WO1995015073A1 - A method and device for removing a surface mounted component from a circuit board - Google Patents

A method and device for removing a surface mounted component from a circuit board Download PDF

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Publication number
WO1995015073A1
WO1995015073A1 PCT/SE1994/001124 SE9401124W WO9515073A1 WO 1995015073 A1 WO1995015073 A1 WO 1995015073A1 SE 9401124 W SE9401124 W SE 9401124W WO 9515073 A1 WO9515073 A1 WO 9515073A1
Authority
WO
WIPO (PCT)
Prior art keywords
component
circuit board
adhesive joint
surface mounted
components
Prior art date
Application number
PCT/SE1994/001124
Other languages
French (fr)
Inventor
Bo Wikström
Original Assignee
Xicon Ab
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 Xicon Ab filed Critical Xicon Ab
Priority to EP95902374A priority Critical patent/EP0764394A1/en
Publication of WO1995015073A1 publication Critical patent/WO1995015073A1/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
    • H05K13/00—Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
    • H05K13/04—Mounting of components, e.g. of leadless components
    • H05K13/0486—Replacement and removal of components

Definitions

  • the present invention relates to a method and a device for removing a surface mounted component from a circuit board.
  • the removal is performed in a conventional way in that the solder joint is melted, so that the component is loosened.
  • circuit board is made dirty and/or is damaged. It is also a clear risk that neighbouring components are damaged at such physical working.
  • An object of the present invention is accordingly to bring about a method and a device for removing surface mounted components, the above described risks and drawbacks being avoided.
  • the removal shall further be performed quickly and inexpensively.
  • Different types of passive components as well as semiconductor components and non-enclosed chips are defined as surface mounted components.
  • This object is obtained in that the component and the adhesive joint are subjected to a thermal shock by being cooled down and in that the adhesive joint is imparted with internal mechanical stresses by the thermal shock, so that the component is loosened.
  • the drawing shows a circuit board 10, on which a first component 11 and a second component 12 have been surface mounted by means of an adhesive joint on the circuit board.
  • the circuit board is made of plastic and is provided with circuitry 13 and connection pads 14 of metal.
  • the device shown in the drawing comprises a tube 15, which is vertically movable in relation to the circuit board 10.
  • the dimensions of the tube 15 are such that areas with other components on the circuit board except the area around a certain component 11 are shielded, when a first end of the tube is placed over the component .
  • Other components are shielded on one hand so that material added to the compo- nent 11 is prevented from reaching other components and on the other hand so that heat transmission from the other components to the area shielded by the tube 15 is obstructed.
  • the tube 15 is in its other end connected with a con- tainer 16 for liquid gas, preferably nitrogen.
  • the container has an outlet, which in the shown embodiment consists of a nozzle 17, through which the gas can be admitted to the area shielded by the tube 15.
  • the amount of gas admitted through the nozzle 17 is limited by a valve 18, which is operatively connected with a control unit 19.
  • the container 16 and the tube 15 are movable together in relation to the circuit board 10, so that the tube can shield the desired component on the circuit board.
  • the relative movement between the circuit board and the tube is controlled by the control unit 19 in a conventional way, not further described.
  • the tube 15 is connected to the container 16 by means of a pipe, so that the container does not need to be movable.
  • the nozzle 17 and other elements of the invention may be carried out in many different ways within the limits of the invention.
  • the shield can be brought about by means of a heat buffer or the like, for example by means of guided air streams. Other types of heat conduction may also solve the problem with the shielding or the isolation of the component which shall be removed.
  • the method according to the invention is especially suitable at the removal of non-enclosed semiconductor components, chips and the like but is also suitable for other surface mounted components.
  • the thermal expansivity of the circuit board the adhesive and the component shall be different, so that shear forces appear between them.
  • the material in the circuit board can be plastic, but also ceramic and other materials may be used.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Electric Connection Of Electric Components To Printed Circuits (AREA)
  • Cooling Or The Like Of Electrical Apparatus (AREA)

Abstract

A method and a device for removing a surface mounted component (11) from a circuit board (10), the component being attached by means of an adhesive joint. According to the method the component and the adhesive joint are subjected to a thermal shock by being cooled down and are imparted with such internal mechanical stresses that the component is loosened. The device comprises means (16, 17, 18) for supplying cooling medium to the component (11), shielding means (15) for shielding the component (11) from other components (12) and control means (19) for controlling the supply of the cooling medium and for positioning the shielding means (15) in relation to the component (11).

