JP2000332394A - Substrate for mounting electronic parts and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control extrusion of paste solder by providing a protrusion to a portion of a land on a substrate, wherein the height of the protrusion from the principal surface of the land is set to be equal to or less than a desired thickness of the paste solder coated to the principal surface of the land. SOLUTION: A spherical conductive protrusion 15 is provided on each of lands 14. Height H1 of the protrusion 15 from the principal surface of the land 14 is set to be equal to or less than a desired thickness of the paste solder 18 coated to the principal surface of the land 14. In mounting an electronic part 12, the paste solder 18 is coated in layer on the land 14 of the substrate 11 at a predetermined thickness by means of a printing, an electrode 17 of the electronic part 12 is pressed against the land 14, and the electronic part 12 is temporarily fixed to the printed wiring board 11 with the paste solder 18. In this case, an extrusion occurs due to press of the paste solder 18, but a quantity of press of the paste solder 18 is restricted by the protrusion 15. As a result, a quantity of the extrusion of the paste solder 18 can be restricted, and short-circuit of the land to adjacent lands of electronic parts can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for mounting electronic components such as capacitors and resistors using paste solder, that is, cream solder, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As shown in FIG.
When connecting the electrodes 3a of the electronic component 3 to the electronic component 3, the paste solder 4 is applied on the lands 2 of the substrate 1, the electronic component 3 is arranged on the paste solder 4, and then heat treatment is performed.

[0003]

In the case where a large number of electronic components 3 are mounted on the substrate 1 at high density, if the paste 4a protrudes from the lands 2 and becomes larger, the adjacent electronic components 3 are protruded by the protrusions 4a. A short circuit occurs between components. Further, even if the short-circuit state does not occur, the protruding solder may adversely affect the characteristics of the adjacent electronic component.

Accordingly, an object of the present invention is to provide a solder paste 4
It is an object of the present invention to provide an electronic component mounting board and a method of manufacturing the same, which can suppress protrusion.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the above-mentioned objects, the present invention provides a substrate for mounting an electronic component having electrodes using paste solder. A projection is provided on a part of the land, and the height of the projection from the main surface of the land is set to be equal to or less than a target thickness of the paste solder applied to the main surface of the land. Related to the substrate for use.

It is to be noted that the protrusion can be formed in a hemispherical shape. Further, the projection can be formed in a belt shape as described in claim 3. In addition, an insulating protrusion can be provided on a surface facing the electronic component. Further, the projections can be formed based on the printing of the conductive paste. Further, the projections can be formed by a ball bonding method. Further, the projection can be formed by a solder ball.

[0007]

According to the invention of each claim, the protrusion or the insulating protrusion functions as a stopper of the electronic component, so that the crushing of the paste solder more than necessary is prevented, and the protrusion of the paste solder is suppressed. Can be. This allows
An improvement in the mounting density of the electronic components or an improvement in the reliability of the mounting of the electronic components is achieved. According to the second aspect of the present invention,
The hemispherical projection can be easily obtained by the same forming method as the bump electrode for face-down bonding, for example. Also, a sufficient contact surface of the solder with the electronic component can be secured. According to the third aspect of the present invention, the projection can be easily formed simultaneously with the land forming step or as an extension of this step. Further, the height of the protrusion can be easily controlled. According to the fourth aspect of the present invention, the insulating protrusion functions as a stopper for the electronic component, and the protrusion of the solder can be prevented well. According to the invention of claims 5 to 7, the projection can be easily formed.

[0008]

Embodiments and Examples Next, embodiments and examples of the present invention will be described with reference to FIGS.

[0009]

First Embodiment A circuit board device according to a first embodiment shown in FIGS. 2 and 3 comprises an insulating circuit board 11 and electronic components 12. FIG. The circuit board 11 has a pair of lands 14 as conductor patterns for mounting electronic components on one flat main surface 13, and further has two hemispherical conductor protrusions 1 on each land 14.
5 The rectangular parallelepiped electronic component 12 is a porcelain capacitor and has a main body 16 and a pair of electrodes 17. The paired electrodes 17 are fixed to the paired lands 14 using cream solder or paste solder 18.

