JPH0476989A - Bonding method for electronic component - Google Patents

Abstract

PURPOSE:To snugly secure leads to solders by bending the leads of a molded form of an electronic component, landing the leads on the solders on a board, adhering the form by a bond, and thermally melting and solidifying the solders. CONSTITUTION:Leads 4 are horizontally extended from a molded form 3, and bent in a key type. In this case, the leads 4 are bent excessively downward, then returned and bent upward. Then, the leads 4 are landed on solders 5 formed on a board 1, and an electronic component 2 is placed on a bond 6 of the board 1. The solders 5 are heat treated. In this case, since the leads 4 are excessively bent downward, they are bent in a burying direction. Thereafter, the solders 5 are gradually cooled to be solidified, and the leads 4 are snugly secured to the solders 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for bonding electronic components, and more particularly, the present invention relates to a method for bonding electronic components. Concerning the means to do so.

(Prior art) As a means of bonding an electronic component having leads such as a QFP to a board, solder is formed on the board by plating means or a solder leveler, and the leads extending from the mold body are made to land on this solder. There is a known method of fixing leads to a substrate by heating and melting and solidifying them using reflow means.

FIG. 3 shows such a honding means for electronic components, where l is a board, 2 is an electronic component, 3 is a molded body, 4 is a lead, 5 is solder, and 6 is a molded body 3 attached to a board. This is a bond for temporary fixing by adhering to 1.

(Problem to be Solved by the Invention) The lead 4 is bent into a hook shape by a forming means. However, when the lead 4 is heated during reflow as described above, the lead 4 tries to return to its original shape and tends to float upward (see the chain line in the same figure), and as a result, the lead 4 separates from the solder 5 and is firmly attached to the solder 5. There was a problem that it was difficult to stick to. Incidentally, the amount of this lifting varies depending on the type of electronic component, but is approximately 10 μm.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a means for preventing the leads from floating during solder flow and for reliably fixing the leads to the solder.

(Means for Solving the Problems) For this purpose, the present invention bends the leads extending from the molded body of the electronic component excessively, then bends them back, and then bends the leads extending from the molded body of the electronic component. The leads are fixed to the solder by landing on the solder, bonding the molded body to the substrate with a bond, and heating and melting the solder to solidify it using a reflow means.

(Function) In the above structure, when the lead is heated during reflow, the lead is bent downward, that is, in the direction of being embedded in the solder, and is firmly fixed to the solder.

(Example) Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a forming process for the leads 4 of the electronic component 2. As shown in FIG. Initially, as shown in Figure (a), lead 4
extends horizontally from the mold body 3, and is bent into a hook shape by the forming means. In this case, the lead 4 is bent downward excessively, and then bent back upward (FIGS. 4B and 3C). Like this one do 4
The bending forming may be performed simultaneously with punching from the lead frame, or after punching from the lead frame.

Next, as shown in FIG. 2, the leads 4 are landed on the solder 5 formed on the substrate 1, and the electronic component 2 is mounted on the substrate 1. 6 is a bond for temporarily fixing the molded body 3 to the base ItIi1, and 7 is a circuit pattern formed of copper foil or the like.

The board I on which the electronic component 2 is mounted is sent to a reflow apparatus, and the solder 5 is heated.

The melting temperature of the solder 5 is generally about 183°C, and therefore the solder 5 is heated to above this melting temperature (-generally about 230°C). When the lead 4 is heated during reflow, the lead 4 has been bent downward excessively as described above, so it tries to return to its original shape and bends downward, that is, in the direction of being embedded in the solder 5, as indicated by the chain line in the figure. ), the solder 5 is then gradually cooled and solidified, thereby firmly fixing the leads 4 to the solder 5.

(Effects of the Invention) As explained above, the present invention bends the leads extending from the molded body of the electronic component excessively, then bends them back, and then connects the leads to the solder formed on the top surface of the substrate. The leads are fixed to the solder by placing the molded body on the board, bonding the molded body to the substrate using a bond, and heating and melting the solder using reflow means, so that the leads can be firmly fixed to the solder. can.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is a front view of a lead being formed, Fig. 2 is a front view of an electronic component mounted on a board, and Fig. 3 is a front view of a conventional means. It is. 1... Board 2... Electronic component 3... Mold body 4... Lead 5... Solder 6... Bond

Claims (1)

[Claims] The leads extending from the molded body of the electronic component are bent excessively, then bent back, and then the leads are landed on solder formed on the upper surface of the board, and the molded body is bonded to the board with a bond. A bonding method for electronic components, characterized in that the leads are fixed to the solder by heating and melting and solidifying the solder using a reflow means.