GB2336951A - Connecting a connector to a PCB using a flexible circuit film - Google Patents

Abstract

The pins (34) of a connector 2 are connected to the tracks of a PCB 20 by a flexible film 38. The flexible film has tracks which lead from apertures 42 to connection zones 52. The film is laminated to a rigid substrate 36 which has plated through holes 58 lining up with those of the film.

Description

ELECTRICAL CONNECTOR 2336951 This invention relates to electrical

connectors and is particularly applicable to those electrical connectors for printed circuit boards where the electrical connection must be made to opposing sides of the boards without passing through the board.

There are numerous applications where it is necessary to form an electrical interconnection between the printed circuit board and a mating component. One example is a mother board/daughter card interface. A pin field would typically be on the mother board while a receptacle header would be on the daughter card or vice versa. In these instances, the plugging direction of the daughter card is typically along the axis thereof and the connector used is commonly referred to as a right angle header. Additionally, it is common to incorporate the electronic components utilised on the daughter card on both sides of the printed circuit board. The conductive tracks relating to these components both must be interconnected to the header. This is normally accomplished by way of plated through-holes that extend transversely across the printed circuit board such that all of the contacts associated with the header engage the board from a common side but by way of platedtrough-holes that are connected to conductive tracks on either side of the printed circuit board.

In some specialised cases, it is not possible to utilise plated throughholes that extend transversely across the printed circuit board. one such instance is when a metal core printed circuit board is utilised. A typical metal core printed circuit board is a laminated structure having a highly heat conductive core sandwiched between conventional laminated glass epoxy printed circuit boards. As the heat conductive core is typically metal, the utilisation of plated through-holes between the opposing 40795 GB(1) glass epoxy printed circuit boards would result in all of the plated through-holes being shorted together. ' In order to address this problem, a common solution has been to form a header that fits along one of the edges of the daughter card straddling the printed circuit board and has contacts with boarding engaging legs extending on either side of the board to the various pads for an interconnection. An example of this is shown in US 5,174,764. While designs of this type perform acceptably, a problem is that in specialised applications involving low quantities of components or non standard interconnection patterns, the tooling cost associated with such a connector is often cost prohibitive.

US 4,861,272 discloses an electrical connector of the 15 type described where the contacts include tail portions that extend from a body in a simple fashion, generally paral lel to the axis of the printed circuit board. These tail portions are then connected to the conductive traces upon the printed circuit board by way of flex circuitry that takes the place of the formed contact tails in the previously described prior art. The connection between the contact tails and the flex circuit is effected by soldering which adds a significant cost or at least an additional manufacturing step.

US 5,194,010 discloses an electrical connector having contacts with tail portions, a flexible circuit having holes corresponding to the terminal tail portions so that when these holes of the flexible circuit sheet are aligned with and pressed upon the tail portions, the conductive circuits are electrically terminated to the terminals. A problem with this design relates to the characteristics of the flexible circuit sheet in that it is thin and compliant which possibly results in damage to the flexible circuit during the mating process. Additionally, such structure may 40795 GB(1) require particular tail portions that are designed especially for mating with a flexible circuit sheet.

Therefore, there still remain numerous problems in the prior art in the utilisation of flexible film circuitry in order to form an economical and reliable interconnection between connectors and mating components. such as printed circuit boards. In particular, these problems are: the need to solder the tail portions of the contacts directly to the circuitry upon the flex film; the potential for damaging the flex film during attachment to the tail portions; and the possible need for specialised tail portions to engage the conductive pads of the flex circuitry. Where specialised contacts may be needed to engage flex circuitry, there may still be a cost improvement over completely custom contacts where the contacts themselves engage the printed circuit board; however, even needing this specialisation prevents one from taking advantage of the high volumes of production associated with contact tail portions designed to engage more conventional printed circuit board structure, such as plated throughholes.

Therefore, it would be advantageous to provide a flexible circuit interface that is engageable in a simple manner that eliminates the possibility of damage to the flexible circuit and effects the termination in a solderless manner by using common contact tail portions, such as those used in plated through-hole printed circuit board interconnection.

