JPS61148706A - Flexible cable assembly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates generally to printed circuits, and more particularly to flexible interconnects between parts of a display system, such as between matrix display elements and drive electronics.・Regarding ribbons and cables.

BACKGROUND OF THE INVENTION Conventional electronic device packaging technology has typically involved mounting active and passive electronic components on single or multilayer printed wiring boards (PWBs). Multiple such printed wiring boards are connected by plugging the boards into a "mother" connection panel.

If space is insufficient, flat or panel panels can be used instead of connection panels to interconnect the end connections of the display element to the end connections of the display drive electronics printed wiring board. In matrix display systems, flexible ribbon cables are run straight.

There are typically 500 to 6000 electrical connections between the display element and the drive electronics, resulting in substantial space requirements for the drive electronics, increased assembly costs, and ), the amount of time for maintenance is also limited. When the connection between the drive electronics and display element needs to be removed for field testing or inexpensive replacement of a failed device, the display assembly must be returned to the service center for reassembly. No. As a result, display elements and drive electronics are kept in reserve in the field as single line replaceable units (LRUs), which are expensive. If the components of the display system are designed to be easily removable, repair of the drive electronics can be done in the field by simply keeping relatively inexpensive parts or devices in reserve.

The high voltage driver circuit is suitable for matrix displays and
It accounts for most of the volume required for the drive electronics in the system. Packaging the high voltage driver circuit in a leadless chip carrier (LCC) II structure can significantly reduce the volume of the display system. However, surface mounted LCC and dual inline package (DI
A problem arises when well-known through-board integrated circuit (IC) devices such as R) are mounted on the same printed wiring board because they require two incompatible assembly techniques. And this method itself does not appreciably reduce the number of interconnections required between the display drive electronics and the display elements.

SUMMARY OF THE INVENTION In accordance with the present invention, a flexible cable assembly is provided having a flexible insulating substrate on which a plurality of conductors are formed.

A predetermined group of solder pads are electrically connected to the conductors and a circuit package is attached to the solder pads. A pin inserted into one end of the flexible cable assembly provides a means of connection to the printed wiring board, and an exposed conductor with conductive plating on the first side of the second end of the flexible cable assembly is connected to the second end of the flexible cable assembly. to a matching conductor. A heat sink/backing is laminated to the bottom area of the circuit package and board. A plurality of flexible cable assemblies interconnect the drive electronics module to the matrix display element within the display assembly.

The circuit package is a leadless chip carrier (LC).
C) consists of a high voltage driver circuit mounted within the
The volume required for drive electronics can be reduced. Furthermore, the circuit package attached to the flexible cable provides a means of reducing the number of connections required between the drive electronics and each flexible cable assembly. flexible·
The cable assembly provides an easily field repairable display assembly.

According to another aspect of the invention, a method of manufacturing a flexible cable assembly is provided, the method comprising: a flexible cable having a plurality of strip conductors arranged in one or more layers; providing a flexible insulation means on each side of the plurality of conductor layers, the flexible cable having a first
Some solders arranged on a part of the first surface of the i area.
a pad, a portion of the solder pad being coupled to the first portion of the strip conductor, and an uninsulated second portion of the strip conductor on a second side of a second end of the flexible cable assembly; a conductive plated step;
soldering a circuit device to solder pads arranged on the first side of the flexible cable; and a heat sink on a portion of the second side of the flexible cable below the flexible cable and the circuit device. / laminating a backing means and soldering terminal pin means on a first end of said flexible cable proximate said circuit board, said pin means being attached to said strip conductor and a portion of said solder pad; and a combined step.

[Description of Examples J The present invention will be explained in detail below according to examples.

1, 2 and 7, a flexible cable assembly 10 is shown that includes insulated strip conductors 24 and 32.
a flexible cable 11 in which a layer of
, a leadless chip carrier 12 attached to one end of the flexible φ cable 11, and a flexible chip carrier under the area covered by the leadless chip carrier 12.
Heat sink/lining 1 attached to cable 11
4 and a connecting device having pins 15 and strip conductor end connectors 16 at each end of the flexible cable 11 for connecting between portions of the display assembly 50. Leadless chip carrier 12 provides a means for interconnecting one or more circuit chips or other devices within the carrier. pin 15
provides a means for electrically connecting one end of flexible cable assembly 10 to a printed wiring board. The connector 16 at the other end of the flexible cable assembly 10 is connected to a 1/4 inch (6,35 mm) strip conductor layer 32.
,) consists of the ends of the The end connector 16 has no insulating material coating and has a conductive plating that allows the assembly to be connected to the cross-section on the display element 58 of the display assembly 50 as shown in FIG. Allow the ends of 10 to be clamped. Flexible cable assembly 1
0 is used to interconnect a portion of drive electronics module 54 to a portion of display element 58 within display assembly 50 . The pins 15 are plugged into the drive electronics module 54 and the end connector 16 is wrapped around the end of the display element 58 with its exposed strip conductor connections connected to the bottom surface of the display element 58 (not shown). ) are aligned with the joints that they have. Clamp 62 secures end connector 1G to the code connection on display element 58. The side view of flexible cable assembly 10 in FIG. 2 shows heat sink/backing 14 and pins 15 for connection to a printed wiring board.

