GB2308185A - Inspecting component solder joints and leads inserted in printed circuit boards - Google Patents
Inspecting component solder joints and leads inserted in printed circuit boards Download PDFInfo
- Publication number
- GB2308185A GB2308185A GB9525466A GB9525466A GB2308185A GB 2308185 A GB2308185 A GB 2308185A GB 9525466 A GB9525466 A GB 9525466A GB 9525466 A GB9525466 A GB 9525466A GB 2308185 A GB2308185 A GB 2308185A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit board
- printed circuit
- rear side
- image
- components
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/28—Testing of electronic circuits, e.g. by signal tracer
- G01R31/302—Contactless testing
- G01R31/308—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation
- G01R31/309—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation of printed or hybrid circuits or circuit 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
- H05K13/00—Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
- H05K13/08—Monitoring manufacture of assemblages
- H05K13/081—Integration of optical monitoring devices in assembly lines; Processes using optical monitoring devices specially adapted for controlling devices or machines in assembly lines
- H05K13/0815—Controlling of component placement on the substrate during or after manufacturing
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Operations Research (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Health & Medical Sciences (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Electromagnetism (AREA)
- Toxicology (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
Description
Printed circuit board inspection
The present invention relates to the inspection of printed circuit boards, to check whether components have been correctly assembled to the boards.
Commonly components are assembled automatically to printed circuit boards, the pins or wire leads of the components being inserted through respective holes in the circuit boards, then bent over or clinched onto the opposite side of the board and soldered to conductor tracks on that side of the board. The circuit boards then have to be inspected, to make sure that each board has had all its required components assembled correctly to it: this inspection process must at present be carried out manually.
We have now devised a method of and apparatus for carrying out an automatic inspection of a circuit board once its components have been assembled to it.
In accordance with the present invention, there is provided a method of inspecting a printed circuit board after components have been assembled to the board, the method comprising directing a video camera at the rear side of the printed circuit board, illuminating the rear side of the printed circuit board at an inclined angle so that significantly more light is reflected into the camera from bent-over leads of the components and soldered joints than from the printed circuit board itself, capturing an image of the rear side of the circuit board, and analysing said image.
Preferably the captured image is compared with a previously-captured image of a complete circuit board.
Accordingly, the positions of the correctly bent-over or clinched component leads can be checked, and a count of these can also be made. Additionally or instead, surface mount components and/or solder joints can be checked for one or more of position, shape, size, texture, and component count.
Also in accordance with the present invention, there is provided an apparatus for inspecting a printed circuit board after components have been assembled to the board, the apparatus comprising a station to receive successive printed circuit boards, a video camera arranged to view the rear side of each circuit board, a light source for illuminating the rear side of each circuit board at an inclined angle, and means for controlling the video camera to capture an image of the rear side of the circuit board and for analysing that image.
The method and apparatus of this invention can be used to inspect printed circuit boards which mix axial and/or radial components with surface mount components: in such cases the axial and/or radial components are mounted to the front side of the board and the surface mount components are glued to the rear side of the board, after which the board is presented for soldering. Different solder joints will be of different sizes, shapes and orientation and can be checked in the method of the present invention. The surface mount components can also be distinguished, in the captured image, from the board itself and the shape, position and size of these components can therefore be checked.
An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawing, the single Figure of which is a schematic side view of an apparatus in accordance with the invention.
Referring to the drawing, each printed circuit board 10 is advanced to a predetermined position relative to a video camera 20, the video camera being directed at the rear side of the circuit board 10 (i.e. the side opposite that on which the components are mounted). The rear side of the circuit board 10 is illuminated by a light beam B directed at the circuit board 10 at a relatively low angle e.g. up to about 50: preferably the light beam is provided by a ring-shaped fluorescent light 22 positioned in a plan parallel to but spaced from the circuit board 10. For example the light 22 may be of 14 inches diameter and positioned 1 inch above the plane of the circuit board 10.
