EP0437035A2

EP0437035A2 - Modular connector system

Info

Publication number: EP0437035A2
Application number: EP90312923A
Authority: EP
Inventors: David Edward Welsh
Original assignee: Deutsche ITT Industries GmbH; ITT Industries Inc
Current assignee: TDK Micronas GmbH; ITT Inc
Priority date: 1990-01-11
Filing date: 1990-11-28
Publication date: 1991-07-17
Also published as: EP0437035A3

Abstract

An electrical connector has several rows of contacts connected to two rows of leads that engage terminals on a circuit board assembly, which enables a large number of contacts to be located in a connector of moderate cost. A connector insert comprises a wafer device and multiple leads, the leads having front lead portions connected to multiple rows of contacts on the wafer device, middle lead portions moulded into the wafer device, and rearward lead portions lying in two parallel rows for contacting terminals on opposite sides of the circuit board assembly. Each wafer device includes two substantially identical wafers, to allow moulding of a single row of leads at a time into a wafer. Each wafer has forwardly projecting towers that each lie around the front portion of a lead, and each contact has a periphery captured by a tower portion and a hole that receives a lead front portion. The contacts are arranged in columns on the wafer device, with at least four contacts in each column, and some of the lead middle portions extend both laterally and longitudinally to provide a small spacing or pitch of the lead rear portions. The insert has leaf springs at opposite sides for centering the insert in the connector housing while allowing the insert to "float" within the housing.

Description

This invention relates to electrical connectors and modular connector systems incorporating such connectors and to methods of fabricating electrical connectors.
Aircraft and military electronic equipment is often designed to include circuit board assemblies or modules that are each formed of a plate-like metal heat sink sandwiched between a pair of circuit boards. The module is connected to a back plane or mother board through an electrical connector system with one electrical connector joined to an edge of the module. The connector has two rows of leads that contact two rows of electric terminals extending along the edges of the boards.
The connector usually must have a large number of contacts, such as more than 300, and yet the length of the connector is limited. Such a large number of contacts is accommodated by arranging them in multiple rows, such as in eight rows (i.e. four staggered rows). however, the leads extending from the contacts to the circuit boards, must lie in two parallel rows, with the leads closely spaced along the rows, such as at a spacing or pitch of 25 mil (one mil equals 0.001 inch). A reliable connector having multiple leads that extend from the multiple rows of contacts into two rows of lead rear portions, which can be constructed at moderate cost, would be of considerable value.
The plate-like heat sink can be thermally connected to a heat dissipator such as a metal cold plate, by clamping an edge of the heat sink thereto. Such clamping may displace the heat sink and module by a small but significant amount such as 10 mil. In order to avoid the need to transmit such sideward displacement through the connector to the mother board, it is desirable that an insert in the connector on which the contacts are mounted, be capable of slight lateral displacement without significant stress. A connector which enabled efficient "floating" of a connector insert would also be of considerable value.
In a connector wherein separate contacts must be attached to the front ends of leads that project from a layer of insulation formed by a wafer, it is desirable to mechanically hold each contact to the wafer in addition to its soldered or similar connection to the lead, to prevent stresses from being transmitted to the lead electrical connections. The wafer must hold the contacts precisely centred on the axes of the lead front portions, for all of a large number of such contacts. A connector which assured secure holding of each contact in a position precisely aligned with the projecting front end of each lead, would also be of considerable value.
In accordance with the present invention an electrical connector comprises a wafer device of insulative material having front and rear faces, and a plurality of leads that include front portions projecting from the wafer device front face and lying in at least four rows, rear portions projecting from the wafer device rear face and having locations lying in two rows, and middle portions lying in the wafers, characterised in that the wafer device includes a pair of substantially identical wafers having adjacent edges extending primarily parallel to the rows of front lead portions with the wafer edges of the pair of wafers lying adjacent to one another, and in that the leads include a plurality of leads having middle portions moulded into each wafer, with the plurality of leads of each wafer having front portions lying in at least two rows and rear portion locations lying in a single row.
