阅读说明：本技术 在陶瓷制成的载体层中制造过孔的方法和含过孔的载体层 (Method for producing a via in a carrier layer made of ceramic and carrier layer containing a via ) 是由 卡斯滕·施密特 斯特凡·布里廷 安德烈亚斯·迈尔 雷纳·赫尔曼 马丁·雷格 于 2018-07-04 设计创作，主要内容包括：本发明提出一种用于在由陶瓷制成的载体层(1)中制造过孔(3)的方法,所述方法包括：-提供载体层(1)；-在载体层中实现穿通留空部(2)；-用膏至少部分地填充穿通留空部；以及-执行接合法,用于将金属化部接合到载体层上,尤其活性焊接法或DCB法,其中在执行接合法时由穿通留空部中的膏来实现过孔。(The invention relates to a method for producing a via (3) in a carrier layer (1) made of ceramic, comprising: -providing a carrier layer (1); -realizing a through-going vacancy (2) in the carrier layer; -at least partially filling the through-going vacancy with paste; and-performing a bonding method for bonding the metallization to the carrier layer, in particular an active soldering method or a DCB method, wherein the via is realized by a paste which penetrates through the remaining space when the bonding method is performed.)

1. A method for manufacturing vias (3) in a carrier layer (1) made of ceramic, comprising:

-providing the carrier layer (1);

-realizing a through-going vacancy (2) in the carrier layer (1);

-at least partially filling the through-going vacancy (2) with paste (3); and

-performing a bonding process for bonding the metallization (5) to the carrier layer (1), in particular performing an active soldering process or a DCB process,

wherein a via (3') is realized in the through-opening (2) by the paste (3) when the bonding method is performed.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein a specific resistance of the via (3') is set by the method.

3. The method according to any one of the preceding claims,

wherein the resistance of the via (3') is set by setting one or more process parameters of the bonding method.

4. The method according to any one of the preceding claims,

wherein the inner side (9) of the through-opening (2) is covered with a paste (3), wherein the through-opening (2) is preferably filled at least partially, preferably completely.

5. The method according to any one of the preceding claims,

wherein the via (3') is formed as a coating of a coating thickness (D1) on the inner side (9) of the through-opening (2), wherein the bonding process is configured such that a specific coating thickness occurs.

6. The method according to any one of the preceding claims,

wherein a paste (2) with an additive material is used, which paste has in particular an additive material that lowers the melting temperature of the paste.

7. The method of claim 6, wherein the first and second light sources are selected from the group consisting of,

wherein the additive material comprises indium, tin and/or gallium, preferably in a concentration of 0.1 to 20 wt.%, preferably in a concentration of 0.25 to 15 wt.%, and particularly preferably in a concentration of 0.5 to 10 wt.%.

8. The method according to any one of the preceding claims,

wherein the metallic components of the paste (3) are applied by means of a printing method, in particular a 3D printing method, and/or a screen printing method and/or a squeegee printing method.

9. The method according to any one of the preceding claims,

wherein the pierced blank (2) has a diameter (D2) or an equivalent cross section of between 0.01mm and 5mm, preferably between 0.03mm and 2.5mm and particularly preferably between 0.05mm and 2 mm.

10. The method according to any one of the preceding claims,

wherein the through-openings (2) are partially filled with the paste (3), wherein the through-openings are filled preferably between 20% and 90%, preferably between 40% and 80% and particularly preferably between 60% and 75% in time before the bonding process.

11. The method according to any one of the preceding claims,

wherein the through-openings (2) are partially filled with an electrically conductive material after the bonding process, wherein the through-openings (2) are filled preferably between 20% and 80%, preferably between 40% and 75% and particularly preferably between 60% and 70% in time before the bonding process.

12. The method according to any one of the preceding claims,

wherein the through-recess (2) is conically shaped.

13. The method according to any one of the preceding claims,

wherein the paste (3)

-is arranged on the carrier layer (1) and/or is configured,

so that the paste provided on the edges of the through-openings (2) flows from the carrier layer (1) into the through-openings (2) during the joining process and/or

-being provided in said through-going hollow (1) by means of a screen printing process.

14. The method according to any one of the preceding claims,

wherein the ratio of the electrically conductive material in the paste (3) to the total paste (3) has a value between 0.2 and 0.8, preferably between 0.35 and 0.75 and particularly preferably between 0.4 and 0.6.

15. A carrier layer (1) with vias (3'), in particular produced by means of a method according to one of the preceding claims, comprising:

-a support layer (1) comprising a ceramic and

-a through-going vacancy introduced into the carrier layer (1),

wherein the punch-through recess (2) is at least partially filled with a metal, so that it can contribute to the electrical conduction, preferably between 20% and 100%, preferably between 40% and 100% and particularly preferably between 60% and 100% being filled.

Technical Field

The invention relates to a method for producing a via in a carrier layer made of ceramic and to a carrier layer having a via.

Background

Such carrier substrates are known, for example, as circuit boards or printed circuit boards. Typically, a metallization is provided on the carrier top side of the carrier substrate, which metallization can subsequently be used to form the conductor tracks. For special applications, a carrier layer which has an insulating layer with a high electrical insulation strength for the electrical insulation of the individual electrical components and conductor tracks, such as a carrier layer made of ceramic, for example, has proven to be particularly advantageous.

In order to be able to achieve a very compact arrangement of the electrical or electronic component and to reduce or suppress parasitic inductive effects, it has proven to be expedient to engage the additional metallizations not only on the carrier top side but also on the carrier bottom side opposite the carrier top side, and to connect the metallizations lying opposite one another in an electrically conductive manner to one another, for example via vias through the carrier layer. Examples of this are known from DE 19753149 a1 or DE 19945794C 2.

A ceramic substrate with vias is known from JP H06-13726 a. Here, the vias are realized when the metallization is bonded onto the upper side. For this purpose, silver-containing and copper-containing pastes enter into the respective holes.

A method is known from EP 1478216 a1, in which paste is introduced into through-holes and hardened before the copper film is applied.

Disclosure of Invention

The object of the present invention is to provide an improved method in relation to the methods known from the prior art, by means of which the vias can be produced simply and controllably.

This object is achieved by a method for producing vias in a carrier layer made of ceramic according to claim 1 and by a carrier layer according to claim 15. Further advantages and features of the invention emerge from the dependent claims as well as from the description and the drawings.

According to the invention, a method for producing a via in a carrier layer made of ceramic is proposed, the method comprising:

-providing a carrier layer;

-realizing a through-going vacancy in the carrier layer;

-at least partially filling the through-going vacancy with paste; and

performing a bonding process for bonding the metallization to the carrier layer, in particular performing an active soldering process or a DCB process,

-wherein the via is realized in the punch-through clearance by the paste when performing the bonding method.

In contrast to the methods in the prior art, the vias are advantageously produced during an active soldering process for joining the metallization to the carrier layer. By forming the vias simultaneously, the otherwise required additional work steps, by means of which the vias are formed, are advantageously dispensed with. In particular, it is used in the active soldering process, but the temperatures used in the active soldering process can also be used for forming the vias. It is proposed here, in particular, that the paste comprises an active solder material. The same active solder material used to form the connection between the carrier layer and the metallization can be used here, or other solder materials, such as, for example, glass-filled hard solders, in particular based on AgCu. In the case of joining metallizations by means of the DCB method, preferably a paste is used, the melting range of which is below the temperature set in the DCB method.

In particular, it is proposed that the support layer has Al₂O₃、Si₃N₄AlN or HPSX ceramics (that is, with Al₂O₃Ceramic of a matrix, comprising ZrO with a percentage fraction of x₂For example, with 9% ZrO₂Al of (2)₂O₃HPS9 or ZrO with 25%₂Al of (2)₂O₃HPS 25). Preferably, the carrier layer has a carrier top side and a carrier bottom side, on which a metallization can be arranged in each case. The distance between the upper side of the carrier and the lower side of the carrier, that is to say the thickness of the carrier layer, for example, takes a value of between 30 μm and 3 mm. The metallization is made of, for example, copper alloy, molybdenum Mo, tungsten W, composite material or the like, and has a thickness between 30 μm and 3 mm. In order to form the tracks or the connection regions, the metallization applied to the carrier layer is at least partially structured, for example etched away, before and/or after the joining process in order to electrically insulate the individual regions of the metallization from one another.

Preferably, the through-openings are through-holes which, in the case of the already sintered ceramic, are introduced mechanically and/or optically, for example by means of a laser, into the carrier layer.

