KR100516043B1 - Ceramic multilayer printed circuit boards with embedded passive components - Google Patents

Abstract

Passive elements such as capacitors, resistors, and RF filters can be made by screening appropriate inks on green tapes with conductor layers on top and bottom of the constituent ink layers. The resulting green tape stack is fired to form inherent capacitors. By stacking the green tapes stack on a metal support substrate, it limits the shrinkage in the x and y directions, allowing the devices to maintain small tolerances. If many green tapes are to be laminated, more green tapes with an appropriate amount of oxide filler, e.g., less than about 15% by weight of the green tape, such as at least about 25% or more oxide filler of the green tape When inserted with green tape, improved shrinkage characteristics can be obtained.

Description

CERAMIC MULTILAYER PRINTED CIRCUIT BOARDS WITH EMBEDDED PASSIVE COMPONENTS

The present invention relates to a multilayer, ceramic, supported printed circuit board having low two-way shrinkage during firing. In particular, the present invention relates to a metal support multilayer ceramic printed circuit board having cofired passive elements.

When mixing the ceramic composition of crystallized glass with amorphous glass, it is possible to form a green tape composition that can be attached to a metal core support substrate, such as a copper / nickel plated or sheet metal bavar support substrate. It is known. Kovar is a Fe / Co / Ni alloy commercially available from Carpenter Technology. One such alloy consists of 53.8% by weight iron, 29% by weight nickel, 17% by weight cobalt, and 0.2% by weight manganese. These alloys exhibit a sharp change in coefficient of expansion at certain temperatures. The alloys are used by coating copper and nickel to one millimeter thickness on both sides of the coba core. The alloys have a coefficient of thermal expansion (TCE; room temperature (RT) to 300 ° C.) of 5.8 ppm / ° C. and a thermal conductivity (z or thickness direction) of 21.8 Watt / m · K.

In order to use such a coba sheet metal as a support substrate for a printed circuit board, the coba sheet metal is heat-treated in air to oxidize a nickel coating, and then a bonding glass, generally CaO-AL ₂ O ₃ -ZnO-B ₂ O ₃ Apply glass. The adhesive glass can be screen printed onto the support substrate by making a printable ink of adhesive glass powder mixed with an organic binder and a solvent. The adhesive glass is generally attached on the support substrate to a thickness of 40-70 microns. The adhesive glass is then dried and heated to 700-800 ° C. to densify it. About 6% by weight of copper powder may be added to the adhesive glass to improve the adhesion of the adhesive glass to the coba substrate. The coba support substrate thus prepared is used, and when co-laminated in a low temperature calcined green tape composition, the coba support substrate prevents the ceramic layers from shrinking in the x and y directions during firing.

As described above, low temperature calcined green tapes attached to the metal core support substrate to which the adhesive glass is applied are made from a mixture of crystallized glass and amorphous glass.

Suitable crystallized glasses include, for example, 20-55% by weight ZnO; 20-28% by weight MgO; 10-35% by weight of B ₂ O ₃ ; And 10-40% by weight of SiO ₂ . These glasses have a coefficient of thermal expansion (TCE) matching the cobar, and also have low dielectric loss characteristics; However, the glasses have a low crystallization temperature which prevents the densification of the glass upon firing. Thus, these glasses can be mixed with lead-based amorphous glass. Suitably, these amorphous glasses comprise 30-80% by weight of PbO; 15-50% by weight SiO ₂ ; 10% by weight of Al ₂ O ₃ ; 15% by weight of B ₂ O ₃ ; And 10% weight ZnO. However, when the crystallized glass is mixed with lead-based amorphous glass, the TCE is lowered and the dielectric loss characteristic is increased. The lateral contractions x and y are also too large than desired. The addition of small amounts of oxide fillers, such as quartz, alumina, and forsterite, reduces lateral shrinkage during firing, and the ceramics modified by these fillers have the desired dielectric properties, during Low shrinkage, and TCE matching to the cobar.

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Green tape compositions useful herein generally incorporate amorphous glass with an appropriate glass powder comprising crystallized glass of the ZnO-MgO-B ₂ O ₃ -SiO ₂ type, and are generally resins, solvents, dispersants, and the like. It is formed by mixing an organic vehicle containing an oxide and an oxide filler, and then molding the resulting slurry into a thin tape known as a green tape.

The conductive ink may be screen printed on the green tapes to form a circuit pattern. Several green tapes can be aligned, stacked, and stacked under pressure. Via holes formed by punching in green tapes and filled with a conductive ink, such as a conductive metal powder, an organic vehicle, and a mixture of glass used to make the green tapes, are formed on other green tape layers. It provides an electrical pathway between the patterns. These laminated green tape laminates are also co-laminated under pressure in alignment with the support substrate to which the adhesive glass is applied. Since only shrinking in the thickness z direction during firing, the circuit is not disturbed during firing and can maintain close tolerances. Such ceramics are compatible with low melting temperature conductive inks, such as silver-based inks used to form electrically connected circuits on various layers and to form adhesive pads and the like. Thus, ceramic circuit boards as described above have low dielectric loss characteristics and are useful for use in microwave / digital packages.