Each of the lead front portions projecting from the front face of a wafer may be received by a hollow rear portion of a contact that surrounds a lead front portion and which is joined thereto as by soldering. Each wafer may have a forwardly projecting tower that closely surrounds the rear portion of each contact to mechanically hold the contact. The fact that the front portions of the leads are moulded into the wafer at the same time that the towers are formed, assures precise concentricity of the front lead portions and towers.
The wafer device assembly may be part of an insert that lies in a housing that is fixed to the circuit board assembly. The insert is allowed to "float" with respect to the circuit board assembly, by providing the insert with rearwardly projecting leaf springs whose free ends bear against opposite inside surfaces of the housing. The leaf springs tend to hold the insert centred in the housing, but allow the insert to shift sidewardly with respect to the housing without substantial stress on any parts of the system.
The invention also provides an electrical connector system incorporating a connector associated with a circuit board assembly and a method of fabricating such connectors.
By way of example the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a partial exploded view of a connector system constructed in accordance with one embodiment of the present invention;
Figure 2 is a more detailed exploded perspective view of a portion of the connector system of Figure 1;
Figure 3 is a partially sectional end view of the connector system of Figure 2;
Figure 4 is an enlarged view of a portion of the connector system of Figure 3;
Figure 5 is an enlarged view of a portion of the connector system of Figure 4;
Figure 6 is a plan view of the wafer device assembly of Figure 4, but without the towers being shown, and with all portions of the leads being shown;
Figure 7 is an enlarged view of an end portion of the wafer device assembly of Figure 6; and,
Figure 8 is a sectional view of a portion of a wafer assembly constructed in accordance with another embodiment of the invention, showing a pin contact installed.

Referring to the drawings, Figure 1 illustrates a connector system 10 which includes two mateable connectors 12,14 that can be mated to connect a circuit board assembly 16 to a mother board 20. The circuit assembly 16 includes two circuit boards 22,24 joined facewise by a thermally-conducting adhesive to opposite faces of a plate-like heat sink 26. The connector 12 has a large number of contacts 30, socket contacts being shown, with the contacts arranged in multiple rows and columns to accommodate a large number of contacts in a connector of limited length. Complex equipment using this type of connector system usually requires more than 300 contacts in a length such as five inches. The contact assembly includes an insert 32 that lies within a housing 34 which is rigidly mounted to the heat sink 26 of the circuit board assembly. The mounting is accomplished through lugs 33 (Figure 2) on the housing that straddle locations 35 on the heat sink and that are pinned to the heat sink. The assembly also includes a thin metal shell 36 around the housing. The insert includes a large number of leads 40 (Figure 1) that have forward portions connected to the contacts 30 and rearward portions that engage terminals 42,43 on the circuit boards 22,24, with the terminals lying near an edge of each board.
Figure 3 illustrates some details of the connector 12. The insert 32 includes a wafer device 44 of insulative material and a forward insulator 46 lying on a forward face of the wafer device. Each lead 40 includes a forward portion 50 connected to a contact 30, a rearward portion 52 with a location 54 that engages a terminal 42 on a circuit board such as 22, and a middle portion 56 that lies within the wafer device 44. The middle portion 56 of each lead is moulded into part of the wafer device 44.
For the particular connector shown, the contacts 30 lie in eight rows as indicated by row lines 61-68. However, the rearward lead portions 52 lie in only two rows indicated at 70a and 72a to contact the two rows of terminals 42,43 on the two circuit boards 22,24. Accordingly, the middle portions 56 of different leads such as 40A-40D that connect to contacts in four different rows 61-64 are bent differently so as to extend the four leads to rear lead portions that all lie in the same row 72a. 8X(It should be noted that the forward portions of leads 40A-40D do not all lie in the same column, as will be discussed below).
As shown in Figure 6, the wafer device 44 is formed of two separate wafers 74,76. Each wafer has a first or outer side 74a, 76a, and a second or inner side 74b, 76b, the wafers being joined together at their inner sides or edges. The inner edge of each wafer forms complimentary tongues 80 and grooves 82 between tongues. A first end such as 74c of a wafer has a groove 82e closest to its end, while the opposite end 74d of the wafer has a tongue 80e closest to its end. The two wafers 74,76 are identical, and can be joined at their inner edges to form the wafer device 44. Each wafer such as 74 holds four rows of contacts at 61-64 and leads with rear portions lying along a single row 72. When the two wafers are joined, they provide eight rows of contacts and two rows of rear lead portions (at 72 and 70).