The circuit board 10 does not itself reflect much light towards the camera. However, light is reflected well from the wire leads or terminals e.g. 12 which have been bent onto the rear side of the board 10, and also from the soldered joints.
Wire leads e.g. 14 which have not been correctly bent over do not reflect much light towards the video camera 20.
The video camera 20 is arranged to capture an image of each printed circuit board 10, and the captured image is then analysed by a microprocessor (for example a PC). The analysis of the captured image identifies the positions and angular orientation of the wires which have been bent flat against the board, as detected by the corresponding reflections, and compares this pattern with a pattern previously read into memory from a "good" circuit board. The analysis also identifies the positions of solder joints and also (from a variation in brightness) their sizes, and compares these also with the stored pattern of the "good" circuit board.
It will be appreciated that the above-described method and apparatus enables each printed circuit board to be inspected automatically and checked that the appropriate number of components have been assembled to the board, that all of the wire leads have been bent over correctly, and that all of the soldered joints have been correctly made. This saves the work involved in manually inspecting circuit boards.
Claims (10)
1) A method of inspecting a printed circuit board after components have been assembled to the board, the method comprising directing a video camera at the rear side of the printed circuit board, illuminating the rear side of the printed circuit board at an inclined angle so that significantly more light is reflected into the camera from bent-over leads of the components and soldered joints than from the printed circuit board itself, capturing an image of the rear side of the circuit board, and analysing said image.
2) A method as claims in claim 1, in which the captured image is compared with a previously-captured image of a complete circuit board.
3) A method as claimed in claims 1 or 2, comprising checking the positions of the bent-over component leads and soldered joints.
4) A method as claimed in any preceding claim, comprising counting the number of bent-over component leads and soldered joints.
5) A method as claimed in any preceding claim, comprising checking the shape of the bent-over component leads and soldered joints.
6) A method of inspecting a printed circuit board, the method being substantially as herein described with reference to the accompanying drawing.
7) An apparatus for inspecting a printed circuit board after components have been assembled to the board, the apparatus comprising a station to receive successive printed circuit boards, a video camera arranged to view the rear side of each circuit board, a light source for illuminating the rear side of each circuit board at an inclined angle, and means for controlling the video camera to capture an image of the rear side of the circuit board and for analysing that image.
8) An apparatus as claimed in claim 7, in which the analysing means is arranged to compare the image with a previously-captured image of a complete circuit board.
9) An apparatus as claimed in claims 7 or 8, in which the light source is ring-shaped.
10) An apparatus substantially as herein described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9525466A GB2308185A (en) | 1995-12-13 | 1995-12-13 | Inspecting component solder joints and leads inserted in printed circuit boards |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9525466A GB2308185A (en) | 1995-12-13 | 1995-12-13 | Inspecting component solder joints and leads inserted in printed circuit boards |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9525466D0 GB9525466D0 (en) | 1996-02-14 |
| GB2308185A true GB2308185A (en) | 1997-06-18 |
Family
ID=10785354
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9525466A Withdrawn GB2308185A (en) | 1995-12-13 | 1995-12-13 | Inspecting component solder joints and leads inserted in printed circuit boards |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2308185A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0228963A2 (en) * | 1985-12-27 | 1987-07-15 | AT&T Corp. | Linescan inspection system for circuit boards |
| US4728195A (en) * | 1986-03-19 | 1988-03-01 | Cognex Corporation | Method for imaging printed circuit board component leads |
| EP0435326A2 (en) * | 1989-12-29 | 1991-07-03 | Omron Corporation | Circuit board inspection device |
-
1995
- 1995-12-13 GB GB9525466A patent/GB2308185A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0228963A2 (en) * | 1985-12-27 | 1987-07-15 | AT&T Corp. | Linescan inspection system for circuit boards |
| US4728195A (en) * | 1986-03-19 | 1988-03-01 | Cognex Corporation | Method for imaging printed circuit board component leads |
| EP0435326A2 (en) * | 1989-12-29 | 1991-07-03 | Omron Corporation | Circuit board inspection device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9525466D0 (en) | 1996-02-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |