TESTING FASTENINGS OF PRINTED CIRCUIT BOARD

Abstract: The invention relates to a method comprising supplying a test signal to a first pad part of the pad (200); measuring the occurrence of the test signal through a second pad part of the pad (200) or a part of the printed circuit board (100) connected to the second pad part, which second pad part is separate from the first pad part, and the leg (104) of the connector is fastened both to the first pad part and to the second pad part during the manufacturing process in order to establish a connection between the pad parts (112, 114) through the leg (104). The invention further relates to a printed circuit board (100) comprising: at least one pad (200) connectable to a test device (118); at least one connector (102) comprising at least one leg (104) fastened to the pad. The pad (200) comprises at least two separate pad parts (112, 114), i.e. a first and a second pad part, and the test device (118) is connectable to at least one pad part. The leg (104) of the connector is fastened both to the first pad part and to the second pad part in order to establish a connection between the pad parts (112, 114) through the leg (104).

Description: TESTING FASTENINGS OF PRINTED CIRCUIT BOARD FIELD OF THE INVENTION The invention relates to a method of testing the fastening of a connector to a printed circuit board. BACKGROUND OF THE INVENTION Typically, a connector is fastened to a printed circuit board by soldering the connector by its legs onto pads located on the printed circuit board. Typically, connectors are tested by inserting the counterpart of a connector into an automatic testing processor for a short period of time, which has pre- sented the problems that the fastenings of the legs of the connector to the pads on printed circuit board have come off and connectors have broken; the problems have further resulted in poor gain in the manufacturing process and large additional costs. Another way to test the connectors is a method in which test signals are supplied from a testing device to the printed circuit board by test pins. Also in this method, the fastenings of the legs of the connectors to the pads remain untested. Since it has been impossible to ensure the fastenings of the legs of the connectors to the pads of the printed circuit board in the testing, defective fastenings considerably reduce the gain of the printed circuit boards. BRIEF DESCRIPTION OF THE INVENTION An object of the invention is thus to provide a method and a printed circuit board implementing the method so as to enable the above-mentioned problems to be solved. This is achieved by the following method of testing the fastening of a connector fastened by its leg to a pad of a printed circuit board. The method comprises supplying a test signal to a first pad part of the pad; measuring the occurrence of the test signal through a second pad part of the pad or a part of the printed circuit board connected to the second pad part, which second pad part is separate from the first pad part, and the leg of the connector is fastened both to the first pad part and to the second pad part during the manufacturing process in order to establish a connection between the pad parts through the leg. The invention further relates to a method of testing the fastening of a component fastened by its leg to a pad of a printed circuit board. The method comprises supplying a test signal to a first pad part of the pad, meas- uring the occurrence of the test signal through a second pad part of the pad or a part of the printed circuit board connected to the second pad part, which second pad part is separate from the first pad part, and the leg of the component is fastened both to the first pad part and to the second pad part during the manufacturing process in order to establish a connection between the pad parts through the leg. The invention further relates to a printed circuit board comprising: at least one pad connectable to a test device; at least one connector comprising at least one leg fastened to the pad. The pad comprises at least two separate pad parts, i.e. a first and a second pad part, and a test device is connectable to at least one pad part, and the leg of the connector is fastened both to the first pad part and to the second pad part in order to establish a connection between the pad parts through the leg. The invention further relates to a printed circuit board comprising: at least one pad connectable to a test device; at least one component comprising at least one leg fastened to the pad. The pad comprises at least two separate pad parts, i.e. a first and a second pad part, and the test device is connectable to at least one pad part, and the leg of the component is fastened both to the first pad part and to the second pad part in order to establish a connection between the pad parts through the leg. Preferred embodiments of the invention are disclosed in the dependent claims. The idea underlying the invention is that while the leg of the connector fastens to at least two separate parts of the pad, the leg establishes a connection between the pad parts in question. A signal enabled by the connection is measured through a second pad part or a part of the printed circuit board connected to the second pad part, whereby it is ensured that the leg is securely fastened to the pad parts; if the leg of the connector is unsuccessfully fastened to at least one pad part, no connection exists between the pad parts, and thus, no signal to be measured to indicate the connection either. In other words, it then becomes apparent that the leg of the connector has come off one pad part, possibly