JPH11160380A - Test head of circuit board and test method of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately test high density circuit board in a short time by one operation in relation to a test head of a circuit board and a test method of the circuit board. SOLUTION: A head is brought into contact with points on a circuit board with a plurality of probe pins and tests electric characteristics of a network that is constituted on the circuit board. In this case, points (S1) whose distance to other point are at least a specified value, are extracted at least one from each network as first-class points, and points (S2) whose distance to other point are less than the specified value are classified every other point into the first group and the second group in a fixed sequence. Probe pins in contact with points in first-class and the first group are allocated to the first head, and probe pins in contact with points in the second group and points both in the first-class and same net as the points in the second group are allocated to the second head (S2-S8). Thereby, a test head is constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test head for a circuit board and a test method for a circuit board, and more particularly to a head used for testing a so-called high-density substrate having a fine pad pitch formed on the board and the head. The present invention relates to a test method using a head.

[0002]

2. Description of the Related Art With the downsizing of electronic devices such as computers, the use of SMT and high-density printed circuit boards has been rapidly progressing, and the electrical inspection of printed circuit boards also uses a conventional batch test head using a basic grid. By the way,
It is becoming impossible to cope with diversified printed circuit boards.

At present, most of the general substrates have a pattern (so-called off-grid) that deviates from the basic grid, and it is general to manufacture a dedicated jig according to the type of the substrate. The pad pitch of ultra-high-density substrates such as MCM and CSP exceeds the limit of the pad pitch determined by the probe pin diameter (currently, approximately 200 μm or less, referred to as the lower limit pitch). Jigs cannot be manufactured for some types.

[0004] Also, regarding the apparatus, the positioning accuracy between the substrate and the test head is an important theme, and the method of correcting the test head while confirming the displacement of the substrate is as follows.
Highly accurate positioning is not possible.

[0005]

As described above,
In the conventional method of inspecting printed circuit boards, when the diversified printed circuit boards, especially the pad pitch formed on the board is narrower than the achievable minimum value of the probe pin interval determined from the pin diameter of the probe pins of the test apparatus. However, there is a problem that it is impossible to manufacture a dedicated jig or to perform highly accurate positioning.

In view of the above circumstances, the present invention provides a test method and a test apparatus capable of easily and easily inspecting an ultra-high-density substrate having a (narrow) pad pitch exceeding a limit based on the limitation of the probe pin diameter. The purpose is to provide.

[0007]

SUMMARY OF THE INVENTION In a test head of a circuit board for testing the electrical characteristics of a net formed on the circuit board by contacting a probe pin to a point on the circuit board, a distance from another point is measured. The first head is provided with a probe pin that contacts a representative point, which is a first type point having a certain value or more and is a point extracted at least one from each net, and has a constant distance from other points. A probe pin that contacts a point belonging to the first group among the points selected in the two groups of the first group and the second group in a fixed order every other type 2 point that is less than the value, A probe pin, which is further provided on the first head and which contacts a point belonging to the second group among the points selected in the two groups, A probe pin provided on the head and contacting the first type point of the net to which each point belonging to the second group belongs is further provided on the second head, and a circuit is provided by the first head and the second head. Construct a substrate test head.

Further, the first head and the second head are arranged at regular intervals, and a probe of the first head is placed in a state where a circuit board to be tested is moved below the first head. A pin is brought into contact with a point on the circuit board to test an electrical characteristic of the circuit board. The circuit board to be tested is moved under the second head, and the second head is The electrical characteristics of the circuit board are tested by contacting the probe pins with points on the circuit board.

When a test head for a circuit board is constructed as described above, the first head can perform all of the insulation test and the majority of the continuity test, and the second head can perform the continuity test. The points to be tested (therefore, probe pins) are distributed to the respective heads so that a part of the test can be performed. If the continuity test still needs to be performed at a pitch less than the lower limit pitch using two heads, the first head and the second head, a third head will be provided. If not all of the insulation tests are possible with the first head, the probe pins are arranged so that the second head can perform an insulation test on the adjacent net.

As described above, after the heads are sorted, the substrate and the test head are aligned, and the printed circuit board is tested.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a flow chart of probe pin assignment, showing a procedure for assigning probe pins to respective heads according to the present invention. Hereinafter, a procedure of a configuration of a test head used for testing a high-density substrate according to the present invention and a test method using the head configured according to the procedure will be described with reference to FIGS. In the test method using the head according to the present invention, the configurations of the continuity test circuit and the insulation test circuit connected to the probe pins of the head and the range of the test method using them, which are performed in the related art, are described in detail. No explanation is given. First, the figures referred to will be described.

