GB2222310A - Excimer laser trimming of resistor - Google Patents

Excimer laser trimming of resistor Download PDF

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Publication number
GB2222310A
GB2222310A GB8818744A GB8818744A GB2222310A GB 2222310 A GB2222310 A GB 2222310A GB 8818744 A GB8818744 A GB 8818744A GB 8818744 A GB8818744 A GB 8818744A GB 2222310 A GB2222310 A GB 2222310A
Authority
GB
United Kingdom
Prior art keywords
thick film
polymer thick
resistance element
excimer laser
resistance
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
GB8818744A
Other versions
GB8818744D0 (en
GB2222310B (en
Inventor
Peter Linley Kirby
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Crystalate Electronics Ltd
Original Assignee
Crystalate Electronics Ltd
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 Crystalate Electronics Ltd filed Critical Crystalate Electronics Ltd
Priority to GB8818744A priority Critical patent/GB2222310B/en
Publication of GB8818744D0 publication Critical patent/GB8818744D0/en
Publication of GB2222310A publication Critical patent/GB2222310A/en
Application granted granted Critical
Publication of GB2222310B publication Critical patent/GB2222310B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/003—Thick film resistors
    • H01C7/005—Polymer thick films
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
    • H01C17/22—Apparatus or processes specially adapted for manufacturing resistors adapted for trimming
    • H01C17/24—Apparatus or processes specially adapted for manufacturing resistors adapted for trimming by removing or adding resistive material
    • H01C17/242—Apparatus or processes specially adapted for manufacturing resistors adapted for trimming by removing or adding resistive material by laser

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnetism (AREA)
  • Apparatuses And Processes For Manufacturing Resistors (AREA)
  • Parts Printed On Printed Circuit Boards (AREA)

Abstract

The electrical resistance value of a polymer thick film resistance element on an electrically insulating substrate is adjusted to a desired value, measured between conductive terminations, by removing polymer thick material of the resistance element using an excimer laser. Alternatively, one or more polymer thick film electrical conductors is or are provided on the substrate and arranged to shunt portions of the resistance element. The excimer laser is then used to selectively cut through the one or more polymer thick film conductors to provide step-wise adjustment of the resistance value, measured between the terminations. The process is advantageous in that, unlike other lasers, the excimer laser does not cause charring of the organic polymer material.

Description

SPECIFICATION TITLE : ELECTRICAL RESISTOR ADJUSTMENT PROCESS This invention relates to polymer thick film electrical resistance elements deposited on electrically insulating substrates and provided with electrically conductive terminations. More particularly, the invention provides a method of adjusting, to a predetermined value, the electrical resistance of a polymer thick film resistance element measured between the conductive terminations.
The invention is applicable to fixed and variable resistors incorporating polymer thick film resistance elements.
Polymer thick film electrical resistance elements are well known and comprise an organic polymer material having dispersed therein particles of electrically conductive material, usually carbon. Polymer thick film electrical conductors are also known and which may be used as terminations for the resistance elements. Such conductors also comprise organic polymer materials having dispersed therein particles of electrically conductive material, but in this case the conductive material has a higher electrical conductivity and suitably comprises silver or copper. The resistance elements and conductors are usually provided on insulating substrates by means of screen printing techniques.
As with other forms of film resistance elements, it is not usually possible to deposit polymer thick film resistance elements in such a way that precisely a required resistance value is achieved, measured between conductive terminations. With other forms of film resistance elements it has become common practice to use solid state lasers (eg YAG lasers) or carbon dioxide or xenon gas lasers for adjusting the electrical resistance to a desired value, such lasers operating to vapourise material of the resistance element in the form of one or more narrow cuts. However, such lasers have been found to be unsuitable for use with polymer thick film resistance elements since they result in undesirable charring of the organic polymer materials which are employed in such elements.
We have now found that it is possible to overcome this problem by a process in which an excimer laser is used to adjust, to a desired value, the resistance of a polymer thick film resistor. By means of an excimer laser, polymer thick film resistive or conductive material can be removed in controlled manner without any residual charring of organic polymer material, removal of material being by a process known as ablation.
The e excimer laser can be used in two methods of adjustment. In a first method an excimer laser is used to remove polymer thick film resistance material from a polymer thick film resistance element provided on an electrically insulating substrate, until a desired resistance value is obtained measured between conductive terminations provided in electrical contact with the element on the substrate.
In a second method, a polymer thick film resistance element is provided on an electrically insulating substrate and one or more polymer thick film electrical conductors is or are provided on the substrate and adapted and arranged to shunt (ie short-circuit) portions of the resistance element. An excimer laser is used to selectively cut through the one or more polymer thick film conductors whereby the resistance value, measured between conductive terminations provided on the substrate in electrical contact with the resistance element, is adjusted in step-wise manner until a desired value is obtained.

Claims (5)

1A process for adjusting, to a desired value, electrical resistance of a polymer thick film resistance element provided on an electrically insulating substrate, said process comprising: removing, by means of an excimer laser, polymer thick film resistance material of said resistance element or polymer thick film conductor material associated with said element.
2 A process according to Claim 1 in which electrically conductive terminations are provided in contact with the resistance element and material of the resistance element is removed by means of the excimer laser until a desired electrical resistance value is achieved, measured between the conductive terminations.
3 A process according to Claim 1 in which one or more polymer thick film electrical conductors is or are provided on the substrate and arranged to shunt one or more portions of the resistance element, the excimer laser being used to selectively cut through the one or more polymer thick film conductors whereby the resistance value, measured between electrically conductive terminations provided in contact with the resistance element, is adjusted in step-wise manner until a desired value is achieved.
4 A process for adjusting electrical resistance of a polymer thick film resistance element substantially as hereinbefore described.
5 A polymer thick film resistance element whenever adjusted by the process of any preceding Claim.
GB8818744A 1988-08-06 1988-08-06 Electrical resistor adjustment process Expired - Lifetime GB2222310B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8818744A GB2222310B (en) 1988-08-06 1988-08-06 Electrical resistor adjustment process

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8818744A GB2222310B (en) 1988-08-06 1988-08-06 Electrical resistor adjustment process

Publications (3)

Publication Number Publication Date
GB8818744D0 GB8818744D0 (en) 1988-09-07
GB2222310A true GB2222310A (en) 1990-02-28
GB2222310B GB2222310B (en) 1990-12-05

Family

ID=10641741

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8818744A Expired - Lifetime GB2222310B (en) 1988-08-06 1988-08-06 Electrical resistor adjustment process

Country Status (1)

Country Link
GB (1) GB2222310B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998013836A1 (en) * 1996-09-28 1998-04-02 Dynamit Nobel Gmbh Explosivstoff- Und Systemtechnik Method for balancing layer resistors using an excimer laser radiation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998013836A1 (en) * 1996-09-28 1998-04-02 Dynamit Nobel Gmbh Explosivstoff- Und Systemtechnik Method for balancing layer resistors using an excimer laser radiation
DE19640127A1 (en) * 1996-09-28 1998-04-02 Dynamit Nobel Ag Method for matching sheet resistances with excimer laser radiation

Also Published As

Publication number Publication date
GB8818744D0 (en) 1988-09-07
GB2222310B (en) 1990-12-05

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930806