both pad parts. Several advantages are achieved by the method and printed circuit board of the invention. The invention enables the fastenings of the legs of connectors to the printed circuit board to be tested. This considerably im- proves the gain of the manufacturing process of printed circuit boards, in other words, the invention enables large costs to be saved. BRIEF DESCRIPTION OF THE DRAWINGS The invention is now described in greater detail in connection with the preferred embodiments and with reference to the accompanying drawings, in which Figure 1A is a top view of a printed circuit board and the testing environment thereof; Figure 1 B is a side view of the printed circuit board and the testing environment thereof; Figure 2 shows a solution of the invention for fastening a connector to the printed circuit board; Figure 3 shows a first preferred embodiment of the invention, and Figure 4 shows a second preferred embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION Figure 1A is a top view of a printed circuit board 100 and the testing environment thereof. A connector 102 is fastened by its legs 104 to pad parts 112, 114 located on the printed circuit board 100. The pads, which are known to be one-piece, are thus divided into two separate parts 1 12, 114 in the present invention. The printed circuit board 100 comprises a circuitry 116 located on the printed circuit board, the circuitry 116 being connected to a second pad part 114. A test device 118 as seen in Figure 1 B is connectable to different parts of the printed circuit board 100, to the pad parts 112, 114, for example, by e.g. a test pin 120 in order to convey signals to the printed circuit board 100 or to measure the signals from the printed circuit board 100, or both, in which case there are two test pins. The printed circuit board 100 is a base station card, for example, and the fastenings on the printed circuit board 100 are most often carried out by soldering. Figure 1 B is a side view of the printed circuit board and the testing environment thereof. In addition to the subject matter disclosed in Figure 1A, Figure 1 B comprises an inlet 124 provided on the printed circuit board, through which inlet a test pad 126 is fastened to a first pad part 112. Through the test pad 126, it is possible to measure what kind of signal occurs on the first pad part 112, or to supply a signal of the desired kind to the first pad part 112. These functions can be carried out by the test device 118 and the test pin 120. Figure 2 shows a solution of the invention for fastening the connector 102 to the printed circuit board 100. The distance between the pad parts 112, 114 is 0.03 mm to 10 mm. The distance between the pad parts 112, 114 is preferably 0.25 mm to 0.3 mm. The distance between the pad parts 112, 114 is preferably 0.1 mm to 0.3 mm. The leg 104 of the connector is fastened to both pad parts 112, 114, so the leg 104 of the connector establishes a connection between the pad parts 1 12, 114. Figure 3 shows a first preferred embodiment of the invention, comprising a printed circuit board 100 comprising at least one pad 200 connect- able to a test device 118, and at least one connector 102 comprising at least one leg 104 fastened to the pad 200. The pad 200 comprises at least two separate pad parts 112, 114, i.e. a first 112 and a second 114 pad part, and the test device 118 is connectable to at least one pad part. The leg 104 of the connector is fastened both to the first pad part 112 and to the second pad part 114 in order to establish a connection between the pad parts 112, 114 through the leg 104. The distance between the pad parts 112, 114 is preferably 0.25 mm to 0.3 mm. In the present preferred embodiment of the invention, the first 112 and the second 114 pad part are determined in such a manner that the first pad part 112 is the pad part 1 12 whereto the leg 104 of the connector is fastened first as seen from the connector 102 along the leg 104 of the connector, and the second pad part 114 is the pad part 114 whereto the leg 104 of the connector is fastened second as seen from the connector 102 along the leg 104 of the connector. The second pad part 114 is connected to a circuitry 116 located on the printed circuit board 100. A test pad 126 is connected to the first pad part 112 in order to convey a test signal from the test device 118 to the first pad part 112. The test pad 126 is fastened to the first pad part 112 through an inlet 124 provided on the printed circuit board 100. The test device 118 is an automatic testing processor, for example. The method according to the first preferred embodiment of the in- vention, shown by Figure 3, comprises testing the fastening of the connector 102 fastened by its leg 104 to the pad 200 of the printed circuit board 100 by supplying a test signal to the first pad part 112 of the pad 200 and measuring the occurrence of the test signal through the second pad part 114 of the pad 200 or a part of the printed circuit board connected to the second pad part, i.e. the circuitry 116, which second pad part 114 is separate from the first pad part 112, and the leg 104 of the connector is fastened both to the first pad part 112 and to the second pad part 114 during the manufacturing process in order to establish a connection between the pad parts 112, 114 through the leg 104. If a signal is detected in the measurement, the fastening of the leg 104 of the connector is considered to be successful. If no test signal is detected in the measurement, the fastening of the leg 104 of the connector is considered to be defective. The occurrence of the test signal is inferred from whether the strength