1. Field of the Invention
The present invention concerns a connecting strip for the manufacture of electric components intended to be used for wave or flow soldering.
These electric components are especially represented by parallelepiped shaped capacitors otherwise known as "chips" capacitors. These elements comprise metallized terminals located on two opposite faces of the parallelepiped and which are directly carried over onto the printed circuits by gluing then passing through a soldering flow at about 260.degree. C. for several seconds.
2. Description of the Prior Art
Manufacturing "chips" capacitors from metallized dielectric film raises a certain number of problems. It is known, for example from French patent published under No. 2,011,553, corresponding to U.S. Pat. No. 3,670,378 to produce parallelepiped shaped capacitors of the stacked type from metallized plastic dielectrics. After winding upon a wheel having a large diameter so as to form superposed mother capacitors, then schooping of the lateral faces of the said mother-capacitors, the resulting devices are punched into individual capacitors, perpendicularly to the lateral schoopings. Such capacitors, while having the required form, cannot in practice be used as soldering chips capacitors according to the method mentioned hereinabove. In fact, it has been observed that such capacitors, for example made of metallized polyester, are damaged by mechanical deformations due to the withdrawal of the films utilized, between the two non-schooped faces of the parallelepiped corresponding to the severing face of the mother-capacitor.
French patent application FR 2,555,356 filed on Nov. 18, 1983 describes a novel solution to limit this damage. According to this patent application, the terminals of the capacitor are defined by electric contacts constituted by U-shaped sections comprising constricted zones so as to reduce thermal conduction with respect to contact fingers while ensuring a satisfactory electric conduction. In fact, the use of contact or controller fingers between each lateral schooping of the parallelepiped and the external electric connection of the finished capacitor reduces thermal conduction between the capacitor itself and the external electric connection. In this way, during the flow soldering step, the heat transmission is sufficiently low so as not to provoke any damage or degradation of the capacitor itself.
The method of manufacturing this capacitor causes the intervention of two U-shaped sections having contact fingers that are welded onto the schoopings, the space between the sections being thereafter filled with resin and the resulting structure being punched out to form individual capacitors.
The drawback of this process consists in the utilization of two sections that have to be arranged exactly parallel to each other, upon the positioning of the electric elements with respect to these sections. The coating of these elements is also a rather delicate operation to perform.
In order to overcome these drawbacks, the invention proposes a connecting strip acting throughout the whole manufacturing cycle: firstly, as a support for the elements which are soldered onto tags integral with the strip. The strip thereafter acts as a joining plane for the molding of the coating resin. A punching out of the strip thereafter allows the electric connections of the component to be obtained. The tightness achieved by the strip during molding prevents any risk of the definitive connections or terminals of the capacitor getting dirty. Due to its general conception, this strip allows simple and accurate positioning and reliable contacting time and consequently greater reliability and improved quality for welding the components onto the tags.