The projection 15 is formed of a hemispherical conductor, and is formed by the same method as the method of forming an IC bump electrode for face-down bonding. That is, in the present embodiment, the conductive paste is selectively printed on the lands 14, and thereafter, the conductive paste is shaped into a hemispherical shape by a mold, and the resultant is subjected to a heat treatment to form the protrusions 15.

As shown in FIG. 3, two protrusions 15 are formed on one land 14 in order to enhance the stability of the electronic component 12.
Are arranged. The height H1 of each projection 15 from the main surface of the land 14 is set to be equal to or less than the target application height of the paste solder 18 from the main surface of the land 14. If the height H1 of the projection 15 is equal to or less than the target height, that is, the thickness, of the paste solder 18, the effect according to the present invention can be obtained, but the variation of the height H1 of the projection 15 and the thickness of the layer of the paste solder 18 can be obtained. The height H1 of the projection 15 is set to 50 to 90 of the target thickness of the paste-like solder 18 in consideration of the dispersion of the soldering, the bonding strength of the electronic component 12 to the land 14 and the protrusion of the solder.
% Is desirable. Further, in order to surely achieve the electrical and mechanical coupling between the land 14 and the electrode 17 of the electronic component 12, the area of the projection 15 in plan view is
It is desirable to set the area of the region facing the fourth electrode 17 to 50% or less, preferably about 5 to 20%. In addition, it is desirable that the four protrusions 15 for one electronic component 12 be arranged at corners of the virtual rectangle in order to stably support the electronic component 12.

When mounting the electronic component 12, the substrate 11
A paste solder 18 is applied in a layer to a predetermined thickness on the land 14 by a printing method. The protrusion 15 is a solder paste 1
Since the thickness is equal to or less than the predetermined thickness of 8, ie, the target thickness, the printing of the paste-like solder 18 is not hindered. Next, the electronic component 1
The second electrode 17 faces the land 14, the electronic component 12 is pressed in the direction of the land 14, and the electronic component 12 is temporarily fixed to the circuit board 11 with the paste solder 18. At this time, the paste-like solder 18 is crushed to form a protruding portion, but the amount of the crushing of the paste-like solder 18 is limited by the protrusion 15. For this reason, the amount of protrusion of the paste-like solder 18 is also limited, and a short circuit does not occur between a land or an electrode of an adjacent electronic component. Thereafter, the paste solder is heat-treated, and the electrode 17 is electrically and mechanically coupled to the land 14 by a known reflow.

As apparent from the above, the present embodiment has the following effects. (1) Since the projections 15 function as stoppers and limit the crushing of the paste solder 18, the paste solder 1
8 can be prevented from protruding. If the reliability or the defect occurrence rate can be the same as in the related art, the mounting density of the electronic component 12 can be increased. In addition, a required amount of solder can be interposed between the electrode 17 and the land 14, so that both can be satisfactorily coupled. (2) Since the protrusion 15 is hemispherical, the contact area of the solder 18 with the electrode 17 can be increased, and the land 1
4, the electrode 17 can be satisfactorily coupled. (3) Since the height H1 and the area of the projection 15 are set so as not to hinder the connection by the paste solder 18, the connection between the land 14 and the electrode 17 can be favorably achieved. (4) Since the projections 15 are formed by the same method as the method for forming the bump electrodes, the projections 15 can be easily formed. (5) Since the projection 15 is a conductor, it does not hinder the electrical connection between the electrode 17 and the land 14.

[0014]

Second Embodiment Next, a circuit board device according to a second embodiment of the present invention and a method of manufacturing the same will be described with reference to FIG. However, in FIG. 4 and FIGS. 5 to 9 showing third to fifth embodiments to be described later, parts common to FIGS. 2 and 3 are denoted by the same reference numerals and description thereof is omitted.