of the test signal exceeds a predetermined threshold value. In the present preferred embodiment of the invention, the first 112 and the second 114 pad parts are determined in such a manner that the first pad part 112 is the pad part 112 whereto the leg 104 of the connector is fastened first as seen from the connector 102 along the leg 104 of the connector, and the second pad part 114 is the pad part 114 whereto the leg 104 of the connector is fastened second as seen from the connector 102 along the leg 104 of the connector. The second pad part 114 is connected to a circuitry 116 located on the printed circuit board 100. A test pad 126 is connected to the first pad part 112 in order to convey a test signal from the test device 118 to the first pad part 112. The test pad 126 is fastened to the first pad part 112 through an inlet 124 provided on the printed circuit board 100. The test signal is supplied from the test device 118 to the first pad part 112 through the test pad 126 by, for exam- pie, a test pin 120. Similarly, the occurrence of the test signal is measured for the test device 118 by a test pin 121 through the second pad part 114, a test pad 128 connected to the second pad part or a part of the printed circuit board connected to the second pad part, i.e. a circuitry 116. Figure 4 shows a second preferred embodiment of the invention, which comprises a printed circuit board 100 which is an otherwise similar entity to the one shown in Figure 3 in the first preferred embodiment except for the following points: the printed circuit board 100 comprises a second pad part 112, which is the pad part 112 whereto the leg 104 of the connector is fastened first as seen from the connector 102 along the leg 104 of the connector, and a first pad part 114, which is the pad part 114 whereto the leg 104 of the connector is fastened second as seen from the connector 102 along the leg 104 of the connector. The first pad part 114 is connected to a circuitry 116 located on the printed circuit board 100. The printed circuit board 100 comprises a test pad 126 fastened to the second pad part 112 through an inlet 124 pro- vided on the printed circuit board 100 in order to measure the occurrence of a test signal from the second pad part 112 by a test device 118 and a test pin 120. It is possible to supply the test signal to the first pad part 114 or to the test pad connected thereto or to a circuitry 116 also elsewhere than from the test device 118, e.g. from the operating voltage of the circuitry 116. The method according to the second preferred embodiment of the invention, shown by Figure 4, comprises testing the fastening of the connector 102 fastened by its leg 104 to the pad 200 of the printed circuit board 100 in an otherwise similar manner except for the following points: the second pad part 112 is the pad part 112 whereto the leg 104 of the connector is fastened first as seen from the connector 102 along the leg 104 of the connector, and the first pad part 114 is the pad part 114 whereto the leg 104 of the connector is fastened second as seen from the connector 102 along the leg 104 of the connector. The first pad part 114 is connected to the circuitry 116 located on the printed circuit board 100. A test pad 126 is fastened to the second pad part 112 through an inlet 124 provided on the printed circuit board 100. The occur- rence of a test signal is measured through the test pad 126 by a test device 118 and a test pin 120. It is possible to supply the test signal to the first pad part 114 or to the test pad connected thereto or to a circuitry 116 also elsewhere than from the test device 118, e.g. from the operating voltage of the circuitry 116. The test signal can be anything from a voltage signal from a direct voltage signal to radio frequency voltage signals. When the radio frequency voltage signals are used, the fastenings of the leg 104 of the connector to the pad parts 112, 114 can be measured based on s-parameter measurements, which refers to measurements based on signal transmission or reflection, or both. In the situation shown by Figure 3, the test device 1 18 transmits a radio frequency signal by the test pin 120 to the pad part 112. The fastenings are tested by measuring either the reflection back from the pad part 112 or the transmission through the pad part 114 along the test pin 121 to the test device 118. The transmission can also be measured from a point of the circuitry 116 located on the printed circuit board 100. The number of the tests can be reduced by an application wherein a radio frequency signal is transmitted by the test pin 120 to the pad part 112 of the pad 200 and the measurement is carried out for the pad 200 in question from the pad part 114 of a parallel pad, which pad is not necessarily the adja- cent parallel pad. The pads can be thought to form a filter structure. From the result obtained in the measuring point can be inferred whether the fastening of a pad part of the pad has come off. Hence, the fastenings of the pad parts of more than one pad can be tested by one measurement. A component whose fastenings by its legs to the printed circuit board 100 are tested can be other than a connector 102, such as an IR trans- mitter or a short-distance radio transmitter, for example. Hence, the part 102 in the figures can be considered to represent the connector or another component. Although the invention has been described above with reference to the examples according to the accompanying drawings, it is obvious that the invention is not restricted thereto but can be modified in many ways within the scope of the inventive idea disclosed in the attached claims.

