KR100690354B1 - Fabrication Process of Thermally Curable Thick-Film Resistor And Resistor made by the Process - Google Patents

Abstract

The present invention relates to a method for manufacturing a thermosetting thick film resistor and a resistor according to the present invention, particularly comprising depositing a metal material on a substrate; Etching a portion of both sides of the metal material by a photo etching process to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming an insulating layer by applying an insulator material on the substrate on which the resistor is not formed; And depositing a metal material on the resistor and the insulating layer, and then etching both portions of the metal material to form an upper metal pad, between the lower and upper metal pads. The resistor is located, the contact surface between the metal pad and the resistor is formed very precisely, there is an effect that can be produced a resistor with a significantly uniform resistance value.

Thick Film Resistors, Insulation Layers, Metal Pads

Description

Fabrication method of thermosetting thick film resistor and register according thereto {Fabrication Process of Thermally Curable Thick-Film Resistor And Resistor made by the Process}

1A to 1E are flowcharts illustrating a process of manufacturing a thermosetting thick film resistor by a screen printing method according to the related art.

2 is a flow chart showing a thermosetting thick film resistor manufacturing process according to an embodiment of the present invention,

3A to 3J are flowcharts illustrating a process of manufacturing a thermosetting thick film resistor according to an exemplary embodiment of the present invention.

4 is a flowchart illustrating a process of manufacturing a thermosetting thick film resistor using a photosensitive insulator material according to another preferred embodiment of the present invention;

5A through 5J are flowcharts illustrating a process of manufacturing a thermosetting thick film resistor using a photosensitive insulator material according to another exemplary embodiment of the present invention.

** Simple explanation of symbols for main parts of drawing **

1: substrate 2: metal material

3: photoresist 4: bottom metal pad

5: resistor 6: insulation layer

7: upper metal pad 8: photosensitive insulating layer

TECHNICAL FIELD The present invention relates to a thick film resistor, and more particularly, to a method for manufacturing a thermosetting thick film resistor that can be embedded and a resistor according to the present invention. More specifically, a resistor formed by a resistor is formed in a uniform shape, and the resistor and the metal pad are precisely formed. The present invention relates to a resistor manufacturing method that can reduce the variation in resistance value by achieving contact.

The versatility, speed, and mobility of electronics, and the desire for consumers to connect all their products to the Internet, put pressure on product designers and manufacturers to create more circuitry in smaller spaces. For example, mobile communication terminals not only provide real-time information such as market data and sports information associated with computers, but also wireless internet. As the product's functionality improves, passive components also increase relative to the number of ICs. Passive devices include resistors, capacitors, and inductors.

Functions that meet the needs of consumers must continue to be added, but if the size is limited, passive elements will disappear from the printed circuit board surface. This is why embedded passive devices have emerged. In short, embedded passives mean that many surface-mounted passives are placed inside the printed circuit board.

At present, in order to develop a small electronic device, the size of passive elements such as resistors is reduced and the size of the printed circuit board is reduced by reducing the distance between the circuit width and the line width, and recently, a material that functions as a passive element inside the printed circuit board. It is intended to obtain the effect of widening the space on the surface of the circuit board by putting the inside of the substrate.

Among them, thick film resistors have been widely used as resistor components in hybrid electronic circuits because they can realize a wide range of resistance values. The manufacturing procedure of the conventional thick film resistor is shown in Figs. 1A to 1E. This is a flowchart showing a process of manufacturing a thermosetting thick film resistor by the screen printing method according to the prior art.

In detail, first, the copper foil 102 is attached onto the substrate 101 (FIG. 1A) or the metal pad 103 having a desired shape is formed by plating (FIG. 1B). Then, a thick film resistor paste or ink 104 is applied between the metal pads 103 by using a screen printing method (FIG. 1C). The coated thick film resistor is volatilized and organic solvent is passed through leveling and drying, followed by curing the organic binder through a thermosetting process to obtain a final resistor (Fig. 1D). Finally, the thick film resistor is completed by treating the protective film on the surface of the resistor thus produced (FIG. 1E).

