FR2885738A1 - Circuit board mounted electrical connector, has contacts with extending portions that extend from rear wall in direction away from circuit board up to flexible portions, and linear portions of leg portion are partially tin plated - Google Patents

Abstract

The connector has an insulative housing with a rear wall that receives a set of contacts (6) in a set of rows. A leg portion protrudes outwardly from the wall is connected to a circuit board (14). The contacts have extending portions that extend from the rear wall in a direction away from the circuit board, up to flexible portions (18b). Linear portions of the leg portion are partially tin plated.

Description

The invention relates to an electrical connector for mounting on a wafer,

  which is intended to be mounted on a circuit board. The invention relates in particular to an electrical connector mounted on a plate,

  of the type in which contact leg portions used in the electrical connector extend outwardly from the rear wall of a housing, are bent to be substantially perpendicular to the circuit board and are connected to openings of the circuit board.

  A wafer-mounted electrical connector as disclosed in Japanese Unexamined Patent Publication No. 9 (1997) -069371 is known. This connector has contacts that are arranged in three rows, and an insulating housing for holding the contacts. Each of the contacts of this connector comprises: a contact portion, which has an axis substantially parallel to a circuit board, on which the housing is mounted; and a branch portion extending outwardly from the rear wall of the housing, then extending in a direction perpendicular to the axis of the contact portion, and is. connected to openings of the circuit board. Each leg portion includes: a protruding portion extending away from the circuit board from the rear wall of the housing; a flexible portion which is formed continuously with the projecting portion; el: a linear part which extends substantially perpendicularly to the circuit board from the flexible part.

  In board-mounted electrical connectors, the thermal expansion rates differ between the insulating housings that make up the connectors, and the circuit boards on which the insulators are mounted. Due to the difference between the thermal expansion rates, the degrees of expansion and contraction of the parts under the effect of temperature variations differ. This results in the generation of a stress at the connection portions (soldered portions) between the contacts and the circuit board, which can cause a break in the soldered portions. For this reason, the known and aforementioned electrical connector has adopted the protruding portions which extend away from the circuit board, thereby extending the entire lengths of the leg portions. The extended lengths of the leg portions absorb dimensional differences due to the expansion and contraction of the parts, so as to tend to reduce the stress applied to the connection portions between the contacts and the circuit board. As a result, the dimensions of the branch portions can be increased even if the intervals between the contacts and the circuit board are small. It is therefore possible to mount low-profile, high-density connectors on circuit boards.

  Normally, the branch portions of the contacts are coated with a solder that contains lead. This is because the branch portions are welded to the circuit board with a solder that contains lead and, if the branch portions are coated with a solder that contains lead, the solder properties are connection become favorable. As a result, there is a possibility of environmental pollution by the lead during the production of the electrical connector or during its rejection at the end of the life of the connector. In the case where all the parts of branches is coated with a metal that does not contain lead (lead-free solder), for example tin, the possibility of environmental pollution is less. However, whiskers or whiskers (phenomenon whereby needle-like crystals form on the surface of the coating) can be generated at the flexible portions of the branch portions. The cause of these whiskers is an internal constraint that is generated in the contacts, and the whiskers may appear at the level of the flexible parts. If they are generated, they cause short-circuiting of adjacent contacts, thus posing a problem of impossibility of obtaining desired electrical connection properties.

  The invention has been developed taking into consideration the above circumstances. An object of the invention is to provide a wafer-mount electrical connector capable of providing low profile, high density mounting while preventing environmental pollution by lead and avoiding the generation of whiskers. or beards.

  The first circuit-mounted electrical connector of the invention comprises: contacts; and an insulative housing for carrying the contacts in multiple rows; each of the contacts comprising: a contact portion for contacting another connector; and a branch portion projecting outwardly from a rear wall of the housing: _solant to be connected to a circuit board; each of the branch portions comprising: an elongate portion extending from the rear wall of the insulating housing; a flexible portion formed continuously with the elongate portion; and a linear portion extending from the flexible portion to the circuit board, substantially perpendicular thereto, to be inserted into and connected to openings in the circuit board; at least the contacts of the row closest to the circuit board having elongated portions extending from the rear wall of the insulating housing in a direction away from the circuit board, extending to the flexible portions ; and the linear portions of each of the branch portions being partially tinned.

  The second wafer-mounted electrical connector according to the invention comprises: contacts; and an insulative housing for carrying the contacts in multiple rows; each of the contacts comprising: a contact portion for contacting another connector; and a branch portion projecting outwardly from a rear wall of the insulative housing to be connected to a circuit board; each of the branch portions comprising: an elongate portion extending from the rear wall of the insulating housing; a flexible portion formed continuously with the elongated portion; and a linear portion extending from the flexible portion to the circuit board, substantially perpendicular thereto, to be inserted into and connected to openings in the circuit board; the elongated portions extending from the rear wall of the insulating housing in a direction away from the circuit board, rising to the flexible portions; and the linear portions of each of the branch portions being partially tinned.