To date, when a multilayer ceramic circuit board has to include passive components such as resistors or capacitors, it is necessary to use solder or epoxy type adhesives to attach the dispersed components to attach the components to the multilayer ceramic. It must be mounted on top of the firing board. The addition of these devices increases the number of steps needed to make such circuit boards. That is, the devices must be aligned and attached to the ceramic multilayer board and connected to a power supply. Also, in order to accommodate a large number of discrete devices, the multilayer substrate must be large. Therefore, the manufacturing cost of these boards is high.

Being able to screen print passive elements on specific green tapes of multilayer low temperature cofired ceramic circuit boards can increase packing density, reduce packing size and cost, and reduce process steps required There is an advantage to this. The use of recently developed low temperature fired glass and metal support substrates that have reduced shrinkage in the x and y directions allows for precise tolerance device screen printing, and high precision placement. In addition, since fewer interconnects exist, reliability is also improved.

However, when a large number of green tapes are arranged and fired with elements in between, it is difficult to maintain reduced shrinkage during firing and to prevent delamination of the green tape stack from the support substrate.

1 is a graph of dielectric constant versus capacitor size for low dielectric constant inks.

2 is a cross-sectional view showing one embodiment of a buried capacitor of the present invention.

3 is a graph of dielectric constant versus capacitor size for capacitors of the present invention.

4 is a graph of capacitor temperature coefficient vs. capacitor size for capacitors of the present invention.

5 is a graph of dielectric constant versus capacitor size for capacitors of the present invention.

6 is a graph of resistance area versus resistance value and TCR for resistors having a first magnitude.

7 is a resistance area versus resistance value and TCR graph for resistors having a second magnitude.

8 is a cross-sectional view of the multilayer ceramic circuit board of the present invention with embedded silver layers.

9 is a cross-sectional view of the multilayer ceramic circuit board of the present invention with RF filters formed inside the layers.

It has been found that passive elements such as capacitors, resistors, and RF elements can be embedded in green tape stacks made of suitable glass on a support substrate that prevents shrinkage in the x and y directions. Suitable capacitor ink or resistive inks and conductive layers are screen printed on the green tapes, the green tapes being positioned between the other green tapes to produce a printed circuit board having a tight tolerance in which the elements are inserted. And laminated and fired at a constant low temperature, ie 850-900 ° C., so as not to shrink in the y direction and to be delaminated from the support substrate.

Capacitor dielectric inks can be made by sintering at low temperatures by mixing barium titanate, titanium oxide and lead magnesium niobate dielectrics with appropriate glass. The capacitor dielectric ink may be screen printed on ceramic green tapes and connected to the silver conductor layer by vias of the green tape filled with the appropriate conductor ink. After printing the passive element precursor ink and other circuits on the green tape, the multiple green tapes are aligned, stacked and co-fired in air at a temperature of about 850-900 ° C. Capacitors with a wide range of dielectric constants can be made.

Shunt capacitors can also be made by using ground plane metal as the bottom capacitor plate. The capacitors are disposed in one or more layers from above the stack. Capacitors can be terminated by screen printing a conductive layer above and below the printed capacitor dielectric ink.

Thick film resistant inks are made based on ruthenium oxide (RuO ₂ ) and suitable glass sintered at low temperatures with suitable organic vehicles. The resistive ink is screen printed on the arrayed green tapes and laminated on the support and fired to complete the embedded resistors having a wide range of resistive values and resistive thermal coefficient (TCR) values. To adjust the TCR values, a small amount of barium titanate can be added. The resistors are connected to the power source by a conductive layer screen printed on top of the green tape stack. After printing the resistors and other circuits, the multilayer green tape layers are aligned, laminated to each other, attached to the metal support substrate by adhesive glass, and formed to form a printed circuit board having resistances formed therein that are stable and reliable It is cofired in air at a temperature from 780-900 ° C.

It has been found that when lamination of multiple green tape layers is required to produce a fired laminate of about 2 mm thickness or more, de-lamination and shrinkage problems still occur. Thus, by inserting green tape layers containing low dielectric loss glasses mixed with trace amounts of oxide filler into green tape layers made of the same glass containing a higher amount of oxide filler, more green tape layers are inserted in the x and y directions. It has been found that lamination and firing can be performed without shrinkage to and delamination from the metal support substrate. Such thick multilayer metal support circuit board stacks are particularly useful when RF elements must be formed within the stacks.

First, the tester results of embedded capacitors with various capacitor dielectric inks, formation methods, and other dielectric constants are described.

It has been found that capacitor dielectric inks based on barium titanate and titanium oxide powders have a low dielectric constant, K = about 50. These powders are sintered at a temperature of about 1100-1300 ° C., thus allowing the barium titanate / glass or titanium oxide / glass compositions to be sintered at a low temperature of about 850-900 ° C., and controlling the dielectric constant (K) and To minimize the temperature coefficient of capacitance, the powders must be modified in combination with low molten glasses.

Barium titanate is commercially available from the Degussa Company under the trade name AD302L (hereinafter referred to as D), and a mixture of barium titanate and barium tin oxide is traded under the trade name YL12000 (hereinafter referred to as F). It can be purchased from Ferro Corporation. The properties of these powders are presented in Table I below. In Table I, the dielectric loss is Tan And the temperature is in degrees Celsius. Particle size is expressed as average particle size in microns (μm).

Suitable titanium oxide, # 4162-01, can be purchased from Mallincrodt Baker Co.

Prior to making the capacitor dielectric ink composition, barium titanate or titanate oxide powder is mixed with various low firing temperature glasses. The weight percentages of the appropriate glass compositions are shown in Table II below.

* Is glass available as SCC-11 from Semcom. Representative low dielectric constant capacitor dielectric inks were made of barium titanate powder mixed with various glass and glass mixtures, along with conventional dispersants, resins, and solvents, and screen printed on green tapes. The ink compositions are summarized in Table III below. Here, the glass compositions are as shown in Table II.

The capacitor dielectric ink can be screen printed on a metal phase, in particular on green tapes formulated on a kovar support substrate, for simultaneous firing. The primary crystallized glass used comprises the following oxides: 29.4% ZnO, 24.5% MgO, 19.6% B ₂ O ₃ , 24.5% SiO ₂ , and 2.0% Co ₃ O ₄ . Make a mixture. Typical green tape compositions are as shown in Table IV below.

The capacitor dielectric inks are screen printed on the green tapes in square capacitor patterns of 1.27, 2.54 and 5.08 mm sizes. From the top of the stack are made three four-layer green tapes with one layer of the capacitor dielectric ink layer. The green tapes are stacked at 278 psi and co-laminated on the cobar substrate at 347 psi. Silver based powder or silver flake based conductor ink is embedded to make an embedded cofired capacitor. Suitable conductor ink compositions are shown in Table V.

The resulting laminated laminate was fired at 850 ° C. Capacitance and dielectric loss (tanδ) are measured at 10 Hz. The dielectric constant of each capacitor is calculated from the measurement of capacitance C of ㎊, capacitor area A of square centimeter and thickness of centimeter according to function K.

K = Ct / Aε ₀

Here, epsilon ₀ is a constant of 0.0885 dl / cm. These capacitor dielectric inks are suitable for operation at high frequencies (1 Hz). The capacitor sizes and characteristic measurements are presented in Table VI below, where the thickness is for the firing capacitor, the capacitance is in units of mm / mm2, the dielectric loss is given as tanδ, K is the dielectric constant, and TCC is given in ppm / ° C from room temperature (RT) up to 125 ° C. In Table VI, the glass is given in volume%, except as noted elsewhere.

Additional low dielectric constant capacitor dielectric inks made of barium titanate are screen printed to form capacitors of various sizes, stacked at 1670 psi, terminated by a silver ink layer, co-laminated in cobar at 1740 psi, and 865 Calcined at < RTI ID = 0.0 > Several screen printing techniques are applied to produce the minimum thickness of the fired capacitor. Its composition, size and plastic properties are summarized in Table VII below. In table VII, the glass is given in volume%.

The magnitude dependence of the capacitance on the unit area, the dielectric constant of the embedded capacitors and the TCC values can be seen. In general, as shown in FIG. 1, the dielectric constant decreases with increasing capacitor size. However, TCC exhibits a greater amount of capacitance. The smaller the capacitor, the higher the capacitance, which may be due to the peripheral capacitance effect and the interaction between the capacitors and the surrounding ceramic layers.

However, the design of high and dielectric constant embedded cofired capacitors (K = 1500) is a more difficult problem. Since capacitor dielectric materials have a high sintering temperature, low temperature firing using the green tapes presented above results in a porous dielectric; The mixture of low temperature calcined glass and barium tinate dilutes the dielectric constant; Ambient low dielectric constant glass-ceramics diffuse into the capacitor to further increase the dilution effect; And the diffusion of silver metal into the capacitor also dilutes the dielectric constant. Thus, the resulting embedded capacitors based on barium titanate are limited to K values of less than 700, as shown in tables VIII and VIII.

Table VII summarizes capacitor characteristics for embedded BaTiO ₃ -based capacitor dielectric inks using a silver powder conductor layer. Green tape and capacitor layers are laminated at 280 psi and fired at 850 ° C. Glass is given in volume%.

The capacitors are then fabricated by stacking the green tape and capacitors at 1670 psi and firing at 865 ° C., as shown in Table VIII. The silver conductors used are silver flakes. The glass is given as volume percent.

The capacitor compositions promote sintering at low temperatures so that the dielectric constant is minimally diluted and can be dissolved in a BaTiO ₃ perovskite lattice structure of PbO, B ₂ O ₃ , ZnO, CdO or PbTiO ₃ materials It is formulated to contain less than 10% by volume of low molten oxides or glass additives. Such firing compositions have a maximum dielectric constant of about 700.

When a low TCC is required, i.e. less than 60 ppm / ° C in either the room temperature to -25 ° C and the room temperature to 85 ° C, the barium titanate-based capacitor type is also suitable. SrZrO ₃ , TCC modulator.

Table VII shows the compositions of two suitable capacitor dielectric inks given in weight percent.

The silver-based inks were 83.78% silver powder, 0.65% glass 3 filler, 4.2% 15% ethylcellulose mixture of texanol solvent, 7.61% 13% elvacite resin. Terpineol solvent mixture, 1.22% Hypermer PS2, and 2.54% butyl carbitol solvent. The bottom electrode is screen printed as a single layer, the dielectric layer is screen printed in three layers, and the top electrode is printed as a single.

The green tape laminate was laminated at 1670 psi and co-laminated on the cobar support at 1100 psi, the whole being baked at 865 ° C. The dielectric constant (K) and TCC at two temperatures are shown in Table II below.

Capacitor dielectric inks with low TCC and low dielectric constant can also be made using titanium oxide (TiO ₂ ) as the dielectric. The dielectric ink contains a mixture of 42.1% TiO ₂ powder, 29.6% glass, 1.4% Hypermer PS dispersant, and 26.9% 20% Elvacite resin terpineol solvent mixture. Make using

The dielectric ink is attached to at least one layer of green tape underneath the top layer of the laminate, to which a finishing layer is attached using conductor ink. The laminate is laminated and fired as described above. TCC and dielectric constant K are shown in Table II below.

It has been found that lead-magnesium-niobate-based (PMN) compositions must be used to achieve higher dielectric constants (K> 1000) of buried cofired capacitors. Appropriately high dielectric constant capacitor dielectric inks based on PMN are summarized in Table II below, where% is the weight ratio.

The use of the lead-magnesium-niobate-based capacitor dielectric inks and co-firing on an alumina support substrate can generate more than 2000 K values of silver powder conductor ink. However, when internally laminated to green tape on a coba support substrate, the K values dramatically decrease by about 30-50 with the aforementioned dilution effects. To obtain a high dielectric constant capacitor on the cobar, a barrier layer can be used that prevents the ceramics from diffusing into the capacitors during the co-firing. Such barrier layers may be made of more efficient silver metal compositions or different dielectric materials.

It has been found that BaTiO ₃ based capacitor dielectric inks can be used as barrier material when using glass of very low melting temperature lower than the glass used in green tape layers. Such barrier glass is densified and crystallized at a temperature lower than the temperature required to soften the green tape glasses sufficiently. Thus, the barrier glass can prevent the green tape glasses from diffusing into the capacitor. In such a case, the barrier is printed as a pad wider than the capacitor below the bottom conductor pad and above the top conductor pad, as shown in FIG. 2. In FIG. 2, a three layer capacitor 12 having two layers of top and bottom layers 14 and 15 respectively is located between two top and bottom barrier layers 16 and 17. The embedded capacitor is in turn stacked on each of the upper and lower green tape layers 18 and 19.

As previously described, the barrier layer as a 19 × 19 mm pad around a 5.08 × 5.08 mm capacitor made of PMN ink containing 74.16% PMN, using a capacitor dielectric ink comprising glass 6 and 71.07% BaTiO ₃ . Is printed. Silver powder is used to make the conductor ink. Various layers were employed to determine how much barium titanate barrier layer is required to obtain a high dielectric constant capacitor on a Cova supported multilayer circuit board. Control without the barrier layers was also tested. The experimental results are shown in the table XVI below. Here, the number of printing is the number of screen printing for each layer.

As such, when a barrier layer of minimum thickness is presented, the dielectric constant becomes much larger than when no barrier layer is used or when a thin barrier layer is used. Using double metallization printing and double barrier layer printing, an embedded capacitor with a high dielectric constant was obtained. By increasing the number of barrier printings on one side of the conductor layers by three times, dielectric constant (K) values of 3000 or more could be obtained. Although high dielectric constant capacitors can be manufactured through the process described above, some special printing steps are required, and the barrier thickness must be about 16-20 microns in order to be effective.

In addition, due to the thickness of some barrier layers, conductor layers, and capacitor layers, care must be taken as the upper green tape layer is easy to tear. In addition, if a very large number of screen printing steps (up to eleven times in the above description) are required, the process cost increases.

Thus, a more effective barrier with a reduced number of printing times and a reduced thickness without tearing the green tapes has been found, and a modified embedded capacitor dielectric ink has been found.