The person skilled in the art understands the "DCB method" (Direct-Copper-Bond Technology) as a method, for example for connecting metallizations or metal plates (for example Copper plates or Copper films) to one another and/or to ceramic or ceramic layers, more precisely by means of metal plates or Copper plates or metal films or Copper films having on their surface side a layer or coating (molten layer) of a chemical compound consisting of a metal and a reactive gas, preferably oxygen. In the method described, for example, in US-PS 3744120 or in DE-PS 2319854, the layers or the coating (melting layer) form a eutectic mixture with a melting temperature below that of the metal (for example copper), so that the thin film can be connected to one another by applying it to the ceramic and by heating all the layers, to be precise by melting the metal or copper substantially only in the region of the melting layer or oxide layer.

In particular, the DCB process then has, for example, the following process steps:

-oxidizing the copper film so as to obtain a uniform copper oxide layer;

-laying a copper film onto a ceramic layer;

-heating the compound to a process temperature of between about 1065 ℃ and 1083 ℃, for example about 1071 ℃;

-cooling to room temperature.

Active welding, for example, for connecting metallizations or metal films, in particular copper layers or copper films, to ceramic materials is understood to mean a method which is also used exclusively for producing cermet substrates. The connection between the metal film, for example a copper film, and the ceramic substrate, for example an aluminum nitride ceramic, is produced here at a temperature of approximately between 650 ℃ and 1000 ℃ using a hard solder which contains an active metal in addition to the main constituents, for example copper, silver and/or gold. The active metal, which is for example at least one element of the group Hf, Ti, Zr, Nb, Ce, establishes a connection between the solder and the ceramic by means of a chemical reaction, while the connection between the solder and the metal is a metal braze connection.

According to a further embodiment of the invention, it is proposed that a specific resistance of the via is set by the method. The resistance is set, for example, by the size of the through-hole and/or the degree of filling of the through-hole. This advantageously enables a targeted implementation of the electrical resistance. In particular, the size and/or the degree of filling of the through-openings can be adapted to the respective coefficients of expansion of the first carrier layer and the second via-forming coating or filling, in order to reduce the probability of thermomechanical stresses being formed in the finished carrier layer.

In a further embodiment of the invention, it is proposed that the resistance of the via is set by setting one or more process parameters of the bonding method. The resistance of the via can thus advantageously be set without great additional effort. For example, the electrically effective filling degree of the through-openings or the wall thickness of the filler metal in the through-openings is changed by the hardened paste during the bonding process. Preferably, a paste is used for this purpose, which comprises or is filled with glass solder or ceramic powder, wherein the glass solder or ceramic powder is a matrix of a non-conductive material in the joining process.

It is expediently provided that the inner side of the through-openings is covered with paste, wherein the through-openings are preferably at least partially, preferably completely, filled. By means of a covering or cladding of the inner side of the through-hole, the paste is advantageously arranged in the region in which it forms the via according to the method. It is conceivable here for the paste to cover only a part of the inner side of the through-openings. In order to be able to provide a conductive connection between the carrier top side and the carrier bottom side later on, the paste extends continuously from the carrier top side as far as the carrier bottom side. Preferably, the through-openings are partially filled at the edges or completely with paste. Thereby providing vias that are as stable as possible. Furthermore, complete filling with paste proves to be simpler than the method of introducing a metal block into the punch-through clearance to form a via. It is also conceivable that the degree of filling of the through-openings in the finished state is reduced by the bonding method, in particular by selected parameters of the bonding method, compared to the degree of filling during or directly after filling of the through-openings. It is particularly conceivable to form a cavity included in the via during the bonding process. It is particularly preferably provided that the degree of filling after the joining process has a value of between 20% and 100%, preferably between 40% and 100%, and particularly preferably between 60% and 100%. The filling degree is understood by the person skilled in the art to mean, in particular, the ratio between the volume fraction filled with material and the total volume of the unfilled through-openings. The unfilled through-openings are delimited by the carrier layer and are flush with the carrier bottom and/or carrier top, respectively.

According to a further embodiment of the invention, it is proposed that the via is formed as a coating on the inside of the through-opening with a coating thickness, wherein the parameter setting determining the bonding methodSo that a specific coating thickness is set. At the predetermined amount of paste applied to the inner side of the through-hole, the process pressure in the receptacle, for example, is decisive for forming the cavity in the through-hole. To completely fill the via needs to be below 1mbar, preferably below 10 mbar^-2mbar, particularly preferably below 10^-4As low a pressure as possible in the mbar range. In order to realize a cavity by means of a through-opening that is not completely filled with paste, in addition to the process pressure, the smallest possible dwell time of the paste component of the joining method according to the method in the melting region of less than 60min, preferably less than 30min and particularly preferably less than 10min is required in order to prevent the melted paste component from diffusing into the metallization. When the residence time of the solder (active solder or CuO) in the molten state is long, in particular when the residence time is greater than 10min, the melting point-lowering additives diffuse into the metallization over time and thus reduce the metal volume forming the via. The resistance of the via is advantageously set by the cladding thickness. It is particularly conceivable for the ratio of the coating thickness to the diameter determined by the inner side of the through-opening to have a value of between 0.05 and 0.5, preferably between 0.1 and 0.45 and particularly preferably between 0.15 and 0.35.