FIG. 2 is a diagram showing an example of representative point extraction. In the figure, four pads indicated by a, b, c, and d are:
This shows the pads that connect the terminals of the IC.
It is assumed that the pitch is 100 μm and less than the lower limit pitch (200 μm). Of the six pads A, B, C, D, E, and F, four pads A, B, C, and D are connected to the pads a, b, c, and d, respectively. , E, F
Are connected to the pads C and D, respectively. Therefore, Aa, Bb, Cce, D-
There will be four nets d-F.

FIG. 3 is a diagram for explaining probe allocation, and shows an example in which six LSIs are mounted on an MIC substrate. The partially enlarged view is a view of a pad to which a terminal of the LSI is connected, and the interval is determined by the LSI. At present, as shown by a, b, c, and d in FIG. Is smaller than the lower limit pitch based on the limit of the probe pin diameter. The circles and triangles in the figure indicate the portions where the probes of the first head and the second head according to the present invention are in contact with each other.

FIG. 4 is a layout diagram of a test head, which is used, for example, for testing an MIC substrate as shown in FIG. The first head and the second head are fixed at a fixed distance (for example, the distance between the centers is 50 mm). As shown in the test method of FIG.
The test head is moved down from the bottom of the head to the bottom of the second head, or vice versa, and the test head is lowered with the base fixed at a predetermined position to perform a predetermined test. FIG. 4 shows the arrangement of the probe pins of the first head and the second head.
The positions of the probe pins of the heads are indicated by triangles, and the positions of the centers of both heads are indicated by crosses. It should be noted that the illustrations for illustration have been partially enlarged and emphasized because they are drawn with emphasis on legibility.

By using two heads as shown in FIG. 4, it is possible to select and measure every other pad shown in the partially enlarged view of FIG. In FIG. 3, circles and triangles are illustrated as being arranged in a zigzag pattern, whereas in FIG. 4, for simplicity, the symbols are illustrated as being simply arranged in a straight line. There are, however, any of them.

FIG. 5 is a diagram showing a test method as described above. Each probe pin of the first head and the second head is connected to a predetermined test circuit, and a continuity test and an insulation test between the pins can be performed. FIG.
Is a diagram for explaining a case where a large number of heads are required, and will be described after a description of a case of two divisions.

In the following, how to allocate to the heads in the case of FIG. 2, that is, how to set the probe pins for the respective points on which heads will be described with reference to the flow of FIG. 1. Steps are indicated by S1 and the like.

In S1, one or more points for each net are extracted as representative points from all data, and are extracted as data 1. Note that the data refers to a set of names of pads to be measured, and the names are accompanied by a display (coordinate display or the like) indicating the position. However, in the following description, only the names (A, b, etc.) of each point are shown for convenience of explanation. In the example of FIG. 2, data 1 includes A, b, C, and D. When selecting a representative point, the representative point is selected from the first type points whose distance to other points is equal to or more than a certain value.
Even a second type point, such as point b, whose distance to another point is less than a certain value, may be a target for selection if the distance to another representative point is more than a certain value.

At S2, a point less than the lower limit pitch is extracted from all the data and is set as data 2. In the example of FIG. 2, the data 2 includes a, b, c, and d. In S3, it is checked whether data 1 and data 2 have a common point. If there is, go to S4, otherwise go to S5. In the example of FIG. 2, since the data 1 and the data 2 have a common point b, the process proceeds to S4.

In S4, the common point is deleted from the data 1, and if the data 1 does not include another point belonging to the same net, it is newly added to the data 1. In the example of FIG. 2, b is deleted from data 1 and data 1 is deleted.
As a result of adding B to data 1, data 1 is composed of A, B, C, and D. Proceed to S5.

In S5, if there is data that is not included in either data 1 or data 2, it is added to data 1. In FIG. 2, E and F correspond to each other, and as a result of adding them to data 1, data 1 is composed of A, B, C, D, E, and F.

In step S6, the data 2 is sorted and selected every other data. One is added with the data 1 to obtain the data 3, and the other is added with the points of the net to which the selected points belong to obtain the data 4. In the example of FIG. 2, data 3 is A,
B, C, D, E, F, a, c, and data 4 are b, B, d,
D.