Claims: CLAIMS 1. A method of testing the fastening of a connector (102) fastened by its leg (104) to a pad (200) of a printed circuit board, characterized by supplying a test signal to a first pad part of the pad (200); measuring the occurrence of the test signal through a second pad part of the pad (200) or a part of the printed circuit board (100) connected to the second pad part, which second pad part is separate from the first pad part, and the leg (104) of the connector is fastened both to the first pad part and to the second pad part during the manufacturing process in order to establish a connection between the pad parts (112, 114) through the leg (104). 2. A method as claimed in claim 1, characterized by considering the fastening of the leg (104) of the connector to be successful if the test signal is detected in the measurement. 3. A method as claimed in claim 1, characterized by considering the fastening of the leg (104) of the connector to be defective if the test signal is not detected in the measurement. 4. A method as claimed in claim 2 or 3, characterized by inferring the occurrence of the test signal from whether the strength of the test signal exceeds a predetermined limit. 5. A method as claimed in claim 1, characterized by the distance between the pad parts (112, 114) being 0.03 mm to 10 mm. 6. A method as claimed in claim 5, characterized by the distance between the pad parts (112, 114) preferably being 0.25 mm to 0.3 mm. 7. A method as claimed in claim 5, characterized by the distance between the pad parts (112, 114) preferably being 0.1 mm to 0.3 mm. 8. A method as claimed in claim 1, characterized by a first pad part being the pad part (112) whereto the leg (104) of the connector is fastened first as seen from the connector (102) along the leg (104) of the connector, and a second pad part being the pad part (114) whereto the leg (104) of the connector is fastened second as seen from the connector (102) along the leg (104) of the connector. 9. A method as claimed in claim 8, characterized by connecting the second pad part (114) to a circuitry (116) located on the printed circuit board (100). 10. A method as claimed in claim 8, characterized by fas- tening a test pad (126) to the first pad part (112). 11. A method as claimed in claim 10, characterized by carrying out the connection between the first pad part (112) and the test pad (126) through an inlet (124) provided on the printed circuit board (100). 12. A method as claimed in claim 8, characterized by sup- plying the test signal to the first pad part (112) through the test pad (126). 13. A method as claimed in claim 1, characterized by a second pad part being the pad part (112) whereto the leg (104) of the connector is fastened first as seen from the connector (102) along the leg (104) of the connector, and a first pad part being the pad part (114) whereto the leg (104) of the connector is fastened second as seen from the connector (102) along the leg (104) of the connector. 14. A method as claimed in claim 13, characterized by connecting the first pad part (114) to the circuitry (116) located on the printed circuit board (100). 15. A method as claimed in claim 13, characterized by fastening a test pad (126) to the second pad part (112). 16. A method as claimed in claim 15, characterized by carrying out the connection between the second pad part (112) and the test pad (126) through an inlet (124) provided on the printed circuit board (100). 17. A method as claimed in claim 15, characterized by measuring the occurrence of the test signal through the test pad (126). 18. A method as claimed in claim 1, characterized by transmitting the test signal and measuring the occurrence of the test signal by a test device (118). 19. A method as claimed in claim 13, characterized by supplying the test signal to the first pad part (114) from the operating voltage of the circuitry (116) of the printed circuit board (100). 20. A method as claimed in claim 18, c h a r a c t e r i z e d by the test device (118) being an automatic testing processor. 21. A method as claimed in claim 1, characterized by carrying out the fastenings by soldering. 22. A printed circuit board (100) comprising: at least one pad (200) connectable to a test device (118); at least one connector (102) comprising at least one leg (104) fastened to the pad, characterized in that the pad (200) comprises at least two separate pad parts (112, 114), i.e. a first and a second pad part, and the test device (118) is connectable to at least one pad part, and the leg (104) of the connector is fastened both to the first pad part and to the second pad part in order to establish a connection between the pad parts (112, 114) through the leg (104). 