KR100545966B1 - High density connector system - Google Patents

Abstract

The present invention relates to electrical connectors shown as plugs and receptacles. In one embodiment, the connector includes a base member having a plurality of holes. The first plurality of contact elements are located in any holes. The tail of each contact element extends beyond the base member. The second plurality of contact elements are located in the other holes. It is sufficient to retain the tail of the first plurality of contact elements on the circuit board by inserting the tail of the second plurality of contact elements into the circuit board. The tail of the second plurality of contacts is preferably capable of axial movement when a compressive force is applied. In another embodiment, the connector includes a frame and a contact element layer, each contact element comprising a front end and a tail. The end of the tail is located adjacent to the bottom surface of the frame. Many fusible elements, such as solder balls, are located adjacent the ends of the tail. In such embodiments, the solder balls preferably take a modified sphere with an aspect ratio greater than one.

Description

High Density Connector System {HIGH DENSITY CONNECTOR SYSTEM}

The present invention relates to electrical connectors, in particular high density connectors for interconnection of daughter boards and back panels.

The continuing technological advances in the design of electronics for data processing and communication systems place stringent requirements on the design of electrical connectors. In particular, high density and high pin count electrical connectors are needed for design advancements to increase the density and data processing and communication speeds of solid-state devices. When designing a connector having a high density and a high pin number, it is necessary to carefully consider the problem caused by the reduction of the distance between the contacts. This is especially true for applications related to daughter board / back panel connections where the connector functions to make electrical connections and mechanically holds the daughter board in place.

While density and pin count are often identified, there are important differences. Density means the number of contacts provided per unit length. Pin count, on the other hand, refers to the number of contact elements that can ideally withstand mating and separating forces. As more functions are integrated into a semiconductor chip or flexible circuit board and more chips are provided on a printed circuit board (PCB), each PCB or flexible circuit must provide more input and output (I / O). do. The need for more I / O can be understood as the demand for higher densities, without sacrificing electrical or mechanical performance, especially when such devices and integrated technologies are utilized in devices with back panels.

The importance of the electrical performance of high density connectors was recognized in US Pat. No. 4,824,383 to Lemke, which is incorporated herein by reference. The patent proposed the design of plug and receptacle connectors for multi-conductor cables or multi-trace boards. Electrical performance in such designs is ensured by individual contact elements or a group of contact elements that are electrically insulated through the use of conductive walls to prevent or minimize crosstalk and signal degradation. The connector disclosed in US Pat. No. 4,824,383 increased the contact element density, but the industrially required density continued to increase. US Patent No. 5,057,028 to Lemke et al. And US Pat. No. 5,169,324 to Lemke et al. (Now US Reissue Patent No. 35.508) disclose a two-row plug and receptacle connector for attaching to a printed circuit board. The connector has shown excellent electrical performance through the use of conductive walls that provide insulation.

Electrical performance of high density connectors has also been focused on US Pat. Nos. 4,846,727, 5,046,960, 5,066,236, 5,104,341, 5,496,183, 5,342,211 and 5,286,212. The patents disclose various forms of stripline structures for use in plug and receptacle systems. In the high density stripline structure, the pillars of the contact elements are arranged in a side by side array with conductive plates disposed between each pillar. The connectors are designed so that the plug and receptacle ground plates contact each other, providing insulation between the pillars. Another aspect of this system is the modular design of the receptacle. Each pillar of the receptacle contact element is formed by forming a contact element in the dielectric frame. One of the problems with these types of connectors is that space is required by using conductive walls for electrical insulation. In some cases, the space or volume required for such insulation cannot be used.

Where space is critical, it has been proposed to use a high density connector with one pin selected for signal transmission between grounded pins to achieve the required electrical performance. Such a pattern is known as a gap arrangement. Such contact element patterns have been proposed in US Pat. Nos. 5,174,770, 5,197,893 and 5,525,067. If such an insulating structure is installed in a smaller connector, it can be seen that such a structure requires more pin count than is available in the connector using the conductive wall described previously.

In the case of the back panel, increasing the pin count directly affects mechanical integrity. As the number of pins increases, the number of holes or through holes in the back panel and daughter board increases. As in the case of high density, as the number of holes in the printed circuit board increases and at the same time the distance between each hole decreases, the mechanical integrity of the substrate decreases. As mechanical integrity decreases, the ability of the back panel to hold the daughter board in place decreases.

In the case of the back panel, it can be seen that the daughter board is sometimes maintained independently in position, ie vertical and horizontal orientation, by the connector used to electrically connect the two. The daughter board size, the number of daughter boards and the components mounted on the daughter boards combine to create stresses and moments acting on the back panel after assembly. If the number of through-holes spaced apart closely reduces the amount of back panel material at a particular location, back panel breakage, that is, deformation or breakage of the back panel may occur.

