KR101072125B1 - Multi-layer board - Google Patents

Abstract

The present invention relates to a multilayer substrate and a method of manufacturing the same.

Multilayer substrate according to an embodiment of the present invention is a ceramic substrate; And an LTCC substrate stacked on the ceramic substrate.

Multilayer board

Description

Multilayer substrate and its manufacturing method {MULTI-LAYER BOARD}

The present invention relates to a multilayer substrate and a method of manufacturing the same.

With the miniaturization and light weight of chip components, miniaturization and weight reduction are also required for circuit boards on which chip components are mounted.

Typically, a glass-ceramic multilayer circuit board is used as the multilayer circuit board. The glass-ceramic multilayer circuit board is capable of high-density wiring and thinning, and can be miniaturized and lightweight.

On the other hand, the glass-ceramic multilayer circuit board is formed through a sintering process, in which the substrate shrinks in a horizontal direction parallel to the main surface of the substrate and thus cannot be manufactured to an accurate dimension.

In addition, a glass-ceramic multilayer circuit board formed of a material including glass has a problem that heat dissipation is not easy due to the low thermal conductivity of glass. Although thermal vias are formed to solve this problem, there is an additional problem in that the manufacturing cost of the glass-ceramic multilayer circuit board is increased and an electrical short may be generated by the thermal vias.

The embodiment provides a multilayer substrate and a method of manufacturing the same.

The embodiment provides a multilayer substrate having improved heat dissipation efficiency and a method of manufacturing the same.

The embodiment provides a multilayer substrate and a method of manufacturing the same that can be fabricated with more accurate dimensions.

Multilayer substrate according to an embodiment of the present invention is a ceramic substrate; And an LTCC substrate stacked on the ceramic substrate.

Multi-layer substrate manufacturing method according to an embodiment of the present invention comprises the steps of preparing a ceramic substrate and green sheet; Pressing the green sheet onto the ceramic substrate; And firing the green sheet pressed into the ceramic substrate to form an LTCC substrate.

The embodiment can provide a multilayer substrate and a method of manufacturing the same.

The embodiment can provide a multilayer substrate having improved heat dissipation efficiency and a method of manufacturing the same.

The embodiment can provide a multilayer substrate and a method of manufacturing the same, which can be manufactured to more accurate dimensions.

In the description of an embodiment according to the present invention, each layer (film), region, pattern or structure may be "on" or "under" the substrate, each layer (film), region, pad or pattern. In the case of being described as being formed "in", "on" and "under" include both "directly" or "indirectly" formed. In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

Hereinafter, a multilayer substrate and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The multilayer substrate according to the embodiment of the present invention includes a ceramic substrate and an LTCC substrate stacked on the ceramic substrate.

The ceramic substrate is pre-fired at a higher temperature than the LTCC substrate, and after firing, the ceramic substrate is compressed with the green sheet forming the LTCC substrate. And the baking process with respect to the said green sheet is advanced. Since the firing process for the green sheet is performed at a temperature lower than the firing temperature of the ceramic substrate, the ceramic substrate does not undergo a phase transition.

On the other hand, the green sheet shrinks in the vertical / horizontal direction during the firing process, in particular, the horizontal shrinkage greatly affects the quality of the product. However, in the exemplary embodiment of the present invention, since the green sheet is fixed to the ceramic substrate, the green sheet may reduce shrinkage in the horizontal direction during the firing process.

In the present invention, an LTCC substrate is laminated on the ceramic substrate having a good thermal conductivity as a main substrate. Thus, heat generated in the LTCC substrate can be quickly released through the ceramic substrate.

1 is a flowchart illustrating a method of manufacturing a multilayer substrate according to an embodiment of the present invention.

Referring to FIG. 1, first, a ceramic substrate is prepared (S100). Here, the ceramic substrate is used as the ceramic substrate is completed firing.

Next, the green sheet is prepared (S110). Here, the green sheet is formed of a glass-ceramic material.

Next, the ceramic substrate and the green sheet are bonded (S120).

Then, the bonded ceramic substrate and the green sheet are fired to form a multilayer substrate on which the LTCC substrate is stacked on the ceramic substrate (S130).

The multilayer substrate according to the embodiment of the present invention bonds a plastic substrate having a high thermal conductivity with a plastic sheet and a glass-ceramic green sheet, and forms the multilayer substrate by plastic processing the green sheet.

Since the green sheet is plastically processed while being bonded to the ceramic substrate, shrinkage in the horizontal direction may be reduced, and thus the green sheet may be manufactured to an accurate dimension.

In addition, since the ceramic substrate has high thermal conductivity, heat generated in the multilayer substrate can be easily released to the outside.

2 to 5 are several embodiments of a multilayer substrate that can be fabricated in accordance with embodiments of the present invention. The multilayer substrate according to the embodiment of the present invention may be manufactured in various forms, and is not limited to the embodiments shown in FIGS. 2 to 5.

2 is a diagram illustrating a multilayer substrate according to a first embodiment of the present invention.

Referring to FIG. 2, a Low Temperature Co-fired Ceramics (LTCC) substrate 20 formed of a glass-ceramic material is formed on the ceramic substrate 10.

A conductive film 51 formed in a predetermined circuit pattern is formed on at least one of an upper side surface and a lower side surface of the LTCC substrate 20, and a conductive via 52 penetrating the LTCC substrate 20 is formed.

3 is a diagram illustrating a multilayer substrate according to a second embodiment of the present invention.

Referring to FIG. 3, LTCC substrates 20 formed of glass-ceramic material are formed on the ceramic substrate 10.

A conductive film 51 formed in a predetermined circuit pattern is formed on at least one of upper and lower surfaces of the LTCC substrates 20, and conductive vias 52 penetrating the LTCC substrate 20 are formed.

In the first embodiment shown in FIG. 2, it is disclosed that one LTCC substrate 20 is formed. In the second embodiment shown in FIG. 3, it is disclosed that two LTCC substrates 20 are formed. The number of stacked substrates 20 may be further increased, and a plurality of LTCC substrates 20 may be stacked on the ceramic substrate 10.

4 is a diagram illustrating a multilayer substrate according to a third embodiment of the present invention.

Referring to FIG. 4, LTCC substrates 20 formed of glass-ceramic material are formed on the ceramic substrate 10.

A conductive film 51 formed in a predetermined circuit pattern is formed on at least one of upper and lower surfaces of the LTCC substrates 20, and conductive vias 52 penetrating the LTCC substrate 20 are formed.

A conductive via 12 may be formed in the ceramic substrate 10, and a conductive film 13 formed in a circuit pattern may be formed below the ceramic substrate 10. In addition, a thermal via 11 may be formed to maximize the heat dissipation effect of the ceramic substrate 10.

5 is a diagram illustrating a multilayer substrate according to a fourth embodiment of the present invention.

Referring to FIG. 5, LTCC substrates 20 formed of glass-ceramic material are formed on the ceramic substrate 10.

A conductive film 51 formed in a predetermined circuit pattern is formed on at least one of an upper side surface and a lower side surface of the LTCC substrate 20, and a conductive via 52 penetrating the LTCC substrate 20 is formed.

At least some of the LTCC substrates 20 may be at least partially removed to form a cavity 60. Passive elements such as resistors, capacitors, and inductors or chips may be mounted in the cavity 60.

As described with reference to FIGS. 2 to 5, the multilayer substrate according to the embodiment of the present invention may be formed in various forms, and the present invention is not limited to the structure shown in the drawings.

Hereinafter, a multilayer substrate and a method of manufacturing the same according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5.

Ceramic Substrate Preparation

In the multilayer substrate according to the embodiment of the present invention, the LTCC substrate 20 is stacked on the ceramic substrate 10 with the ceramic substrate 10 having a good annual conductivity as a main substrate.

At least one of alumina (Al ₂ O ₃ ), AlN, Si ₃ N ₄ , and SiC may be used as the ceramic substrate 10. In an embodiment, alumina (Al ₂ O ₃ ) may be used. Or that AlN is used. The alumina substrate has a very good thermal conductivity.

In the multilayer substrate according to the embodiment of the present invention, the ceramic substrate 10 is sintered through a sintering process in advance, and the LTCC substrate 20 is sintered after bonding with the ceramic substrate 10. Since the ceramic substrate 10 has a higher sintering temperature than the LTCC substrate 20, the ceramic substrate 10 undergoes a sintering process separately from the LTCC substrate 20.

As an embodiment of the ceramic substrate 10, the alumina substrate may be manufactured by a casting method or may be manufactured by a press method.

Casting method

91 to 99% by weight of alumina powder is mixed with bentonite or talc as 1 to 9% by weight as a sintering aid (flux) to prepare a raw ceramic powder. 2 to 10% by weight of an organic binder and 0.2 to 2% by weight of a plasticizer are mixed with the mixed ceramic powder, dissolved in 20 to 60% by weight of organic solvent, and aged for 24 hours. Mix with In this case, 0.1 to 2% by weight of a dispersant may be added as needed, and the dispersant may be at least one of Polyisobutylene, linoteic acid, aliphatic hydrocarbons, and Manhaden Fish oil.

The mixing method uses a mixing method such as a ball mill or a basket mill.

The mixed slurry is tape-casted through defoaming and aging to prepare a sheet having a thickness of 10 to 1000 μm. At this time, the viscosity is suitable about 50 ~ 1200cps.

Thereafter, the sheet is sintered at a temperature of 1400 to 1600 ° C. for 30 minutes to 2 hours in a reducing atmosphere to prepare an alumina substrate.

(Example)

2000 g of ceramic powder containing 1840 g of alumina powder and 160 g of bentonite or talc as a sintering aid were prepared, 50 g of PVB (polyvinyl butyral) as an organic binder, 18 g of BBP (butylbenzylphthalate) as a plasticizer, 256 g of ethanol as an organic solvent, and toluene 544 g was added, which was mixed with the ceramic powder with 2.5 kg of alumina balls having a diameter of 20 mm in a volume 5 l alumina ball mill for 24 hours to obtain a slurry viscosity of 70 cps.

Next, 150 g of PVB and 72 g of BBP were added thereto, and the slurry prepared by mixing by ball milling again for 24 hours was formed into a sheet having a thickness of 0.6 mm by defoaming and aging.

The prepared sheet was cut to a size of 40 × 40 mm, and then heat treated at a temperature of 1550 ° C. for 1 hour in a reducing atmosphere to prepare an alumina substrate.

Press method

91 to 99% by weight of alumina powder is mixed with bentonite or talc as 1 to 9% by weight as a sintering aid (flux) to prepare a raw ceramic powder. The ceramic powder is sufficiently dried at a temperature of 100 to 150 ° C. for 24 hours by using a dry mixing method V-mixer or by mixing 20 to 60 wt% of organic solvent or distilled water and 0.1 to 2 wt% of a dispersant by a wet mixing method. It is prepared as possible. 0.5 to 3% by weight of an organic binder is mixed with the mixed powder, and is molded at a pressure of 1 to 15 tons using a mold press, and sintered at a temperature of 1400 to 1600 ° C. for 30 minutes to 2 hours in a reducing atmosphere to prepare an alumina substrate. .

(Example)

2000 g of a ceramic powder containing 1840 g of alumina powder and 160 g of bentonite or talc as a sintering aid are prepared, and 20 g of PVA (polyvinylacetate) is added and mixed as an organic binder. The mixed powder was put into a molding press, and a pressure of 5 tons was applied for 1 second to form a sheet, which was heat-treated at a temperature of 1550 ° C. for 1 hour in a reducing atmosphere to prepare an alumina substrate.