It has also been found that the mixture of silver flakes and silver powder as the conductor layer forms a very effective barrier layer that is superior to using only silver flakes and silver powder. Silver powder inks form capacitors of low dielectric constant. Silver flakes alone form a very good barrier layer (K = 3600), but cause the top green tape layer to tear during lamination or firing. Thus, although not an excellent barrier to silver flakes alone, a mixture of 75% weight silver flakes and 25% weight silver powder allows for the production of high dielectric constant capacitors. However, outgassing of capacitors during firing is a problem. If the silver metal has sealed the capacitor very well, the gases formed from the additional material (including PbO) may not be released. Thus, while the silver flakes form a high dielectric constant capacitor, the silver flakes form a structure that becomes denser during firing, causing the green tapes on top torn. Thus, although the use of a mixture of silver powder and silver flakes is a compromise in dielectric constant, not only do the top green tape layers tear, but these structures do not cause gas emissions or bubble problems.

Many embedded PMN-based capacitors on a COVA substrate are formed using silver powder, silver flakes, and mixed silver powder and silver flake conductor layers. The layers were laminated at 1670 psi and fired at 865 ° C. The results are summarized in table XV below.

The insulator resistance (IR) of the first capacitor of 5.08 mm size is 3.8 × 10 ¹⁰ mA. The IR of the 5.08 mm second capacitor using silver flakes is 6.0 × 10 ¹⁰ Hz. The IR of the first capacitor of the same size using the mixed silver is 1.0 × 10 ¹⁰ Hz.

The embedded capacitors formed from the mixture of silver flakes and silver powder as a conductor layer require smaller printing steps without creating a problem of bubble or gas emissions. It is noted that there is no tearing of the green tape layer located on top.

The dielectric constant of the PMN capacitors shows a large size dependency: that is, the dielectric constant increases as the capacitor size increases, and the TCC also increases (more negatively) as the capacitor size increases. This is the result of dilution of the capacitor dielectric by the surrounding low dielectric constant ceramic. Wide capacitors have a weaker dilution effect than small capacitors. This phenomenon is shown in Table XVI below, and a graph of dielectric constant and TCC versus capacitor size is shown in Figures 3 and 4, respectively. In Table XVI, the capacitors are based on the PWN of the silver powder-silver flake mixed inks.

Barium titanate-based buried capacitors in the middle range (K = 500-700) are made of the same mixed silver flake / powder conductor layers stacked at 1670 psi and fired at 865 ° C., but the size dependence is different.

FIG. 5 shows a graph of dielectric constant versus capacitor size using mixed silver conductors, and FIG. 5 illustrates the difference in size dependence of barium titanate-based capacitors and PMN-based capacitors. Thus, for applications requiring intermediate dielectric constant values, the barium titanate-based intrinsic capacitors are more consistent and have a lower TCC compared to PMN-based capacitors.

The inherent capacitors of the present invention, i.e., one or more buried tapes below the top of the stack, have a HHBT reliability test (85 ° C./85%/50 VDC) for more than 1000 hours without capacitance decay, insulator resistance (IR) or dielectric loss of the buried capacitor. Received.

The co-fired multilayer ceramic circuit board with buried capacitors of the present invention is useful in a variety of applications such as cellular telephones.

Formation of various resistance inks, methods of forming resistances therein, and inspection results will be described in detail below.

Resistive inks having resistance values of TCR from 300 ohm / sq to 100 Kohms / sq and <+200 ppm / ° C. can be prepared according to the invention. Targeted properties for application to specific cellular telephones are TCRs below 200 ppm / ° C from 1 Kohm / sq and up to 125 ° C from room temperature.

The resistive inks are made of a material of refined particle size and high surface area RuO ₂ having the characteristics as outlined in Table XVI.

The RuO ₂ is mixed with one or more glasses to reduce the firing temperature of the conductor powder. Glass 1 and 3 presented above are suitable. TCR modifiers such as BaTiO ₃ are also added.

The glasses are mixed with RuO ₂ , optional modifiers, and appropriate organic vehicles to form a screen printable composition that can be fired at a low temperature similar to the firing temperature of the green tape laminates to be applied. The resistive ink powder generally comprises 17.33 to 24.8% by weight of RuO ₂ , 74.3-81.7% by weight of glass 1, and 0.99 to 1.10% by weight of barium titanate. Preferred compositions consist of 19.8 to 23.14% by weight of RuO ₂ , 75.87-79.21% by weight of glass 1, and 0.99 to 1.1% by weight of BaTiO ₂ .

Resistive inks are screen printed in various patterns (1/2 square and square) of size 0.508 × 0.508 to 2.032 × 4.064 mm on the green tape to be a laminated green tape laminate. Green tape compositions suitable for use of the resistive ink include the following components summarized in Table XVI. The median particle size of the glass and filler is in macrons.

The resistors were finished with silver conductor screen printed. Suitable silver ink compositions include 83.78% weight silver powder, 0.65% weight glass 3, 1.22% weight dispersant, 0.88% weight ethyl cellulose resin, 0.80 elbasite 2045 resin available from Monsanto Company. ), And a mixed solvent of 3.32% by weight texanol, 6.81% by weight terpineol, and 2.54% by weight butyl carbitol.