Each wafer such as 74 and the leads 40 moulded therein form a wafer assembly, there being two wafer assemblies 84,86. When joined together they form a wafer device assembly 90 which includes the wafer device 44 and all of the leads moulded into it. Each wafer assembly such as 84 is formed separately from the other one 86, which makes manufacture of the apparatus much easier. During the moulding of the wafer assembly such as 84, a large number of lead devices must be held in precise positions relative to the mould that forms the wafer 74. The mould traps the rear and front portions 52,50 (Figure 3) of each lead while a plastic material is injected into the mould to form the wafer. The fact that the mould has to position only a single row of leads, facilitates manufacture. If the mould had to accurately position two rows of leads, then the mould would have to be much more complex. By moulding each wafer with a single row of leads (at least at their rearward portions) and thereafter coupling it to another similar wafer assembly with its own row of leads, production is simplified. Furthermore, by making each of the two wafer assemblies identical, only a single design of wafer assembly has to be formed, which further reduces cost.
As shown in Figure 7, the contacts are located in columns such as 92,94,96, with each column having four contacts. The first column 92 has four contacts 101,103,105 and 107, while an adjacent second column 94 has four contacts 102,104,106 and 108. The rows of contacts are staggered, in that a second contact 102 lies on a row line 62 that extends between first and third contact rows 61,63. Also, some contacts in the first and third rows 61,63 lie in first and third columns 92,96, while contacts in the second and fourth rows 62,64 lie in a column 94 halfway between the first and third columns. It can be seen from Figure 6, that the first column 92 which lies nearest the first end 74c of a wafer contains contacts in the first and third rows 61,63 while a last column of contacts 110 on the same wafer contains contacts 112,114 in the second and fourth rows 62,64. This results in the two wafer assemblies 84,86, oriented with one 86 turned 180° (about an axis extending in a forward-rearward direction) from the orientation of the other 84, creating a meshing pattern (i.e. the contacts 112,114 combine with contacts 116,118 on the other wafer to create a column of evenly spaced contacts).
Referring to Figure 7, it can be seen that the leads have four different configurations on each wafer. The lead middle portions 56 form transitions between the single row of rear lead portion 52 and the multiple row front lead portions 50. In a first lead configuration 40A, the lead includes a front portion 50 with an axis 119 lying concentric with a contact, a first middle portion 120 extending in a longitudinal direction x parallel to a row, and a second middle portion 122 extending in a longitudinally direction y parallel to a column. The rear end of the middle portion lies at 124 where it merges with the top of the rearward lead portion 52. A next lead 40C has a first middle portion 126 which extends only parallel to the column direction. Another lead 40D is a mirror image of the first one 40A, while a lead 40B is a mirror image of 40C. This arrangement results in the lead rear portions 52 lying in a row such as 70, at a spacing or pitch B which is one half the spacing or pitch C of the columns of contacts. It also may*p781 beed that the rear of the middle lead portions (at 128 in Figure 4) are bent to extend at an incline in the x direction, in order to align the rear lead portions of the two rows of leads.
Figure 5 illustrates the manner in which a contact 30 is connected to a lead front portion 50. The wafer 76 is moulded to include a tower 130 which is in the form of a tube that projects forwardly from a front face 132 of the wafer. The tower 130 is of a size to closely surround a rearward portion 134 of the contact. The contact has a hollow rear portion that surrounds the lead forward portion 50. In the particular construction shown in Figure 5, a sleeve 136 of solderable material is placed around the lead front portion 50 prior to inserting the contact 30 into the tower 130. After all contacts are inserted, the wafer device assembly is heated to melt the sleeve 136, so it flows onto the contact and lead front portion to electrically connect them. Other connection schemes can be resorted to, such as coating portions of the contacts and/or lead forward portions with solderable material or applying solder after the contacts are installed.