The alumina substrate has a thermal conductivity of 27w / m.k.

As another embodiment of the ceramic substrate 10, the AlN substrate may be used.

The AlN substrate is made of aluminum nitride powder, which is mixed with CaO 2 wt% or less or Y ₂ O ₃ 8 wt% or less as a sintering aid and heat treated at a temperature of 1900 ° C. under nitrogen atmosphere for 8 hours to manufacture AlN substrate. do. The AlN substrate has a density of 3.262 g / cm 3 and a thermal conductivity of 200 to 250 w / mk.

Meanwhile, as illustrated in FIG. 4, the conductive substrate 12 may be formed on the ceramic substrate 10, or the conductive layer 13 formed in a circuit pattern may be formed. In addition, a thermal via 11 may be formed to maximize the heat dissipation effect of the ceramic substrate 10.

The conductive via 12 and the thermal via 11 form a hole by using a laser drilling method, and filling at least one conductor of Ag, Ag-Pd, Pd, Pt, Cu, and Ni therein. The conductive film 13 may be formed by screen printing.

Preparation of green sheet (preparation of LTCC board)

The green sheet for forming the LTCC substrate 20 may be formed using a glass-ceramic material. For example, the green sheet may be SiO ₂ -CaO-Al ₂ O ₃ -based glass, SiO ₂ -MgO-Al ₂ O ₃ -based glass, SiO ₂ -B ₂ O ₃ -CaO-R ₂ O-based glass (here, R may include at least one of Li, Na, and K). The embodiment discloses that SiO ₂ -CaO-Al ₂ O ₃ -based glass is used, and the LTCC substrate 20 formed of SiO ₂ -CaO-Al ₂ O ₃ -based glass has a coefficient of thermal expansion with the ceramic substrate 10. Since is similar, the warpage phenomenon in the bonding state of the ceramic substrate 10 and the LTCC substrate 20 has an advantage that can be prevented.

In addition, the green sheet is a filler (Filler), Al ₂ O ₃ , BaTiO ₃ , TiO ₂ , SiO ₂ , ZrO ₂ , ZrSiO ₄ may be included in less than 50% by weight.

Production of the green sheet is preceded by slurry production. 30-80% by weight of glass-ceramic mixed powder (for example, 50-100% by weight of SiO ₂ -CaO-Al ₂ O ₃ based glass powder and 0-50% by weight of Al ₂ O ₃ powder mixed) 0.1-3 weight% of a dispersing agent is added, and 3-50 weight% is mixed using at least any one of toluene, isopropyl alcohol, ethanol, and MEK (methyl ethyl ketone) as a solvent. And using a mixing and grinding equipment such as a ball mill 30 minutes to 4 hours to disperse, 3 to 20% by weight of the binder of at least one of PVB-based, acrylate, methacrylate and 0.5 to 3% of Phthalate-based plasticizer Mix and grind for 1 to 24 hours. The particle size of the final solid is preferably 0.5 to 8 µm. The slurry thus prepared is cast by a tape casting method using a doctor blade to prepare a green sheet. The thickness of the green sheet may be variously selected from 10 to 300㎛.

A circuit pattern for forming the conductive film 51 is formed on the green sheet by screen printing using at least one of Ag, Ag-Pd, Pd, Pt, Cu, and Ni. In addition, vias are formed to form the conductive vias 52 and the conductors are filled. In the embodiment of the present invention, the conductive film 51 and the conductive via 52 are formed using Ag.

In addition, as shown in FIG. 5, a mechanical punching process for forming the cavity 60 may be used in the green sheet to form a window.

As shown in Figures 3 to 5, at least two or more of the plurality of green sheets may be bonded.

The stacking of the green sheets may be applied at a pressure of 25 kgf / cm 2 at a temperature of 25 ° C. to 90 ° C. (eg, 70 ° C.) so that the green sheets are bonded to each other.