Description

A METHOD AND DEVICE FOR REMOVING A SURFACE MOUNTED
COMPONENT FROM A CIRCUIT BOARD Technical Field
In the electronic industry it has recently become common to surface mount circuit components on circuit boards.
Components which have been surface mounted on circuit boards and which have been found to be defective have to be removed from the circuit board and be replaced by functioning components.
The present invention relates to a method and a device for removing a surface mounted component from a circuit board.
Technical Background
When the attachment between the component and the circuit board is performed in the conventional way by means of soldering, the removal is performed in a conventional way in that the solder joint is melted, so that the component is loosened.
It has become increasingly common to surface mount by means of electrically conducting or non-conducting adhesives, which often are epoxy based, so that the component is attached to the circuit board by means of an adhesive joint. As the most commonly used adhesives have different properties than solder material in relevant respects, the removal thus has to be performed in another way. The adhesive joint can normally not be loosened in a way which corresponds to melting of the solder joint.
Methods are given according to which the component is sheared loose by physical influence or is worked by means of impulse hammers or similar tools. It is also possible to use a rotationally oscillating tool for weakening the adhesive joint, so that the component is loosened. These methods are usually supplemented by local heating of the circuit board for impairing the mechanical properties of the adhesive.
The techniques described above for removing components from circuit boards have several deficiencies. There is for example a great risk that the circuit board is made dirty and/or is damaged. It is also a clear risk that neighbouring components are damaged at such physical working.
Short Summary of the Invention
An object of the present invention is accordingly to bring about a method and a device for removing surface mounted components, the above described risks and drawbacks being avoided. The removal shall further be performed quickly and inexpensively. Different types of passive components as well as semiconductor components and non-enclosed chips are defined as surface mounted components.
This object is obtained in that the component and the adhesive joint are subjected to a thermal shock by being cooled down and in that the adhesive joint is imparted with internal mechanical stresses by the thermal shock, so that the component is loosened.
The Drawing
The invention will now be described by means of embodiments under reference to the attached drawing being a schematic perspective view of a device for carrying out the method according to the invention.
Detailed Description
The drawing shows a circuit board 10, on which a first component 11 and a second component 12 have been surface mounted by means of an adhesive joint on the circuit board. The circuit board is made of plastic and is provided with circuitry 13 and connection pads 14 of metal. The device shown in the drawing comprises a tube 15, which is vertically movable in relation to the circuit board 10. The dimensions of the tube 15 are such that areas with other components on the circuit board except the area around a certain component 11 are shielded, when a first end of the tube is placed over the component . Other components are shielded on one hand so that material added to the compo- nent 11 is prevented from reaching other components and on the other hand so that heat transmission from the other components to the area shielded by the tube 15 is obstructed.
The tube 15 is in its other end connected with a con- tainer 16 for liquid gas, preferably nitrogen. The container has an outlet, which in the shown embodiment consists of a nozzle 17, through which the gas can be admitted to the area shielded by the tube 15. The amount of gas admitted through the nozzle 17 is limited by a valve 18, which is operatively connected with a control unit 19. When the component is exposed to a certain volume liquid gas, the component and the adhesive joint is subjected to a thermal shock. The great temperature differences appearing between the circuit board and the component create great local me- chanical stresses, above all in the adhesive joint. The stresses become so great that the adhesive joint breaks and the component is made loose. Experiments show that the adhesive joint usually breaks in a layer between the component and the circuit board, so that adhesive layers remain on the lower side of the component as well as on the upper side of the circuit board.
The container 16 and the tube 15 are movable together in relation to the circuit board 10, so that the tube can shield the desired component on the circuit board. The relative movement between the circuit board and the tube is controlled by the control unit 19 in a conventional way, not further described.
In other embodiments the tube 15 is connected to the container 16 by means of a pipe, so that the container does not need to be movable. Depending on actual application and form and dimensions of the circuit board and the components the tube 15, the nozzle 17 and other elements of the invention may be carried out in many different ways within the limits of the invention. Instead of by means of a tube 15, the shield can be brought about by means of a heat buffer or the like, for example by means of guided air streams. Other types of heat conduction may also solve the problem with the shielding or the isolation of the component which shall be removed.
The method according to the invention is especially suitable at the removal of non-enclosed semiconductor components, chips and the like but is also suitable for other surface mounted components. For obtaining the best possible effect the thermal expansivity of the circuit board, the adhesive and the component shall be different, so that shear forces appear between them. The material in the circuit board can be plastic, but also ceramic and other materials may be used.
Most presently used adhesives, which are used in this application, get impaired strength at cooling down and the adhesive joint becomes brittle, which leads to the positive effect that a thermal shock by means of for example liquid gas gives a double effect and an especially good result.

Claims

1. A method for removing a surface mounted component from a circuit board, the component being attached by means of an adhesive joint, c h a r a c t e r i z e d in that the component and the adhesive joint are subjected to a thermal shock by being cooled down and in that the adhesive joint is imparted with internal mechanical stresses by the thermal shock, so that the component is loosened.
2. A method according to claim 1, c h a r a c t e ri z e d in that the component is exposed to a
predetermined amount of a cooling medium for bringing about the thermal shock.
3. A method according to claim 2, c h a r a c t e ri z e d in that the component is exposed to a
predetermined amount of liquid gas.
4. A method according to claim 3, c h a r a c t e ri z e d in that the component is exposed to a
predetermined amount of liquid nitrogen gas.
5. A method according to any of claims 2 - 4,
c h a r a c t e r i z e d in that the component is
shielded in relation to other components, before it is exposed to the material for bringing about the thermal shock.
6. A device for removing a surface mounted component (11) from a circuit board (10), the component being
attached by means of an adhesive joint, c h a r a c t e ri z e d by means (16, 17, 18) for supplying cooling medium to the component (11) and by control means (19) for controlling the supply of cooling medium.
7. A device according to claim 6, c h a r a c t e ri z e d by shielding means (15) for shielding the
component (11) from other components (12) and in that the control means (19) is intended for positioning of the shielding means (15) in relation to the component (11).
PCT/SE1994/001124 1993-11-25 1994-11-24 A method and device for removing a surface mounted component from a circuit board WO1995015073A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95902374A EP0764394A1 (en) 1993-11-25 1994-11-24 A method and device for removing a surface mounted component from a circuit board

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9303909-7 1993-11-25
SE9303909A SE502007C2 (en) 1993-11-25 1993-11-25 Method and Device for Removing a Surface Mounted Component Attached to a Circuit Board

Publications (1)

Publication Number Publication Date
WO1995015073A1 true WO1995015073A1 (en) 1995-06-01

Family

ID=20391880

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1994/001124 WO1995015073A1 (en) 1993-11-25 1994-11-24 A method and device for removing a surface mounted component from a circuit board

Country Status (3)

Country Link
EP (1) EP0764394A1 (en)
SE (1) SE502007C2 (en)
WO (1) WO1995015073A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6875774B2 (en) * 2002-08-06 2005-04-05 The University Of North Carolina Aza-bridged bicyclic amine derivatives for use as novel cholinergic receptor ligands

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0305696A2 (en) * 1987-08-31 1989-03-08 Siemens Aktiengesellschaft Process for desoldering glued SMD components

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0305696A2 (en) * 1987-08-31 1989-03-08 Siemens Aktiengesellschaft Process for desoldering glued SMD components

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
ADVANCING SURFACE MOUNT TECHNOLOGY, 1988, B.P. RICHARDS, "The Sensitivity of Surface Mount Technology to Component Quality", pages 143-154. *
ELEKTRONIKTIDNINGEN, Nr. 16, 14-10-93, p. 19-20, (Sweden), PER HENRICSSON, "Snart aer Problemen Med Limmade Lomponenter Loesta". *
ELTEKNIK MED AKTUELL ELEKTRONIK, Nr. 4, (25-02-88), p. 25 and 27 (SWEDEN), KERSTIN LJUNGGREN, "Limma Istaellet foer att loeda". *
IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 31, No. 1, June 1988, "Extractor for Glued Small Surface-Mounted Components", pages 258-259. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6875774B2 (en) * 2002-08-06 2005-04-05 The University Of North Carolina Aza-bridged bicyclic amine derivatives for use as novel cholinergic receptor ligands

Also Published As

Publication number Publication date
SE9303909D0 (en) 1993-11-25
SE502007C2 (en) 1995-07-10
SE9303909L (en) 1995-05-26
EP0764394A1 (en) 1997-03-26

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