In a further embodiment of the invention, it is proposed to use a paste with an additive material, in particular with a melting temperature-lowering additive material. This advantageously ensures that the paste melts at the temperatures occurring in the joining process and then hardens to form the vias. Preferably, the active solder used in the active soldering process is based on a eutectic mixture of silver and copper, with a melting temperature of substantially 780 ℃ and with a composition of 72 to 28 wt.% (Ag) to Cu. Preferably, reactive metals such as, for example, Ti, Zr and/or Hf are added to the reactive solder.

It is preferably provided that the additive material comprises indium, tin and/or gallium, preferably in a concentration of 0.1 to 20% by weight, preferably in a concentration of 0.25 to 15% by weight and particularly preferably in a concentration of 0.5 to 10% by weight. The flow behavior of the active solder can be influenced advantageously by setting the concentration. In this case, a concentration range of between 0.5% and 10% by weight has proven to be advantageous with regard to the flow behavior during the formation of the vias or during the filling of the through-cutouts. Preferably, the concentration of the additive material is matched to the desired degree of filling of the through-hole.

In a further embodiment of the invention, it is proposed that the paste is applied by means of a printing method, in particular a 3D printing method, and/or a screen printing method and/or a squeegee printing method. It is conceivable that a sealing layer is provided during filling, in particular during filling by means of screen printing, wherein the sealing layer delimits the through recess to one side and prevents the paste from escaping during filling. Preferably, the penetrating vacancy is made of a porous material or a non-porous material. The use of a porous material allows the application of a vacuum by means of which the paste can be drawn into the through-going voids. It is also conceivable to form the sealing layer at a distance from the carrier top side and/or the carrier bottom side in order to simplify the connection between the vias and the metallization.

According to a further embodiment of the invention, it is provided that the pierced clearance has a diameter of between 0.01mm and 5mm, preferably between 0.03mm and 2.5mm and particularly preferably between 0.05mm and 2 mm. In particular for the pierced cutouts having a diameter of between 0.05mm and 2.5mm, the requirements placed on the carrier layer with regard to resistance or conductivity and resistance to temperature changes are ensured.

In particular, it is proposed that the through-openings are filled partially, in particular only partially, with paste, wherein the through-openings are preferably filled between 20% and 90%, preferably between 40% and 80% and particularly preferably between 60% and 75% in time before the joining process. Surprisingly, it has been found that the local filling of the through-hole is sufficient for the process to reliably achieve an electrically conductive connection through the produced via. Preferably, the through-openings are only partially filled here by means of screen printing and/or 3D printing. In the partial filling, it is preferably to be noted here that the inside of the through-openings is covered. It is thereby ensured that the electrically conductive connection can be provided by means of the paste after the bonding process. For example, the inner side is covered or smeared in a targeted manner or a slightly liquefied paste is guided onto the inner side during the joining process. For example, the carrier layer may be inclined thereto. Furthermore, it is conceivable that the through-openings are first completely filled and then a portion of the paste is removed again from the through-openings before the bonding process.

In a further embodiment of the invention, it is proposed that the through-openings are partially filled with an electrically conductive material after the bonding process, wherein the through-openings are filled between preferably 20% and 80%, preferably between 40% and 75% and particularly preferably between 60% and 70% in time before the bonding process. The electrically conductive material is, for example, a metal, in particular copper. In particular, it is proposed that the degree of filling during the bonding process is reduced. In other words: a portion of the paste introduced through the vacancy is volatilized during the bonding process. It is also conceivable to design the paste or the components of the paste and/or the joining process such that a specific reduction of the degree of filling is specifically taken into account in order to limit the conductivity of the vias.

Preferably, it is provided that the through-recess is conically shaped. The flow of paste from the carrier layer into the through-openings can be promoted by the tapering, so that the filling during the bonding process can be set in a controlled manner, for example via the inclination of the through-openings.