The circuit board device of the second embodiment shown in FIG. 4 is substantially the same as the first embodiment except that the method of forming the projections 15 is changed. In this second embodiment, as shown in FIG. 4A, a ball 22 is formed on an Au (gold) wire 21 derived from a well-known capillary 20 of a wire bonding apparatus. 4A, and the wire 21 is cut to form the protrusion 15 shown in FIG. 4B. Next, as shown in FIG. 4C, a paste-like solder 18 thicker than the projections 15 is applied. Next, as shown in FIG. 4D, the electrode 17 of the electronic component 12 is
Then, the electrode 17 is electrically and mechanically coupled to the land 14 by heat treatment.

The second embodiment has the same effect as the first embodiment, and also has the effect that the projection 15 can be easily formed by using a wire bonding apparatus.

[0017]

Third Embodiment A third embodiment shown in FIG. 5 is substantially the same as the first embodiment except that the method of forming the projections 15 of the first embodiment is changed. In the third embodiment, first, FIG.
As shown in (A), a flux 30 is applied on the land 14 by printing. Next, as shown in FIG. 5B, a solder ball 31 is temporarily fixed on the land 14 using the adhesive property of the flux 30, and this solder ball 31 is formed as a protrusion similar to the protrusion 15 of the first embodiment. Use as Next, as shown in FIG.
The paste-like solder 18 is printed on the first solder paste 1 thicker than the diameter of the solder ball 31. Next, as shown in FIG. 5D, the electrode 17 of the electronic component 12 is pressed against the layer of the paste solder 18. At this time, the solder ball 31 is used as a stopper. Thereafter, the electrode 17 is soldered to the land 14 by performing a heat treatment.

The third embodiment has the same effects as the first embodiment, and also has a flux 30 and a solder ball 31.
This also has the effect that the projection can be easily formed.

[0019]

Fourth Embodiment A band-like projection 15a is provided on a land 14 of a circuit board 11 shown in FIGS. The strip-shaped projection 15a is formed of a conductor layer formed by plating in an extension step of the step of forming the land 14. Therefore, the band-like projection 15a can be regarded as a part of the land 14. The band-shaped protrusion 15 a is arranged so as to face a part of the electrode 17 of the electronic component 12. The height of the band-like projection 15a from the main surface of the land 14 and the electrode 17 of the land 14
The ratio of the area of the protrusion 15a to the region facing the area is determined by the same principle as in the first embodiment.

When the electronic component 12 is mounted on the substrate 11, a paste solder 18 is applied to the land 14. FIG.
Although the paste-like solder 18 is not applied to the upper surface of the belt-like protrusion 15a in the embodiment, the paste-like solder 18 can be applied to the upper surface of the protrusion 15a. In this case, the height of the upper surface of the paste-like solder 18 becomes flat, so that the thickness of the paste-like solder 18 on the protrusion 15a becomes thinner than other portions. Next, the electrode 17 of the electronic component 12 is
The electrode 17 is soldered to the land 14 by applying heat treatment.

The fourth embodiment is the same as the first embodiment (1).
(3) In addition to having the same effect as (5), since the projection 15a is formed by plating, there is also an effect that this height becomes accurate.

[0022]

Fifth Embodiment A substrate 11 according to a fifth embodiment shown in FIGS. 8 and 9 has an insulating protrusion formed on the principal surface 13 of the substrate 11 in a region facing the electronic component 12 based on printing of a resist. It has a minute 15b. The insulating protrusions 15b are arranged between the lands 14 and are formed thicker than the lands 14. The protrusion height of the insulating protrusion 15b from the main surface of the land 14 is the same as the protrusions 15, 15 of the first and fourth embodiments.
It is set to the same value as the height of a. When the electronic component 12 is mounted on the substrate 11 shown in FIGS.
A paste-like solder 18 is applied by printing to a thickness equal to or greater than the height of the protrusion 15b from the land 14, and the electrode 17 of the electronic component 12 is pressed against the solder, followed by heat treatment. The fifth embodiment has the same effect as (1) of the first embodiment, and also has the effect that electrical separation between the pair of lands 14 can be reliably achieved.

