JP2008103547A - Solder paste applying method, and electronic circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for applying a solder paste capable of adequately conducting a soldered joint without a bridge or an unsoldered joint, and to provide an electronic circuit board with an appropriate soldered joint conducted. <P>SOLUTION: The method for applying the solder paste for the connection of a surface mount component to the electronic circuit board 1 by the reflow method comprises a step of partially applying the solder paste 3 to at least a crossover region with a terminal on the surface of the land 2 for component terminal connection on the electronic circuit board 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solder paste coating method and an electronic circuit board, and more particularly, to a solder paste coating method for connecting a semiconductor integrated circuit to an electronic circuit board by a reflow method and to connecting a semiconductor integrated circuit using the solder paste coating method. The present invention relates to an electronic circuit board.

  The technology for mounting a mounting component such as a semiconductor integrated circuit (semiconductor IC) on an electronic circuit board (printed wiring board) by soldering is based on the SIP, because of the high integration of the circuit, automation of mounting, and advantages of electrical characteristics. A flat pack type mounting part such as a QFP (Quad Flat Package) 200 as shown in FIG. The method of surface mounting to connect to the land of the shape is moving. Such a flat pack type mounting component is highly integrated and has many terminals (leads).

  Connection of surface mount components such as QFP 200 to an electronic circuit board is often performed by reflow soldering. In the reflow method, for example, land is required by placing a metal mask made of stainless steel or the like with a predetermined hole on an electronic circuit board, and then soldering the solder paste using a squeegee. Apply solder paste at a certain thickness to the location. Then, the mounting component is mounted on the land to which the solder paste is applied, the electronic circuit board on which the mounting component is mounted on the land is heated in a furnace, the solder paste is melted, and then the solder is cooled to mount Connect the component terminals to the land.

In a conventional method of applying solder paste to a land for reflow method as described in Patent Document 1 (see FIG. 1 of the document), the electronic circuit board 100 as shown in FIG. The solder paste 70 is applied to the entire land 50 as shown in FIG.
Japanese Patent Laid-Open No. 2004-260049

  By the way, as shown in FIG. 9, a flat pack type mounting component such as the QFP 200 which is highly integrated and has a large number of terminals has a very narrow interval between the terminals 200a. The interval between the lands 50 provided on the electronic circuit board 100 is naturally narrow. In this way, when connecting the QFP 200 having a very small interval between the terminals 200a to the electronic circuit board using a conventional solder paste coating method as described in Patent Document 1, the distance between the terminals 200a is set. Since the solder paste 70 is applied to the entire area of each narrow land 50, when heated by a furnace, the molten solder paste 70 is pushed out of the area of the land 50 and comes into contact with the solder 70 of the adjacent land 50, There is a problem that a bridge as shown in FIG. 8 is easily formed. As measures for preventing such bridge formation, it is conceivable to narrow the width of the lands 50 or shorten the length of the lands 50 in order to widen the interval between the lands 50. However, such measures should be taken. However, unsold solder defects may occur.

  The present invention has been made in view of such a problem, and a solder paste application method capable of performing appropriate solder connection without causing a bridge or unsolder failure, and an appropriate solder connection. An object is to provide an electronic circuit board.

  In order to achieve the above object, a solder paste application method according to claim 1 is a solder paste application method for connecting a surface mount component to an electronic circuit board by a reflow method. It is characterized in that a solder paste is partially applied to at least an overlapping region with the terminal on the surface of the land to which the terminal of the component is connected.

  In this method, a solder paste application method for connecting a surface mounting component to an electronic circuit board by a reflow method, on the surface of a land to which a terminal of the surface mounting component provided on the electronic circuit board is connected, Solder paste is applied at least partially in the overlapping region with the terminals of the surface mount component. Here, the “overlapping region” is a region on the surface of the land, and means a region where the terminal of the surface mounting component abuts when the terminal of the surface mounting component is connected to the land.

  In this way, since the solder paste is partially applied to the overlapping area of the land surface with the terminals of the surface mount components, each solder applied partially when the solder paste melts in the furnace. A large amount of molten solder is not formed integrally with the paste, and it is possible to prevent the molten solder from being pushed out of the land area and coming into contact with the molten solder of the adjacent land to form a bridge. Accordingly, the terminals of the surface mount component can be appropriately soldered to the land.