The conventional screen printing technique described above uses a mask in which a pattern to be printed is formed. The mask is placed on the substrate with a suitable distance from the substrate to be printed, the thick film resistor paste or ink is loaded onto the mask, and the paste is applied to the substrate while applying pressure using a squeegee.

The electrical properties of the thick film resistors here depend on the properties of the resistor material itself and the shape of the formed resistor and the shape of the contact surface of the resistor and the metal pad. The x and z axes, i.e. the width and thickness of the resistor, are determined by the screen printing process, while the y-axis dimensions are determined by the pattern on which the resistor is formed. The metal pad can be formed by plating or copper foil etching before or after printing of the resistor paste.

When the thick film resistor is formed using the screen printing method described above, the coated thick film resistor is dried and thermally cured and converted into an appropriate resist film that is attached to the substrate and the lower metal pad. However, since it is difficult to make the film thickness constant and uniform during printing of the resist ink after drying and thermosetting, a variation in resistance value occurs for each part. As shown in FIG. 1E, the shape of the resistor formed according to the prior art is crushed, and the contact surface with the metal pad is irregular. The resistance value variation of the resistor thus formed is very large at 20%.

Recently, in order to precisely implement resistance values, efforts have been made to reduce the variation of resistance values by using laser trimming of the resistors thus formed. Nevertheless, the variation of the resistance value that is reduced is insignificant, and it is very difficult to form an inexpensive resistor due to additional trimming and cost by separate trimming.

Therefore, in order to reduce the variation of the resistance value and to form a precise resistance value, the formation of a precisely shaped resistor and precise contact between the resistor and the metal pad are required. As in the prior art, when the contact between the thick film resistor and the metal pad on the y-axis is implemented by the screen printing method, it is very difficult to achieve precise contact. This is because overlapping the thick film resistor and the metal pad cannot be prevented. Therefore, there is an urgent need for a technology that can realize precise contact between the thick film resistor and the metal pad while utilizing the screen printing method, which is an inexpensive process.

An object of the present invention for solving the above problems is to provide a thermosetting thick film resistor and a manufacturing method that can be embedded in a multilayer printed circuit board and a ceramic polymer composite substrate.

More specifically, a method of forming a resistor that realizes a precise resistance value by precise etching of a lower metal pad in contact with a resistor, forming an inner layer according to a photosensitive insulating layer, and precise contact between a resistor and a metal pad by forming a metal pad. To provide.

According to the present invention, the resistor is formed in a uniform form to prevent the thick film resistor and the metal pad from overlapping. In addition, the present invention is to implement the precise contact between the thick film resistor and the metal pad, and to implement a precise thick film resistor having a low resistance resistance while utilizing a simple and inexpensive screen printing method.

The present invention relates to a method for manufacturing a thermosetting thick film resistor and a resistor according to the present invention. More particularly, the resistor is formed in a uniform form, and the resistor and the metal pad do not overlap so as to achieve precise contact resistance. The present invention relates to a register and a method of manufacturing the same, which can reduce variations in values.

One preferred embodiment of this invention comprises the steps of depositing a metal material on a substrate; Etching a portion of both sides of the metal material by a photo etching process to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming an insulating layer by applying an insulator material on the substrate on which the resistor is not formed; And depositing a metal material on the resistor and the insulating layer, and etching both portions of the metal material to form an upper metal pad.

The etching process may include applying a photoresist on the metal material; Exposing both partial regions of the metal material to which the photoresist is applied with light using a photomask; After developing the exposed photoresist; Etching both partial regions of the metal material; Preferably, the photoresist remaining on the unetched metal material is stripped off.

