DE2225730A1 - Ceramic body and its manufacture - Google Patents

Description

Ceramic body and its manufacture

The invention relates to ceramic substrates for electronic circuit technology and, in particular, bases produced by burning at low temperatures.

For the production of electronic circuits, ceramic under "« layers of high dielectric constant are required. Circuit manufacturing economics require that the dielectric base and the electrode metallization applied to it can be burned at the same time. Since materials based on barium titanate (which the usual used dielectric base) must be sintered at temperatures in the range from 1200 to 1400 ° C the electrode materials have high melting points (so that the exact delimitation of the pattern is maintained during firing •remain); in a corresponding manner, there should also be no reaction enter the substrate while it is burning. Mat has therefore

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expensive, refractory precious metals and alloys of the same are used as electrodes. The USA "Patent 3 ^ 56 3-0 z. B. describes capacitors with a high dielectric constant in which palladium or platinum electrodes are used. There is a need for dielectric substrates which can be fired at temperatures of 1200 ° C. or below and preferably below 1100 ° C. and can accordingly be used in connection with cheaper noble metals such as silver.

The invention provides raw (unfired) ceramic bodies, such as tapes, which exhibit excellent storage stability in terms of their durability properties and which can be fired to form ceramic bodies as low as 1200 ° C. or below. Due to such low firing temperatures, these tapes are compatible with silver, silver / palladium and palladium / gold metallizations (bavr. Combustible with these). Accordingly, significant cost savings are obtained, since the use of higher-melting metallizations is unnecessary. The ceramic · rohbänder are free of solvents and essentially \ consist essentially of the masses with öcr Weight: - composition gernäss Tebelle I, in both contemporary and preferred composition limits mentioned. Table II gives preferred composition limits for component B of Table I, ie the bismuth glass frit. The preferred organic binder (D) is a polyacrylic acid ester. The inorganic components A, B and C must be finely divided Poru Laben, i.e. they are ball-ground to such a fineness that they pass a sieve with a clear mesh size of 0.0 Vl i / im (325-MascVien sieve of the US standard sieve series).

BATH ORIGINAL

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PC-5760

The ceramic raw bodies (four strips) are made from slip "masses or slips, which also form part of the invention and whose constituents are present as a slurry in a volatile, liquid medium in accordance with the components according to Table I in the quantities given there. A preferred liquid medium is essentially formed by water. The slip preferably contains at least 20% water, based on its total solids content. Specifically, the slip is a slurry of finely divided, inorganic, particulate substances A, B 'and C in a mixture with an organic dispersion Binder D in a liquid medium, where, if desired, up to 1 %, based on the content of the slip, of inorganic material, surface-active wetting agent E can be present.

The invention also makes fired or hardened ceramic bodies or "moldings available, which by forming the above-described slip, glazing the slip a film, drying the film to remove liquid medium and firing the resulting, dried ceramic raw tape at temperatures in the range from 900 to 1200 and often from 900 to 1100 ° C with burning times in the range of 10 minutes. up to 6 * 1 hours.

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Tabel

Raw mass

component

Inorganic powder (percent of total inorganic substances)

A) barium titanate ⁺ ^

B) bismuth glass frit ⁴ "'

C) Fe ₀ O * ^

according to the invention

preferred

85-99 85-96 0.5-10 1-6 0.5-5 0.7-3

Organic material ien (percent of gesamtenImorgän is chen substances)

D) Organic., Polymeric binder : internally softened thermosetting resin

E) Surfactant wetting agent

+) finely divided 0-1

2.5-10 0.1-07

T a b e 3 Ie II

Composition of bismuth glass frit

Component GjL ^v .L- $ _

invention «

_22nd

Other oxides ⁴ " ¹ " 30-98
O-6O
1-20
0-5

preferred

46-93 0 "* 10 ·

7-1 ^; i 0-2

-} -) ratio SiO ,. : B ₀ O-? in the range from 0 to 2, preferably 0.5 to 1.5i i ^ s be ahn others over ¹ 1.

