DE3545527A1 - FLEXIBLE ELECTRICAL CONNECTING DEVICE AND METHOD FOR THEIR PRODUCTION - Google Patents

Description

Munich, December 19, 1985 / J Lawyer files .: 27 - Pat. 373

\ Raytheon Company, 141 Spring Street, Lexington, Mass. 02173, Ι United States of America

Flexible electrical connection device and method for their production.

The invention relates generally to printed circuits ^; and in particular to flexible ribbon cables for connecting ^; Circuit assemblies, in particular parts of a display system, with a flexible ribbon cable, for example, a Ma-

■ trix display unit with its electronic driver switchgear
gen connects.

Previously used assembly techniques or packaging techniques for electronic assemblies typically provide that active and passive electronic components on a single-layer or multi-layer printed wiring board or circuit board to be ordered. A plurality of such printed wiring boards or circuit boards are used interconnected again in that these circuit carrier plates be plugged into a plug-in board used for connection. In certain applications where space problems play a role, the connecting plug-in board is replaced by a piece of flexible ribbon cable, such as in a flat panel matrix display system in which the contacts on the edges of the display unit with the contacts on the edge a wiring board for the electronic drive circuits of the display system are to be connected. For example

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measure between 500 and 6000 electrical connections between the display unit and the electronic driver circuits, resulting in a considerable space requirement for these driver circuits, considerable assembly costs and a limitation of the possibility of maintenance and repair outside the workshop. When the connections between the electronic driver circuits and the display unit have to be solved outside the workshop in order to carry out a test or to only deal with a single cheap faulty component to be replaced, the display system must be taken to a service center for reassembly. this has result that the display unit and the electronic driver circuits outside the workshop as a single

uniform spare part are handled, which is expensive. If the parts of the display system can be designed in such a way that they can be easily separated from one another, the repair of the electronic driver circuits outside the factory does not present any difficulties and only requires the stock of spare parts for relatively cheap parts or devices. \

In a matrix display device, the high-voltage ί Driver circuits contribute most to the space requirements of the electronic circuitry for such devices. The putting together of high voltage driver circuits in a circuit j

device carrier chip without connecting lines can lead to considerable '

; Space savings in such display systems lead. It arises; however, there are mounting problems when a surface mount ■ Circuit carrier chip (LCC) and integrated circuits with

; Licher, the circuit board penetrating contact ^:

j I

tion, for example with two parallel rows of contact pins: (dual in-line package) on one and the same printed connector ^;

wiring board are to be mounted, since this requires two non-compatible mounting techniques. This construction itself does not allow a reduction in the large number of connections made between the electronic Driver circuits and the display element produced

Need to become.

The invention aims to achieve the object of designing an electrical connection device so that a large number of electrical connections can be produced with a reduction in space requirements, so that the connection device is particularly suitable for making the connections between
electronic driver circuits and a flat panel display system.

j This task is indicated by the appended claim 1

; benign features solved. The invention also includes a ver-

; drive to establish a flexible electrical connection

j forming device.

In detail, the electrical connection specified here contains
; connection device a flexible cable with a flexible iso- i! lating substrate on which a plurality of conductors are arranged;

net is. A prepared group of solder points is located

j is also on the substrate and a number of these solder \ !

! Punkte is electrically connected to the conductor tracks. To the j

! An electrical circuit pack is connected to the soldering points. Contact pins which are inserted into one end of the flexible electrical J

See connecting devices are inserted, form the connections to a printed wiring board and exposed conductor sections with a conductive plating on one
Side at the other end of the flexible electrical connection device are intended to be attached to a suitable arrangement
to be clamped by conductors for electrical connection of this other end j of the connecting device. A support plate that acts as a heat sink is laminated onto the circuit package and the substrate in the area below the circuit package. A plurality of flexible ribbon cables or connection devices are used to connect an electronic driver circuit unit to a matrix display unit in one

Display device. The circuit package includes the high voltage j

354S527

voltage driver circuits that are in a wireless circuit! chip carrier (LCC) are housed, whereby a ^{Räumeinspa-:} tion with respect to the electronic driver circuits is achieved. In addition, the use of the damage package attached to the flexible tape leads to the fact that the number; is reduced in connections that must be made between the electronic driver circuits and each flexible ribbon cable. The use of the flexible electrical connection device specified here results in an easily repairable display unit for repair and maintenance outside the manufacturing facility.