  Here, tinning may be a coating of pure tin or tin alloys that do not contain lead, such as tin-copper alloys and tin-bismuth alloys.

  The linear part can be perfectly.Linear. Alternatively, the linear portion may have a slightly bulged shape to impart elasticity in the direction perpendicular to its axis. The bulge portion may be configured to be connected to the circuit board.

  The term "partially tinned" indicates some or all of the linear portion is tinned and other portions of the leg portion, such as the flexible portion, are not tinned.

  The flexible portion may be formed intensively with a curved portion of large radius. Alternatively, the flexible portion may have a curved portion of small diameter, formed by simply folding a linear branch portion.

  According to the first wafer-mounted electrical connector according to the invention, at least the contacts of the row closest to the circuit board have elongated portions extending from the rear wall of the insulating housing in a direction away from from the circuit board, up to the flexible parts. In addition, the linear portions of the branch portions are partially tinned. Therefore, a low profile mounting of the electrical connector is achieved, while avoiding environmental pollution by lead. In addition, since the flexible parts are not tinned, it also avoids the generation of whiskers or whiskers.

  According to the second wafer-mounted electrical connector according to the invention, the elongate portions extend from the rear wall of the insulating housing in a direction away from the circuit board, up to the flexible portions. In addition, the linear portions of the branch portions are partially tinned. Therefore, environmental pollution by lead is avoided, as well as the generation of whiskers or whiskers, because the flexible parts are not tinned.

  The invention will be described in more detail with reference to the accompanying drawings by way of non-limitative examples and in which: FIGS. 1A and 1B are schematic views of electrical connectors mounted on a wafer according to a first embodiment of the invention. the invention, FIG. 1A illustrating a case where the integer lengths; branch portions are relatively short and FIG. 1B illustrating a case where the entire lengths of the branch portions are relatively long; and Figure 2 is a schematic view of a wafer-mounted electrical connector according to a second embodiment of the invention.

  FIGS. 1A and 1B are schematic views illustrating a wafer-mounted electrical connector 1 (hereinafter referred to simply as a "connector") according to the first embodiment of the invention. FIG. 1A illustrates a case where the integer lengths of the branch portions are relatively short and FIG. 1B illustrates a modification in which the integer lengths of the branch portions are relatively large. First, a description will be given with reference to FIG. 1A. . The connector 1 comprises: an insulating housing 2 intended to be mounted on a circuit board 14, and a plurality of contacts 6 (6a, 6b) which are held by the insulating housing 2. A recess 8 of engagement, intended to receive another connector (not shown), is formed in the insulating housing 2.

  The contacts 6 consist of upper contacts 6a and lower contacts 6b. The upper contacts 6a and the lower contacts 6t are all arranged in directions perpendicular to the surface of the sheet of the drawing of Figures 1A and 1B. In the first embodiment, the upper and lower contacts 6 are arranged in two rows. However, one can provide three rows of contact or more. Each of the contacts 6 comprises: a holding portion 10 which is inserted through a rear wall 4 of the insulating casing 2 and is thus held by tight fit or the like; a contact portion 12 which extends in a straight line forward, i.e. toward a direction of engagement from the holding portion 10, to contact contacts of another connector ( not shown); and a branch portion 16 which extends rearwardly from the rear wall 4 to be connected to the circuit board 14. It should be noted that the insulating housing 2 can be fixed to the circuit board 14 only by the branch portions 16. Alternatively, other fastening means such as screws (not shown) can be used as the parts of branches 16 to secure the insulating housing 2 to the wafer 14 circuit.

  Each of the branch portions 16a of the upper contacts 6a comprises: an elongated portion 18a extending from the rear wall 4 in a slightly upward inclined direction; a flexible portion 18b which is formed continuously with the elongate portion 18a; and a linear portion 18c extending downwardly from the flexible portion 18b in a direction substantially perpendicular to the circuit board 14. The linear portion 18c is inserted through an aperture 20 corresponding thereto of the circuit board 14, and is soldered to the circuit board 14 with a lead-free solder, such as tin and copper solder.

  Furthermore, each of the branch portions 16b of the lower contacts 6b comprises: an elongated portion 22a extending from the rear wall 4 in a steeply inclined upward direction; a flexible portion 22b which is formed continuously with the elongate portion 22a; and a linear portion 22c. The differences between the leg portions 16b and the leg portions 16a are that: the entire lengths of the lower leg portions 16b are shorter than those of the upper leg portions 16a, and the elongate portions 22a extend in one direction. away from the wafer 14 circuit at a relatively acute angle. The elongated portions 18a and 22a extend in directions away from the circuit board, to increase the lengths of the branch portions 16a and 16b from the rear wall 4 to the circuit board 14, as far as possible in a limited mounting surface area. Thus, the difference between the degrees of expansion / contraction, due to the difference in the coefficient of thermal expansion between the connector 1 and the circuit board 14, can be absorbed. Therefore, the magnitude of the force exerted on the connection portions between the circuit board 14 and the linear portions 18c and 22c is reduced, thereby preventing cracking at the soldered portions 29 of the connection portions.

