WO1997034451A1 - System for realising connection jumpers between the tracks of double-sided printed circuit boards - Google Patents

System for realising connection jumpers between the tracks of double-sided printed circuit boards Download PDF

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Publication number
WO1997034451A1
WO1997034451A1 PCT/IT1997/000049 IT9700049W WO9734451A1 WO 1997034451 A1 WO1997034451 A1 WO 1997034451A1 IT 9700049 W IT9700049 W IT 9700049W WO 9734451 A1 WO9734451 A1 WO 9734451A1
Authority
WO
WIPO (PCT)
Prior art keywords
hole
tracks
double
holes
realising
Prior art date
Application number
PCT/IT1997/000049
Other languages
French (fr)
Inventor
Pierluigi Volpi
Original Assignee
So.Ma.Ci.S. - S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by So.Ma.Ci.S. - S.P.A. filed Critical So.Ma.Ci.S. - S.P.A.
Priority to AU19388/97A priority Critical patent/AU1938897A/en
Publication of WO1997034451A1 publication Critical patent/WO1997034451A1/en

Links

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
    • H05K3/40—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
    • H05K3/4038—Through-connections; Vertical interconnect access [VIA] connections
    • H05K3/4053—Through-connections; Vertical interconnect access [VIA] connections by thick-film techniques
    • 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
    • H05K2201/09—Shape and layout
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/09981—Metallised walls
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/01—Tools for processing; Objects used during processing
    • H05K2203/0195—Tool for a process not provided for in H05K3/00, e.g. tool for handling objects using suction, for deforming objects, for applying local pressure
    • 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
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/14—Related to the order of processing steps
    • H05K2203/1453—Applying the circuit pattern before another process, e.g. before filling of vias with conductive paste, before making printed resistors
    • 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
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1216—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by screen printing or stencil printing

Definitions

  • PCB's known as "double-sided" PCB's, namely those consisting of a laminated board plated with copper on both sides and having the tracks of the circuit printed on both sides.
  • This type of PCB generally raises the problem of making the electrical connection between the tracks printed on the two opposing sides of the laminated board.
  • This problem is currently resolved by making numerous through holes on the opposing tracks between which the electric connection jumper is to be made; these holes - known technically as "through holes" - are then filled with conductive polymer lacquer such as copper or silver paste, whose purpose is to ensure the electric connection between the two tracks with the entry and exit of each hole.
  • conductive polymer lacquer such as copper or silver paste
  • the simplest and less expensive of the filling techniques used today consists of a silk screen printing operation during which a drop of conductive lacquer is placed in each hole; the first problem of this technique is that it involves two printing stages, one for each side of the circuit in order to ensure that a sufficient amount of lacquer is placed in each hole to fill it completely so as to guarantee the connection between the two mouths of each hole.
  • the considerable quantity of lacquer that with this first filling technique tends to accumulate in each hole for the reason explained above, often creates problems during the subsequent welding stage during which the electronic components are fixed onto the PCB.
  • the circuit is in fact subject to high temperatures which may cause a phenomenon known as "blowhole"; this is a phenomenon whereby the conductive lacquer in the hole cracks due to bursting of small drops of solvent which do not evaporate during the silk screen printing process because of the excessive accumulation of paste and thus remain trapped in the paste.
  • the purpose of this invention is to design a new system for filling the "through holes " of double-sided PCB's without any of the above problems and which is simple and economical to realise and does not require the use of special and expensive plants and tooling.
  • the system according to the invention is based on the idea of pushing and spreading in the hole a small amount of conductive lacquer using a suitable punch which not only pushes the lacquer deep into the hole but also spreads it on the inner side wall of the hole which is in this way coated by a layer of conductive lacquer having a thickness equal to the distance between the external wall of the punch and the internal wall of the hole.
  • the filling system involves the following operating stages: - silk screen printing of one of the two sides of the PCB in order to deposit a small amount of conductive lacquer on all the "through holes”; - insertion into all the "through holes” of the same number of corresponding punches which push and spread in each hole the lacquer deposited on the mouth of each hole during the previous printing stage - extraction of the punches from the corresponding "through holes”.
  • - figs. 1 - 4 are a schematic view of one of the "through holes" of the circuit as the PCB is subjected to the filling system according to the invention.
  • fig. 1 shows a section (1) of a double-sided PCB cross-sectioned over one of its "through holes" (2) into which the conductive lacquer for the connection of the two opposing tracks (P) crossed by holes (2), has not yet been inserted.
  • the filling system includes the following operating stages: a) silk screen printing of one (1 a) of the two sides of the PCB (1) in order to deposit a small amount of conductive lacquer (3) on the mouth of all the "through holes” (2), as shown in fig. 2; b) insertion into each "through hole” (2) of a corresponding punch (4) which pushes and spreads the conductive lacquer (3) deposited on the mouth of each hole (2), into the hole (2), as shown in fig. 3; c) extraction of the punches (4) from the corresponding "through holes” (2) as shown in fig. 4.
  • the inner side wall (2a) of the holes (2) is completely coated by a layer of conductive lacquer (3) having a thickness equal to the difference between the outer wall of the punch (4) and the inner wall of the hole
  • the first silk screen printing stage as described in point a), is performed with conventional operating modalities and times.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Dc Digital Transmission (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Printing Elements For Providing Electric Connections Between Printed Circuits (AREA)

Abstract

This invention concerns a system for realising connection jumpers between the tracks (P) of double-sided printed circuit boards (1), consisting in depositing a small amount of conductive lacquer (3) on the mouth of all the 'through holes' (2) and inserting a corresponding punch (4) designed to push and spread the conductive lacquer (3) into the 'through hole'. (2)

Description

Description
System for Realising Connection Jumpers between the Tracks of Double-sided Printed Circuit Boards
This patent application concerns a system for realising connection jumpers between the opposing tracks of printed circuit boards (PCB's). The patent protection is also extended to the PCB obtained with the above system.
The system in question is designed to improve and economise the various techniques used to realise PCB's known as "double-sided" PCB's, namely those consisting of a laminated board plated with copper on both sides and having the tracks of the circuit printed on both sides.
This type of PCB generally raises the problem of making the electrical connection between the tracks printed on the two opposing sides of the laminated board. This problem is currently resolved by making numerous through holes on the opposing tracks between which the electric connection jumper is to be made; these holes - known technically as "through holes" - are then filled with conductive polymer lacquer such as copper or silver paste, whose purpose is to ensure the electric connection between the two tracks with the entry and exit of each hole. Two different techniques have to date been used to fill these holes with conductive lacquer, both of which give rise to a number of problems which the processing system according to the invention is designed to resolve.
The simplest and less expensive of the filling techniques used today consists of a silk screen printing operation during which a drop of conductive lacquer is placed in each hole; the first problem of this technique is that it involves two printing stages, one for each side of the circuit in order to ensure that a sufficient amount of lacquer is placed in each hole to fill it completely so as to guarantee the connection between the two mouths of each hole. The considerable quantity of lacquer that with this first filling technique tends to accumulate in each hole for the reason explained above, often creates problems during the subsequent welding stage during which the electronic components are fixed onto the PCB. During the welding operation, the circuit is in fact subject to high temperatures which may cause a phenomenon known as "blowhole"; this is a phenomenon whereby the conductive lacquer in the hole cracks due to bursting of small drops of solvent which do not evaporate during the silk screen printing process because of the excessive accumulation of paste and thus remain trapped in the paste.
In order to resolve the problems related to this first "through hole" filling technique, an alternative technique has been developed whereby the conductive lacquers are printed on only one of the two sides of the PCB, followed by an aspiration phase thanks to which lacquer which has been deposited over the mouth of each hole is drawn into and along the hole to escape on the bottom of the circuit. This second "through hole" filling technique in fact eliminates the phenomenon of "blowholes" and does not require two silk screen printing stages on the two sides of the PCB board; however it requires special and expensive plants for the aspiration stage making this technique available to very few circuit manufacturers, namely only those which can afford to purchase these plants.
The purpose of this invention is to design a new system for filling the "through holes " of double-sided PCB's without any of the above problems and which is simple and economical to realise and does not require the use of special and expensive plants and tooling.
The system according to the invention is based on the idea of pushing and spreading in the hole a small amount of conductive lacquer using a suitable punch which not only pushes the lacquer deep into the hole but also spreads it on the inner side wall of the hole which is in this way coated by a layer of conductive lacquer having a thickness equal to the distance between the external wall of the punch and the internal wall of the hole. Substantially, the filling system according to the invention involves the following operating stages: - silk screen printing of one of the two sides of the PCB in order to deposit a small amount of conductive lacquer on all the "through holes"; - insertion into all the "through holes" of the same number of corresponding punches which push and spread in each hole the lacquer deposited on the mouth of each hole during the previous printing stage - extraction of the punches from the corresponding "through holes".
For major clarity the description continues with reference to the enclosed drawings which are intended for purposes of illustration and not in a limiting sense whereby:
- figs. 1 - 4 are a schematic view of one of the "through holes" of the circuit as the PCB is subjected to the filling system according to the invention.
In particular fig. 1 shows a section (1) of a double-sided PCB cross-sectioned over one of its "through holes" (2) into which the conductive lacquer for the connection of the two opposing tracks (P) crossed by holes (2), has not yet been inserted.
The filling system according to the invention includes the following operating stages: a) silk screen printing of one (1 a) of the two sides of the PCB (1) in order to deposit a small amount of conductive lacquer (3) on the mouth of all the "through holes" (2), as shown in fig. 2; b) insertion into each "through hole" (2) of a corresponding punch (4) which pushes and spreads the conductive lacquer (3) deposited on the mouth of each hole (2), into the hole (2), as shown in fig. 3; c) extraction of the punches (4) from the corresponding "through holes" (2) as shown in fig. 4.
Following extraction of the punch (4), the inner side wall (2a) of the holes (2) is completely coated by a layer of conductive lacquer (3) having a thickness equal to the difference between the outer wall of the punch (4) and the inner wall of the hole
(2).
Finally, it should be noted that the first silk screen printing stage, as described in point a), is performed with conventional operating modalities and times.

Claims

Claims
1) A system for realising connection jumpers between the tracks of double-sided PCB's characterised in consisting of the following operating stages: a) silk screen printing of one (1a) of the two sides of the PCB (1) in order to deposit a small amount of conductive lacquer (3) on the mouth of all the "through holes" (2); b) insertion into each "through hole" (2) of a corresponding punch (4) which pushes and spreads the conductive lacquer (3) deposited on the mouth of each hole (2), into the hole (2); c) extraction of the punches (4) from the corresponding "through holes" (2).
2) A double-sided PCB characterised by the fact that the same is realised using the system described in claim 1) for the realisation of connection jumpers between the tracks printed on its sides.
PCT/IT1997/000049 1996-03-13 1997-03-06 System for realising connection jumpers between the tracks of double-sided printed circuit boards WO1997034451A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU19388/97A AU1938897A (en) 1996-03-13 1997-03-06 System for realising connection jumpers between the tracks of double-sided printed circuit boards

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMC96A000032 1996-03-13
IT96MC000032A IT1289327B1 (en) 1996-03-13 1996-03-13 SYSTEM FOR THE IMPLEMENTATION OF CONNECTION JUMPERS BETWEEN THE TRACKS OF DOUBLE-SIDED PRINTED CIRCUITS

Publications (1)

Publication Number Publication Date
WO1997034451A1 true WO1997034451A1 (en) 1997-09-18

Family

ID=11357175

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IT1997/000049 WO1997034451A1 (en) 1996-03-13 1997-03-06 System for realising connection jumpers between the tracks of double-sided printed circuit boards

Country Status (3)

Country Link
AU (1) AU1938897A (en)
IT (1) IT1289327B1 (en)
WO (1) WO1997034451A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1094447A (en) * 1965-11-19 1967-12-13 Telas A method of electrically interconnecting double-sided printed circuits
US3576669A (en) * 1968-08-15 1971-04-27 Nasa Method for coating through-holes
US4383495A (en) * 1980-06-02 1983-05-17 Western Electric Company, Inc. Apparatus for coating surfaces of a substrate
EP0194247A2 (en) * 1985-03-05 1986-09-10 Svecia Silkscreen Maskiner AB A screen printer adapted for providing a layer of material on the inner surface of a hole passing through a plate

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1094447A (en) * 1965-11-19 1967-12-13 Telas A method of electrically interconnecting double-sided printed circuits
US3576669A (en) * 1968-08-15 1971-04-27 Nasa Method for coating through-holes
US4383495A (en) * 1980-06-02 1983-05-17 Western Electric Company, Inc. Apparatus for coating surfaces of a substrate
EP0194247A2 (en) * 1985-03-05 1986-09-10 Svecia Silkscreen Maskiner AB A screen printer adapted for providing a layer of material on the inner surface of a hole passing through a plate

Also Published As

Publication number Publication date
AU1938897A (en) 1997-10-01
ITMC960032A1 (en) 1997-09-13
ITMC960032A0 (en) 1996-03-13
IT1289327B1 (en) 1998-10-02

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