In addition, another preferred embodiment of the method of manufacturing a thermosetting thick film resistor according to the present invention comprises depositing a metal material on a substrate and etching both partial regions of the metal material to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming a photosensitive insulating layer by applying a photosensitive insulator material over the resistor and the substrate; Etching a portion of the photosensitive insulating layer on the resistor by a photolithography process to expose the upper portion of the resistor; After depositing a metal material on the exposed resistor and the photosensitive insulating layer, it is also possible to etch both portions of the metal material to form an upper metal pad.

Here, the photolithography process may include applying a photoresist on the photosensitive insulating layer; Exposing a portion of the resistor on which the photoresist and the photosensitive insulating layer are formed with light using a photo mask; After developing the exposed photoresist; Etching the photosensitive insulating layer of the partial region; It may be a preferred method of manufacturing a thermosetting thick film resistor consisting of peeling off the photoresist remaining on the unetched photosensitive insulating layer. In this case, part of the photosensitive insulating layer must be etched by a photolithography process so that the upper portion of the resistor is exposed, so that the photo mask is preferably made of a photoresist material in the form of a dry film.

In the present invention, the step of applying the thick film resistor paste or ink is screen printing using a metal mask having a pore size in the range of 400 mesh to 1000 mesh and a thickness in the range of 10 μm to 70 μm. It is possible to apply by a screen printing method. In the forming of the resistor, the resistor may be formed by leveling the applied thick film resistor paste or ink, and trimming after drying and heat treatment. Further, after the forming of the upper metal pad, it is preferable to further include finishing the heat treatment while applying heat and pressure to all the layers of the thermosetting thick film resistor.

Hereinafter, one preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

The present invention is to implement a built-in resistor using a thermosetting thick film resistor. Specifically, forming a lower metal pad first on a printed circuit board or a polymer ceramic composite substrate; Applying a thick film resistor paste or ink to form a resistor; Coating an insulating layer by a screen printing method or forming a precisely shaped insulating layer pattern using a film or paste of a photosensitive insulating material; Attaching a metal material or forming an upper metal pad through plating. Through this, a resistor is formed along the z-axis, that is, in the thickness direction, and precise contact between the resistor and the metal pad is formed to form a resistor having a small resistance value.

Preferred embodiments of the present invention having the above characteristics can be broadly divided into two types. The first method is a process of depositing a metal material on a substrate as shown in the flowchart of FIG. 2, forming a lower metal pad by a photolithography process, and then manufacturing a resistor, an insulating layer, and an upper metal pad. In the second method, as shown in FIG. 4, a lower metal pad and a resistor are formed on a substrate, an insulating layer is formed using a photosensitive insulator material, and a portion of the insulating layer on the resistor is etched by a photolithography process. After revealing, the process of manufacturing the upper pad metal.

That is, the first method is characterized by etching both partial regions of the metal material by a photolithography process, and then manufacturing a resistor, an insulating layer and an upper metal pad. In the second method, a photosensitive insulator material is usually used instead of a general insulator material. It is different from the first method by using and etching part of the insulating layer on the resistor by a photolithography process.

Among them, the first method of etching both partial regions of the metal material by the photolithography process is as shown in the flowchart of FIG. 2 and the flowcharts of FIGS. 3A to 3J. 2 is a flowchart illustrating a process of manufacturing a thermosetting thick film register according to an exemplary embodiment of the present invention, and FIGS. 3A to 3J are flowcharts illustrating a process of manufacturing a thermosetting thick film resistor according to an exemplary embodiment of the present invention.

In one preferred embodiment of the present invention, the first method first undergoes a step S 11 of depositing a metal material 2 on a substrate 1 (FIG. 3A). The printed circuit board 1 or the ceramic polymer composite board | substrate 1 by which copper foil or the metal substance 2 is plated is prepared. Here, the substrate 1 may be a printed circuit board, a flexible substrate, a ceramic and organic compound substrate, or a ceramic to silicon substrate.

Next, a portion of both regions of the metal material 2 is etched by a photo etching process to form the lower metal pad 4 (S 12) (FIG. 3F). The metal material 2 on the substrate 1 is formed by the optical etching process to form the metal pad 4 of the desired precise shape. In addition, it is also possible to include a process of processing the surface of the metal pad 4 formed as described above to make a flat surface.