23. A printed circuit board as claimed in claim 22, characterized in that the distance between the pad parts (112, 114) is 0.03 mm to 10 mm. 24. A printed circuit board as claimed in claim 23, character- i ze d in that the distance between the pad parts (112, 114) is preferably 0.25 mm to 0.3 mm. 25. A printed circuit board as claimed in claim 23, characterized in that the distance between the pad parts (112, 114) is preferably 0.1 mm to 0.3 mm. 26. A printed circuit board as claimed in claim 22, characterized in that the printed circuit board (100) comprises a first pad part which is the pad part (112) whereto the leg (104) of the connector is fastened first as seen from the connector (102) along the leg (104) of the connector, and a second pad part which is the pad part (114) whereto the leg (104) of the con- nector is fastened second as seen from the connector (102) along the leg (104) of the connector. 27. A printed circuit board as claimed in claim 26, characterized in that the second pad part (114) is connected to a circuitry (116) located on the printed circuit board (100). 28. A printed circuit board as claimed in claim 26, characterized in that the printed circuit board (100) comprises a test pad (126) fastened to the first pad part (112) in order to convey a test signal from the test device (118) to the first pad part (112). 29. A printed circuit board as claimed in claim 28, character- i ze d in that the printed circuit board (100) comprises an inlet (124) for car- tying out the fastening between the first pad part (112) and the test pad (126) through said inlet (124). 30. A printed circuit board as claimed in claim 22, characterized in that the printed circuit board (100) comprises a second pad part which is the pad part (112) whereto the leg (104) of the connector is fastened first as seen from the connector (102) along the leg (104) of the connector, and a first pad part which is the pad part (114) whereto the leg (104) of the connector is fastened second as seen from the connector (102) along the leg (104) of the connector. 31. A printed circuit board as claimed in claim 30, characterized in that the first pad part (114) is connected to a circuitry (116) located on the printed circuit board (100). 32. A printed circuit board as claimed in claim 30, characterized in that the printed circuit board (100) comprises a test pad (126) fas- tened to the second pad part (112) in order to measure the occurrence of the test signal from the second pad part (112). 33. A printed circuit board as claimed in claim 32, characterized in that the printed circuit board (100) comprises an inlet (124) for carrying out the connection between the second pad part (112) and the test pad (126) to the printed circuit board (100) through said inlet (124). 34. A printed circuit board as claimed in claim 22, characterized in that the test device (118) is connectable to the printed circuit board (100) in order to convey the test signal and to measure the occurrence of the test signal. 35. A printed circuit board as claimed in claim 30, characterized in that the circuitry (116) of the printed circuit board (100) comprises the operating voltage for conveying the test signal to the first pad part (114). 36. A printed circuit board as claimed in claim 34, characterized in that the test device (118) is an automatic testing processor. 37. A printed circuit board as claimed in claim 22, characterized in that the fastenings are carried out by soldering. 38. A method of testing the fastening of a component (102) fastened by its leg (104) to a pad (200) of a printed circuit board, characterized by supplying a test signal to a first pad part of the pad (200); measuring the occurrence of the test signal through a second pad part of the pad (200) or a part of the printed circuit board (100) connected to the second pad part, which second pad part is separate from the first pad part, and the leg (104) of the component is fastened both to the first pad part and to the second pad part during the manufacturing process in order to establish a connection between the pad parts (112, 114) through the leg (104). 39. A printed circuit board (100) comprising: at least one pad (200) connectable to a test device (118); at least one component (102) comprising at least one leg (104) fastened to the pad, c h a r a c t e r i z e d in that the pad (200) comprises at least two separate pad parts (112, 114), i.e. a first and a second pad part, and the test device (118) is connectable to at least one pad part, and the leg (104) of the component is fastened both to the first pad part and to the second pad part in order to establish a connection between the pad parts (112, 114) through the leg (104).

Inventors: PINOLA TIMO, PINOLA, TIMO
Applicants: NOKIA NETWORKS OY, PINOLA TIMO, PINOLA, TIMO
Application year: 2000
Main classification: G01R31
IPC codes: G01R31, H05K1, H05K3