The present invention addresses this problem by providing a flexible circuit member having conductive tracks upon a flexible sheet where the conductive tracks extend between a first end for terminating with a mating component and second end having a mating pad with aperture therethrough, where the flexible circuit is laminated with a insulating support member along the second end of the conductive traces, the support member including plated 40795 GB(1) through-holes located to correspond to the second end of the conductive traces and to be electrically engaged therewith, the plated through-holes and the aperture through the second end of the conductive traces being adapted for receiving a conventional press fit solderless contact tail. Examples of contact tails of this type are disclosed in, for example, WO 88/01795, EP 0 0731 526, US 5,452,512.

A flex circuit interconnection of this type is particularly advantageous for use with a basic header of conventional design having terminal tail portions adapted for solderless interconnection with plated through-holes on a printed circuit board that is to be mounted along one of the edges of a printed circuit board such that the tail portions extend generally parallel to the board where at least some of the tail portions need to be connected to one side of the board and others of the tail portions need to be connected to the other side of the board. A particularly advantageous embodiment of a connector of this type can be realised where the flex circuit further includes conductive tracks that act as crossover or jumpers between he conductive traces on one side of the board and the conductive traces on the other side of the board but are not terminated to any of the contacts in the connector. 25 The present invention will now be described by way of example with re'ference to the accompanying drawings wherein-. Figure 1 is a front view of an electrical connector incorporating the present invention; Figure 2 is a side view of the electrical connector according to figure 1;' Figure 3 is a top partially cut-away view of the electrical connector of figure 1; Figure, 4 is a plan view of a flexible circuit incorporated within the electrical connector of figure 1 40795 GB(1) Figure 5 is a side cut-away view of the interconnection member incorporated into the electrical connector of figure 1; and, Figure 6 is a side view corresponding to figure 2.

With reference first to figure 1, an electrical connector incorporating the present invention is shown generally at 2. The electrical connector 2 incorporates a base connector 4 that has a plurality of interconnection points 6 in a housing 7 that includes contacts 8 for mating with a complementary connector. The base connector 4 shown is a standard offering that is a vertical female connector and is part of the AMP Z- PACK 2mm HM Hard Metric Interconnection System. It is also envisioned that the present invention can be utilised with other basic connectors, including male pin headers. The basic connector 4 includes opposing ends 10, 12 where mounting portions 14, 16 are included. Each mounting portion 14, 16 includes a hole 18 for fixing the connector 2 to a substrate in a manner described below.

With reference now to figure 2, the electrical connector 2 is shown fixed to substrate 20. The basic connector 4 has a mating face 22 and opposite thereto is fixed to the substrate 20. This is accomplished by way of the mounting portion 14, 16 having L-shaped brackets 24, 26 attached thereto. A rivet 28 or any other suitable mechanical fastener or bonding material may be used to hold the L-shaped brackets 24, 26 to their respective mounting portions 14, 16. Furthermore, a second rivet or screw 30 may also be used to hold the connector 2 to the substrate 20. The electrical interconnection between the contacts 8 in the basic connector 4 and conductive traces (not shown) upon the substrate 20 is effected by an interconnection member 32. The interconnection member 32 is best described below with reference to figure 4 and figure 5.

40795 GB(1) With reference now to figure 3, the electrical connector 2 is shown in cut-away fashion such that connection tails 34 of the terminals 8 for a given row are exposed within the interconnection member 32. These termination tails 34 are formed as AMP ACTION PIN solderless plated through hole contacts, in particular, electrical printed circuit board connectors. Where the tail portions 34 extend through the interconnection member 321' the interconnection member 32 is formed as a lamination of a first support substrate 36,a flexible circuit 38 and a second support substrate 40. Conveniently, these support substrates 36, 40 are formed from conventional printed circuit board material. Additionally, the laminated section 35 could be extended at the mounting portion ends 14, 16, to take on the function of supporting the L-shaped brackets 24, 26.

