JPH02112993A - Manufacture of thick film circuit board and mesh mask for manufacture - Google Patents

Abstract

PURPOSE:To eliminate an irregularity in the quantity of paste and to maintain the paste to be coated in a suitable shape by reducing in thickness a layer of nonopening around an opening thinner than the nonopening of the other part, and employing a mesh mask having a space to be engaged with the protrusion of a thick film pattern on a circuit board. CONSTITUTION:A resistor 4 is printed from the protrusion (conductor 5) of a circuit board having a protrusion conductor pattern 5 on a board 3 over the protrusion (conductor 5). A mesh mask is formed with an enlarged space having an opening area larger than that of an opening 1 at the board side of the opening, and the thickness of the nonopening of the periphery of the opening is reduced. The vertical wall face of the enlarged space is so composed as to be brought into contact with the vertical face of the outer periphery of the conductor 5. Accordingly, the protrusion (conductor 5) on the face of the board is formed in shape to be engaged within the enlarged space. Thus, the contact state of the mask with the board face is stabilized, and easy wear of the edge of a pattern hole of a conventional mesh mask is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for applying a method to a substrate on which a thick film pattern has already been formed.
The present invention relates to a method for manufacturing a thick film circuit board that includes a step of screen printing a paste such as a dielectric or a resistor so as to partially overlap the thick film pattern, and a mesh mask used in the manufacturing.

[Prior Art] A method for producing a thick film hybrid integrated circuit includes printing a conductor on a ceramic M[2 such as alumina, firing it, and printing a cross glass when the conductors cross each other. It includes many steps such as printing the dielectric, baking it, printing the resistor, baking it, printing the solder paste, mounting the surface mount component, and flowing the solder. .

Usually, thick film printing is carried out by a screen printing method, which consists of placing a paste on a stencil-made screen, extruding it through a pattern with a squeegee, and transferring it onto a substrate. There is a mesh mask in which an opening pattern is formed in the mask layer.When forming electrode patterns, dielectric patterns, resistance patterns, etc., mesh masks are generally used in consideration of printing accuracy, density, etc.

The detailed structure of the mesh mask is as follows. In other words, a mesh made of stainless steel wire or resin fiber such as nylon is attached to a metal frame, and a pattern is created by applying an emulsion to the mesh and curing the emulsion. Alternatively, the pattern is made by printing a pattern on a Mylar film coated with an emulsion, developing it, and pressing it onto the mesh. The cross section of the mesh mask is as shown in FIGS. 1b and 2b, and the squeegee side and the substrate side of the non-opening portion 2 are in the opposite direction. In other words, the thickness of the non-opening area is uniform, and the thickness of the pattern hole (opening area) is uniform.
1 is provided perpendicularly to this plane.

[Problems to be solved by the invention] However, since the screen printing mask was originally created on the assumption that the surface to be contacted was flat, it overlapped with a part of the convex part of the thick film pattern. When printing in this way, when the squeegee scrapes the top surface of the mask, the mask layer is abraded by the protrusions of the thick film pattern on the substrate. This tendency was particularly noticeable at the periphery of the opening of the mask.

When the periphery of the screen opening becomes worn, variations in the amount of paste applied during printing, so-called sagging and smearing, occur, resulting in variations in resistance and disconnection of electrode wires. Resulting in.

Therefore, it is an object of the present invention to print on a part of a thick film pattern on a substrate on which a thick film pattern has been formed, by adjusting the contact surface of the mesh mask or the pattern on the substrate to reduce the amount of paste. It is an object of the present invention to provide a method for manufacturing a J1 film circuit board in which the shape of the applied paste can be maintained in an appropriate shape without causing variations.