Here, the etching process is to apply a photoresist (3) on the metal material (Fig. 3b); Exposing both partial regions of the metal material to which the photoresist 3 is applied with light using a photomask (FIG. 3C); After developing the exposed photoresist 3 (FIG. 3D); Etching both partial regions of the metal material (2) (FIG. 3E); It is preferable that the photoresist 3 remaining on the unetched metal material 2 is peeled off (Fig. 3F).

After the lower metal pad 4 is formed, a step (S 13) of applying a thick film resistor paste or ink to cover the lower metal pad 4 is performed (not shown). It is preferable that the thick film resistor covers only the lower metal pad, and it is possible to apply the thick film resistor paste or ink by utilizing a conventional screen printing method using a mask.

In application, the squeegee, the printing speed, and the printing process conditions are set to form a uniform thickness and a uniform line in consideration of the printability of the paste or ink. In the present invention, the step of applying the thick film resistor paste or ink is preferably a screen using a metal mask having a pore size in the range of 400 mesh to 1000 mesh and a thickness in the range of 10 μm to 70 μm. It is possible to apply by a screen printing method.

Viscosity of the paste which is affected in the operation of transferring a thick film of constant thickness to the pattern of the mask to be designed on the substrate (screen printing) is greatly influenced by the temperature and humidity management during printing and the conditions of the squeeze. When printing the screen shape and the screen used as a mask using a mask, it is preferable to use a 400 mesh to 1000 mesh range, SUS (steel use stainless: that is referred to as 'STS' also referred to as stainless) It is more preferable to use a screen having a material.

When printing paste, the squeeze slips while maintaining about 45 ° at the appropriate pressure. At this time, the gap between the mask and the diaphragm should be maintained about 1.5mm, and only the part where the squeeze touches is printed, and it is formed cleanly in the shape of a mask without the phenomena, and each resistance error can be minimized. The factors influencing screen printing have different printing thicknesses depending on the type of mesh, so it is necessary to make a mask for obtaining a desired shape shape and a certain thickness according to the resistance size.

Subsequently, the coated thick film resistor paste or ink is dried and heat treated to form a resistor 5 (S 14) (FIG. 3G). The thick film resistors used in the present invention may be composed of an electrically conductive material, an organic binder, and an organic solvent and an organic material that enables fluidity for printing. The coated thick film resistor is obtained by drying the volatilized organic solvent and curing the organic binder through a heat curing step of heat treatment.

Subsequently, the insulating layer 6 is formed by applying an insulator material on the substrate 1 on which the resistor 5 is not formed (S15). The paste material is applied by screen printing to form an insulating layer 6, that is, a dielectric layer, and is dried.

Finally, after depositing the metal material 2 on the resistor 5 and the insulating layer 6 (FIG. 3i), a portion of the metal material 2 is etched to form the upper metal pad 7 It goes through step S16 (FIG. 3J). The copper foil or the metal material 2 is attached by using plating, and after attachment, a desired metal pad shape is formed through a conventional optical etching process.

In addition, after the forming of the upper metal pad 7, it is preferable to further include finishing the heat treatment while applying heat and pressure to all the layers of the thermosetting thick film resistor. Finally, it is to increase the adhesion between the layers through heat curing while applying heat and pressure to all the layers. By repeating the above process, the built-in thermosetting thick film resistor can be formed.

Meanwhile, a second method of using a photosensitive insulator material as a method of manufacturing a thermosetting thick film resistor according to the present invention and etching a portion of the insulating layer on the resistor by a photolithography process will be described with reference to the flowchart of FIG. 4 and FIGS. 5A to 5J. As shown in the flowchart. 4 is a flowchart illustrating a process of manufacturing a thermosetting thick film resistor using a photosensitive insulator material according to another preferred embodiment of the present invention, and FIGS. 5A to 5J are photosensitive insulator materials according to another preferred embodiment of the present invention. Is a flow chart showing the manufacturing process of a thermosetting thick film resistor using

In another preferred embodiment of the present invention, the second method first deposits a metal material (2) on a substrate (1), and then etching both partial regions of the metal material to form a lower metal pad (4). The step S 21 is performed (FIG. 5A). As in the first method described above, the metal material 2 on the substrate 1 is etched to form the lower metal pad 4 of the precise shape desired. The etching process may use a conventional optical etching process, but is not limited thereto.