  It is important to note here that the parts of branches 16 are partially tinned. The linear parts 22c of the branch portions 16b Its lower contacts 6b are tinned. In other words, the branch portions 16 are tinned from their ends 22d to the beginning of the flexible portions 22b. The tinned portions are represented by hatching in FIGS. 1A and 1B. The branch portions 16a of the upper contacts 6a are tinned from their ends 18d to the same heights as the tinned portions of the linear portions 22c of the branch portions 16b. In other words, the branch portions 16a are tinned to the position indicated by an arrow 24 in FIG. 1A.

  The branch portions 16a of the upper contacts 6a may be tinned on all of the linear portions 18c to the flexible portions 18b. In other words, the branch portions 16a can be tinned to the position indicated by an arrow 28 in FIG. 1A.

  The tinning is applied either on the whole or on a portion of the linear portions 18c and 22c, but not on the flexible portions 18b and 22b. Therefore, it is not possible for whiskers or barbs to form on the flexible portions 18b and 22b.

  It should be noted that tin, which is used as a coating material, may be pure tin or tin alloy not containing lead. For example, a lead-free tin-copper solder may be coated, and welding may also be accomplished using lead-free tin-copper solder. In this case, the welding properties are favorable and the manufacturing costs can also be reduced. Alternatively, a coating may be made using a lead-free, tin alloy and bismuth solder.

  We will now describe the manufacturing steps of the connector 1 until tinning. The contacts 6 are punched in a metal sheet made of copper alloy or the like, by stamping. Then, each of the contacts 6 is nickel-plated in its entirety. Then, portions of the limb portions of the contacts 6 are tinned for a predetermined length from their ends 18d and 22d. In other words, the branches 16 are tinned to the position indicated by the aforementioned arrow 24 or, in the case of the branches 16a parts, to the position indicated by the arrow 28. Then, the contacts 6 are folded into predetermined shapes and then force-fitted into the rear wall 4 of the insulating housing 2 to constitute the connector 1. In a variant, the contacts 6 are forced into the rear wall 4 of the insulating housing 2 and then folded into their predetermined shapes. to constitute the connector 1.

  We will now describe a connector 40 which is a modification of the connector 1, with reference to FIG. 1B.

  It should be noted that in the following description elements identical to those illustrated in FIG. 1A will be described with the same reference numbers. In addition, the internal structure of the connector 40 is identical to that of the connector 1 and its description will not be repeated. The connector 40 differs from the connector 1 in that the entire lengths of the leg portions 56 (56a, 56b) of the contacts 46 (46a, 4Gb) are larger. For this reason, the connector 40 is more adapted to absorb a stress generated at the connection parts, that is to say soldered portions 29, between the connector 40 and the wafer 14 circuit, because of the differences between their coefficients of dilation / entrainment.

  As a result, elongate portions 58a of the upper contacts 46a extend substantially parallel to the circuit board 14. The angle, under which the elongate portions 62a of the lower contacts 46 extend away from the circuit board 14 from a rear wall 44 of an insulative housing 42, is smaller than that of the elongate portions 22a of the connector 1. Linear portions 58c and 62c of the branch portions 56 of the connector 40 are partially tinned, in the same manner as in the connector 1. The tinning is performed on the linear portions 58c and 62c, while avoiding the flexible portions 58b and 62b, in the same way as in the connector 1. We will not give back a detailed description.

  In the connectors 1 and 40 shown in Figs. 1A and 1B, the lengths of the leg portions 16 and 56 may be extended, even if the distance between the holding portions 10 and the lower surfaces 30 of the connectors 1 and 40 is short. This is done by forming the elongate portions 18a, 22a and 62a so that they move away from the circuit board 14. Therefore, if the circuit board 14 is placed in the position indicated by 14 ', a low profile mounting of the connectors is possible. As a result, the mounting surface areas of the connectors 1 and 40 can be kept small, while allowing a low profile high density multiple mounting, on the wafer 14 to now a connector 80 according to an embodiment of the invention. Fig. 2 is a sc-iematic view of the connector 80 according to the second embodiment. The connector 80 of the second embodiment differs from the connectors 1 and 40 shown in Figs. 1A and 1B in that elongated portions 98a and 120a of the leg portions 96 (96a, 96b) of the contacts 86 (86a, 86b) , which are held by an insulating housing 82, extend substantially parallel to the wafer 14 circuit. The shape of these leg portions 96 is suitable in cases where there is ample space for long leg portions 96 or in cases where the difference between the coefficients of thermal expansion between the insulative housing 82 and the wafer : _4 circuit is weak. In this case also, the linear portions 98a and 102c may be partially tinned, at the portions indicated by hatching in FIG. 2. This partial tinning may be carried out as far as the flexible portions 98b and 102b, in the same manner as in the case of connectors 1 and 40 illustrated in FIGS. 1A and 1B.

