected silicon CMOS devices (Motorla 4011 devices packed by Norsk Industries) were coated with samples of the hydrogen, methyl and copolymer silane hydrolysates prepared in the above examples.

Samples are coated onto the device for 10 seconds using a spin coating process at 3000 rpm. The coated device is then oxidized in air at 400 ° C. for 1 hour.

The 80x magnetization of the individual coated surfaces shows good coverage. These coated devices are exposed to salt spray according to the 1009.4MIL-STD 883C method with several uncoated controls. The salt spray system used is the Associated Environmental Systems, Model MX-9204.

The coated device is removed from the salt spray chamber after 10 minutes and then washed with purified water. The apparatus is then heated at 100 ° C. for 15 minutes to evaporate remaining water. The devices are then tested on a Teradyne Analytical Circuit Test Instrument, Model J133C. The devices that passed the test are again subjected to salt spray. This process is repeated every two hours until the devices are all worn out.

As a result shown in Table IV, it can be seen that the hydrolyzate of the present invention provides better protection to the device than commercially available glass-phase spins. The hydrolyzate of the present invention also performs similarly to fully condensed hydrogen silsesquioxane resins (100-150 ppm platinum catalyst) prepared by the method of US Pat. No. 3,615,272 to Collins and Fryer.

TABLE 4

(a) Equivalent to average for 12 devices in the 4.5 to 16.0 hour range.

(b) It is equivalent to testing five devices.

(c) Commercial products of Allied Chemical

(d) Commercially available products of Petrarch Systems, Inc.

(e) The hydrogen silsesquioxane (condensed) sample is a material containing a platinum oxidation catalyst (100-150 ppm). Specific representative embodiments and detailed descriptions have been presented for the purpose of illustrating the invention from which the skilled in the art can make various changes to the methods and apparatus described herein without departing from the scope of the invention. This will be obvious.

Claims (2)

a) coating the substrate with a solution containing a sulfur-free polar organic solvent containing the product of formula (I), wherein the product has a silanol content of about 1 to 10% by weight, b) evaporating the solvent to deposit an insoluble silsesquioxane paint on the substrate, thereby forming a protective film of silsesquioxane resin on the substrate. Wherein R is hydrogen or a methyl group, n is an integer of at least about 8 and x is a number from 0 to 2. a) coating on a substrate a solution comprising a sulfur-free polar organic solvent containing the product of formula (I) and having a silanol content of about 1 to 10% by weight in the product; b) evaporating the solvent to deposit an insoluble silsesquioxane paint on the substrate; c) converting the silsesquioxane paint into a silicon dioxide-containing ceramic by applying atmospheric oxidation at a temperature of about 100 ° to about 1000 ° C. to form a ceramic or ceramic coating. (Ⅰ) Wherein R is hydrogen or a methyl group, n is an integer of at least about 8, and x is from 0 to 2 It is a number.