JP3064483B2 - Lead height measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the height of a lead, which removes abnormal data due to noise and precisely measures the height of a lead protruding from a chip.

[0002]

2. Description of the Related Art When a chip with a lead such as a QFP or TAB chip is mounted on a substrate, if the lead is floating, the lead cannot be grounded to the substrate for bonding.

Therefore, prior to mounting the chip with the lead on the substrate, the lead is irradiated with laser light and its reflected light is received by the light receiving portion , or the laser light is emitted by the lead.
It is known to measure the height of a lead by measuring the length of a light-shielding time .

[0004]

However, if the lead is damaged or an impurity is adhered, the laser beam is reflected abnormally and becomes noise, which causes a deviation in height data.

Accordingly, an object of the present invention is to provide means for removing noise and accurately measuring the height of a lead.

[0006]

SUMMARY OF THE INVENTION The present invention To this end, when toward the lead projecting from the chip is irradiated with a laser beam in a direction transverse to the lead for measuring the height of the lead edge on both ends of the lead Are cut off and an allowable range of height data is set, data outside the allowable range is removed as noise, and the lead height is obtained from the data within the allowable range.

[0007]

According to the above construction, when the laser beam is abnormally reflected due to a scratch or an impurity on the lead, the height data is removed as noise, and the height of the lead is obtained from the remaining data. .

[0008]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of a lead height measurement. In the figure, reference numeral 1 denotes an XY table on which a transfer head 2 is mounted. The transfer head 2 adsorbs the chip P to the nozzle 3 and mounts the chip P on the substrate 5 positioned by the positioning unit 4.

Reference numeral 6 denotes a laser device, which is an XY table 1
Is driven to move the chip P in the X and Y directions while scanning the laser beam in the direction traversing the lead L protruding from the chip P to irradiate a spot, and receiving the reflected light. , The height of the lead L is measured. Reference numeral 7 denotes a laser light emitting unit, and reference numeral 8 denotes a light receiving unit. 9 is a collection box for defective chips P, and a lead L
The defective chip P in which the floating of the chip is detected is discarded in the box 9.

Reference numeral 11 denotes storage means for storing height data of each lead L measured by the laser device 6. 12
Denotes an operation unit of the CPU,
It comprises an average value calculation means 14 and a lead floating determination means 15.

FIG. 2 is a graph showing a measurement result of the laser device 6.
It shows height data in the transverse direction of the book lead L. In the present embodiment, the height of 16 spot points n1 to n16 is measured.

As shown in the figure, the heights of the spot points n1 to n3 and n14 to n16 at both edges of the lead L generally tend to be measured low. When the lead L has a flaw a, the height data of the spot point n7 irradiated on the flaw L is abnormally low. Therefore, a high threshold value HT and a low threshold value LT are set, and an interval between them is set as an allowable range A. Data outside the allowable range A is cut as noise.

Next, the measuring method will be described with reference to the flowchart of FIG. By driving the XY table 1,
The chip P is moved directly above the laser device 6 and irradiated with laser light in a direction crossing the leads L to obtain height data as shown in FIG.

The height data is stored in the storage means 11 (step 1). Then, among the height data, data n1 to n3, n which are data of both edge portions of the lead L.
14 to n16 are cut (step 2). Next, data outside the allowable range A (n7 in FIG. 2) is cut as noise (step 3). Such a cut of data is
This is performed by the valid data extracting means 13.

Next, if the number of continuous data in the allowable range A is less than 6, the data is cut (step 4). The reason is as follows. That is, for example, in FIG.
There are three data, 4 to n6, and n8 to n on the right.
There are 13 data sets. In such a case, if six or less data are adopted as valid data, it is erroneously recognized that two leads L exist. Therefore, all data n4 to n6 on the left, which is six or less, are cut, and only data n8 to n13 on the right are adopted as valid data. By setting the effective minimum number of spots in this way, it is possible to avoid erroneous recognition of one lead as a plurality of leads. Of course, the effective minimum number can be freely set according to the number of spot points and the like.

Next, the average value X of the remaining data is calculated by the average value calculating means 14 (step 5). Next, the difference between the individual data remaining as valid data and this average value X is obtained, and this difference is set to a separately set tolerance (for example, ± 5).
0 μm) is determined (step 6). Then, if a value outside the allowable range is included, the data is cut, and the average value X of the remaining data is obtained again.

Next, it is determined whether or not the lead is lifted by the lead float determining means (step 7). If Yes, the lead is mounted on the substrate 5;

[0019]

The present invention described above, according to the present invention, on the occasion toward the lead projecting from the chip is irradiated with a laser beam in a direction transverse to the lead for measuring the height of the lead, Li
The data at the edges at both ends of the lead is cut, and the allowable range of the height data is set. Data outside this allowable range is removed as noise, and the lead height is obtained from the data within the allowable range. So generally lower than actual
Cut the data at both edges that tend to be measured.
By doing so, the error can be eliminated, the error due to noise can be eliminated, and the height of the lead can be accurately measured, and the chip can be mounted on the substrate.

[Brief description of the drawings]

FIG. 1 is an overall view of a lead height measuring system according to the present invention.

FIG. 2 is a diagram showing lead height data according to the present invention;

FIG. 3 is a flowchart of a calculation according to the present invention.

[Explanation of symbols]

 Reference Signs List 5 substrate 6 laser device 7 laser emitting part 8 light receiving part P chip L lead

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102 H05K 13/04

Claims (1)

(57) [Claims] When measuring the height of a lead by irradiating a laser beam in a direction traversing the lead toward the lead protruding from the chip , data at both end edges of the lead is measured.
And setting a permissible range of height data, removing data outside the permissible range as noise , and obtaining a lead height from data within the permissible range. Method.