Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/46—Manufacturing multilayer circuits
  • H05K3/4688—Composite multilayer circuits, i.e. comprising insulating layers having different properties
  • H05K3/4691—Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/36—Assembling printed circuits with other printed circuits
  • H05K3/361—Assembling flexible printed circuits with other printed circuits
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/04—Assemblies of printed circuits
  • H05K2201/043—Stacked PCBs with their backs attached to each other without electrical connection
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/0011—Working of insulating substrates or insulating layers
  • H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
  • H05K3/0047—Drilling of holes
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
  • H05K3/4038—Through-connections; Vertical interconnect access [VIA] connections
  • H05K3/4053—Through-connections; Vertical interconnect access [VIA] connections by thick-film techniques
  • H05K3/4069—Through-connections; Vertical interconnect access [VIA] connections by thick-film techniques for via connections in organic insulating substrates
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
  • H05K3/42—Plated through-holes or plated via connections
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
  • H05K3/42—Plated through-holes or plated via connections
  • H05K3/429—Plated through-holes specially for multilayer circuits, e.g. having connections to inner circuit layers

Definitions

• the present invention relates to the field of printed circuits.
• the present invention relates more particularly to the connection between two printed circuits to form a hybrid printed circuit flex-rigid type.
• the two connected circuits are one rigid type and the other flexible or flexible type.
• Said flexible circuit consists of an electrically conductive layer deposited on a flexible insulating material such as polyethylene terephthalate (PET).
• PET polyethylene terephthalate
• the flexible circuit is then bonded by means of a heat-reactive insulating adhesive containing electrically conductive particles.
• Another flexible insulating layer is deposited, by screen printing, on the conductive portion of the flexible circuit.
• the prior art also discloses, by Japanese Patent Application JP 07 105 785 (Matsushita Electronic), a similar method of connecting a rigid circuit with a flexible printed circuit.
• the rigid circuit is glued to one end of a printed face of a flexible circuit.
• Said flexible circuit is constituted by the printing of a predefined circuit pattern on a synthetic resin using a conductive ink and by adding an insulating paste on the assembly except the ends, points of contact .
• a protective tab is added between the flexible circuit and the rigid circuit to prevent any circuit disconnection.
• Scientific publication XP000004823 also discloses a flex-rigid circuit produced by the standard laminating methods of the various layers of the circuit concerning both the rigid part and the flexible part; US Pat. No. 5,100,492, a flex-rigid circuit realized by standard technology in which a trimming of the rigid substrate is performed to provide a flexible area to the circuit; by patent application JP 07 170029, a flex-rigid obtained by standard technology; and European Patent Application EP 0 197 595, a method of metallizing the holes by suction using a vacuum chamber. All of these solutions do not relate to the field of the present invention in that the flex-rigid circuit obtained is not derived from the connection of a flexible printed circuit with a rigid circuit.
• a rigid printed circuit connection body consisting of conductive metal deposited in a hole through the circuits to be electrically connected. It is clear from FIGS. 2 and 3 that the method used does not implement a screen printing deposit of this conductive metal. Indeed, this metal is inserted into cavities present in the intermediate layers, which can not be achieved by a screen printing process.
• the present invention intends to present a very low cost method for connecting a rigid circuit with a flexible printed circuit (or flex).
• the bond is made for example by gluing or by adhesive attached to the rigid printed circuit.
• a conductive ink provides the electrical connection between the two circuits.
• the invention relates in its most general acceptance a method for connecting a rigid printed circuit with a flexible printed circuit, comprising a step of bonding the end of the flexible printed circuit on the end of the rigid circuit, so as to ensure the back-to-back superposition of electrical contact pads of the two circuits, a step of drilling this assembly at the level of said electric contact pads, and a step of electrically connecting said holes produced by screen printing a conductive paste.
• the two circuits are assembled by bonding the insulating surface of the end of the flexible printed circuit to the insulating surface of the end of the rigid circuit.
• said conductive ink is a polymeric ink.
• said conductive ink is a conductive adhesive.
• said gluing step implements means ensuring the superposition of the flexible circuit on the rigid circuit.
• said means ensuring the superposition of the two circuits comprise holes on the rigid circuit and corresponding holes on the flexible circuit, and positioning pins passing through the two circuits in said holes which correspond in pairs.
• said means ensuring the superposition of the two circuits implement a marking on the rigid circuit, said marking corresponding to the home position of the flexible circuit.
• said rigid circuit is a rigid printed circuit.
• said rigid printed circuit is a single-sided circuit.
• said rigid printed circuit is a double-sided circuit.
• said rigid printed circuit is a multilayer circuit.
• the invention also relates to a hybrid circuit comprising at least one rigid component and a flexible printed circuit bonded to said rigid component, the rigid component having superposed electrical contact pads with homologous contact pads provided for the flexible printed circuit, the stacking glued being pierced at said contact pads so as to "bare" the various layers and said contact pads of the flexible printed circuit being electrically connected to said contact pads of the rigid component by a conductive ink.
• the rigid component is constituted by a rigid printed circuit.
• the rigid component is constituted by a liquid crystal screen.
• the rigid component is constituted by a keyboard.
• said hybrid circuit comprises at least two rigid components connected by a flexible printed circuit.