  A solder paste application method according to a second aspect is the solder paste application method according to the first aspect, wherein at least the solder paste is applied to an end portion of the overlapping region of the land.

  According to this method, at least the solder paste is applied to the end of the overlapping region with the surface-mounted component terminal on the surface of the land. Therefore, the fillet can be formed at the end portion of the surface mount component, so that the connection between the terminal of the surface mount component and the land can be strengthened.

  The solder paste application method according to claim 3 is the solder paste application method according to claim 1, wherein, in the overlap region of the land, an end portion of the overlap region partitioned from other regions by a material. Is characterized in that at least solder paste is applied.

  According to this method, at least the solder paste is applied to the end portion of the overlapping area partitioned from the other area by the material in the overlapping area with the surface-mounted component terminal on the surface of the land.

  In this way, since at least the solder paste is applied to the end of the overlapping region partitioned from the other region by the material, when the solder paste is melted in the furnace, the other part of the surface of the melted solder land Therefore, the fillet can be easily formed because the amount of solder at the end of the overlapping region is sufficiently secured. The connection between the terminal and the land of the surface mount component can be strengthened.

  An electronic circuit board according to a fourth aspect is characterized in that surface-mounted components are connected by using the solder paste application method according to any one of the first to third aspects.

  In such an electronic circuit board, since the surface mount components are connected using the solder paste coating method according to any one of claims 1 to 3, a bridge is not generated, and a fillet is formed appropriately. This is an electronic circuit board with solder connection.

  In order to achieve the above object, an electronic circuit board according to claim 5 is an electronic circuit board in which surface-mounted components are solder-connected by a reflow method, and at least a surface of a land provided on the electronic circuit board. The terminal of the component is connected by solder partially applied to an overlapping area with the terminal of the component.

  According to this configuration, the terminals of the surface mount components are connected by the solder partially applied to at least the overlapping area of the surface of the land provided on the electronic circuit board with the terminals of the surface mount components. Here, the “overlapping region” means a region on the surface of the land and a region where terminals of surface-mounted components connected to the land are in contact.

  In this way, since the terminals of the surface-mounted components are connected by solder partially applied to the area of the surface of the land that overlaps at least the terminals of the surface-mounted components, surface-mounting is unlikely to occur between the lands. The component terminals and lands are properly soldered.

  The electronic circuit board according to claim 6 is the electronic circuit board according to claim 5, wherein terminals of the component are connected by solder applied at least to an end portion of the overlapping area of the land. It is characterized by.

  According to this configuration, the terminals of the surface mount component are connected by the solder applied at least to the end of the overlapping area with the terminal of the surface mount component of the land. Therefore, the fillet is formed at the end of the terminal of the surface mount component, and the connection between the terminal of the surface mount component and the land is strong.

  The electronic circuit board according to claim 7 is the electronic circuit board according to claim 6, wherein a material for partitioning the end portion and the other area is provided in the overlapping area of the land. It is characterized by being.

  According to this configuration, in the overlapping region of the land with the terminal of the surface-mounted component, the provision for partitioning the end of the overlapping region and the other region is provided. Therefore, the amount of solder at the end of the overlapping region is sufficient and the fillet is formed, so that the connection between the terminal of the surface mount component and the land is strong.

  Hereinafter, a solder paste application method and an example of an electronic circuit board according to the present invention will be described with reference to the drawings. In addition, the figure used for the following description is a schematic representation of the solder paste application method according to the invention and the items related to the electronic circuit board. Relative dimensions do not indicate actual values or relationships.

  The solder paste application method of the present invention is characterized by the position (and range) of applying the solder paste to the land, and the electronic circuit board of the present invention is located at the position (and range) of solder on the land. Since there are features and the other parts can be the same as the conventional solder paste coating method and electronic circuit board, only these feature parts will be described.

[First Embodiment]
FIG. 1A is an explanatory diagram showing a part of a plurality of lands 2 provided for connecting terminals of surface-mounted components on the electronic circuit board 1. The land 2 is formed, for example, by forming a pattern of copper foil on the surface of the glass nonwoven fabric epoxy resin laminate E by a known method. The surface of the glass nonwoven fabric epoxy resin laminate E is covered with an insulating resist coating R except for the land 2 formation portion. As this resist paint R, an existing one can be adopted.