In another embodiment of the invention, provision is made for the paste to be applied

Arranged on the carrier layer and/or configured in such a way that the paste arranged on the edges of the through-openings flows from the carrier layer into the through-openings during the joining process and/or

-being provided in the through-going hollow by means of a screen printing method. For example, it is conceivable to dimension the through-openings such that the paste reaches or is drawn into the through-openings by an adhesive effect during the bonding process. The movement of the carrier layer may also facilitate or push the inflow of paste.

It is preferably provided that the proportion of the electrically conductive material in the paste to the total paste has a value of between 0.2 and 0.8, preferably between 0.35 and 0.75 and preferably between 0.4 and 0.6. This advantageously enables the conductivity and the degree of filling of the through-hole to be influenced in a targeted manner.

Another subject of the invention is a carrier layer with vias, in particular manufactured by means of a method according to any one of the preceding claims, the carrier layer comprising:

-a support layer comprising a ceramic; and

-through-going holes introduced into the carrier layer,

wherein the through-going hole is at least partially filled with a metal such that it can contribute to the electrical conduction, preferably between 20% and 100%, preferably between 40% and 100% and particularly preferably between 60% and 100% filling. All the features described for the method according to the invention and their advantages can be transferred analogously to the carrier layer according to the invention and vice versa.

Drawings

Further advantages and features emerge from the description of a preferred embodiment of the subject matter according to the invention which follows, with reference to the attached drawings. The individual features of the individual embodiments can be combined with one another within the scope of the invention.

The figures show:

fig. 1a to 1 d: a method for producing a via in a carrier layer made of ceramic according to an exemplary embodiment of the invention;

FIG. 2: a top view of a carrier layer with vias according to an exemplary embodiment of the present invention.

Detailed Description

Fig. 1a to 1d show a method according to an exemplary embodiment of the present invention for producing a via 3' in a carrier layer 1 made of ceramic. In this case, it is preferably a ceramic-containing carrier layer 1 which is advantageous for special applications and is provided as a carrier for electrical or electronic components. In order to electrically connect the individual electrical or electronic components, a metallization is provided, in particular, for forming conductor tracks on the carrier top side 11. In order to reduce parasitic inductive effects and to optimize the use of the carrier layer 1, it is advantageously provided that, in addition to the metallization on the carrier top side 11, a metallization is also provided on the carrier bottom side 12 opposite the carrier top side 11. In order to connect one or more metallizations 5 on the carrier upper side 11 with a metallization on the carrier lower side 12, vias 3' are preferably provided. In order to form the vias 3', the punch-through cutouts 2, in particular the through holes, are preferably first introduced into the carrier layer 1 comprising ceramic, as is shown in fig. 1 b. Here, the through hole has a diameter D2. Paste 3 is then introduced into the through-voids 2 (see fig. 1). Here, the paste 3 is preferably an active solder material and/or a paste including copper. It is preferably provided that the paste 3 covers the inner side 9 of the through-opening 2 at least partially, preferably completely.

It is also proposed to apply metallizations to the carrier top side 11 and the carrier bottom side 12 by means of an active soldering process (Aktivlotverfahren) with active solder 4. It is proposed that, in the context of a joining process by means of an active soldering method, a via 3' is formed from the paste 3 in the through-opening 2. This advantageously enables the vias 3' to be realized together with the metallization 5 or the bonding process of the metallization in one method step. It is preferably provided that the vias 3' are formed by a coating having a coating thickness D1 which bears against the inner side 9 of the through-opening. In particular, in the finished state, a cladding layer lying on the inner side 9 and a core region 7 without cladding layer are provided in the through-opening 2. The electrical conductivity of the vias 3' can be set in a targeted manner, preferably by means of the volume ratio of the applied cladding and the uncoated core region 7. It is also preferably provided that the metallization 5 extends over the core region 7 without cladding, in particular completely covers the core region without cladding.

Fig. 2 shows a plan view of the carrier layer 1 or a section through the carrier layer 1 with vias 3' according to an exemplary embodiment of the present invention. The coating disposed on the inner side 9 of the through-opening 2, which coats or surrounds the core region 7 without coating, is visible in a plan view. Preferably, the core region 7 without cladding has a radius, wherein the ratio of the radius of the core region 7 without cladding to the inner radius of the punch-through recess 2 has a value of between 0.2 and 0.9, preferably between 0.4 and 0.8 and particularly preferably between 0.5 and 0.7.

List of reference numerals:

1 support layer

2 through the clearance

3 ointment

3' via hole

4 active solder

5 metallization

7 core region

9 inner side

11 carrier upper side

12 carrier underside

D1 coating thickness

D2 diameter