It can be concluded that the solution to the mechanical failure of the back panel is to use surface mount technology to make electrical connections to the back panel. Surface mount technology does not require the use of through holes, so such technology can connect high density connectors to the back panel without affecting mechanical integrity. Unfortunately, such a solution is not successful.

Surface mounting techniques generally involve the use of pastes to temporarily secure parts to a printed circuit board. After pasting, the substrate and temporary fixing parts are heated to remelt the brazing material previously coated on the lead of the surface mount parts. In the case of a back panel, many connectors are typically attached to the back panel substrate, which is a relatively large circuit board. The back panel substrate must be subjected to considerable heat in order to ensure proper remelting for scattering of many components on a relatively large substrate and thereby to achieve good electrical connection. Unfortunately, excessively high or excessively long heating times can hinder good surface mounting termination. As a result, surface mount technology is not a solution that requires high density connectors for back panel applications.

Thus, there is still a need for a connector system that maximizes the number of contact elements available for grounding / signal assignment and does not compromise electrical or mechanical integrity in back panel applications.

Another consideration that must be taken into account when designing high density connectors for back panel applications is the design of structures for attaching the receptacle portions of the connectors. An important factor in receptacle attachment is alignment. If one receptacle contact element is displaced, the insertion force increases slightly. However, if misalignment occurs in the high density contact receptacle, the insertion force may increase unacceptably. In other words, if misalignment occurs while mounting the receptacle on the circuit board, the board may not be mounted to the plug or vice versa.

Thus, there is still a need for a high density connector system that provides proper alignment after mounting so that the insertion force remains within acceptable limits.

The present invention is to provide a high density connector system that is in proper alignment so as to maximize the number of contact elements while maintaining insertion force within acceptable limits without compromising electrical mechanical integrity.

The novel high density electrical connector solves the problems described above and other advantages are achieved. In one embodiment, the connector includes a base member having a plurality of holes. The first plurality of contact elements are located in any holes. The second plurality of contact elements are located in the other holes. The tail of each contact element extends beyond the base member. It is sufficient to retain the tail of the first plurality of contact elements on the circuit board by inserting the tail of the second plurality of contact elements through the aperture.

The tail of the first plurality of contacts is preferably capable of axial movement when a compressive force is applied. In this embodiment, it is particularly preferable that the tail of the first plurality of contacts has an S-shaped structure.

In another embodiment, the connector includes a frame and a contact element layer attached to the frame. Each contact element includes a receptacle and a tail. The end of the tail is located near the bottom of the frame. Many fusible elements, such as solder balls, are located near the ends of the tail. In such an embodiment, the solder ball extends within a predetermined distance from the base. This result is obtained by using a solder ball having a modified spherical shape. It is particularly preferred that the modified sphere has a flat bottom surface.

In another embodiment, a protrusion is attached to the bottom of the frame to lock and space the frame against the printed circuit board. In this embodiment as well, it is preferable that the solder ball has a deformed spherical shape, and the deformed spherical shape is flat, that is, the aspect ratio of the solder ball has a length greater than the height.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood from the detailed description taken in conjunction with the drawings below, and many objects and advantages of the present invention will become apparent.

As discussed above, connectors with higher densities are still needed in the industry. To this end, a new connector 10 has been developed and shown schematically in FIG. Although shown as a plug, it will be appreciated that the invention is applicable to a plug or receptacle. It can be seen that the connector 10 includes side walls 12 and 14 and a base wall 16. Multiple blades 18 and 20 are disposed on the bottom wall 16. The blade 18 includes a deformable tail that is preferably in the form of an interference fit extending below the bottom surface of the bottom wall 16. Blade 20, on the other hand, comprises a much shorter and compressible tail extending only a short distance from the bottom surface of bottom wall 16. The serpentine or S-shape of the blade 20 tail permits compression when a force is applied to the tail. 2 is a plan view of the plug 10.

Connectors constructed in accordance with the present invention have the advantage that only half of the pins with through holes are required and the other half is utilized as contact pads for making electrical connections. In the case of a back panel, such a configuration preserves the mechanical integrity of the back panel, which provides significantly higher pin density. 3 shows a portion of the printed circuit board 22 on which the plug 10 is to be mounted. The circuit board 22 includes a pattern of holes 24 and contact pads 26. The diameter of the contact pads is smaller than the diameter of the holes and the holes and the contact pads are aligned in a cross pattern.

When the plug 10 is mounted to the circuit board 22, the tails of the blade 18 are inserted into the holes 24. The insertion force causes the end of the compressible blade 20 to make electrical contact with the pad 26. The tail of the blade 18 may be deformable or the friction between the tail and the circuit board 22 may hold the plug 10 in place and maintain electrical contact between the tails of the blade 20 and the contact pads. It is preferable that it is sufficient shape.

The connector 30 according to the present invention will be described with reference to FIG. Although shown as a receptacle, it will be appreciated that the present invention may be applied to a plug or receptacle. The connector 30 is schematically shown as including a plurality of contact elements 32. The contact elements are generally located coplanar and are provided as layer modules. Assembly of the receptacle 30 requires the process of stacking layers of multiple contact elements side by side. As shown in FIG. 5, each contact element layer includes a positioning frame 34 formed from an upright 36 and a base 38. In manufacturing it may be desirable to form the parts 36 and 38 integrally with the row of contact elements 32 and thereby form a contact element module.

The traditional method of mounting the receptacle 30 to the printed circuit board 40 has been to use an extension tail 42 that penetrates an appropriately sized hole in the circuit board 40 for soldering or similar attachment. However, as indicated in the relationship with the plug to be mounted on the circuit board 22 of FIG. 3, the hole size can have a limiting effect on the contact element density. To this end, the receptacle of the present invention includes a novel structure for making electrical contact between the module 30 and the circuit board 40.

The present invention uses fusible elements such as solder balls to mount the module 30 to the substrate 40. Since the module 30 is a high density module, the use of solder balls will be sufficient to provide not only electrical contact but also sufficient mechanical force to maintain attachment of the module 30. For this purpose, a pattern of contact pads (not shown) is disposed on the surface of the circuit board 40.

A locking wedge 44 is provided on the base 38 to align the tail end of the contact element 32 over the individual contact pads. Shoulder 46 and leg 48 space the bottom of base 38 away from the top of circuit board 40. It is desirable to fix this distance accurately. As described in more detail with respect to FIGS. 6-8, the contact elements 32 are electrically connected to contact pads (not shown) through the use of solder balls on the circuit board 40.

6, the end of one of the contact elements 32 is disclosed. A soluble element such as solder ball 50 is shown attached to the end 52. Attachment of the solder balls 50 may be by any means, for example by remelting techniques. The bottom surface of the base 38 extends slightly beyond the end surface of the end 52. In other words, the end face of the end 52 is received in the base 38. After attaching the solder ball 50 to the end 52, the solder ball extends beyond the bottom surface of the base 38.

Although the use of solder balls allows for high density connections without through holes, one problem remains. Because the solder balls extend beyond the bottom of the base 38, the connector 30 can be suspended over a short distance over the circuit board when the connector is assembled to the circuit board. In such a situation, movement of the module 30, i.e., rearrangement, occurs when the solder ball 50 is remelted to make an electrical connection with the contact pad (not shown). Such rearrangement can raise the insertion force to an unacceptable level. This problem is sufficiently overcome by the present invention.

In the present invention, the fusible elements are deformed so that the length (dimensions parallel to the circuit board on which the connector is to be mounted) has an aspect ratio much larger than the height (dimensions parallel to the line from the attachment point to the circuit board of the frame). In such cases, the aspect ratio of the fusible element is greater than one. In other words, the fusible element or solder ball is wider than high.

Brief description will be made of a technique for placing a modified fusible element, such as a solder ball, at the end of the contact element 32. Two general techniques are considered. In the first technique, fusible elements such as solder balls are deformed by pressing strongly on the ends of the elements 32. Deformation operations may include securing the frame and pressing or striking a device such as a platen (not shown) to the bottom surface of each solder ball or pressing each solder ball against a device such as an anvil. In both cases, the solder balls are preferably deformed into a flat shape.

In the second technique of attaching a soluble element, such as a solder ball, to the end of the contact element 32, the soluble element is placed near the end or terminal portion of the contact element and heated to cause remelting. Remelting allows the fusible elements to be attached to the terminal portion. The fusible elements are then deformed. Likewise, the deforming operation may include securing the frame and pressing or striking a device such as a platen to the bottom surface of each fusible element or pressing each solder ball against a device such as an anvil. In both cases, the soluble element is preferably deformed to have a flat shape as well.

Note the use of solder balls as fusible elements. After manufacture, the ends of the solder balls may extend beyond the separation distance formed by the shoulders 46 and legs 48. In other words, when the connector is positioned on the circuit board, it may initially be supported by any solder ball rather than shoulder 46 and leg 48. When the solder melts during remelting, the connector physically moves towards the circuit board and thereby rearranges the connector. The connector travels a short distance when flat or deformed (greater than aspect ratio) solder balls are used. Thus, the possibility of misalignment is considerably less because the connector is in a position closer to the required position in three dimensions (x, y and z) prior to remelting. It is most crucial to position the connector as close to the ultimate z coordinate position as possible prior to remelting.