The green tape laminates were stacked together and co-fired in air at 850-900 ° C. on a coba support substrate. The resistors are printed and embedded in one layer below the top surface of the ceramic laminate. After co-firing, the resistors were connected to the outside by printing silver-palladium or gold conductor ink and post-fired in air at 700-750 ° C.

Table VI below summarizes the properties of RuO ₂ -glass compositions and fired resistors. In Table VI, the composition is% weight and TCR is a measurement from room temperature to 125 ° C. A short term overload test (STOL) was also implemented.

Therefore, it is effective to use glass 3 to form high value resistors of 2 Kohms / sq or more. The compositions of Glass 1 were selected for 1 Kohm / sq resistance development.

The resistive compositions are composed of dispersant (1.44% weight), ethyl cellulose resin N300 (0.10% weight), Evasite resin 2045 (3.9% weight), and 25.18% weight tepineol and butyl calvi to form an ink composition. It is mixed with organic 비 erk using tall mixed solvent. The resist ink is adjusted to about 38% solids.

In order to minimize circuit density, it is desirable to print small sized resistors, such as a 0.508 × 1.016 to 1.016 × 2.032 mm pattern, which can achieve a 510 Ohm resistance. Various resistive inks were prepared while varying the proportion of solids or maintaining a dispersion concentration of 2% weight of the total powder weight to control the resistance and TCR values while maintaining a volume of 38%. Powder compositions of useful resistance inks are summarized in Table VII below.

Suitable resistive ink compositions for making the powder mixtures are shown in Table II below.

After screen printing the resistors on one of the 4-5 layer laminated green tapes co-laid on baba at 850-900 ° C., apply a top surface conductor ink made of silver-palladium or gold, and at 750 ° C. Post fired. The resistance is measured at DC or low frequency (10 Hz), and TCR is calculated from the resistance measured at room temperature and 125 ° C. The results are shown in Table II below.

It can be seen that the resistance values increase by an average of 7.3% after post-firing at 750 ° C. In addition, the resistance values increase as the resistance size increases. The increase in resistance value with size is due to the dilution by the silver finish conductor layer during firing which reduces the sheet resistance of the small sized resistors.

Additional resistances from resistive ink compositions 1 and 2 are shown in the following Tables II and IV, respectively.

The printing thickness of the 1/2 sq. 1.02 × 2.03 mm resistor was 18.6 microns.

Data of the resistors of the resistive ink composition 1 are shown in FIGS. 6 and 7. 6 and 7 are graphs of resistance area versus resistance for each of (1) square and (1/2) square resistors.

The resistors were also tested for reliability. Test 1 was for 1000 hours at 85 ° C./85%RH, and Test 2 consisted of more than 200 repetitions between −55 and 125 ° C. In inspection 3, 15.5 Watts / cm 2 was applied to the resistance at 70 ° C. for 1000 hours. The resistors went through these tests.

Resistor Ink 1 is used to fabricate a 510 ohm buried resistor measuring 1.016 x 2.032 mm on a receiver board designed for operation at 1 kHz. If the dried thickness is maintained between 18 and 25 microns, after post firing, a resistance of 510 ohms of ± 10% can be obtained.

The ceramic printed circuit board of the present invention is also useful for forming other elements such as RF filters. In such a case, after firing, a thick multilayer laminate having a thickness of at least 2 mm is made. However, many green tape layers after firing impede precise control of shrinkage in the x and y directions, and also, multilayer laminates tend to be unlaminated from metal support substrates upon firing.

Therefore, a method has been developed that can control the shrinkage and prevent the non-lamination of many thick green tapes from the metal substrate. More green tape layers by interleaving green tape layers made of low dielectric loss glasses mixed with a small amount of oxide filler together with green tape layers made of the same glass mixed with a higher amount of oxide filler It has been found that they can be fired, laminated and formed into a laminate without shrinking in the x and y directions and delaminating from the metal support substrate. Such thick multilayer metal support circuit board stacks are particularly useful when RF elements must be formed within the stack. Useful conventional glasses used to make one type of green tape are made from zinc-magnesium-borosilicate crystallizing glasses, as described above. Suitable crystallized glass is Glass 3 above, with 2.0% weight of Co ₃ O ₄ colorant added.

This glass is mixed and mixed with 9.6% by weight of amorphous lead-based glass in a lead-zinc-aluminum silicate system. Typical glasses include 42.0% PbO, 10.0% Al ₂ O ₃ , 38.8% SiO ₂ and 10.0% ZnO.

These crystallizing-non-crystallizing glass mixtures provide alumina, cordierite, quartz, cristobalite and posterlite for reduction control and TCE modification. compound with oxad fillers, such as forsterite, and willemite. A second oxide filler may be added to achieve dielectric properties, shrinkage properties, and TCE that correspond to COVA. For example, traces of filler oxards, for example 1.5-2% by weight of coirlite and 9.5-10.0% by weight of phosphoruster, produce excellent ceramics in this application.