As already indicated, the invention also includes a method for producing a flexible electrical connection device, wherein a flexible cable having a plurality of therein arranged Strip lines is provided which are grouped in one or more layers. Flexible insulation layers are provided on both sides of the conductor layers and carry a group of solder points, a part on a first side in the region of a first end of the flexible Ribbon line is provided. A part of the soldering points is connected to a first part of the strip lines, while having a non-insulated section of striplines on the other side of the ribbon cable at the other end a conductive plating is provided. A circuit unit comes with the prepared solder points on the first Side of the flexible ribbon cable is soldered and a support plate effective as a heat sink is in a certain area the other side of the flexible ribbon cable below it and below the circuit package. Terminal contact pins are attached to the first end of the flexible ribbon cable in close proximity to the circuit package and are connected to part of the stripline and part of the soldering points.

otherwise, advantageous configurations and further training

; Tongues of the flexible electrical connection specified here!

ι ι

device and a method for its production counter-;

j stood the claims subordinate to claim 1, the content of which j is here expressly made part of the description.

! without repeating the wording at this point. ;

I embodiments are described below with reference to the ^;

Drawing explained in more detail. It represent:;

Fig. 1 is a plan view of a flexible electrical: connecting device of the i specified here Art with two layers of conductor tracks, j Fig. 2 is a side view of the flexible electrical I. j I

j Connection device with a connecting cable

power-free circuit carrier chip that is attached to a j

! first end of the flexible electrical connection j

I formation device near plug-in contact pin j

and a support plate serving as a heat sink is attached, which is located directly below the flexible ribbon cable and the circuit carrier chip without connecting cables
is laminated on,

3 is an exploded perspective view of FIG
connection device specified here,

Fig. 4 is a schematic representation for designation

of the different material layers of the flexible
electrical connection device according to Figure 3,

Fig. 5 is an illustration to illustrate the shape
the top layer of copper striplines for the device specified here,

Fig. 6 is an illustration to illustrate the shape
the lower layer of copper striplines for the device specified here and

7 is an exploded perspective view of a
Matrix display device with a flexible

Ribbon cable for connection between a circuit board for the electronic Driver circuits and a matrix display unit.

In Figures 1, 2 and 7 are flexible electrical connections devices with 10 designated. They contain a flexible ribbon cable 11 in which layers of isolated strip conductors 24 and 32 are provided. A leadless circuit carrier chip 12 is at one end of the flexible ribbon cable 11 attached to this. Below the area that is covered by the circuit carrier chip 12 is on the flexible Ribbon cable an effective as a heat sink support plate 14 attached. Connection means in the form of contact pins 15 and , Connection areas 16 at the ends of the strip conductors each serve; because to connect the ends of the flexible ribbon cable with Share a display device 50. The connection line-free

j circuit carrier chip 12, which is also referred to as a chip carrier

forms the means for connecting one or more circuit chips or other components within the Carrier 12. Contact pins 15 are used for the electrical connection of one end of the flexible connecting device 10 with a printed wiring board. The connector 16 at the other end of the flexible ribbon cable is from a 6 mm end portion of the strip conductor layer 32 is formed. The connection area 16 is not provided with an insulating cover layer provided, but has a conductive plating so that this end of the flexible ribbon cable 10 to mating Conductor elements of a display unit 58 of the display device 50 can be clamped, as shown in FIG. The flexible electrical connection device 10 is used within the display device 50 to connect a part a module 54 containing the electronic driver circuits with part of the display unit 58. The contact pins 15 are plugged into the module 54 containing the electronic driver circuits, while the end connection

I rich 16 is wrapped around the edge of the display unit 58, where-

I with the exposed strip conductors with corresponding contact areas on the underside (not shown) of the display input. ί is called 58 curses. A clamp 62 holds the stripped connection ^! Area 16 on the '< parts of the display unit 58 which are provided with corresponding contact elements.