Bonding of Ceramic Substrate and Green Sheet

After the green sheets are stacked on the ceramic substrate 10 at a pressure of 5 to 100 kgf / cm 2, the ceramic substrate 10 and the green sheets may be bonded to each other by applying a pressure of 20 to 400 kgf / cm 2. For example, the pressure to allow the ceramic substrate 10 and the green sheets to be bonded may be 220 kgf / cm 2.

Green sheet firing

The ceramic substrate 10 on which the green sheets are stacked is fired at a temperature of 700 to 1000 ° C. for 5 minutes to 2 hours. For example, after degreasing at a temperature of 450 ° C. for 30 minutes for degreasing, the temperature may be raised at a temperature of 10 ° C. per minute and calcined at a temperature of 870 ° C. for 20 minutes. Then, cooling to room temperature completes the manufacturing process of the LTCC substrate 20. On the other hand, in order to facilitate the separation of the multi-layer substrate may be included a step of cutting the green sheet part before firing.

In the manufacturing process of the multilayer substrate according to the embodiment, the green sheets are fired in a state in which the green sheets are pressed onto the ceramic substrate 10 which has already been fired.

Therefore, since the green sheets are fixed by the ceramic substrate 10 and the ceramic substrate 10 is not contracted during the firing process of the green sheet, the green sheets may be suppressed from shrinking in the horizontal direction during the firing process. have. Therefore, the multilayer substrate, which has been sintered, is suppressed from warping or distortion due to lateral shrinkage.

On the other hand, in the multilayer substrate according to the embodiment, since the ceramic substrate 10 having excellent thermal conductivity is formed under the LTCC substrate 20, the generated heat can be easily discharged to the outside.

Although the above description has been made based on the embodiments, these are merely examples and are not intended to limit the present invention. Those skilled in the art to which the present invention pertains may not have been exemplified above without departing from the essential characteristics of the present embodiments. It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 is a flow chart illustrating a method of manufacturing a multilayer substrate according to an embodiment of the present invention.

2 shows a multilayer substrate according to a first embodiment of the invention;

3 shows a multilayer substrate according to a first embodiment of the invention;

4 shows a multilayer substrate according to a first embodiment of the invention;

5 shows a multilayer substrate according to a first embodiment of the present invention;

Claims (18)

delete delete delete delete delete delete delete delete delete Preparing a ceramic substrate and green sheet; Pressing the green sheet onto the ceramic substrate; And Firing the green sheet pressed into the ceramic substrate to form an LTCC substrate, At least one of a cavity, a conductive film, and a conductive via in which a passive element or a chip is mounted on the LTCC substrate. The method of claim 10, The ceramic substrate is fired at a temperature of 1400 ~ 1600 ℃ after the multilayer substrate manufacturing method that is pressed with the green sheet. The method of claim 10, The green sheet is a method of manufacturing a multilayer substrate is baked at a temperature of 700 ~ 1000 ℃. The method of claim 10, The ceramic substrate is formed of at least one of alumina (Al ₂ O ₃ ), AlN, Si ₃ N ₄ , SiC. The method of claim 10, The ceramic substrate is a multilayer substrate manufacturing method comprising alumina powder, a sintering aid and an organic binder. 15. The method of claim 14, The alumina powder is a multilayer substrate manufacturing method comprising 91 ~ 99% by weight. The method of claim 10, The green sheet is a multilayer substrate manufacturing method formed of a glass-ceramic material. The method of claim 10, The green sheet may be formed of SiO ₂ -CaO-Al ₂ O ₃ -based glass, SiO ₂ -MgO-Al ₂ O ₃ -based glass, SiO ₂ -B ₂ O ₃ -CaO-R ₂ O-based glass, wherein R is Li, At least any one of Na, K) and a method of manufacturing a multilayer substrate formed. The method of claim 10, The green sheet is a multi-layer substrate manufacturing method formed of a plurality of layers.

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