Thus, these glasses have a large amount of glass and a small amount of oxide filler (<15%). These glasses have good dielectric properties at microwave frequencies such as 1 kHz. These ceramics are hereinafter referred to as type 1 glass-ceramics.

The second type of glass-ceramic is made from the same zinc-magnesium-borosilicate glasses, but they contain an increased amount of oxide filler of at least 25% by weight. Such glasses have smaller shrinkage properties than type 1 glass-ceramic, which is subsequently referred to as type 2 glass-ceramic. The following table XXV shows a fourth example of another ceramic composition useful for forming the second type of green tape layer.

Such ceramics therefore comprise a large amount of filler, for example about 25-50% by weight of a filler.

Green tapes are made by formulating type 1 and type 2 glass-ceramics in a resin binder with a plasticizer, a dispersant, and a solvent, as is known to form a thick slurry. Typical glass-ceramic compositions used herein include crystallized glass particle size of about 10-12.5 micron particle size, amorphous glass of about 6.5-8 micron particle size, posterlite of 3-5 micron particle size, and about 2-3 micron Have a particle size cordierite. A suitable ceramic green tape formulation in% weight is given in Table VI below.

The resulting slurry is molded to form a green tape of about 0.15-0.20 mm thick, and the green tape is dried.

Two types of green tapes are interleaved, prepared using trace and large amounts of oxide filler, respectively. Silver or another metal pattern is screen printed to form a circuit pantone on the green tapes. Preferably, the Type 2 (high filler amount) glass-ceramic tends to be porous as soon as it fires than the Type 1 glass-ceramic, so the circuit phantoms have two Type 1 green tapes for the formation of hermetic ceramics. Printed between them.

To provide various conductor patterns on green tapes, co-fireable conductor metal-based thick film conductor inks based on the glass compositions of the present invention, together with known dispersants, resins and solvents for forming screen printable conductor inks. It may be made of a conductive metal powder such as silver powder mixed with the small amount of glass disclosed. Silver-palladium powder or gold powder can be used to make the top conductor ink in a similar manner. Via filled inks for connecting circuit patterns on various green tape layers can be made of silver powder, in a known manner.

The green tape laminate was suitably laminated for 4 minutes at a pressure of about 1.174 kg / mm 2, about 93 ° C., and co-fired with the prepared metal support substrate at a pressure of 1.3-1.4 kg / mm 2. After lamination and co-firing, the multilayer laminate on the metal is fired in a belt furnace up to a 850-900 ° C. peak temperature at a belt speed of 0.4 inch / minute. During firing, the organic materials evaporate and the low molten glaze glass softens, attaching the multilayer ceramic laminate to the metal core. The metal core limits the shrinking of the green tapes on top in the x and y directions. Thus, most of the shrinkage occurs in the z direction perpendicular to the metal substrate. The presentation of the inserted type 2 glass-ceramics with low shrinkage properties is also provided to suppress shrinkage of the multilayer stack in the x and y directions.

After firing, conductor ink may be applied on top of the fired multilayer stack to form adhesive pads, inductors, microstrip interconnects, etc., in known manner.

The present invention describes the following examples, but the present invention is not limited to the described contents. In the examples, the putter is weight ratio.

Example 1

As shown in FIG. 1, the eleven layers (A) of Yugen 1's green tape comprising three layers (C, D) to which silver-based ink is applied, and the seven layers (B) of type 2's green tape (B) are shown in FIG. Is inserted. The green tape laminates are stacked, placed on a coba support substrate, and then co-laminated. The laminate is fired.

The shrinkage was 17.0% in the z direction, but 0.96% and 0.61% in the x and y directions, respectively. After firing, the entire laminate was 2.50 mm thick.

Example 2

Eleven layers of type 1 green tape with metallized faces on the three layers are inserted with type 2 green tapes, as shown in FIG. 8. FIG. 8 shows Type 1 green tapes, denoted as A, Type 2 green tapes, denoted as B, C denotes the embedded RF filters, and D denotes the patterning. The green tapes are inserted, stacked, stacked, co-laminated with the coba support substrate and then fired. The laminate is 2.40 mm thick.

The reduction is 17.0% in the z direction and 0.64% and 0.60% in the x and y directions, respectively.

Example 3

11 layers of type 1 green tape and 7 layers of type 2 green tape are inserted, stacked, stacked and fired. The laminate is 2.20 mm thick.

The reduction is 17.% in the z direction and 0.83% and 0.98% in the x and y directions, respectively.

Example 4

As shown in FIG. 9, fifteen layers of type 1 (A) and eight types of green tape (B) with filters (C) inherent in one layer and ground planes on two layers The layers are inserted, stacked up, laminated and fired to form a 2.52 mm thick laminate.

The reduction is 17.% in the z direction and 0.35% and 0.85% in the x and y directions, respectively.

The physical properties of the multilayer tapes are shown in Table VII below.