Figure 2 shows a side view of the flexible electrical connection device 10 with the support plate 14 acting as a heat sink and the contact pins 15 for establishing the connection to a printed wiring board. '

Figures 3 and 4 show as already stated, a perspective-\ vische exploded view of the flexible electrical connecting device 10 and the layer structure of the flexible band? Cable 11 with a plurality of layers of material. It should be noted that in the vertical direction the scale in FIG. 3 is greatly enlarged and that the thicknesses of the material layers are shown greatly exaggerated. In FIG. 4, the individual layers of the various materials are designated which form the flexible ribbon cable 11 which contains the two conductor layers. The base material in the flexible ribbon cable 11 are the insulation layers 20, 28 and 36, which consist of a condensate polyimide which can be obtained from duPont de Nemours & Co. Inc. under the trademark "Kapton". The "Kapton" polyimide is chosen because it has particular flexibility, tensile strength and extremely good insulation properties in a film thickness of 25.4 to 50.8 μm. The conductors 24 and 32 are made of soft copper foil weighing 28.3 g to 56.6 g (1.4 or 2.8 mil), the copper being tempered and rolled so that a relatively soft conductor layer is formed. The adhesive layers 22, 26, 30 and 34 consist of an acrylic adhesive, for example "Paralux", which is also brought onto the market by duPont de Nemours. These adhesive layers are used to connect the "Kapton" insulation layers 20, 28 and 36 with

the copper conductor layers 24 and 32. The acrylic adhesive layers are provided in a thickness of 25.4 µm to 50.8 µm. The lead-free chip carrier 12, which is a structural unit known to those skilled in the art of microelectronics is common, has lead-free connections se 23 which are lined up around the circumference of the component. This component is firmly soldered to specially provided corresponding soldering points 25 of the flexible ribbon cable 11. In the "Kapton" layer 20 openings 27 are cut through wel before it is prevented that the tops of the solder points 25 isolie rend are covered so that the soldering points extend through the aligned openings 27 and contact pins in the flexible ribbon cable 11 can be inserted and soldered in place. Acting as a heat sink support plate 14 can be of a Epoxy glass, for example the G10 material known to the person skilled in the art be formed or the shape of another thermally conductive material body, such as aluminum oxide or a relative of the expansion coefficient matched material, such as a copper-invar-copper laminate, depending on which Cooling conditions for the relevant chip carrier 12 must be observed. The support plate 14 serving as a heat sink can be dimensioned in this way be, as shown in Figures 1 and 3 and cover the area below the chip carrier 12 or also be made larger so that the area around the contact pins 15 is covered. The plate 14 is on the flexible Ribbon cable 11 attached by means of an adhesive. Serving as a heat sink support plate 14 is used to stiffen the flexible electrical connection device 10 to ensure that the input contact pins 15 are in the correct position remain that the chip carrier 12 remains in good contact with the support plate 14 and that the area of the flexible ribbon cable 11 is solidified where the chip carrier 12 is located, in order to prevent fatigue in the soldered connections to the chip carrier 12 to avoid. The contact pins 15 are inserted, shaped and each in the nine plated through holes 29 at one end of the flexible electrical connection

'. direction 10 firmly soldered and the contact pins 15 so form the. ; Connecting means for attaching one end of the connecting means; device 10 on a printed circuit board. The other end of the flexible electrical connection device 10 with the connection areas 16 can be seen in the broken away part of FIG. The lower ends of the copper strip lines in the layer 32 are stripped to a length of about 6 mm, as has already been noted, and gold-plated, so that these conductors can be used as a connection area and here the end of the flexible electrical connection device 10 in question can be clamped to suitably arranged conductors of the display unit 58 by means of a U-shaped bracket 62, as can be seen from FIG. ■

The method for producing a flexible ribbon cable 11 corresponds to the production of one-sided, double-sided or multilayer printed circuit boards, this method being familiar to the person skilled in the art after at both processes etched copper conductor tracks on a dielectric Carriers are generated. Printed wiring boards are generally used to connect components, while flexible ribbon cables are generally used for printed wiring boards and circuit boards to connect to other printed circuit boards or other active device units. After the two Components are so similar to each other, so are most of the process steps the same, although some of the materials used are different. The process of making a flexible ribbon cable 11 of the type considered here contains the following process steps:

1. Selection of the material, the layer thicknesses and the structure, namely, for example, the aforementioned "Kapton" for the insulation layers, for the adhesive layers for example "Paralux" and soft copper as conductor layers.