  The land 2 is for connecting terminals (leads) 200a of a QFP (Quad Flat Package) 200, which is a flat package type semiconductor integrated circuit as shown in FIG. 9, by soldering. As shown in FIG. 9, the QFP 200 includes a plurality of terminals 200a at very small intervals on each of the four periphery of the package 200b. Since the land 2 connects the terminal 200a, the interval between the adjacent lands 2 is narrow as in the terminal 200a.

  When the terminal 200a of the QFP 200 is connected to such a land 2 by reflow soldering, for example, a metal mask (not shown) having a hole corresponding to a portion to which a solder paste is applied is used as the electronic circuit board 1. An application process is performed in which the solder paste is applied to the lands 2 by squeezing the solder paste using a squeegee (not shown).

  In the first embodiment, in the solder paste application process (method), using a metal mask and a squeegee, the solder paste 3 is partially applied to the surface of the land 2 as shown in FIG. Apply. When the terminal 200a of the QFP 200 is connected to the land 2, if the entire area of the surface of the land 2 does not contact (connect) to the terminal 200a of the QFP 200, at least the terminal 200a on the surface of the land 2 overlaps (contacts). The solder paste 3 is partially applied to the region. As shown in the example shown in FIG. 1B, at least the end 2a of the overlapping region of the surface of the land 2 with the terminal 200a, that is, both ends 2a in the longitudinal direction of the land 2 (left and right direction in the drawing) It is preferable to apply the solder paste 3 (a).

  FIG. 2 shows the area around the land 2 of the electronic circuit board 1 to which the QFP 200 is connected by applying the solder paste 3 by the solder paste application method of the first embodiment, and then melting the solder paste 3 and then cooling it. It is sectional drawing. As can be seen from this figure, the land 2 and the terminal 200a of the QFP 200 are connected by solder 4 partially provided between the land 2 and the terminal 200a. As described above, since the solder paste 3 is partially applied to the lands 2, when the solder paste 3 is melted in the furnace, the partially applied solder pastes 3 are integrated. Therefore, it is possible to prevent the molten solder from being pushed out of the land 2 region and coming into contact with the molten solder of the adjacent land 2 to form a bridge. Therefore, the terminal 200a of the QFP 200 can be appropriately solder-connected to the land 2.

  Also, since the solder paste 3 (a) is applied to the end 2a of the overlapping area with the terminal 200a of the land 2, when the solder paste 3 (a) is cooled after being melted, the end of the terminal 200a of the QFP 200 Since the fillet 5 is formed, the connection between the land 2 and the terminal 200a by the solder 4 (5) becomes stronger.

[Second Embodiment]
FIG. 3A is an explanatory view showing a part of the plurality of lands 6 provided for connecting the terminals of the surface mount component on the electronic circuit board 1 ′. In the solder paste application process (method) of the second embodiment, the solder paste 3 is partially applied to the surface of the land 6 as in the first embodiment. However, the end portion 6a of the overlapping area with the terminal 200a on the surface of the land 6 is partitioned from other portions on the surface of the land 6 by the bank 7 provided by application of the resist paint R. At least solder paste 3 (a) is applied to the partitioned end portion 6a.

  FIG. 4 shows the vicinity of the lands 6 of the electronic circuit board 1 ′ to which the QFP 200 is connected by applying the solder paste 3 by the solder paste application method of the second embodiment and then melting the solder paste 3 and then cooling it. FIG. As can be seen from this figure, the land 6 and the terminal 200a of the QFP 200 are connected by the solder 4 partially provided between the land 6 and the terminal 200a. As described above, since the solder paste 3 is partially applied to the lands 6, when the solder paste 3 is melted in a furnace, the partially applied solder pastes 3 are integrated. Therefore, it is possible to prevent the molten solder from being pushed out of the area of the land 6 and coming into contact with the molten solder of the adjacent land 6 to form a bridge. Therefore, the terminal 200a of the QFP 200 can be appropriately soldered to the land 6.