Table ⅩⅩⅦ

Example 5

Various Type 1 and 2 green tapes laminates were calcined at 865 ° C. and then their properties were measured. The results are summarized in Table 아래 below.

As such, the inserted green tapes can be laminated to form a thick calcined metal support multilayer substrate that shrinks only in one direction.

Although the present invention has been described with specific examples, the glass compositions, amount of oxide filler, metal support substrate, number of green tape layers, type of capacitor and capacitor dielectric ink, resistor and resist ink, and conductor and conductor ink, etc. It will be apparent to those skilled in the art that the present invention can be made and included in the present invention. The invention is limited only by the claims.

Claims (25)

A supported ceramic substrate comprising a buried capacitor, the substrate comprising: a) laminated green tape laminate of low firing temperature glass formed on an iron-nickel-cobalt-manganese alloy support, wherein the laminated green tape laminate is screen printed on the laminated green tape laminate With hearing-; b) a dielectric material selected from the group consisting of barium titanate, titanium oxide and red-magnesium-niobate, in an amount sufficient for organic printing to enable screen printing; A buried screen printed capacitor dielectric layer made from a capacitor dielectric ink comprising an organic vehicle and a low temperature calcined glass; c) a silver conductor layer screen printed below and above said capacitor dielectric layer; And d) A supported ceramic substrate comprising an upper green tape layer of low temperature calcined glass. A supported ceramic circuit board having a buried capacitor, the substrate comprising: a) laminated green tape laminate on an iron-nickel-cobalt-manganese alloy support; b) a screen printed buried capacitor dielectric layer made of a dielectric selected from the group consisting of barium titanate, titanium oxide and red-magnesium-niobate; c) a silver conductor layer screen-printed over and below said capacitor dielectric layer; And d) a top green tape layer, And the capacitor is sandwiched between silver barrier layers consisting of a mixture of silver powder and silver flake. delete 3. The supported ceramic circuit of claim 2, wherein the dielectric is red-magnesium-niobate, the capacitor is sandwiched between silver or barium titanate barrier layers, and the capacitor has a dielectric constant of at least 700. 4. Board. delete delete delete delete delete delete delete delete delete Multi-layer ceramic green tape structure, the structure is A plurality of low temperature calcined green tapes mounted on a metal support substrate and not shrinking in the x and y directions during firing, the plurality of low temperature calcined green tapes having circuit patterns on the plurality of low temperature calcined green tapes; A dielectric selected from the group consisting of barium titanate, titanium oxide and red-magnesium-niobate, low temperature calcined glass comprising up to 2% barium oxide, and a sufficient amount of organic beequine to enable screen printing A capacitor dielectric layer screen-printed on one of said green tape layers from said capacitor dielectric ink; One or two layers below the top green tape; And And a silver conductor layer screen printed on top and bottom of the capacitor dielectric layer. delete delete delete delete A method of forming an embedded capacitor in a multilayer ceramic circuit board on a metal support substrate, the method comprising a) forming a capacitor dielectric ink comprising a dielectric selected from the group consisting of barium titanate, titanium oxide and red-magnesium-niobate, low temperature calcined glass, and a sufficient amount of organic vehicle to enable screen printing; step; b) screen printing the bottom conductor layer; c) screen printing capacitor dielectric layers over said bottom conductor layer; d) screen printing the top conductor layer; e) covering said capacitor with one or more green tape layers; f) aligning and laminating the layers together; And g) firing the stacked layers. A capacitor dielectric ink comprising a dielectric selected from the group consisting of barium titanate, titanium oxide and red-magnesium-niobate, low temperature calcined glass, and an organic vehicle. A resistive ink composition comprising ruthenium oxide, an amount of low temperature calcined glass and an organic vehicle that is sufficient to reduce the calcining temperature of the mixture within the range of 850-900 ° C. 22. The resistive ink composition of claim 21, wherein the resistive ink composition further comprises a TCR modifying material of barium titanate. Embedded resistors including a screen printed resistive layer of low temperature calcined glass and ruthenium oxide, printed onto a green tape laminate laminated to a metal support substrate, and covered by one or two green tape layers and a conductive underneath the resistive layer Ceramic multilayer printed circuit board comprising a body layer. The ceramic multilayer printed circuit board of claim 23, wherein the metal support substrate is a cobar. A method for manufacturing an embedded resistor, the method a) forming a resistive ink comprising ruthenium oxide mixed with a low temperature calcined temperature glass with an organic vehicle, wherein the low temperature calcined temperature glass has an amount sufficient for the mixture to have a calcining temperature between about 850-900 ° C. -; b) screen printing the ink on a green tape stack to deposit resistance; c) covering said resistive layer with one or two green tape layers; d) terminating the resistance with a lower first conductive layer; e) laminating the final green tape stack; f) firing the laminate to a temperature from about 850-900 ° C .; g) coating the upper surface of the fired laminate with a second conductive layer; And h) post firing the fired multiple layers.