JPH04111494A - Soldering method for surface-mounting parts - Google Patents

Abstract

PURPOSE:To remove the nonconformity such as a solder bridge, etc., by applying paste-shaped solder on both ends excluding approximately the center of a soldering land, respectively, and positioning the lead terminal of connection so that it may contact slightly with this, and letting solder reflow. CONSTITUTION:Paste-shaped solder 4 is printed at both front and rear ends avoiding approximately the center of a soldering land 2, using a metal screen 3 or the like. A surface-mounting part 5 is temporarily positioned and placed on a circuit board 1 so that it may contact slightly with the paste-shaped solder 4 applied on both ends while spacing and that a great part it may abut on the nonapplication part at the center of the soldering land 2. Next, it is passed in, for example, a tunnel type furnace or the like so as to let the paste-shaped solder 4 applied while being spaced on the soldering land 2 reflow, whereby the required soldering is achieved, and the adjacent fellow paste-shaped solders can be prevented easily from connecting with each other which causes a solder bridge or short circuit, and there is no necessity to repair circuits, etc., after reflow-soldering.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method of soldering surface-mounted components, and particularly relates to a method for soldering surface-mounted components, particularly when the spacing between connection lead terminals to be soldered is narrow and solder bridges, etc. The present invention relates to a soldering method suitable for soldering sensitive surface mount components.

(Prior art) It is known that a desired mounted circuit device is constructed by soldering the connection lead terminals of a multi-connection lead terminal type surface mount component to corresponding predetermined soldering lands on the circuit board surface. It is being The corresponding predetermined soldering on the surface of the circuit board is carried out by flow soldering of lead terminals for connection of surface mount components to lands as follows.

That is, as schematically shown in FIGS. 3 and 4, the solder formed on one side of the circuit board is applied to the entire surface of the land 2 using a metal screen 3 or the like in the form of a paste.
After printing and applying the solder 4 in the form of solder (or cream-like), solder the connection lead terminal 6 of the multi-connection lead terminal type surface mount component 5 so that the part to be soldered comes into contact with the center part of the land 2. So-called reflow soldering is performed by positioning and temporarily placing the surface mount component 5, and then passing it through a heating furnace or the like to melt (reflow) the paste solder 4. Note that 7 in the figure indicates a portion with which the connection lead terminal 5 comes into contact.

Furthermore, as schematically shown in FIGS. 5 and 6, soldering is carried out after applying paste solder 4 on the land 2 in an island-like manner so that coated areas and non-applied areas are alternately arranged. Another method is to solder the connection lead terminal 6 by bringing it into contact with the center of the land 2 and soldering it in the same manner.

In this way, in the conventional method, the connection lead terminal 6 of the surface mount component 5 and the circuit board 1 are soldered by interposing the paste solder 4 between the contact surfaces with the lands 2 to achieve the required soldering. However, in the soldering method described above, when the surface mount component 5 is temporarily placed, the surface mount component 5 is mounted as shown schematically in FIG. As shown in the figure, the paste solder 4 applied to the middle part of the land 2 is crushed from above by the connection lead terminal 6 placed on top of the solder, and the paste on the land 2 is used for soldering adjacent to each other. There was a risk of contact with the shaped solder 4. Moreover,
Since the solder is reflowed in that state, there is a problem in that solder bridges occur and adjacent soldered lands tend to short-circuit. This problem in which solder bridges and soldering tend to cause short circuits between lands becomes even more serious as the lead terminals for multiple connections of surface mount components are used and the pitch of connection lead terminals becomes narrower.

The present invention has been made to solve these problems, and aims to provide a method for soldering surface mount components that completely eliminates the possibility of problems such as solder bridging.

[Structure of the Invention] (Means for Solving the Problems) The method for soldering surface mount components of the present invention is a multi-connection lead terminal type surface mount soldering method on a predetermined position surface of a conductor pattern formed on a circuit board surface. In the method of soldering the connection lead terminals of components, the conductor pattern is soldered by applying paste solder to both ends of the land, excluding the approximately central part, and then applying solder to the parts of the connection lead terminals to be soldered. Most of the soldering methods are characterized by placing the surface mount component in contact with the center of the land, and then reflowing the paste solder through a heating furnace.

