JPH0282173A - In-circuit testing method for package circuit board - Google Patents

Abstract

PURPOSE:To easily and accurately conduct a necessary test without requiring complicate operation nor skillfulness by pressing the tip end surface of a probe pin against a lead part of a surface package type electronic parts which is mounted under specific pressure and conducting the test. CONSTITUTION:For example, a flat package type IC element 1 with two- directional lead terminals is mounted by connecting its lead 1a to the pad part 4 of a printed circuit board 2 by soldering 5. Then, the tip end surfaces 3a of the in-circuit probe pin 3 which is prepared is pressed against the lead 1a within a range of 20 - 50 Gr pressure. The tip end surface 3a is formed in a shape which contacts the opposite surface of the lead 1a easily and sufficiently. Thus, the in-circuit test of a composite system including the element 1 or other packaged electronic parts is conducted without providing any in-circuit pad. Further, the pressing force of the pin 3 is relatively small, so if the lead 1a is in a nonconductive state owing to a defect in soldering, 'float of lead' is easily detected.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to an incircuit test method for mounted circuit boards, and in particular, for testing surface-mounted electronic components such as flat packaged IC devices. This paper relates to an in-circuit test method for a circuit board mounted on and mounted on a board.

(Prior art) For the purpose of miniaturizing and increasing the density of electronic circuits, for example,
Surface-mount electronic components such as flat package IC devices with two-way lead terminals and flat package IC devices with four-way lead terminals are placed on the main surface of a printed circuit board.
Developed a high-density mounting circuit board that is mounted or assembled.
It is used.

However, when making this type of high-density mounted circuit board into a product and putting it into practical use, it is a matter of course that P-level tests are carried out to determine whether the high-density mounted circuit board is sufficiently equipped with the required functions. , FP value. That is, the high-density mounting circuit board is provided in advance with a pad capable of performing an in-circuit test of the mounted circuit, and the in-circuit test is performed by bringing the pad into contact with a probe pin.

(Problems to be Solved by the Invention) By the way, providing the pads for the incircuit test in advance on the high-density mounting circuit board has the following problems:
This increases the layer structure of the printed circuit board on which electronic components are mounted. That is, the structure of the printed circuit board becomes more complicated, the design cost and the board cost increase, and it is uneconomical in terms of mass production.

Therefore, an object of the present invention is to provide a method that does not increase the cost of the high-density mounting circuit board and can easily perform the required in-circuit test.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides an in-circuit test for a mounted circuit board on which required surface-mounted electronic components are mounted. The in-circuit test is carried out by bringing the tip end surface of the probe pin into contact with the lead part under a pressure of 20 to 50 gr.

(Function) As described above, according to the incircuit test method of the present invention,
The tip end surface of the probe pin is brought into contact with the lead portion of the mounted surface mount type electronic component under a pressure of 20 to 50 g to establish the required electrical connection. Since this is done by pressing with a predetermined force, the electrical connection is not only maintained reliably, but also because the pressing force is relatively small, the leads of the surface-mounted electronic components that are in contact with each other are In other words, it is possible to detect not only circuit tests and evaluations of high-density mounted circuit boards, but also defects in soldering in the leads of mounted surface-mounted electronic components.

(Example) The present invention will be described in detail below with reference to FIGS. 1 and 2. FIG. 1 shows a part of a high-density mounting circuit board in which a surface-mounted electronic component, for example, a flat package IC cable 1 with two-way lead terminals, is mounted on a predetermined surface of a printed circuit board 2. It is something that However, in the incircuit test of this high-density mounted circuit board,
The tip surface 3a of the in-circuit probe pin 3 prepared in advance is brought into contact with the lead 1a of the flat package type IC element 1 under a pressure of 20 to 50 gr.

Here, the tip of the in-circuit probe pin 3, the smoke surface 3
A and the lead 1a of the flat package type IC element 1 should be in contact with each other on the flat package type IC element 1 side as much as possible. Further, it is preferable that the tip end surface 3a of the in-circuit probe pin 3 is appropriately set in a shape so that it can easily come into contact with the contact surface of the lead la of the flat package type IC element 1. FIG. 2 is an enlarged perspective view showing a state in which the tip end surface 3a of the in-circuit probe pin 3 and the lead 1a of the flat package type IC element 1 are brought into contact with each other. In addition, in Figure 1, 4
1 is a pad portion to which a lead 1a of a flat package type IC element 1 is soldered.

As shown above, the tip surface 3 of the in-circuit probe pin 3
a to each of the plurality of predetermined leads 1a of the flat package type IC element 1, so that each of the mounted flat package type IC elements 1 or a composite system inserter with other mounted electronic components is connected. Do a kid test. In this in-circuit test, each mounted flat package type IC element 1 or a composite system with other mounted electronic components is tested and evaluated. It is also possible to detect a soldering defect in a predetermined lead la of the flat package type IC cable 1 that the terminals 3a are in contact with. That is, since the contact pressure of the in-circuit probe pin against the lead 1a is relatively small, 20 to 50 gr, it is easy to detect when the lead 1a is in a non-conducting state due to poor soldering (lead lf failure). be done.

In the above, the case where the mounted electronic component is a flat package type IC element with two-way lead terminals is shown, but this electronic component may be, for example, a flat package type IC element with four-way lead terminals, etc. A surface-mounted type may also be used.

Further, the tip surface of the probe pin that is brought into contact with the lead portion of the mounted flat package electronic component may be shaped or structured to match the shape of the lead.
This is desirable for ease of positioning, but is not necessarily required. Therefore, the contact force (pressure) applied to the probe pin that is brought into contact with the lead section is always set at 20 to 50 g.In other words, sufficient electrical connection is made to perform the required in-circuit test. On the other hand, the lead portions are brought into contact with each other to the extent that they do not cause deformation (forcible pressure contact with soldering portions or pads).In other words, the mounted flat package type electronic components and The lead part of the electronic component is brought into contact with the electronic component to the extent that virtually no load is applied.The above method allows the required in-circuit test to be performed, and even if the lead part is floating from the pad, the product is not damaged. It will be detected.

[Effects of the Invention] As can be seen from the above examples, the in-circuit test method of the present invention allows required tests to be easily and accurately performed without requiring complicated operations or skill.

Therefore, in addition to the above-mentioned incircuit test, the method of the present invention can also detect loose leads (soldering defects) of mounted electronic components. In addition, being able to perform the required in-circuit test without providing in-circuit pads as described above means that the circuit board on which the electronic components are mounted will have to have a sloppy layer structure, which can lead to increased costs and design. It can also be said to reduce costs and bring about practical advantages.

[Brief explanation of the drawing]

Figures 1 and 2 are for explaining the in-circuit test method of the present invention, and Figure 1 shows the probe pin end face attached to the lead part of a flat package type IC element mounted on a printed circuit board. FIG. 2 is an explanatory diagram showing a side view of the state in which the probe pins are brought into contact with each other; FIG. . 1...Surface mount type electronic component 1a...Lead portion of surface mount type electronic component 2...Printed circuit board 3...Probe pin 3a...Probe pin tip surface 4...Pad 5... ·solder

Claims (1)

[Claims] In an in-circuit test of a mounted circuit board on which a required surface-mounted electronic component is mounted and mounted, the tip of a probe pin is attached to the lead portion of the mounted and mounted surface-mounted electronic component. An incircuit test method for a mounted circuit board, characterized in that an incircuit test is performed by bringing the surfaces into contact with each other under a pressure of 20 to 50 gr.