  Further, the end 6a of the land 6 is separated from the other parts of the surface of the land 6 by the ledge 7, and when the solder paste 3 (a) is melted, Since the movement to this portion is prevented by the ledge 7, a sufficient amount of solder is secured at the end 6a, and the fillet 5 is easily formed. Therefore, the solder connection can be strengthened while preventing the formation of the bridge.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications may be made within the scope of the technical idea of the present invention. For example, in the above-described embodiment, the solder paste 3 is applied to the lands 2 and 6 in a row in the longitudinal direction of the lands 2 and 6 (left and right direction in the drawing). As shown, the individual solder pastes 3 may be applied in a plurality of rows. Moreover, the solder paste 3 does not necessarily have to be applied regularly so as to form a row.

  Furthermore, in the above-described embodiment, the position where the solder paste 3 is applied to each of the lands 2 and 6 is the same, but instead, the position where the solder paste 3 is applied to each of the lands 2 and 6 is different. May be. In this case, for example, as shown in FIG. 6, the positions and numbers of the solder pastes 3 applied to every other adjacent lands 2, 6 are different, and the solder pastes 3 applied to the adjacent lands 2, 6 are different from each other. It is better to make the distance of. In this way, the solder paste 3 melted and pushed out of the area of the lands 2 and 6 becomes difficult to contact, so that the occurrence of a bridge can be more effectively prevented.

  Note that the number, position, shape, and the like of the solder paste 3 applied to the lands 2 and 6 and the shape of the sword 7 are not limited to the specific examples of the above-described embodiment.

  The present invention can be applied to a solder paste coating method for connecting a semiconductor integrated circuit to an electronic circuit board by a reflow method and an electronic circuit board to which a semiconductor integrated circuit is connected using the solder paste coating method.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged view of a land 2 portion of an electronic circuit board 1 for explaining a solder paste application method and an electronic circuit board 1 according to a first embodiment of the present invention. It is sectional drawing explaining the electronic circuit board 1 to which QFP200 was connected using the solder paste application | coating method of the 1st Embodiment of this invention. It is an enlarged view of the land 6 part of the electronic circuit board 1 'for explaining the solder paste applying method and the electronic circuit board 1' according to the second embodiment of the present invention. It is sectional drawing explaining electronic circuit board 1 'to which QFP200 was connected using the solder paste application | coating method of the 2nd Embodiment of this invention. It is an enlarged view of the land 2 part of the electronic circuit board 1 for demonstrating other embodiment of this invention. It is an enlarged view of the land 2 part of the electronic circuit board 1 for demonstrating other embodiment of this invention. It is an enlarged view of the land 50 part of the electronic circuit board 100 for demonstrating the conventional solder paste application | coating method. It is explanatory drawing which shows a mode that the bridge | bridging has generate | occur | produced between the lands 50 in the electronic circuit board 100 to which QFP200 was connected by the solder paste 70 apply | coated with the conventional solder paste application | coating method. It is explanatory drawing which shows QFP200 as an example of the surface mounting components connected to the solder paste application | coating method of this invention, and the electronic circuit board 1, 1 '.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electronic circuit board 1 'Electronic circuit board 2 Land 2a End part 3 Solder paste 4 Solder 5 Fillet 6 Land 6a End part 7 E E Glass nonwoven fabric epoxy resin laminated board R Resist paint

Claims (7)

A solder paste application method for connecting a surface mount component to an electronic circuit board by a reflow method,
A solder paste coating method, wherein a solder paste is partially coated on at least an overlapping area with the terminal on a surface of a land provided on the electronic circuit board to which a terminal of the component is connected.   The solder paste application method according to claim 1, wherein at least a solder paste is applied to an end portion of the overlapping area of the land.   2. The solder paste application method according to claim 1, wherein at least the solder paste is applied to an end portion of the overlap area divided from the other area by a material in the overlap area of the land.   An electronic circuit board, wherein a surface mount component is connected using the solder paste coating method according to claim 1. An electronic circuit board in which surface mount components are soldered by a reflow method,
An electronic circuit board, wherein the terminals of the component are connected by solder partially applied to at least an overlapping region of the surface of a land provided on the electronic circuit board with the terminal of the component.   6. The electronic circuit board according to claim 5, wherein the terminal of the component is connected by solder applied at least to an end portion of the overlapping area of the land.   The electronic circuit board according to claim 6, wherein a material for partitioning the end portion and another region is provided in the overlapping region of the land.

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