++) CdO, UO ₀ , Nb ₀ O ₁ -, BaO, SrO, Κ-Φ, KnO, ZnO and / or

! • ils position η dkr ^ elben. . · ".

BATH ORIGINAL

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PC-2760

To mix up the slurry according to the invention, the intended inorganic powder, a liquid one, is mixed Carrier, an organic, polymeric binder and, if desired a wetting agent.

The inorganic powders (particulate matter) consist essentially of components A, B and C according to Table 1, in which their relative proportions are expressed as percentages of the total inorganic powder material. If more than 99 % barium titanate is present, the fired ceramic body is too porous, and if it is less than 85 $ barium titanate, the dielectric constant becomes too low.

The bismuth glass frit has the composition according to Table II and is made from the intended amounts of the respective oxides or their precursors according to conventional techniques for melting them to a clear mass (in the present case at temperatures in the range from 700 to 1200 ° C) and then Pour the molten mass into cold water to form the frit. The frit is then ball-milled to the desired particle size, especially for a meal of 1 to K hours. ' Then the ball-milled product is classified through a sieve of Q, oHh mm. Clear mesh size (or finer sieve).

For the purposes of the invention, barium titanate and iron oxide are used in a similar way finely divided (so that it passes a sieve of 0.0 ^ 4 lnr / j clear fairy tale size), and accordingly, it can be ground separately in the desired white or ball-milled with a glass frit.

The organic, polymeric binder is an inner-soft part heat-curing Il-arz. older term dea indoor

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a.

calibrated, thermosetting resin refers to a familiar class of thermosetting resins. General is a thermosetting resin a resin that Pliessvertnögen when heated loses and becomes insoluble. In addition, with the internal softening, there is flexibility in the polymer chain built in, and you get a corresponding permanent flexibility. This is in contrast to externally softened resins, where an external Plasticizers in the form of a physical mixture " and could eventually be lost through volatilization, extraction or oxidation. The use of this internally soft, thermosetting resins thus results better dimensional stability, better storage b ^ resistance, better solvent resistance and in more permanent way of calibrated, raw (unfired) ceramic bodies than the use of known masses.

The internally softened, thermosetting resins are medium to high molecular weight, water-insoluble polymers which, after the formation of foils or films from the slips, produce tough, flexible films. These resins slurry containing give, after brief heating (up duration to 15 min.) At moderately elevated temperatures (50 Mr I50 ⁰ C) viscous, en flexible, crosslinked films or FoIj, examples of the polymers for the purposes of the invention are Vinylacetatmischpolyinero, the ^l j to ^c j0 $ of an internally comparing cornonomer (2. B. ethylene, butyl acrylate, vinyl-2-ethyl) ylhexOate, dibutyl maloate) to ^ l contain 0.3 to 10 / j of an Oornonoinerün, the inx-Si- Polymerization is capable of crosslinking the polymer due to heat treatment (e.g. H-Mathylolaot-.v'iarald). Also small amounts of iiiiurekulfuyiiator l; .ör.nen voflici-; ovu um die Vernet:; ungr.reaktion zu L ^ iichlciuif.-fn. To ο: 1ικ: -ι ·

- ⁶ '* SAD ORfGfNAL

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Another group of thermosetting resins divided into soft internals for the purposes of the invention include copolymers of acrylic acid esters with comonomers which are capable of crosslinking when dried, in particular when heated. Acrylic esters, such as "Rhoplex"E-; 52 or "Rhoplex" HA ~ 8 described in Rohm & Haas Bulletin TP-125a _> are commercially available. However, these specific examples of the internally calibrated thermosetting resins for the purposes of the invention are not to be taken in a limiting or exhaustive sense. Other known internally made thermosetting resins can also be used for the purposes of the invention. Preferred binders are polyacrylic acid esters. The thermosetting resin chosen can be of high or low viscosity, but must be capable of being volatilized during firing to form a stiff ceramic material. In addition, the resin should provide flexible films that can be stored in coiled form without deterioration. Thermosetting resins exhibit generally acceptable flexibility when the initial modulus is less than 2110 kg / cm ² (30,000 pounds / square inch).