The axis 119 of the lead forward portion 50 and the axis of the tower 130, can be maintained precisely concentric, because the lead forward portion is held in the same mould which moulds the tower. This assures that when the contact 30 is installed, it will fit into the space between the tower and lead forward portion, and around the sleeve 136. It may be noted that the contact 30 is often provided with a protective hood 142. The forward insulator 46 lies over the forward face of the wafer 76 and closely holds the hood 142. The forward insulator 46 and wafer device 44 together form an insulator assembly 145.
The connector is constructed by forming multiple leads 40 on a carrier (not shown) attached to the rear ends of the leads, and deforming the middle portions of the leads. A row of leads is placed in a mould, with the front portions of the leads precisely held, and a plastic material is moulded around the middle portions of the leads to form a wafer assembly. Then, the rear portions of the leads, which originally extended in straight lines in line with portion 124, are bent to the configuration shown in Figure 3. The contacts 30 are installed on the front faces of the wafer assembly. Two identical wafer assemblies are joined to form a wafer device assembly. The forward insulator 46 is then installed over the front face of the assembly on which the contacts have been installed, to form the insert 32. The insert is then installed in the connector housing 34. The rear lead portions are spread apart and slid onto the faces of the circuit board 22,24 to contact the terminals 42,43 on the circuit boards. The heat sink 26 (Figure 1) of the circuit board assembly 16 may then be clamped as by clamp mechanism 140 against a heat dissipating apparatus 142.
During clamping of the heat sink 26, the circuit board assembly and the connector housing 34 may be sidewardly displaced by a small distance such as by 0.010 inch. If the insert, including the contacts, were also to be displaced by this amount, then there could be stresses in the housing, wafer, and contacts, if the mating connector resists sideward shifting. To avoid such high stresses, the insert is mounted in the manner shown in Figure 3, where it can be seen that the insert 32 has a pair of centering springs 150,152 at is opposite sides. The springs are of largely leaf spring construction, in that they include an elongated resiliently bendable member. The springs extend primarily in rearward and forward directions. Each centering spring has an inner end 154 mounted on and part of the insert insulator and a free outer end 156 that is biased against an inside surface 160 on the connector housing 34. The springs lie at opposite sides of the insert and tend to centre the insert within the housing. However, if the insert is held against sideward movement as by a mating connector, the housing can move sidewardly relative to the insert by additional deflection of the one of the springs and release of some of the deflection of the opposite spring.
The housing walls include wide front portions 162 and narrower rearward portions 164 against which the spring free ends bear. The housing also has angled wall portions such as 166 which gradually compress the springs as the insert is inserted in a rearward direction into the housing. The connector also includes latches 170 (Figure 2) that hold the insert in place, but allow the insert to be removed by inserting a special tool that deflects the latches toward each other to allow the insert to be pulled forwardly out of the housing. It can be seen in Figure 2, that each insert 32 includes springs 150A, 150B near its opposite ends, and includes latches 170 at its opposite ends.
Figure 8 illustrates another arrangement, wherein pin type contacts 180 are installed, instead of a socket type. The wafer 182 includes a tower 184 surrounding each lead front portion 186 and lying concentric with the axis 190 of the lead front portion. The contact has a hollow rearward portion 192 that is closely received within the tower 184 and which receives the lead front portion 186. The inside of the contact rear portion can be coated with solderable material which, when heated, joins to the lead front portion.
Thus, the invention provides a connector which has leads that connect multiple rows of contacts to two rows of terminals on a circuit board assembly, which can be constructed at relatively low cost. The connector includes an insert with a wafer device assembly that includes two substantially identical wafer assemblies. Each wafer assembly includes leads whose rearward portions extend in a single row, and whose forward portions lie in multiple rows to connect to contacts lying in multiple rows. The centre portions of the leads are moulded into a wafer which has a side or edge which can be joined to an identical wafer. Each wafer is moulded with a forwardly projecting tower concentric with the axis of the forward portion of a lead, to precisely hold a hollow rear portion of a contact between them. Each insert includes elongated centering springs extending in a rearward direction, with free ends bearing against an inside wall of a housing, to centre the insert within the housing but allow the housing to move sidewardly slightly without applying large stresses to parts of the connector.
Although particular embodiments of the invention have been described and illustrated herein, it is recognised that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.

Claims

An electrical connector comprises a wafer device of insulative material having front and rear faces, and a plurality of leads that include front portions projecting from the wafer device front face and lying in at least four rows, rear portions projecting from the wafer device rear face and having locations lying in two rows, and middle portions lying in the wafers, characterised in that the wafer device (44) includes a pair of substantially identical wafers (74,76) having adjacent edges (74b,76b) extending primarily parallel to the rows (61-68) of front lead portions (50), with the wafer edges of the pair of wafers lying adjacent to one another, and in that the leads (40) include a plurality of leads having middle portions (56) moulded into each wafer, with the plurality of leads of each wafer having front portions (50,186) lying in at least two rows and rear portion (52) locations lying in a single row.
An electrical connector as claimed in claim 1, characterised in that contacts (38,180) are attached to the front portions (50,186) and include at least eight rows of contacts (61-68) on the pair of wafers (74,76), in that each of the wafers has first and second opposite ends (74c,74d and 76c,76d) and first and second opposite sides (74a,74b and 76a,76b), with one of the sides forming one of the edges (74b,76b) which is joinable to the corresponding edge of the other wafer, in that the rows of contacts are arranged in at least four rows (61-64) and (65-68) staggered on each wafer (74,76) wherein a second row of contacts on each wafer lies on a row line that extends between first and third rows of contacts of each wafer, and with some contacts in the first and third rows lying in first and third columns and with contacts in the second and fourth rows lying in a column halfway between the first and third columns and in that each of the wafers holds a first column of contacts lying closest to the first end of the wafer with the first column containing contacts in the first and third rows, while a last column of contacts on each wafer lies closest to the second end of the wafer and contains contacts in the second and fourth rows, whereby to provide a meshing pattern of contacts when the wafers lie in positions turned 180° from each other and joined along the adjacent edges (74b,76b).
An electrical connector as claimed in claim 1, characterised in that each of substantially identical wafers (74,76) has first and second opposite ends (74c,74d and 76c,76d) and first and second opposite edges (74b,74a and 76b,76a), the first edges of the pair of wafers being joined and in that the first edge (74b,76b) of each wafer includes a plurality of sidewardly projecting tongues (80), and a plurality of grooves (82) alternating with the tongues and which can each receive a tongue, with a tongue nearest the first wafer end and a groove nearest the second wafer end.
An electrical connector as claimed in claim 1, characterised in that the lead front portions (50) on each wafer lie in the plurality of rows, the lead rear portions (52) of all leads on a wafer lie in a single row extending parallel to the plurality of rows of contacts on the wafer, and in that most of the lead middle portions (56) which are moulded in the wafer are bent to bring their rear end portion (124) to lie in a single row.
An electrical connector as claimed in claim 1, characterised in that each of a plurality of contacts (30,180) has a hollow rearward portion which receives a front lead portion (150,186) and in that each of the wafers (74,76) includes a plurality of tower portions (130,184) that each project from the front face of the wafer and surround the rearward portion of a contact (30,180) and the front portion of a lead, whereby to facilitate precision location of a contact with respect to a front lead portion.
An electrical connector characterised by an insulative wafer device (44) having a front face, by a plurality of lead devices extending through the wafer device with each having a front lead portion (50,186) projecting from the wafer device front face, the wafer device having a plurality of tower portions (130,184) projecting from the front face with each tower portion surrounding one of the front lead portions and by a plurality of contacts (30,180) mounted on the wafer device, with each contact having a hollow rear portion with an inside that receives a front lead portion end with an outside that is closely received in a tower portion that surrounds the lead front portion.
An electrical connector as claimed in claim 6, characterised by a sleeve (136) of solderable material lying within the rear portion of each contact (30) and around the front lead portion (50) and being heat meltable to solder them together.
An electrical connector system characterised by a circuit board assembly (16) having opposite board faces and a row of terminals (42,43) on each of the board faces, by a wafer device (44) of insulative material having front and rear faces, by a plurality of contacts (30,180) arranged in at least four rows (61-68) and a plurality of columns on the wafer device and by a plurality of leads (40) that each has a forward portion (50,186) projecting from the wafer device front face and coupled to one of the contacts, a rearward portion (52) projecting from the rear face, and a middle portion (56) moulded into the wafer device, the lead forward portions (50) lying in the at least four rows, the lead rearward portions (52) including locations lying in two lead rows and bearing against the opposite board faces against the terminals thereon, the pitch of the lead rows being smaller than the pitch of the columns and at least some of the lead middle portions (56) that are moulded into the wafer device each having parts extending in a longitudinal direction primarily parallel to the length of the rows, and also in a lateral direction primarily parallel to the length of the columns.