  In the case of the connector 802 shown in FIG. 2, the elongated portions 98a and 102a are parallel to the circuit board. It is therefore difficult to minimize the extent of the mounting surface of the connector 80 and it is also difficult to perform a low profile mounting of the connector 80. However, it is possible to avoid environmental pollution by the lead and the formation. cracks in the welded portions (connecting portions between the connector 80 and the wafer 14 circuit).

connectors, circuit.

  It will be appreciated that many modifications may be made to the connector described and shown without departing from the scope of the invention.

Claims (4)

  An electrical connector (1, 40, 80) on a wafer, comprising: contacts (6, 46, 86); and an insulative housing (2, 42, 82) for holding the contacts (6, 46, 86) in several rows; each of the contacts (6, 46, 86) having = a contact portion (12) for contacting another connector; and a leg portion (16, 56, 96) projecting outwardly from a rear wall (4, 44) of the insulative housing (2, 42, 82) to be connected to a wafer (14, 14 ') ) with each of the leg portions (16, 56, 96) having: an elongated portion (18a, 22a, 58a, 62a, 98a, 102a) extending from the rear wall (4, 44) of the housing insulation (2, 42, 84); a flexible portion (18b, 22b, 58b, 62b, 98b, 102b) formed continuously with the elongated portion (18a, 22a, 58a, 62a, 98a, 102a); linear (18c, 22c, 58c, 62c, 98c, 102c) extending from the flexible portion (18b, 22o, 58b, 62b, 98b, 102b) to the circuit board (14, 14 ') substantially perpendicular to it to be inserted in and connected to openings (20) of the circuit board (14, 14 ') and at least the contacts (6, 46, 86) of the row closest to the board (14, 14 ') having elongated portions (18a, 22a, 58a, 62a, 98a, 10a) 2a) extending from the rear wall (4, 44) of the insulating housing (2, 42, 82) in a direction away from the circuit board (14, 14 ') to the flexible portions (18b, 22b, 58b, 62b, 98b, 102b); characterized in that: the linear portions (18c, 22c, 58c, 62o, 98c, 102c) of each of the leg portions (16, 56, 96) are partially tinned.   Connector (1, 40, 80) mounted on a circuit board according to claim 1, characterized in that the linear portions (18c, 22c, 58c, 62c, 98c, 102c) of each of the branch portions (16, 56, 96) are coated with a tin alloy.   A circuit board mounted connector, comprising: a wafer-mounted electrical connector (1, 40, 80), comprising: contacts (6, 46, 86); and an insulative housing (2, 42, 82) for holding the contacts (6, 46, 86) in several rows; each of the contacts (6, 46, 86) including: a contact portion (12) for contacting another connector; and a leg portion (16, 56, 96) projecting outwardly from a rear wall (4, 44) of the insulative housing (2, 42, 82) to be connected to a wafer (14, 14). ') to circuit; and each of the branch portions (1E, 56, 96) having.   an elongated portion (18a, 22a, 58a, 62a, 98a, 102a) extending from the rear wall (4, 44) of the insulating housing (2, 42, 84); a flexible portion (18b, 22b, 58b, 62b, 98b, 102b) formed continuously with the elongated portion (18a, 22a, 58a, 62a, 98a, 102a); and a linear portion (18c, 22c, 58c, 62c, 98c, 102c) extending from the flexible portion (18b, 22b, 58b, 62b, 98b, 102b) to the circuit board (14, 14 ') substantially perpendicularly thereto, for insertion into and connection to openings (20) in the circuit board (14, 14 '); and the elongated portions (18a, 22a, 58a, 62a, 98a, 102a) extending from the rear wall (4, 44) of the insulating housing (2, 42, 82) in a direction away from the wafer ( 14, 14 ') circuit to the flexible portions (18b, 22b, 58b, 62b, 98b, 102b); characterized in that: the linear portions (18c, 22c, 58c, 62c, 98c, 102c) of each of the leg portions (16, 56, 96) are partially tinned.   Connector (1, 40, 80) mounted on a circuit board according to claim 3, characterized in that the linear portions (18c, 22c, 58c, 62c, 98c, 102c) of each of the leg portions (16, 56, 96) are coated with a tin alloy.