Next, after the lower metal pad 4 is formed, a step (S 22) of applying a thick film resistor paste or ink to cover the lower metal pad 4 is performed (not shown). Subsequently, the coated thick film resistor paste or ink is dried and heat treated to form a resistor 5 (S 23) (FIG. 5B). Forming a resistor by applying a thick film resistor paste or ink is the same as the first method described above.

In order to prevent abrasion when the paste is applied at a constant pressure, a metal (metal) mask is used in the present invention. In addition, the squeeze is a tool that pushes the paste to the substrate on the mask. The squeeze must have abrasion resistance and initial abrasion resistance, elasticity and softness to absorb minute vibrations, and squeeze angle and hardness are also very important.

Subsequently, after forming the resistor 5, the photosensitive insulator layer 8 is formed by applying a photosensitive insulator material on the resistor 5 and the substrate 1 (S 24). Unlike the first method, an insulator material is applied to cover not only the substrate 1 but also the resistor 5, and the insulator material is preferably a photosensitive insulator material. This is because the insulating layer formed on the resistor is subsequently etched by a photolithography process. Here, the photosensitive insulator material has a photosensitive characteristic in which a conventional insulator material is exposed by light, and includes a photosensitive polymer that reacts when light is received in a specific wavelength band.

In the second method according to the present invention, after the photosensitive insulating layer 8 is formed, a portion of the photosensitive insulating layer 8 on the resistor 5 is etched by a photolithography process to form an upper portion of the resistor 5. The step is made to reveal (S 25) (Fig. 5h). After attaching a photoresist material in the form of a dry film to the photosensitive insulating layer 8 or the dielectric layer formed on the resistor 5 and the substrate 1, a precise empty space is formed on the resistor through an optical etching process.

Here, the etching process is to apply a photoresist (3) on the photosensitive insulating layer 8 (Fig. 5d); A portion of the resistor on which the photoresist 3 and the photosensitive insulating layer 8 are formed is exposed to light using a photo mask (FIG. 5E); After developing the exposed photoresist 3 (FIG. 5F); Etching the photosensitive insulating layer 8 of the partial region (Fig. 5g); It is preferable that the photoresist 3 remaining on the unetched photosensitive insulating layer 8 is peeled off (Fig. 5H).

Finally, after depositing the metal material 2 on the resistor 5 and the photosensitive insulating layer 8 (FIG. 5i), both portions of the metal material 2 are etched to form the upper metal pad 7 The step S 26 is performed (FIG. 5J).

Finally, the thermosetting of the resistor and the insulating layer is simultaneously performed while applying heat and pressure to increase the adhesion between the layers. By doing so, it is possible to form a certain type of thick film resistor, that is, a resistor, and to realize precise contact between the resistor and the metal pad, thereby realizing a built-in thermosetting thick film resistor having a low deviation resistance value.

Another feature of the present invention is the step of applying a thick film resistor paste or ink, and drying and heat treating the thick film resistor paste or ink to form a resistor 5, wherein the applied thick film resistor paste or ink is leveled, dried and heat treated. Thereafter, by trimming, a resistor is formed.

Here, the leveling of the thick film resistor paste or ink is for leveling the surface, that is, also referred to as flattening, preferably before drying and heat treatment, but also afterwards. This is to uniformize the shape of the resistor formed by the thick film resistor paste or ink.