3 and 4, an exploded perspective view (FIG. 3) of the flexible cable assembly 10 is shown;
Flexible cable 11 consists of multiple layers of material. It should be noted that the vertical dimensions in FIG. 3 are not exact and the thickness of each material layer is exaggerated. FIG. 4 clearly shows the layers of material used to form the flexible cable 11, which consists of two conductive layers. The base material of the flexible cable 11 forming the insulating layer 20.28.36 is a compressed (condensed) polyimide, E.1. duPont de Neo+o
urs & co, inc, (fairfield,
Apton® polyimide manufactured by CTO 6433) can be used. The reason for using apton polyimide in the
．． This is because when made into a sheet with a thickness of 0.051 am), it is flexible, has high tensile strength, and has excellent insulation properties. Conductors 24 and 32 are approximately 1 or 2 ounces (1,4
or 2.8 mil) soft copper foil and is stretched and annealed, thereby providing relatively soft copper. Layers 22.26.30.34 are acrylic adhesive;
For example, E,1. duPont de Nemours
The apton insulation layer 20.28.3 can be made using Paralux™ manufactured by Co., Inc.
6 and the copper conductor layer 24.32 are glued together. The acrylic adhesive is used in 1 and 2 mil thicknesses. A leadless chip carrier 12, well known to those skilled in the field of electronics, has leadless terminals 23 disposed around its periphery and corresponding pads 25 disposed in alignment on flexible cable 11. be soldered. An aperture 21 is formed in the aptonlW 20 and has a solder hole protruding through the aperture 27 thereof.
This avoids insulating the top of the pad 25 and allows the pin 15 to be inserted into the flexible cable 11 and soldered. Heat sink/lining! 14 can be made of epoxy glass, such as 010 material, well known to those skilled in the art, or other thermally conductive materials, such as alumina or certain LCC
Depending on the cooling needs of the device, it may be made of a material with a matching coefficient of expansion, such as copper, amber, or copper laminate. The heat sink/backing 14 can be large enough to cover the area below the LCC 12 as shown in FIGS. 1 and 3, or it can be large enough to cover the area around the connection pins 15. It is. The heat sink is attached to the flexible cable 11 with adhesive φ. The heat sink/backing 14 ensures that the input connector pins 15 are maintained in the signed state, the LCC 12 is in proper contact with its heat sink, and the flexible cable 11 is held in the area of the LCC 12 so that the solder connections of the LCC 12 Provides a means for restraining the flexible cable assembly 1G to ensure that fatigue of the flexible cable assembly 1G is prevented. pin 15
are inserted into each of the nine plated through holes 29 in the first end of the flexible cable assembly 10 and soldered, and their pins 15 connect the first end of the cable assembly 10 to the printed circuit. Provides connection means for attaching to the board. A flexible cable assembly consisting of connector 16 is formed as shown in the drawing. Approximately 1/4 inch (6,35S+) of the bottom edge of the copper strip conductors of layer 32
- is not insulated as previously described and is gold plated, thereby allowing its conductor to be used as an end connector 6, connecting this end of this cable assembly 0 to the display element 58 as shown in FIG. It is clamped to the upper code container by a U-shaped lamp 62.

The method of manufacturing flexible cable 11 is similar to the method of manufacturing single-sided, double-sided, and multilayer printed wiring boards well known to those skilled in the art. The reason is that both methods involve copper being etched onto the insulating material. Printed wiring boards are commonly used to interconnect board components, while flexible cables are commonly used to connect printed wiring boards to other printed wiring boards or other active devices. They are similar and most of the steps are the same although some of the materials are different.

The method for assembling flexible cable 11 consists of the following steps.

Thickness 1. Select material, shading and assembly method: Insulating material (
Kapton), adhesive (Paralux), conductor (
soft copper).

2. Drill holes for work (punch or drill): Holes are for artwork and drilling for front and back alignment V.
Match the tape and cover sheet lamina.

3. Drilling the through hole: Pay special attention to the feed and speed of the drill as this will cause the annealed copper to form.

4. Remove excess adhesive: Application is done by generating heat as the drill penetrates the copper, melting the acrylic, and painting the acrylic over the copper during the drill removal process.