AH

2. Punching or drilling mounting holes; the holes must match the corresponding elements of the used mounting devices are aligned and the tape material must be drilled so that with respect to The front and back are covered and the cover layers can be laminated on.

3. Drilling the breakthroughs: Pay particular attention to the feed and the speeds after the soft copper has a tendency to form degrees.

4. Removal of excess glue: The excess that escapes is caused by the when drilling the heat propagates through the copper and melts the acrylic, leaving acrylic material on the copper leaks when the drill is withdrawn.

5. Electroless plating or electroplating of copper to plate the apertures; this happens only if plated breakouts are needed in the circuit, and in the same way proceed as with printed wiring boards.

6. Photographic determination of the conductor pattern: The flexible ribbon cable now has copper layers with plated holes on both sides. There is then a coating with a dry Photoresist mask, the desired pattern is aligned and there is exposure and development so that the positive image is the desired Circuit is left behind and the photoresist mask covers the through-holes to help them with the to protect subsequent treatment steps.

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7. Etching of the conductor pattern: It is done in the usual way as in the manufacture of printed wiring boards. The etching removes the excess copper chemically, see above that the desired conductor pattern remains.

8. Cleaning: Cleaning is an extremely important process step in successful Manufacture of printed wiring boards, multilayer circuit boards or flexible ribbon cables. One cleaning process or various cleaning processes take place before another Process step is added to ensure that these subsequent process steps can be carried out without being disturbed by undesired dirt particles, oxides or material residues occurs.

9. Application of covers: To protect the copper conductor tracks against damage during handling and against electrical short circuits is a Cover layer applied to the conductor tracks. So that the flexibility is retained, is used for the covers the same material as used for the substrate. A thin "Kapton" layer is over the conductive traces are laminated with a suitable amount of acrylic adhesive applied. In this Trap, the adhesive layer is drilled or punched to specific point areas for soldering to keep clear.

10.Lamination of the support plate serving as a heat sink: Acrylic glue is used to attach the heat sink support plate to the flexible one Ribbon cable.

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'Jl * ... Λ.

11. Solder coating: Solder is only required in the point areas provided for this purpose, including the flexible
Ribbon cable after applying the top layers

undergoes a solder coating by lamination. ; This is done by dipping the relevant part in liquid solder and removing the excess solder by blowing hot air or
by hot oil or by wiping with a
Roller to remove excess solder. :

12. Profiling: A shaping with gauges and carbide tools is generally carried out at the end
the manufacture of printed wiring boards and
multilayer circuit boards, but this is im
general expensive. Flexible flat cable can hinge '· gen are very well edited with cheap steel shapes and can also with knives to-be cut j in small quantities. ;

In FIGS. 3, 5 and 6, typical shapes for the upper and lower layers of copper conductors 24 and 32 are one

flexible ribbon cable 11 shown on the dielectric layer 28 of I "Kapton" as they arise after the etching. Figure 5

also shows the circular areas where plated through j

te through holes 29 and 31 are generated, as well as the j

Copper connection arrangement 25 for attaching the connecting line;

free chip carrier 12 on the flexible ribbon cable 11. j

I now consider Figures 1, 2 and 3 again. Is this · If flexible ribbon cable 11 is produced, the following process steps are required to complete the flexible electrical connection! to perform binding device 10: j

1. First examination: The flexible ribbon cable 11 is
for proper manufacture and compliance
examined with the specifications to be complied with.

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2. Application of a soldering paste: A soldering paste is applied to the soldering point areas 25 using the screen printing process / customary screen printing processes are used.

3. Application of the chip carrier free of connection lines: A chip carrier 12 free of connection lines with pre-tinned Solder points 23 are in the correct orientation on points 25 provided with solder paste of the flexible ribbon cable 11 placed.

4. Second examination: the application and alignment of the chip carrier 12 to the flexible ribbon cable 11 is examined to ensure that the pre-tinned solder points 23 of the chip carrier 12 properly on the solder points 25 of the flexible ribbon cable 11 are attached.