An electrical connector system as claimed in claim 8, characterised in that the wafer device includes two identical wafers (74,76) each having an inner edge (74b,76b) the leads (40) being arranged in identical patterns on each of the wafers to form two identical wafer assemblies and wafer assemblies being oriented with one turned 180° with respect to the other so that the inner edges of the two wafers are joined.
An electrical connector system characterised by a circuit board assembly (16) which includes a plate-like heat sink (26) with opposite faces and a pair of circuit boards (22,24), the heat sink being sandwiched between the circuit boards each of which has an edge portion and a row of terminals (42,43) spaced along its edge portion, by a connector housing (34) rigidly attached to the circuit board assembly (16) at the board edge portion and having walls with an inside surface by at least one insert (32) with opposite sides lying within the housing, the insert having an insulator assembly (44), a plurality of rows of contacts on the insulator assembly extending parallel to the opposite sides, and a plurality of leads (40), each lead having a front portion (50) connected to a contact (30), a middle portion (56) extending through the insulator assembly and a rear portion (52) projecting in a rearward direction from the insulator assembly, the lead rearward portions lying in two rows that engage the rows of terminals (42,43) on the circuit boards (22,24), by a heat dissipating apparatus (26) and by a clamp mechanism that clamps the heat sink against the heat dissipating apparats to transfer out heat, the insert (32) having a plurality of centering springs (150,152) each of which comprises an elongated resiliently bendable member extending primarily in a rearward direction and having an inner end (154) mounted on the insert insulator assembly and a free outer end (156) biased against an inside surface (160) of the housing walls, the springs lying at opposite sides of the insert, whereby to allow the insert to float within the housing to avoid stresses when the heat sink (26) is sidewardly displaced during clamping.
An electrical connector system as claimed in claim 10, characterised in that the housing walls have wide front portions (162), narrower rear portions (164), and angled wall portions (166) extending between them, and in that the spring outer ends (156) lie between the narrower rear portions.
A method of forming an electrical connector comprising the steps of forming a multiplicity of leads with rearward lead portions that can lie in a single first row while forward lead portions lie in a plurality of rows extending parallel to the first row, and with middle portions of at least some leads bent to form transitions between the forward and rearward portions, and installing the leads in insulative material, characterised by the additional steps of moulding a pair of wafers (74,76) of insulative material, with each wafer moulded around the middle portions (56) of a plurality of the leads (40) and with each wafer having front and rear faces in order to form a plurality of wafer assemblies that each includes lead rear portions (52) lying in a single row and projecting from the rear face and lead forward portions (40) lying in a plurality of rows and projecting from the front face, and with the wafer of each wafer assembly having an inner edge (74b,76b) and mounting a pair of the wafer assemblies within a connector housing (34) with the inner edges of the two wafers extending parallel and adjacent to each other.
A method as claimed in claim 12, characterised in that the step of moulding to form a wafer assembly includes forming a plurality of identical wafer assemblies, and the step of mounting includes mounting the wafer assemblies so one is oriented in a position turned 180° with respect to the other.
A method as claimed in claim 12, characterised by moulding each wafer (74,76) with a tubular tower (130,184) projecting forwardly from the front wafer face around the front portion (50) of each lead (40) and by inserting a contact (30,180) having a hollow rearward portion into each tower with the hollow rearward portion surrounding a lead front portion (50), and with the contact rearward portion being closely received within a tower.
A method as claimed in claim 12, characterised by forming at least one elongated spring (150,152) on either side of a front insulator and placing the front insulator over the pair of wafer assemblies to form an insert (32), and by inserting the insert into a housing (34) having opposite internal walls with the springs extending in rearward directions and having free outer ends (156) bearing against the opposite internal walls, the insert being free to move toward either of the housing internal walls with restraint solely by the resilience of the springs.