[0023]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The portion of the land 14 other than the portion facing the electrode 17 can be covered with the insulating film. (2) The insulating protrusions 15b of FIGS. 8 and 9 can be partially formed instead of being formed entirely between the pair of lands 14. (3) The protrusions 15 and 15a of the first and fourth embodiments can be formed of an insulator. (4) The protrusions 15 can be formed by a vapor deposition method, a plating method, or the like.

[Brief description of the drawings]

FIG. 1 is a front view showing a conventional circuit board and electronic components partially cut away.

FIG. 2 is a front view of the circuit board and the electronic component according to the first embodiment of the present invention, partially cut away;

FIG. 3 is a plan view of a circuit board with lands and protrusions of FIG. 2;

FIG. 4 is a cross-sectional view illustrating a method of forming projections and mounting electronic components according to a second embodiment in the order of steps.

FIG. 5 is a cross-sectional view showing a method of forming projections and mounting electronic components according to a third embodiment in the order of steps.

FIG. 6 is a partially cutaway front view showing a circuit board and an electronic component according to a fourth embodiment;

FIG. 7 is a plan view of a circuit board with lands and protrusions of FIG. 6;

FIG. 8 is a partially cutaway front view showing a circuit board and electronic components of a fifth embodiment.

FIG. 9 is a plan view of a circuit board having lands and protrusions of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Circuit board 12 Electronic component 14 Land 15 Projection 17 Electrode 18 Paste solder

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaya Shimamura 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. F-term (reference) 5E319 AA03 AB05 AC15 BB04 BB05 CC33 CD29 5E336 AA04 BB01 BC28 CC31 CC51 EE03

Claims (7)

[Claims] 1. A substrate for mounting an electronic component having electrodes using paste-like solder, wherein a projection is provided on a part of a land of the substrate, and the projection extends from a main surface of the land. An electronic component mounting board, wherein a height is set to be equal to or less than a target thickness of the paste solder applied to the main surface of the land. 2. The electronic component mounting board according to claim 1, wherein said projection is a hemispherical projection. 3. The electronic component mounting board according to claim 1, wherein the projection is a band-shaped projection. 4. A board for mounting an electronic component having electrodes using paste solder, wherein an insulating projecting portion is provided on a main surface of the substrate in a region facing the electronic component. The protruding portion is arranged adjacent to the land, and the height of the protruding portion of the insulating protruding portion from the main surface of the land is equal to or less than the target thickness of the paste solder applied to the main surface of the land. An electronic component mounting board characterized by being set. 5. A land for connecting an electronic component having electrodes using solder paste, a projection is provided on a part of the land, and a height of the projection from a main surface of the land is provided. Is a method of manufacturing an electronic component mounting board, wherein the thickness of the paste is set to be equal to or less than a target thickness of the paste solder applied to the main surface of the land. Is formed into a hemispherical shape, and thereafter, the protrusion is formed by heat treatment. 6. A land for connecting an electronic component having electrodes using paste solder, a projection is provided on a part of the land, and a height of the projection from a main surface of the land is provided. Is a method for manufacturing an electronic component mounting substrate, which is set to a thickness not more than a target thickness of the paste solder applied to the main surface of the land, wherein a ball is attached to the tip of the wire using a wire bonding apparatus. Forming a ball, pressing the ball against the land, and then cutting the wire to form the protrusion. 7. A land for connecting an electronic component having electrodes using paste solder, a projection is provided on a part of the land, and a height of the projection from a main surface of the land is provided. Is a method of manufacturing an electronic component mounting board, which is set to a thickness equal to or less than a target thickness of the paste solder applied to the main surface of the land, wherein the protrusion is formed by bonding a solder ball on the land. A method for manufacturing a substrate for mounting electronic components, characterized by being formed.