Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – Distinct contact secured to panel circuit
Reexamination Certificate
2002-02-01
2004-01-20
Luebke, Renee (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
Distinct contact secured to panel circuit
87, 87
Reexamination Certificate
active
06679709
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a connector for mounting an integrated circuit on a circuit board or a connector for connecting a circuit board to another circuit board, and a method for manufacturing such a connector.
2. Description of the Related Art
A ball grid alley type (hereafter referred to as BGA type) connector is conventionally used as a means for mounting an integrated circuit or a circuit board on another circuit board. This BGA type connector comprises a case formed of an insulating material and placed on the circuit board, a through-hole penetrating the case vertically, and a terminal electrically connecting a pin attached to the through-hole to an electrical circuit of the circuit board via a solder ball acting as a thermally fusible conductive material. This solder ball is attached to a concave portion located at a position where the through-hole faces the circuit board. The solder ball is attached in a manner it is partially welded at a lower end of the terminal. The electrical circuit of the circuit board is connected to the terminal by placing the connector on the circuit board with the solder ball mounted and by heating these members to melt the solder ball.
The solder ball between the circuit board and the terminal used by such BGA type connector of the prior art as mentioned above sometimes has a problem that the solder ball comes off the concave portion of the case before being attached to the circuit board, resulting in incomplete connection. It is difficult to manufacture a solder ball having no deformation in a process of once melting solder to form it spherically. The solder ball may be deformed before being attached to the connector because of its low hardness. Therefore, it is difficult to secure coplanarity that shows degree of how uniformly the height of the lower end of each solder ball is horizontally aligned when the solder ball is used to connect the circuit board to the terminal. Thus, there arise places where some solder balls are in contact with the circuit board while the other solder balls are not when the case with the solder balls attached to is placed on the circuit board. This may cause incomplete connection between the terminal and the electrical circuit when the solder balls are melted.
A manufacturing cost of the solder balls themselves becomes high because they must be formed precisely. As it is necessary to surely arrange the solder ball on the concave portion provided in the case and to securely fix it on the terminal, there are problems that manufacturing processes become complicated, and the total cost of manufacturing connectors becomes high.
SUMMARY OF THE INVENTION
An object of the invention is to improve a connector, more specifically to provide a connector which can be easily manufactured and can be connected to a circuit board in good condition in order to solve the problems.
In order to achieve the object, a connector according to a first embodiment of the invention is one to be surface-mounted on a circuit board having an electrical circuit and used to attachably connect an integrated circuit or another connector provided with a plurality of pins extending downward to the circuit board having the following features:
Firstly the connector comprises a case made of an insulating material, a through-hole penetrating the case vertically and into which the pin is inserted, a terminal having a contact section provided in the through-hole to be in contact with the pin, a connecting section facing the electrical circuit and a body section joining the contact section and the connecting section, and a thermally fusible conductive material existing between the connecting section and the electrical circuit. The connecting section extends substantially in parallel with the circuit board and comprises an internal passage connecting upper and lower sides of the connecting section, and the thermally fusible conductive material is attached to the upper and lower sides of the connecting section through the internal passage.
As the thermally fusible conductive material is vertically arranged on the connecting section through the internal passage, the connector according to the first embodiment of the invention can freely move between the upper and lower sides of the connecting section through the internal passage when the thermally fusible conductive material is heated and melted. When the connector is surface-mounted on the circuit board, the thermally fusible conductive material is heated in a condition of being in contact with the electrical circuit. When a space formed between the connecting section and the electrical circuit is filled with the heated and melted thermally fusible conductive material, an excessive amount thereof between the connecting section and the electrical circuit moves upward through the internal passage. Therefore, short circuit to the thermally fusible conductive material of an adjacent terminal and to the electrical circuit can be prevented because no thermally fusible conductive material extends in the right and left direction.
On the other hand, when the connectors are surface-mounted on the circuit board, the thermally fusible conductive material is heated and melted in the condition the thermally fusible conductive material is in contact with the electrical circuit, and when the space formed between the connecting section and the electrical circuit is not filled with the thermally fusible conductive material located in the lower side of the connecting section, the thermally fusible conductive material existing in the upper side of the connecting section moves to the lower side of the connecting section through the internal passage to fill the space between the connecting section and the electrical circuit. Thus the connecting section and the electrical circuit are surely connected.
As mentioned above, according to the first embodiment, even when a clearance between the connecting section and the electrical circuit varies, or even when an amount of the thermally fusible conductive material located at the lower side of the connecting section varies, vertical movement of the heated and melted thermally fusible conductive material enables an appropriate amount of the thermally fusible conductive material to always fill the space between the connecting section and the electrical circuit. Therefore, it is possible to prevent the short circuit to the thermally fusible conductive material of the adjacent terminal or to the electrical circuit or lack of the amount of the thermally fusible conductive material between the connecting section and the electrical circuit.
In the connector according to the first embodiment, it is possible to form the connecting section into a pair of bar-shaped pieces extending and branching substantially in parallel with the electrical circuit, and to form the internal passage by allowing the tip ends of the pair of bar-shaped pieces to be close to each other to provide an annular or a C-letter-like shape. In addition, it is possible to form the connecting section into a plate substantially in parallel with the circuit board, and to form the internal passage into a connecting hole connecting the upper and lower sides of the connecting section. The internal passage can be also formed through the connecting section by providing the connecting section with such shape.
In the connector according to the first embodiment, it is preferable that a surface of the body section comprises a groove or a step. When the surface of the body section is provided with the groove or the step like this, the heated and melted thermally fusible conductive material is prevented from moving upward along the surface of the body section because the groove or the step blocks a way of the thermally fusible conductive material going to move upward. Thus, a sufficient amount of the thermally fusible conductive material filling the space between the connecting section and the electrical circuit can be secured.
It is possible to coat the surface of the body section close
Guss Paul A.
Hammond Briggitte R.
Luebke Renee
Moldec Co., Ltd.
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