A given component of the slip is a surface-active agent or a hardening agent (up to 1 % of the solids content of the slip). The invention is in practice both with a volatile organic liquid and with water as a liquid medium feasible, although preferably the medium consists essentially of \\ 'as £ -c-; r. When working with water, preferably wetting agents are used. A v. Liquid system is preferred, ixui the difficulties of a

ig & niitte] · -Systerns, einschlieoslich Yc.vv.n- atmosphere, flammability, and Toriz:.. itat to Yonr ^ id = a, Far läisnt nicii the iierstcllung of vrassrinen Syst Orjen and ÖIE anschliessc-snde handling and

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Formulation of ceramic bodies from them is much easier than with organic solvent systems.

A wide variety of wetting agents such as polyphosphates, tetraphosphates, silicates, monomeric organic surfactants such as substituted polyethylene glycol , kole or anionic organic surfactants such as sodium salts of higher aliphatic carboxylic acids (sodium stearate) can be used as wetting agents for the ceramic particles. Water-soluble, high molecular weight substances are effective wetting agents for the junk particles and also act as emulsion stabilizers. They include carboxymethyl cellulose and its salts, hydroxyethyl cellulose, methyl cellulose, polyvinyl alcohol, substituted polyvinyl alcohols, polyvinylpyrrolidone and proteinaceous materials (e.g. casein). The wetting agent in the slip facilitates the formation of homogeneous, uniform slurries with the desired spreadability. Without such an agent, increased mixing is required and uniform, defect-free films are difficult to form. The process of formulating slips and forming films from them is surprisingly easy with wetting agents.

Mixing the ingredients of the Schlioker (in the quantities according to Table I) can be carried out in any conventional manner, as long as the mass is thoroughly mixed to form a homogeneous suspension in order to avoid undesirable streaking, To avoid cracks or areas of poor strength in the final fired ceramic product. In particular Cases in which dispersions of the binder are very stable and have a fairly high amount of surface -, contain active agent, one can use the inorganic, partially ■

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add small material directly to the dispersions, this mixing process is accompanied by movement should be. Particle agglomerates can be cut through sharp Movement can be broken up to surface smoothness - properties to obtain. To ensure, however, that the addition of the particulate ceramic material does not result in a The ceramic particles are often in "shock" of the aqueous polymer dispersion and causes coagulation Predispersed water containing a wetting agent and, if desired, an anti-foaming agent, such as Oetyl « alcohol. This ceramic particle «suspension is then after Very sharp treatment and after removal of air by stirring under the action of heat and vacuum gently with the aqueous dispersion of the organic, polymeric binding «by means of mixed« The resulting slip shows some « sometimes after long periods of standing a slight tendency to Sedimentation of the ceramic particulate material. However, this is not a problem because the particulate Can be easily redispersed by gentle stirring.

A convenient method of mixing the components is a Ball milling of the finely divided, inorganic powder> the binding agent, any surfaces used " active agent and the liquid medium (e.g. water) of about 1/2 to 1 hour, duration, Di © mixed mass is then hefr ^ ifc and after under vacuum from Gaskläsahen a conventional layer formation and / or extrusion » Teehnik, such as squeegee, pouring, etc., apply to a smooth surface.

"The weight ratio of inorganic material to ge" The entire liquid medium in the slip can be chosen very differently, but should be as high as possible

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while it is still possible to form a good dispersion and a good ceramic film therefrom. A high ratio of inorganic material to liquid medium reduces the shrinkage that occurs in the ceramic film during firing. Furthermore, in those cases in which the film is to be formed by extrusion techniques, a highly viscous paste is required, and the content of the liquid medium should be very low. In particular, when producing the unfired (raw) tape according to Giessteehniken, such as by knife coating, viscosity values of the dispersion such as 200 cP (determined with the Brookfield viscometer at 100 rpm) to 1200 cP have proven to be desirable. With the wide variety of available application methods, viscosity values from 50 to 5000 cP (determined with the Brookfield viscometer at 100 rpm, and up to 20,000 cP (determined with the Brookfield viscometer at 10 rpm) can be used in general, when working with water as the medium, at least 20 % of the total weight of the slip is formed by water.

The cast body or film is then conventional TroekhunB3 method (e.g. using infrared, air drying, Oven pan) to remove substantially all of the liquid medium. Dan drying lets itself through Accelerate heating to a temperature of up to 150 ° C.

The film that is still in contact with the support surface can be removed from this and many more treatment stages, such as coating, molding, embossing and the like. On the other hand, you can watch the movie, though if it is on a flexible surface, wind it up in the form and store it. These familiar techniques are described in U.S. Patent 2,966 / 19.

- 10 - BATH

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The raw strip obtained in this way has the composition according to Table I. After drying, only traces of liquid remain Medium back * The tape has an excellent shelf life, with at most minimal swelling is to be observed. The tape can be cut in the desired manner and printed with metallizations. Since the raw strip sinters at a low temperature (it is believed that among the inorganic substances, chemical Reactions occur), cheaper metallizations such as silver, silver / palladium can be used for printing patterns and palladium / gold, and the printed raw tape can then be used at temperatures in the range of 900 to 1200 ° C with treatment times of 10 minutes to 64 hours. When you are naturally wet, you choose time and temperature so that the dielectric properties of the product are maximized. This is how you work if you choose a low one Temperature preferably with longer burning times, and in a corresponding manner when using a high temperature short burning times, such as 10 to 15 minutes, acceptable,

The following examples, in which as well as otherwise here Parts, proportions and percentages for the materials or components are based on weight, serve to further explain the invention. '

The dielectric constants are according to the equation

K -

0.0805 A

where C =: capacity in pP,

• 2 A - · Electrode area in cm and d - dielectric thickness in cm.

* - 11 -

209850/1228 bath

The loss factors (DP) are according to the equation

DP - daily

has been determined in which _;

J = loss angle and '

Q = figure of merit.

The glass frits used in the examples were produced as follows: The oxides were weighed out and mixed. To form a clear, homogeneous melt, the mixture was melted in a DistheiWriegel at 700 to 1200 ° C and the melted glass was poured into cold water to form a pritte, which on a normal amount (corresponding to half-filling) of coolant ( Ceramic balls) and the correct amount by weight of water provided ball mill was ground until less than 1 % residue was retained by a 4oö-mesh sieve (US standard).

The barium titanate and F ^ pO used in the examples were also ground to such a fineness that they passed through a ^ OO-Maachen sieve.

Be i s ρ ie 1 e 1, to 1?

In each of these examples ceramic bodies (strips) were produced as follows, for which the glass frits 1 to 17 with the composition according to Table III were mixed with barium titanate and iron oxide as follows: In each of the examples, 57.56 parts of inorganic powder were placed in a ball mill 95 parts of barium titanate., 2.5 parts of Fe ₂ ⁰ ^ and 2.5 parts of the respective Pritte according to Table III, 5. "77 parts of a 2 / sigeii aqueous solution of methyl cellulose as a surface active agent (" Methocel "by Dow 65IIG) ,

«12 -

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6.00 parts of a 46 $ aqueous solution of polyacrylic acid ester as a binder ("Rhoplex" E ~; 52 of Rohm & Haas) and JO, 68 parts of water as liquid Medium abandoned.

The mixture was ball milled for about 1/2 to 1 hour and then freed of gas bubbles in a vacuum and the resulting slip on a flexible, polyethylene-coated Polishing pad made of polyester ("Mylar") cast on the by means of a set to a distance of 1/4 mm Squeegee a layer was formed. After 15 to 45 min. Drying at 80 to 90 ° C was 1/10 mm as the product thick raw caramel wrap.