[Means for Solving the Problems] The present invention attempts to achieve the above object by adopting the following method. That is, the screen printing step of a thick film circuit board manufacturing method includes a step of forming a thick film pattern by performing screen printing using a mesh mask on a substrate on which a thick film pattern is formed so as to overlap a part of the pattern. In,
Adopts a failed method of manufacturing thick film circuit boards, which is characterized by the use of a mesh mask with a special structure. Here, a mesh mask with a special structure is defined by configuring the thickness of the IU opening layer around the opening of the mesh mask to be thinner than other non-opening areas, depending on the convex portion on the circuit board surface. This mesh mask has a structure in which a space is formed on the circuit board side of the mesh mask into which a convex part of a thick film pattern on the circuit board surface is inserted.

[Function] This kind of screen printing mask works as follows.

The screen printing mask of the present invention is provided with four portions having shapes and dimensions corresponding to the respective convex portions at positions corresponding to the convex portions of the thick film pattern on the thick film circuit board, and each convex portion on the substrate. Since the surface of the emulsion is in stable contact with the concave surface of the screen over a wider area, the force of the squeegee pushing the emulsion is dispersed, and local wear around the screen openings is eliminated. Therefore, it does not easily sag even if multiple sheets are printed in succession. Therefore, a plurality of circuit boards without variations in resistance value etc. can be manufactured.

Further, since the four parts of the mesh mask are formed so as to fit into the convex portions on the substrate, the mesh mask does not become misaligned.

FIG. 1a shows that, by the method of the present invention, a resistor 4 is printed across a circuit board having a convex conductor pattern 5 on a substrate 3 from convex part (conductor 5) to convex part (conductor 5). It is a schematic diagram showing a state. FIG. 1b shows the printing of resistors in a conventional manner as well. As can be seen from the comparison between the two figures, the mesh mask used in the present invention has an enlarged space on the substrate side of the opening, which has an opening area larger than that of opening 1, and the mesh mask used in the present invention has an enlarged space with an opening area larger than the opening area of opening 1. The wall thickness of the opening is dirty. The vertical wall surface of the expanded space is configured to be in contact with the outer circumferential vertical surface of the conductor 5, and therefore the convex portion (conductor 5) on the board surface is fitted into the expanded space, so that the mesh mask and the board The state of contact with the surface becomes stable, and the edge portions of the pattern holes are not particularly prone to wear, which is the case when conventional mesh masks are used.

FIG. 2a is a schematic diagram showing a state in which another conductor 7 is printed on the cross glass 6 covering the conductor 5 on the substrate surface using the mesh mask of the present invention. FIG. 2b is a schematic diagram illustrating the same situation as in FIG. 2a using a conventional mesh mask.

FIG. 3a is a schematic diagram showing an example of the shape of the resistor when the resistor 4 is printed across the conductors 5 by the method of the present invention.

FIG. 3b is a schematic diagram showing an example of the shape of the resistor 4 when the same thing as in FIG. 3a is performed using a conventional method.

Figure Q4a is a schematic diagram showing an example of the shape of the conductor when the conductor 7 is printed on the cross glass 6 by the method of the present invention.

FIG. 4b is a schematic diagram showing an example of the shape of the conductor 7 when the same thing as in FIG. 4a is performed using a conventional method.

This will be explained below using examples.

Example 1 A resistor (width 2.0 mm, thickness 0.25 mm) was placed between conductors (Ag-Pd conductors) with a width of 0.3 mm and a distance of 0.15 mm printed on a circuit board with a spacing of 2III11. Printed.

The overlap between the electrode and the resistor was 0.2 mm.

0.1 when using a conventional screen (thickness 20-)
A dragon sag occurred, and furthermore, when 100 copies were printed, a 0.13 mm sag occurred.

On the other hand, in the manufacturing method according to the present invention using a screen having four parts (thickness: 20 μs, depth of the four parts: 15 ρ) with the same pattern as the conductor pattern except that the relationship between the convex and concave portions is reversed on the MIIM side surface of the mesh mask, According to 0.02
Only 0.03 mm of sag occurs even after 100 printings.
A thick film circuit board with only m sag could be manufactured.