5. Electroless plating and electroplating of copper on plated through holes: Used only when plated through holes are on the circuit, it is the same process used for printed wiring boards.

6. Draw the conductor pattern: The flexible cable is now plated with through holes and provided with copper on both sides. It is then coated with dry film photoresist to align the artwork and
After exposure and development, a positive image of the desired circuit is created, and through-
The holes are covered with photoresist to keep them cool during subsequent processing.

7. A similar typical method is used for assembling a niblint wiring board for etching conductor patterns.

Chemically etch away the excess copper, leaving the desired circuit.

8. Cleaning: Cleaning is performed on printed wiring boards, multilayer boards (ML
B) or is an important step for preferably manufacturing flexible cables. Providing one or several cleaning steps before each treatment - allows subsequent treatments to be carried out without interference from undesired dust, oxides or residues.

9. Overcoating: To protect copper conductors from damage during handling and electrical short circuits, a coating is required over the conductors. The same substrate is used for coating to maintain flexibility. A thin layer of aptonljJ is laminated onto the conductor using a suitable acrylic adhesive. In this case, the adhesive is pre-drilled (drilled or punched) to expose the pad for soldering.

10. Laminate the Heat Sink/Backing Attach the heat sink/backing to the flexible cable using Niacrylic adhesive.

11. Solder coating: Since there is no need to solder anything other than the pad, the flexible cable is solder coated after the coating is laminated. This process involves immersing it in molten solder, blowing it with hot air or hot oil to remove excess solder, or wiping it with an O7 hand to remove excess solder.

12. Determining the contour: Routing using templates and carbide tools is commonly used for printed wiring boards and multilayer boards, but can be expensive. However, flexible cables can be cut very effectively using inexpensive steel rule dies, and in small quantities can also be cut with a knife.・ Here, FIGS. 3, 5, and 6 show the apton insulating material 1128 after the etching process of the assembly method.
A typical layout for the top and bottom copper conductors 1124 and 32 of the flexible cable 11 above is shown. FIG. 5 shows plated through holes 29.
A circular dot 31 and a copper pad arrangement 25 for attaching the leadless chip carrier 12 to the flexible cable 11 are shown.

Here, referring again to FIGS. 1, 2, and 3, the flexible cable 11 is connected to the flexible cable.
The steps to complete assembly of assembly 10 will now be described.

1. First inspection: The flexible cable 11 is inspected to see if it conforms to the specifications.

2. Solder paste application: Solder paste is screen printed onto the solder pads 25 using conventional screening equipment.

3. LCC arrangement: pre-tinned pad 2
Leadless chip carrier 12 with 3 solder pads 2 arranged on flexible cable 11
5 in an appropriate manner.

4. Second inspection: LC to flexible cable 11
The placement of C12 is inspected to ensure that the pre-tinned pads 23 on the LCC 12 are properly aligned with the solder pads 25 on the flexible cable 11.

5. Vapor phase (vaporization) soldering: The flexible cable 11 to which the LCC 12 is attached is subjected to vapor phase reflow soldering.

6. Third Inspection: The soldered assembly 10 is inspected for proper solder joint (contour).

7. Cleaning: Cleaning is performed to remove solder flux and other contamination.

8. Connector pin installation: Terminal pins 15 are inserted into each of the nine plated through holes 29 and soldered at the appropriate locations.

9. Cleaning: Cleaning is performed to remove flux residue from previous soldering.

10.R Final Inspection: A final inspection of the flexible cable assembly is performed to ensure proper workmanship and compliance with assembly procedures.

Referring now to FIG. 7, a flexible cable assembly 10 is shown connecting two portions of a flat panel matrix display assembly 50 shown in an exploded perspective view.

The first portion of flexible cable assembly 10 having pins 15 proximate leadless chip carrier 12
The end of the flexible cable 11 is inserted into the drive electronics module 54 and has a strip conductor exposed on one end of the flexible cable 11.
The second end 16 of the assembly 10 is wrapped around the end of a flat glass panel matrix display element 58, with the exposed conductors of the end connector 16 connected to the bottom surface of the display element 58 (not shown). Align the matching conductor on the edge of the End connector 16 is secured to display element 58 by a U-shaped lamp 62. A plurality of flexible cable assemblies 10 are used around the drive module 54 and display element 58 of the flat panel matrix display assembly 50 to provide all necessary interconnections.

Matrix display assembly 50 also includes a controller module 52 for controlling signals to drive module 54 and thus display element 58, a rigid panel 56 for protecting and supporting the integrity of display element 58, and flame/
It has a bezel 60. Display element 58 is manufactured by Electro-Plasma Inc.

(EPI) (Hilbury, Ohio), part No. PDH256512-062.

CCl on flexible Φ cable assembly 10
All input signals from driver module 54 to 2 pass through the connection means formed by pins 15. L.C.
The output signal from C12 to display element 58 is provided by a flexible cable end having an exposed or uninsulated strip conductor aligned and properly clamped with the code conductor on the peripheral edge of display element 58. Passes through connector 16. The number of connector number pins 15 required for the connection between the flexible cable assembly 10 and the drive module 54 is determined by the cable number.
Much fewer than would be required if no active LCCs 12 were placed on assembly 10. Only a small number of pins are required to handle the control drive signal input to the flexible cable assembly 10, and L
The large group of decoded output signals from CC 12 is handled by a non-insulated end connector 1G formed from strip conductor layers 24, 32 and 32. The use of flexible cable assembly 10 in conjunction with matrix display assembly 50 not only reduces the number of direct electrical connections required between drive module 54 and display element 58, but also reduces the number of direct electrical connections required between drive module 54 and display element 58.・Assembly 50
greatly reduces the overall volume of the. Additionally, maintainability of matrix display assembly 50 is improved by allowing driver module 54, display element 58, and flexible cable assembly 10 to be disassembled and reassembled at the installation site. and driver module 58
And field repairs of the flexible cable assembly 10 can be easily performed by replacing failed circuit components with relatively inexpensive spare circuit components or devices.

Although preferred embodiments of the present invention have been described, it will be apparent to those skilled in the art that many modifications and changes may be made within the scope of the invention. For example, a flexible cable can have one conductor layer or multiple conductor layers, and the material of the conductor layer may be copper, gold, silver, aluminum or other material, as well as the plating on the connection end to the matrix display. Similar electrically conductive materials or compound materials can be used. The surface area of the heat sink can be small or large depending on the application, and the type of connection means at each end of the flexible cable assembly can also vary depending on the application.

[Brief explanation of drawings]

FIG. 1 is a top view of a flexible cable assembly according to the invention having two conductor layers. Figure 2 is a side view of the flexible cable assembly;
a leadless chip carrier mounted on the first end of the cable assembly in line with the insertion pin;
A heat sink/plate is shown laminated directly below the cable and leadless chip carrier. FIG. 3 is an exploded perspective view of a flexible cable assembly according to the present invention. FIG. 4 shows the material layers of the flexible cable shown in FIG. FIG. 5 shows the layout of the top layer of copper strip conductors according to the present invention. FIG. 6 shows the layout of the bottom layer of copper strip conductors according to the present invention. FIG. 7 is an exploded perspective view of the matrix display assembly showing the flexible cable assembly interconnecting between the drive electronics and the matrix display elements. (Description of symbols) 10... Flexible cable assembly 11... Flexible cable 12... Leadless chip carrier 14... Heat sink 15... Bin 16... Connector ~-- f, 2nd figure 4

Claims (6)

[Claims] (1) a flexible insulating substrate on which a plurality of conductors are formed; and a group of solder pads arranged in a predetermined arrangement on the substrate, the plurality of solder pads being electrically connected to the conductors. A flexible cable assembly comprising: a pad; and a circuit device having solder pads for attachment to the predetermined array of solder pads disposed on the substrate. (2) The flexible device according to claim 1, wherein a first portion of the plurality of conductors is disposed on the first surface of the substrate, and a second portion of the conductor is disposed on the second surface of the substrate.・
cable assembly. (3) the first portions of the plurality of conductors are covered by a top layer of the insulating substrate, the second portions of the plurality of conductors are covered by a bottom layer of the insulating substrate, and the top layer and said bottom layer is attached by adhesive means.
A flexible cable assembly according to claim 2. (4) The flexible cable assembly of claim 1, wherein said flexible insulating substrate is made of condensed polyimide. 5. The flexible cable assembly of claim 1, wherein said circuit device comprises a leadless chip carrier. (6) A flexible cable having a plurality of strip conductors arranged in one or more layers is provided, a flexible insulating means is attached to each side of the plurality of conductor layers, and the flexible cable has a plurality of strip conductors arranged in one or more layers. a group of solder pads arranged on a portion of a first surface of one end region, a portion of the solder pads being coupled to the first portion of the strip conductor; a second uninsulated portion of the strip conductor on a second side of the two ends is conductively plated with gold, and soldering a circuit device to solder pads arranged on the first side of the flexible cable; A heat sink/a portion of the second side of the flexible cable below the flexible cable and the circuit device.
laminating a backing means and soldering terminal pin means on a first end of the flexible cable proximate the circuit device, the pin means being coupled to the strip conductor and a portion of the solder pad; A method for manufacturing a flexible cable assembly comprising steps.