• FIG. 1 represents a side view of a flex printed circuit board and a rigid printed circuit board
• FIG. 2 represents a side view of the bonding of a printed circuit flex with a rigid printed circuit
• FIG. 3 represents a cross section of the piercing of the circuit constituted by the bonding of a printed circuit flex with a rigid printed circuit
• FIG. 4 shows a cross section of a connection between a flex printed circuit and a rigid circuit.
• the present invention implements a method of connecting a rigid circuit with a flex printed circuit.
• the advantage of the method of the present invention is to provide a flex-rigid circuit from two independent circuits and available at low costs.
• the rigid circuit (1) may be a single-sided rigid printed circuit with or without copper, silver or carbon straps, double-sided, multilayer, rigid-flex.
• it is manufactured using base materials such as FR1, FR2, FR3, FR4, FR5 or CEM1, CEM3.
• It comprises a rigid insulating substrate (11) on which is engraved a copper track (12).
• the thickness of the substrate may vary from a few tenths of a millimeter to several millimeters and that of the copper track from a few microns to a few hundred microns.
• the substrate is 1.6 mm thick and the copper track about 35 microns.
• the end of the copper track is in the form of a chip (13) and acts as a reception area for the electrical connection between the two circuits according to the method of the present invention.
• the flex or flexible printed circuit (2) is common to what is done in the flexible printed circuit industry. It is composed of a flexible substrate (21) of a few microns to a few hundred microns thick, ideally 100 microns, on which are engraved conductive tracks (22). It may be manufactured using, for example, polyimide, polyethylene naphthalate (PEN), polyethylene terephthalate (PET) or polyester, and may be of flex or flex-rigid type.
• the copper tracks also end with pellets (23).
• the process of the present invention comprises three steps.
• an adhesive (3) or substance allowing the gluing of two circuits is deposited, by transfer, by screen printing or by spraying, indifferently on one end of the substrate face of the flexible circuit. corresponding to the pellets (23) or on the end of the rigid circuit, on the back of the location of the pellets (13).
• the adhesive substance (3) used is not electrically conductive.
• an epoxy glue can be used.
• the pellets (13) and (23) correspond to the zones of each of the circuits through which the electrical connection of the different conductive layers of the circuits will be achieved.
• the end of the flexible circuit is then positioned on the rigid circuit so that the pellets of said flexible circuit superimpose those of the rigid circuit, the two circuits being placed back-to-back without direct contact of the pellets.
• the positioning of the flexible printed circuit on the rigid circuit can be realized manually by the presence of holes on said rigid circuit and corresponding holes on said flexible circuit and by the use of ancillary tools.
• This auxiliary tooling has positioning pins. These are positioned so as to successively cross the rigid circuit by a given hole and the flexible circuit through the hole corresponding to the through hole of the rigid circuit (or vice versa), so as to make the two circuits coincide and ensure the superimposition tablets.
• the positioning can be done by marking in marking on the rigid circuit of the position of the flexible circuit host. Bonding is then ensured by pressing, rolling, or simple contact and by the polymerization of the glue if the latter is polymer.
• the second step of the method of the present invention is to pierce the stack thus produced to accommodate the conductive ink to achieve the electrical connection between the circuits.
• the circuits are back-to-back, insulating layer against insulating layer, with an insulating adhesive layer between the two circuits, therefore without electrical connection.
• a drilling (4) of the hybrid circuit obtained by gluing the flexible printed circuit on a rigid circuit as described in the previous step.
• This piercing (4) is made at the level of the pellets (13) and (23).
• An order of magnitude of the diameter of the bore (4) is 0.55 mm.
• One way to accomplish this task is to drill the hybrid circuit by tools commonly used in the printed circuit industry (drill, laser, punching).
• the hybrid circuit thus obtained now has "holes” (4) at the pellets superimposed during the bonding of the two circuits. These holes “expose” the different layers of each of the two circuits.
• the third step allows the electrical connection of the two circuits by metallization or conductive ink supply (5) in the holes and on the surface of the pellets, as shown in FIG. 4.
• Said pellets correspond to the conductive zones of the contact pads. circuits, in the vicinity of the drilling (4) previously performed.
• this step therefore consists in depositing a conductive ink (5) on the surface of the pellets (13) and (23) and in the "holes" (4) made during the second step of the process.
• the ink thus deposited provides the electrical connection between the pads (13) and (23) and therefore the electrical connection between the flex circuit (2) and the rigid circuit (1).
• the deposition of the conductive ink (5) is produced by screen printing.
• the conductive ink (5) is deposited by suction.
• the conductive ink (5) used is preferably of the polymer type. It can be, for example, based on silver, copper or carbon. Alternatively, a conductive adhesive is used as an ink.
• connection is made by metallization of the bore (4).
• a conductive material for example copper, is deposited in the bore (4) and on the pellets (13) and (23) providing the electrical connection between the two circuits (1) and (2).
• the unconnected flexible end of the hybrid circuit obtained by the method of the present invention may be interchangeably coupled with a connector to a liquid crystal display or to a keyboard, or with any other type of rigid circuit.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Production Of Multi-Layered Print Wiring Board (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34944898

Family Applications (1)

Country Status (3)

Families Citing this family (9)

Family Cites Families (9)

• 2004
  • 2004-06-02 FR FR0451084A patent/FR2871336B1/fr not_active Expired - Fee Related
• 2005
  • 2005-06-02 WO PCT/FR2005/001357 patent/WO2006000694A1/fr active Application Filing
  • 2005-06-02 EP EP05775280A patent/EP1803338A1/de not_active Withdrawn

Non-Patent Citations (1)

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