In each example, the raw film was placed in squares of j5 »0 cm Cut up the sides and put on a silver paste (3 parts of silver per part of inert, liquid carrier) in a thickness of 1/80 mm in screen printing (clear mesh- ' width of the sieve 0.044 mm) metallized, the electrode area being 4.06 × 2.36 mm. The metallized Ceramic tapes were then made in the desired order piled up and pressed into a monolithic Laminated structure. The laminate was made by increasing the temperature from room temperature to 500 ° C at one rate Fired at below 10 ° c / min to organic Burning off substances, whereupon the temperature increases to 920 ° C and 30 minutes at this value. On that the dielectric constant and dissipation factor of each sample were determined (see Table III).

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m
> Example Bi ₂ O ₅ PbO Glass fri B ₂ C ₅ D ORK 95.0 0 SiO ₂ 5.5 I. 86.0 0 5.5 7.0 2 87.5 5.5 7.0 5.5 5 82.0 11.0 5.5 5.5 4th 75.0 11.0 5.5 7.0 5 75.0 20.0 7.0 5.5 ro 6th ββ, ο 22.0 5.5 7.0 co 7th 5?, O 4C, 0 7.0 5.5 00
cn 8th 46.0 4o, o 5.5 7.0 O ¹ 9 80.0 11.0 7.0 5.5 • a * 80th C. 11.0 5.5 5.5 N)
K) ¹ 11 80.0 11.0 5.5 5.5 00 12th So, c 11.0 5.5 5,!? 15th 8o, o 11.0 5.5 5.5 80.0 11.0 5.5 5.5 13th So, c 11.0 5.5 3.5 So.o 11.0 5.5 5.5 17th 5.5

Table III Glass Frit Z Composition. Wt.% COEO WO Kb ₂ O ₅ BaO SrO ZnO MgO FmO

2.0

2.0

2.0

2.0 2.0

2.0

2.0

2.0

loss
factor, kHz O
\!> 4 2.0 Ch
O Properties at 1 2.4 Dielectric
citiy con
stante 2.5 785 2.5 818 1.9 850 1.8 728 1.7 717 2.2 756 2.1 * 820 5.0 S. 710 2.7 782 6.2 928 2.9 894 2.5 965 5.0 865 5.2 857 5.5 975 ro
ro
ro
cn 800 co
O 827

PC-3760 example 18

The two experiments in this example show the effect the presence of iron oxide on the dielectric constant and dissipation factor, with the glass frit of Example 4 was used. The tape production method of Example was used to produce metallized substrates 1 to 17 with the following amendments.

In experiment A, 55.5 parts of Hasser, 10.0 parts of a 2% aqueous solution of methylcellulose as a surface-active agent ("Methocel" 64 HG from Dow), 85.44 parts of baritimtanate, 0 , 96 parts of Pritte and 10.1 parts of a 40 # strength aqueous solution of polyacrylic acid ester as a binder ("Rhoplex" V-32 from Rohm & Haas).

In experiment B, the tape was made from the following components: 55.5 parts of water, 10.0 parts of the 2% aqueous methyl cellulose Lb'sraig, 88.8 parts of barium titanate, 24.4 parts of Fe ₀ O, 4.8 parts Glass frit and 10.3. Parts of the aqueous polyacrylic acid ester solution.

The tapes were made using palladium / gold plating metallized, the 10 parts Pd and. Contained 90 parts Au, with 5 parts metal per part inert, more liquid Trager templates. '

The metallized strips in front. A and B were each JO Hin. Fired at IO5O ⁰ C. As Table IV shows, j st die. The dielectric constant in experiment B, in which the inorganic powder contains Fe ₂ O- _7. , Prite and barium titanate, is significantly improved compared to that in experiment A (barium titanate and frit). In contrast to the excellent results shown in "Table IV, this was when fired

~ 15 -

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4th

Band containing barium titanate as the sole, inorganic component, at the same time and in the The product obtained at the same temperature is so porous that it easily disintegrates.

Examples I9 to 25

In each of these examples, further metallized bases were produced from ceramic raw strips according to the invention as in Examples 1 to 17. The metallization used is given in Table V (each metallization was printed as a paste with a content of 3 parts of metal per part of inert liquid carrier) together with the firing conditions and the dielectric constant and the loss factor of the resulting product. The inorganic mass contained 92.5 % BaTiO, 2.5 % ^Pe ₂ ° v and 5.0 % frit; the pritte contained 82.0 % _{BipO v} 11.0% PbO, 5.5 % SiO ₂ and 3.5 % BgO. The substances introduced into the mixer corresponded to Experiment B of Example

T a b e 1 Ie

IV

" Example l8 -

Test composition of the inorganic own saddle ften at 2

Loss factor, %

AWAY

see Powder , Gei Pe ₂ O-, K BaTiO ₃ Glasfrj tte 0
2.5 95
92.5 5
5 1210
I65O

1.7 5.6

- 16 -

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BATH ORIGINAL.

PO3760

Tabel

- Examples ig up to 25 -

Example metal «Firing conditions, K loss factor, paste C, Std.

. 19th Pd-Au ⁺ ) 900, 4th 1050 3.2 20th Au 950 1 850 2.1 21st Pd-Au 950 1 1180 2.0 22nd Pd-Au 1000 1 1425 3.4 23 Au 1000 1 1425 3.3 24 Pd-Au 1050, 1/2 1650 3.6 25th Pd-Au noo, 1/4 1550 2.8

+) 10 Pd / 90 Au

Example 26

Three silver-metallized bases were produced from ceramic raw strips according to the invention as in Examples 1 to 17 with the modification that the inorganic powder had the following composition: 94.0 parts of barium titanate, 1.0 part of Pe ₂ C ₇ and 5.0 parts of glass frit, The glass frit corresponded to Example 4 (Table III).

53.3 parts of water, 10.0 parts of the 2-liter, aqueous solution of methylcellulose, 92.4 parts of barium titanate, 0.96 parts of Fe ₂ O, 4.8O parts of fruit and 10.1 parts were added to the mixing device Parts of the 46 ^ igen, aqueous solution of polyacrylic acid ester are used.

After burning off organic substances as in example 1 to 17 vmrdo each of the three laminated, metallized children ■ ^! Fired for hours at 9? 0 ° C. The average dial ^ klrizltiitskonatantc at 1. kiln was 1258, and the loss factors ranged from 2.8 to 5.1 %.

¹ Z28 _QAn

BATH

Claims (2)

Claims and the organic, polymeric binder is an internally softened, thermosetting--; Resin, which is present in an amount of 1 to 15 % by weight of the inorganic powder, the slurry, if desired, containing up to 1%, based on the weight of the inorganic powder, of surfactant surfactant and wherein the volatile, liquid medium preferably V / ater int. 2. Keramil-oDhlibodyei ¹ , obtained from dor 5c! Hlickerzusanii'ne; np. & Tsv.ng compliant with claim 1, of excellent lacquer hour range that in porous doors, which is significantly below (\ riv sintering temperature of Bnriuri'.titanat Ijegrn, v, \ x einin Reran.!]: · body is bi ^ ninbiu ¹ , which is essentially aur- an ir. with; ^ mixture of füiriteilicejn, inorganic powder nij t tiii ^ iii content voa A) 85 to 99 Oev. £ to EariurntiVanat, B) 0.5 to 10 Gcv ■ J, ^f > an Binnurbatf ;: '! : -i: = frit and 0) 0.5 bifj 5 Geν;. ^ 'Po ₀ O. ,, and 1 b.i s 15 / ', b -'! / .; o [;.; En auf uhr Gf.v.'icht dor; cinor ^ .aniiicl · ': ■; VuJ vero, an orgradschfi'i, polyi.rroni B ^.: jj ·: '.third ä <i l-ot: n c-ii- - 10 - 209850/1228 sad original Z225730 PC-3760 internally softened, thermosetting resin, and, if desired, up to 1 $>., based on the weight of the inorganic powder, of surface-active wetting agent. Body according to claim 2 in fired form. 209850/1228