The applied thick film resistor paste or ink is then dried and heat treated. During sintering during the drying and heat treatment process, the resist ink is heated at a rate slow enough to promote the stability of the resist and burn the organic medium of the ink. Sintering refers to a phenomenon in which the powder is press-molded into an appropriate shape to be tightly adhered and solidified when heated. During this period, physical and chemical changes occur within the thick film resistor, whereby a conductive network or microstructure of the resistor is formed. do. Various additives can typically be used to achieve the specially required resistance, stability and temperature characteristics.

Trimming often uses abrasion or laser technology to form a cut in a thick film resistor, thereby increasing the effective electric field of the resistor to increase the electrical resistance. Resistor trimming is preferably performed to compensate for the loss of resistance that occurs due to conductor diffusion during sintering.

In addition, another embodiment of the present invention for achieving another object of the present invention is also possible a thermosetting thick film resistor manufactured by the method of manufacturing a thermosetting thick film resistor described above.

As described above, the present invention includes the steps of depositing a metal material on a substrate; Etching a portion of both sides of the metal material by a photo etching process to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming an insulating layer by applying an insulator material on the substrate on which the resistor is not formed; And depositing a metal material on the resistor and the insulating layer, and etching both portions of the metal material to form an upper metal pad, and a resistor manufactured by the method. have.

According to the present invention, the resistor by the resistor can be formed in a uniform form, and the overlap of the thick film resistor and the metal pad can be prevented. In addition, the present invention has the effect that the resistor is located between the lower and the upper metal pad, the contact surface of the metal pad and the resistor is formed very precisely, it is possible to implement a precise thick film resistor having a low deviation resistance value.

Claims (8)

Depositing a metal material on the substrate; Etching a portion of both sides of the metal material by a photo etching process to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming an insulating layer by applying an insulator material on the substrate on which the resistor is not formed; and And depositing a metal material on the resistor and the insulating layer, and then etching both portions of the metal material to form an upper metal pad. The method of claim 1, wherein the photolithography process, Applying a photoresist on the metal material; Exposing both partial regions of the metal material to which the photoresist is applied with light using a photomask; After developing the exposed photoresist; Etching both partial regions of the metal material; A method of manufacturing a thermosetting thick film resistor, characterized by peeling off the photoresist remaining on top of the unetched metal material. Depositing a metal material on the substrate and etching both partial regions of the metal material to form a lower metal pad; Applying a thick film resistor paste or ink to cover the lower metal pad; Drying and heat-treating the applied thick film resistor paste or ink to form a resistor; Forming a photosensitive insulating layer by applying a photosensitive insulator material over the resistor and the substrate; Etching a portion of the photosensitive insulating layer on the resistor by a photolithography process to expose the upper portion of the resistor; and And depositing a metal material on the exposed resistor and the photosensitive insulating layer, and etching both portions of the metal material to form an upper metal pad. The method of claim 3, wherein the photolithography process, Applying a photoresist on the photosensitive insulating layer; Exposing a portion of the resistor on which the photoresist and the photosensitive insulating layer are formed with light using a photo mask; After developing the exposed photoresist; Etching the photosensitive insulating layer of the partial region; The method of manufacturing a thermosetting thick film resistor, characterized in that for removing the photoresist remaining on top of the unetched photosensitive insulating layer. The method of claim 1, wherein applying the thick film resistor paste or ink has a pore size in the range of 400 mesh to 1000 mesh and a thickness in the range of 10 μm to 70 μm. A method of manufacturing a thermosetting thick film resistor, characterized in that it is applied by a screen printing method using a metal mask. 5. The method of any one of claims 1 to 4, wherein the forming of the resistor comprises leveling the applied thick film resistor paste or ink, and then trimming after drying and heat treatment. Thermosetting thick film resistor manufacturing method. The heat treatment according to any one of claims 1 to 4, further comprising applying heat and pressure to all layers of the thermosetting thick film resistor after forming the upper metal pad. Curing thick film resistor manufacturing method. A thermosetting thick film resistor manufactured by the method according to any one of claims 1 to 4.

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