5. Soldering in the vapor phase: the flexible ribbon cable 11 A soldering in the vapor phase with reliquefaction is carried out with the chip carrier 12 without connecting leads of the plumb bob.

6. Third Examination: The soldered flexible connector 10 is checked for proper solder joints examined.

7. Cleaning: A cleaning process is performed to remove flux and other contaminants.

8. Fastening the contact pins: The connection pins 15 are each inserted into the nine plated through holes 29 and soldered in place.

9. Cleaning process: A cleaning is carried out,

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to remove flux residues due to the previously carried out to eliminate guided soldering process.

10. Final Exam: A final examination of the flexible electrical connector will be performed to ensure proper manufacture and assembly occurred, and themselves the component inserts flawlessly into the device equipped with it.

j From Figure 7 it can be seen that the flexible electrical An-I Terminal device 10 two parts of a flat panel — matrix connection ! Connects pointing device 50 to one another, which in'Explosions- ; illustration in Figure 7 is sketched. One end of the flexible electrical connection device 10, which has the contact pins 15 near the chip carrier 12, is in a module 54 containing electronic driver circuits inserted and the connection area 16 at the other end of the flexible

j blen connector 10 with the exposed strip-J conductor sections is wrapped around the edge of the display unit 58 in the form of a flat glass panel with the display matrix, while at the same time aligning the exposed conductor ends of the connection area 16 on aligned conductors takes place at the edge of the underside (not shown) of the display unit 58. The connection area 16 at the end of the flexible The ribbon cable is attached to the display unit 58 by a U-shaped bracket 62. A majority of flexible electrical Connection devices 10 are provided with a flat panel matrix display device 50 around the outer periphery of the module 54 containing the driver circuits and the display unit 58 are used to make all the necessary connections to manufacture. The matrix display device 50 also includes a control module 52 for controlling the signals for the Module 54 containing driver circuits and thus the display unit 58, furthermore a stiffening plate 56 and a remote one Frame 60 to protect and support the display

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unit 58. The latter can be a flat panel plasma display element available from Electro-Plasma Inc. (EPI), Milbury, Ohio, United States of America, under ¹ part number PDM 256512-062. The input signals for the chip carrier 12, which via the flexible electrical! see connection device 10 of which the driver circuits ■

containing module 54, all pass through the connection means in the form of the contact pins 15. The output signals from the chip carrier 12 to the display unit 58 flow via the connection area 16 of the flexible ribbon cable, in which the exposed or non-insulated strip conductors are available aligned on the associated conductor on ^: circumferential edge of the display element 58 and fixed there | are clamped. The number of contact pins 15 for turning \ circuit between the flexible electrical Verbindungsvorrich-. device 10 and the module 54 containing the driver circuit; are required is significantly less than the number of connection means which would be necessary without the attachment of an active chip carrier 12 to the flexible electrical connection device 10. Only a small number · pins of contact is required to the control driving signal inputs ι be able to handle to the flexible electrical connection device 10 and the larger group of decoded output i ι signals from the chip carrier 12 is formed by the layers of the '■ stripline 24 and 32 and passed on from the conductor layer 32 via the stripped ends in the connection region 16. The ! Use of a flexible electrical connection device j 10 in the matrix display device 50 not only brings about a connection of the number of direct electrical connections which must be made between the module 54 containing the driver circuits and the display unit 58, but also remarkably sets the overall space requirement of the j matrix display device 50. In addition, the ease of maintenance and repairability of the matrix display device 50 are improved by the fact that the module 54 containing the driver circuits, the display unit 58 and j

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the flexible electrical interconnection device 10 can be disassembled and reassembled outside of the manufacturing facility. Repairs can now be carried out in a simple manner outside the workshop on which the driver circuit is installed
containing module 54 and the flexible electrical connection device 10 can be made by faulty
Circuit parts or device parts are replaced, with relatively cheap replacement parts are used for the circuit or the device units.