(Function) In the method for soldering surface mount components of the present invention, paste solder is applied to both ends of the land except for the approximately central part, and a small amount of solder is applied to the areas where the paste solder is applied. Since the connection lead terminal of the surface mount component is positioned and placed so as to be in contact with the surface mount component, only a portion of the applied paste-like solder is crushed from above by the connection lead terminal. Therefore, when soldering adjacent to each other, it is easily prevented that paste-like solder on the lands connect with each other to cause solder bridges or short circuits, and reflow soldering does not require modification of the circuit later.

(Example) The present invention will be described in detail below with reference to FIGS. 1 and 2.

1 and 2 are a plan view and a cross-sectional view schematically showing an embodiment of the method for soldering surface-mounted components according to the present invention.

First, a required circuit board 1 is prepared, and a required paste-like solder 4 is printed and applied onto the land 2 surface of each solder joint formed on the circuit board 1 surface. In other words, the area corresponding to the main part 7 where the connection lead terminal 6 of the multi-connection lead terminal type surface mount component 5 comes into contact with and is soldered, in other words, the soldering is done at approximately the center of the land 2 surface. avoid,
Paste solder 4 is printed and coated on both the front and rear end portions using a metal screen 3 or the like at a distance.

On the other hand, a multi-connection lead terminal type surface mount component 5 prepared in advance for mounting is attached so that the lower surface of the connection lead terminal 6 to be soldered, which this surface mount component 5 has, is attached to both ends. The surface mount component 5 is positioned on the circuit board 1 so that it slightly contacts the paste-like solder 4 applied at a distance, and most of the solder contacts the non-applied portion of the solder land 2. Place it temporarily.

After the multi-connection lead terminal type surface mount component 5 is mounted on one surface of the circuit board as described above, the component is then passed through a tunnel type heating furnace, etc., and the soldering is performed by applying a paste separately applied to two surfaces of the land. By reflowing the shaped solder 4, the required soldering is achieved. In addition,
In the figure, 7 indicates a portion (area) with which the connection lead terminal 6 comes into contact.

In the means configured as described above, there is almost no paste-like solder 4 pushed out by the connection lead terminal 6 (even if there is, only a small amount), and therefore the solder that is adjacent to each other is the solder 4 on the land 2. Contact between them will also be completely eliminated. In addition, the solder 4 melted in the reflow process using a heating furnace or the like flows into the interface between the connection lead terminal 6 and the solder-free part of the solder land 2, which prevents the formation of solder bridges and improves the electrical connection. will definitely be accomplished. Therefore, reflow soldering eliminates the need to modify the circuit afterwards, and can significantly reduce the time and manpower required for conventional modifications.

[Effects of the Invention] As explained above, according to the method of soldering surface mount components according to the present invention, the possibility of problems such as solder bridging occurring in the connection lead terminals can be easily avoided. Therefore, surface mount components can be efficiently reflow soldered onto a circuit board, and a highly reliable mounted circuit board or mounted circuit device can be easily obtained. Moreover, since soldering does not require subsequent circuit modifications, the time and manpower required for modification can be significantly reduced.

[Brief explanation of the drawing]

1 and 2 are plan views and cross-sectional views schematically showing embodiments of the present invention, respectively, and FIGS. 3 and 4 schematically show embodiments of a conventional method for soldering surface mount components. 5 and 6 are plan views and sectional views schematically showing embodiments of another conventional soldering method, and FIG. 7 is a conventional soldering method. FIG. 2 is a plan view for explaining problems caused by 1...Circuit board 2...Soldering land 3...Metal screen 4...Paste solder 5...Multi-connection lead Terminal type surface mount parts 6・
...Connection lead terminal

Claims (1)

[Claims] A method of soldering connection lead terminals of a multi-connection lead terminal type surface mount component to a predetermined position surface of a conductor pattern formed on a circuit board surface, excluding approximately the center portion on the soldering land of the conductor pattern. After applying paste solder to both ends, place the surface mount components so that most of the soldered parts of the connection lead terminals are in contact with the center of the corresponding soldering land, and then pass the paste through a heating furnace. A method for soldering surface mount components, characterized by reflowing solder.