[Effects of the Invention] Using a printing mask as described above, a thick film pattern is printed over the convex portions of the thick film pattern on a substrate.
By manufacturing the membrane circuit board, the following effects were obtained. That is, the printing mask used in the present invention is purchased so that the thickness of the mask around the opening is thinner than that of other parts in accordance with the convex parts of the thick film pattern on the substrate, and the thickness is 11. % Since the outer walls of the convex parts of the pattern are in contact with the inner walls of the four parts of the mask, the force from the squeegee is dispersed over a wider area, making it easier to apply even when printing on a substrate with many irregularities. Thick film circuit J! that does not cause variations in quantity (so-called sagging or fading) and therefore has stable characteristics! Can you provide the board? Furthermore, since the shape retention of the mask itself is good, the same mask can be used for a long period of time, which is economical.

Further, since the thickness of the opening can be set to a thickness such that an appropriate amount of paste can be applied, the pattern shape is less likely to be disturbed. Furthermore, since the screen printing mask is provided with four parts so that the convex parts on the substrate are fitted into them, there is no possibility of misalignment.

[Brief explanation of the drawing]

FIG. 1a is a schematic cross-sectional view showing the structural features of a mesh mask used in the method of the present invention and a state in which a resistor is printed between conductors protruding on a substrate using the mesh mask. FIG. 1b is a schematic cross-sectional view showing the structural features of a mesh mask used in the conventional method and the state in which a resistor is printed between conductors protruding on a substrate using the mesh mask. FIG. 2a is a schematic diagram illustrating the structural features of another mesh mask used in the method of the present invention and the state in which a conductor is printed on a cross glass disposed over a conductor on a substrate using the mesh mask. It is a diagram. FIG. 2b is a schematic diagram showing the structural features of another mesh mask used in the conventional method and a state in which a conductor is printed on a cross glass arranged in the same manner as described above using this mesh mask. FIG. 3a is a bottom view showing a state in which a resistor is printed across two conductors existing in a protruding manner on a substrate by the method of the present invention. FIG. 3b shows a conventional method in which 2
FIG. 2 is a schematic diagram showing a state in which a resistor is printed across two conductors. FIG. 4a is a flat plate view showing a state in which a conductor is printed on a cloth glass by the h' method of the present invention. FIG. 4b is a schematic diagram showing a state in which a conductor is printed on a cross glass using the conventional X method. The symbols in the figure represent the following, respectively. 1... Opening of mesh mask 2... Non-opening of mesh mask 3... Substrate 4... Resistor 5...
Conductor 6...Cross glass 7...Conductor

Claims (2)

[Claims] (1) A thick film circuit board including the step of forming a thick film pattern by screen printing using a mesh mask on a substrate on which a thick film pattern has been formed, and overlapping a part of the convex portion of the thick film pattern. In the manufacturing method, the thickness of the non-opening area around the opening of the mesh mask that is in contact with the thick film pattern on the substrate is removed, and the thickness of the non-opening area around the opening is greater than the thickness of the non-opening area of other parts. A mesh mask is used in which an enlarged space is formed around the opening on the circuit board side into which the convex part of the thick film pattern on the substrate surface can be inserted by configuring the mask surface to be thinner. A method for manufacturing a thick film circuit board, characterized in that contact between the surface of the circuit board and the surface of the circuit board having a convex portion is stabilized. (2) A mesh mask consisting of a mesh and a mask layer having an aperture pattern, in which the non-aperture portions in contact with the thick film pattern on the substrate around the apertures of the mesh mask are removed, and the non-aperture surrounding the apertures are removed. By configuring the opening so that the wall thickness is thinner than the wall thickness of the other non-opening parts, an enlarged space into which the convex part of the thick film pattern on the board surface can be inserted is created around the opening on the circuit board side. A mesh mask characterized by having a mesh formed in the upper part of the mask.