In S7, the pitch of the data 4 is checked, and it is checked whether there is a point equal to or smaller than the lower limit pitch. If no, go to S8, otherwise go to S9. In the example of FIG. 2, the distance between the two points bd included in the data 4 is the minimum.
At 00 μm, it falls within the lower limit pitch of 200 μm.

In S8, the data 3 is assigned to the first head (strictly speaking, the first head is provided with a probe pin that contacts a pad at a point included in the data 3),
Data 4 is assigned to the second head (strictly speaking, a probe pin is provided on the second head for contacting a pad at a point included in data 4). In the example of FIG. 2, A, B, C, D, E, F, a, c are assigned to the first head, and b, B, d, D are assigned to the second head.

When the heads are assigned as described above, the first
In the head of A, A-
a, CCE and DF continuity tests are performed. Also,
In the second head, continuity tests of Bb and Dd are performed.

In this example, the point assignment to the two heads is determined by changing the representative point. However, if the change of the representative point does not result in convergence, the number of divided heads is increased (using a large number of heads). Do).

FIG. 6 shows an example in which a large number of heads are required. In this example, Aa, Bb, Cc, Dd, E-
e, Ff, Gg, Hh, Ii, Jj, K-
In this case, there are 15 nets of k, L-1, Mm, Nn, and Oo. As in the case of FIG.
The distance between any of the 15 points indicated by O) and any of the other points is set to be larger than the lower limit value.
The 15 points indicated by o) have other points at a distance less than any other lower limit. In this case, when the points are selected according to the flow of FIG. 1, as a result of the determination in S6, the data 3 includes the net representatives of A to O, a, c, and
Although points such as e and g are selected, the intervals such as ae and ce are smaller than the lower limit pitch. Therefore, it is necessary to delete points such as e and assign those points to another head.

The processing A in S9 shows the processing in the case where the division of the head must be continued further, and when Y is determined in S7 in FIG. 1, it corresponds to repeating S6─S7. In this case, the data 2 is sorted and selected every other in S6 of FIG. 1, but in the process A, the data 4 is treated in the same manner. As a result, the assignment to the second head and the third head is determined. If the lower limit pitch is still included in the points assigned to the third head, the division is performed similarly for the points assigned to the third head. In the case of FIG. 6, the fourth
The problem is solved by dividing up to the head.

The first head is assigned representative points A to O of each net and a, c, g, i, m, and o.
The second head is assigned d, D, f, F, j, J, l, L.

The third head includes b, B, h, H, n,
N is assigned. The fourth head has e, E, k, K
Is assigned. If further division is required, the same operation may be repeated.

[0031]

As is apparent from the above description, according to the present invention, a fine pitch division type test head is used.
Substrates that could originally only be handled by the flying prober method can be subjected to batch testing, improving throughput. In addition, the batch insulation test makes it possible to guarantee by applying a constant voltage. Further, the alignment confirmation time and accuracy are improved.

[Brief description of the drawings]

[Figure 1] Probe pin assignment flow

Fig. 2 Example of representative point extraction

Fig. 3 Probe allocation

FIG. 4 is a layout diagram of a test head.

FIG. 5 Test method

FIG. 6 When multiple heads are required

[Explanation of symbols]

A, B, C, D, E, F, G, H, I, J, K, L,
M, N, O are pad points whose distances are equal to or greater than the lower limit pitch. a, b, c, d, e, f, g, h, i, j, k, l,
m, n, and o are pad points whose distances are less than the lower limit pitch.

Claims (2)

[Claims] 1. A test head for a circuit board for testing electrical characteristics of a net formed on the circuit board by contacting a probe pin to a point on the circuit board, wherein a distance from another point is equal to or more than a predetermined value. The first head is provided with a probe pin that is in contact with a representative point that is a point of type 1 that is a point extracted at least one from each net, and a distance from another point is less than a certain value. Of the points sorted into two groups, a first group and a second group, in a fixed order every other type 2 point,
The first head further includes a probe pin that contacts a point belonging to the first group, and a probe pin that contacts a point belonging to the second group among the points selected into the two groups. A probe pin that contacts the first type point of the net to which each point belonging to the second group belongs.
A test head for a circuit board, further comprising: a first head and a second head. 2. The probe of the first head in a state where the first head and the second head are arranged at regular intervals, and a circuit board to be tested is moved below the first head. A pin is brought into contact with a point on the circuit board to perform a test of electrical characteristics of the circuit board. The circuit board to be tested is moved under the second head, and the second head is And testing the electrical characteristics of the circuit board by contacting the probe pins with points on the circuit board.