With reference now to figure 4, the flexible circuit 38 incorporated into the interconnection member 32 is described in greater detail. The flexible circuit 38 is divided into a number of regions where the first region 40 corresponds to the laminated area 35. In this region 40, there are a plurality of connection points 42 that are ultimately to be electrically connected to the tail portions 34 of the contacts 8. Extending from the connection point 42 are individually associated conductive tracks 44. These conductive tracks 44 extend outward from both sides of this first region 40 to opposite edges 46, 48. Between the central portion 40 and the outer edges 46, 48 are a pair of transition regions 50 followed by connection zones 52 and support strips 54. The conductive tracks 44 are supported by insulative material 55 in the central region 40, the transition region 50 and along the support strips 54. The conductive tracks 44 are exposed in the area between the transition region 50 and the support strip 54 for making an interconnection with the circuit 40795 GB(1) traces upon the substrate 20, as shown in figure 6. Furthermore, crossover or jumper conductive tracks 56 can be seen as part of the flex circuit 38 that extend between opposing ends 46, 48 across the central region 40 without an associated connection point 42 for engagement by the tails 34 of terminals 8. Advantageously, these crossover or jumper conductive tracks 56 enable conductive pads associated with one side of the substrate 20 to be interconnected through the connector 2 to conductive pads associated with the other side of the substrate 20 without the need for a separate crossover or jumper structure or passing through the substrate 20.

With reference now to figure 5, the interconnection member 32 is described in greater detail. At the laminate region 35, the support members 36, 40 are disposed on either side of the central region 40 of the flex film 38. The support members 36, 40 are aligned such that plated through holes 58 correspond with the connection points 42 of the flex film 38. The transition regions 50 are formed in an L-shape to bring the exposed conductors 44 at the connection region 52 into opposing positions on opposite sides of a receiving region 60. The receiving region 60 is where the substrate 20 is received. The support strip regions 54 are turned upward therefrom.

With reference now to figure 6, the electrical connector 2 is shown attached to substrate 20 as in figure 2. The solderless interconnection tails 34 of the contacts 8 have been pressed into the plated through holes 58 and the connection points 42 of the laminated structure 35 in order to form a secure electrical and mechanical interconnection therewith. The connection portions 44 can then be surface mount soldered directly to the circuit traces on the substrate 20 or connected therewith by a connector mounted on the substrate 20 that is adapted for flex film interconnections. In this manner, a robust and 40795 GB(1) -B- economical electrical interconnection device is provided for a specialised application.

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Claims (7)

1. An electrical Interconnection member f or connecting solderless contact tails of an electrical connector with conductive traces of a complementary component, comprising a flexible circuit member having connection points with apertures therethrough at an Interconnection region thereof, the. fexible circuit member having conductive tracks extending from the connection points to a connection region, and the conductive track being at least partially supported on an insulative backihg, and a supporting substrate laminated to the flexible circuit at the interconnection region, the supporting substrate having plated through holes therein that are aligned, and in electrical communication, with the connection points of the flexible circuit member.

2. An electrical connector for connecting to a substrate having conductive traces thereupon, comprising a base connector having a plurality of contacts disposed In a connector housing, the contacts having tall portions for solderless connection with plated through holes, and an electrical interconnection member comprising a flexible circuit member having a plurality of connection points corresponding to the plurality of contacts in the base connector and arranged in an interconnection region with conductive tracks extending therefrom to a connection region for attachment to the conductive traces of the substrate, and a supporting substrate having a like plurality of plated through holes extending therethrough and laminated to the flexible circuit member at the interconnection region such that the plated through holes correspond with the connection points and are electrically connected therewith, the tail portion of the contacts being received in the plated through holes of the substrate and the connection points in a solderless manner.

3. The electrical connector of claim 2, including mounting brackets for attaching the electrical connector to the substrate along an edge thereof.

4. The electrical interconnection member or connector of claim 1, 2 or 3. wherein the interconnection member includes a second set of connection points with conductive tracks extending therefrom to another connection region opposite the first mentioned connection region for engaging both sides of the substrate.

5. The electrical interconnection member or connector of claim 4, wherein the flexible member further includes supplementary tracks extending between the two connection regions.

6. An electrical Interconnection member constructed substantially as hereinbefore described with reference to the accompanying drawings.

7. An electrical connector constructed substantially as hereinbefore described with reference to the accompanying drawings.