In particular, Figure 7 shows that the solder ball 50 is deformed by applying a compressive force to the solder ball. Such action of compressive force deforms the solder ball out of a sphere to have a flat bottom shape, that is, an aspect ratio of greater than one. When the solder ball 50 is remelted, the collapsed or deformed shape disappears and the height of the connector changes to return to the spherical shape. Such a remelted solder ball is shown in FIG. As shown in FIG. 8, the remelt solder ball 50 extends by the distance that an electrical connection is made between the circuit board 40 and the end 52 of the contact element 32.

When the solder balls are remelted, mechanical forces are generated that cause the connectors to realign during such operations. Such realignment can raise the insertion force between the mating connectors to an unacceptable level. However, as shown in Fig. 7, the degree of realignment caused by forming the solder ball first is considerably reduced. The insertion force after remelting of the deformed solder ball does not rise to an unacceptable level.

Thus, by using a modified solder ball to make an electrical connection with the circuit board 40, the electrical connection can be made at a much smaller surface area than before, thereby significantly increasing the potential of the contact element density.

While the invention has been described and illustrated with respect to particular embodiments, it will be apparent to those skilled in the art that modifications and variations are possible within the principles of the invention previously described and described in the claims that follow.

The present invention provides a high density connector that provides proper alignment such that the first plurality of contact elements and the second plurality of contact elements are located in the holes of the base member and the insertion force is maintained within acceptable limits.

1 is a partial cross-sectional view of a header constructed in accordance with the present invention.

FIG. 2 is a plan view of the entire header shown in FIG. 1; FIG.

3 is a plan view of a printed circuit board on which the header of FIG.

4 is a schematic side view of a receptacle constructed in accordance with the present invention.

FIG. 5 is an enlarged schematic view of the receptacle shown in FIG. 4; FIG.

6 is an enlarged view of the end of one of the contact elements with solder balls mounted thereon.

Fig. 7 is a cross sectional view of the contact element shown in Fig. 6, showing the state after the solder ball is deformed in the manner according to the invention.

FIG. 8 is a cross-sectional view of the contact element and the printed circuit board shown in FIG. 7 showing a state after the solder ball is remelted to make an electrical connection between the contact element and the printed circuit board. FIG.

<Description of the symbols for the main parts of the drawings>

10, 30: connector

18, 20: blade

24: hole

26: contact pad

32: contact element

34: frame

50: soldering ball

Claims (14)

A base member having a plurality of through holes, A first plurality of contact elements, positioned in any of the holes, each having a longitudinal portion aligned with the insertion portion and each having a tail extending over the base member to contact the conductive material; A second plurality of contact elements located in the other of said apertures, each second contact element having an insert and a tail, and when mounted to a circuit board said second plurality of contact elements in said conductive material. Retaining the tail of the first plurality of contact elements with respect to the connector. 2. A connector according to claim 1, wherein the axial movement is possible when the tail of the first plurality of contacts is subjected to a compressive force. 3. The tail of the second plurality of contacts is configured to be inserted into a hole formed in a printed circuit board, and the tail of the first plurality of contacts is electrically connected to the circuit board only by inserting the tail into the hole. The connector characterized in that the holding. The connector according to claim 2, wherein the tail portions of the first plurality of contacts have an S-shaped structure. Frame, A contact element layer attached to the frame and each having a receiving portion and a tail having an end portion positioned adjacent the bottom surface of the frame; And a plurality of soluble elements comprising a deformation in front of the connector, each positioned adjacent the end of the tail and attached to a surface. 6. A connector according to claim 5, wherein the shape soluble element comprises a solder ball extending within a distance from the base. 7. The connector of claim 6, further comprising a protrusion attached to the bottom of the frame to space the frame from the printed circuit board. 7. A connector according to claim 6, wherein the solder balls take a modified sphere selected to minimize any forces causing realignment by remelting. Preparing a frame with a surface, Providing a plurality of contact elements each having a tail; Creating a number of availability elements, Attaching the plurality of contact elements to the frame such that the tail is located adjacent the surface of the frame; Attaching each of the plurality of fusible elements to each tail of the plurality of contact elements; And attach to the circuit board by a method comprising mechanically deforming the plurality of fusible elements. 10. The electrical connector of claim 9 wherein the modifying step includes compressing the plurality of availability elements such that the width of each of the plurality of availability elements is greater than the height of each of the plurality of availability elements. 10. The method of claim 9, further comprising the step of providing a circuit board and the further steps of attaching the electrical connector to the circuit board subsequent to the deformation step such that the deformation step minimizes any force causing realignment during the electrical connector attachment step. Electrical connector, characterized in that. 12. The electrical connector of claim 11 wherein the step of providing a circuit board comprises positioning the circuit board spaced apart from the fusible element. 10. An electrical connector as in claim 9 wherein the modifying step is performed subsequent to the attaching the fusible element. 10. The electrical connector as claimed in claim 9 wherein the fusible element is a solder ball having a flat portion.