A number of options are available to the person skilled in the art within the scope of the invention
of further training and modification opportunities. For example, the flexible ribbon cable can be made with a single layer of strip conductors or with multiple layers of the same
Strip line be equipped and the material for the
conductive layers as well as for the plating in the
Connection areas to the matrix display device can be copper, gold, silver, aluminum or other electrically conductive ones
Be materials or material compounds. The surface area which is covered by the part serving as a heat sink can be selected to be smaller or larger and the type of connection means at the respective ends of the flexible ribbon cable can also be designed in a different manner, depending on the application of the flexible electrical connection device in question .

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Claims (12)

3145527 claims 1. Flexible electrical connection device (10), characterized in that by a flexible insulating substrate (28) on which a plurality of conductors (24, 32) is arranged, further by a prepared group of solder points (25), which are located on the substrate, with a certain Number of soldering points is electrically connected to the conductors, as well as by circuit means (12), the soldering points (23), which are intended to be soldered to the prepared group of solder points on the substrate will. 2. Connecting device according to claim 1, characterized in that that a first part of the plurality of conductors (24, 32) on one side of the substrate and a second part of conductors is arranged on the other side of the substrate. 3. Connecting device according to claim 2, characterized in that that the first part of conductors (24) through an applied to the insulating substrate (28) insulating Covering layer (20) is covered and that the second part of conductors (32) from one on the underside of the insulating Substrate applied further insulating cover layer (36) is covered, the first-mentioned and the further insulating cover layer are each connected to the insulating substrate by adhesive layers (22, 34). 4. Flexible connecting device according to one of claims to 3, characterized in that the flexible insulating Substrate and optionally the insulating flexible cover layers contain a condensate polyimide. «- 1 mm * * ™ ~ - »■ ■■ · -> ■ j 5. Connecting device according to one of claims 1 to 4, characterized in that the circuit means have an an-I Circuit-free chip carrier (12) included. 6. Connecting device according to one of claims 1 to 5, ■ characterized in that below the circuit means I (12) and the insulating substrate a support plate (14) ! j ! to support the flexible electrical connecting device [ , direction in the area of the circuit means and to dissipate heat from these circuit means. | 7. Connecting device according to one of claims 1 to 6, characterized in that at the ends of the flexible insulating Substrates (28) in each case connection means for connecting the connection device to connection devices neighboring device parts are provided. j 8. Connecting device according to claim 7, characterized draws that at its end, which the circuit means (12) is immediately adjacent, a certain number of contact pins (15) is attached, which are used to connect the relevant end of the connecting device to first connection devices is used, while at the other end of the The connecting device comprises a stripped section (16) of the second number provided with a conductive plating of conductors is provided, this stripped section of the conductor for connection to a further connection device serves. 9. A method for producing a flexible electrical connection device, characterized by the following method steps : 1. Providing a flexible ribbon cable with a plurality of strip conductors arranged in a or several layers are grouped and which are each between flexible insulating Layers are located, with an arrangement of solder points in one area on the flexible ribbon cable on a first side near one end of the flexible ribbon cable is prepared, with part of the solder points is connected to a first part of the strip conductor, while a stripped conductor section j the stripline on the other side on the other The end of the connector is provided with a conductive gold plating; j 2. Solder a circuit assembly to the prepared soldering points on the first side of the flexible j ribbon cable; j 3. Lamination of a support that serves as a heat sink plate in an area on the other side of the flexible ribbon cable below the cable and below the circuit assembly mentioned and 4. soldering connection pins to the first-mentioned end of the flexible ribbon cable in the immediate vicinity of the circuit component, the contact pins with part of the stripline and part of the soldering points are connected. 10. Display device, in particular matrix display device with flexible electrical connection devices according to a of Claims 1 to 7, characterized in that a display unit (58) for displaying a plurality of symbols it is provided that driver circuits (54) are effective for selecting one or more of the symbols, that further a number of the flexible electrical connection devices are provided each and that / one end of the connecting device to the driver circuits and the other end of the connecting device is attached to the display unit. 11. Display device according to claim 10, characterized in that the display unit (58) is a matrix display unit is. • # ♦ + 12. A display device according to claim 10 or 11, characterized labeled in j j is characterized in that that end of the connecting device, WEL> I ches having the stripped portions of the conductors, with an overall ι matching conductor arrangement of the display element in combination | attached, especially to the edge area of the display unit. is bracketed. | -A-