LCM common defects and quality standards

Mar 1, 2021 | Articles

A. Description of main parts
Item Criterion Remark
1. FPCA The criterion for chip component solder point: IPC-A-610C CLASS 2 on general occasion。 Vision inspection / Microscope
2. Backlight 2.1 Defect of no light is unaccepted。
2.2 The brightness (test with BM-7 equipment ) and power consumption must meet SPEC
3. Bezel Any damage, distortion and other solder sparks on the bezel surface is unaccepted。
4. FPC 4.1 Criterion for bending and crease. In picture 22, “a” is the angle composed of the extended lines of the crease. This angle must be more than 90 degrees.
4.2 The area of the crack, damage, foreign material and the air bubble is not allowed to be more than 1/5 of that of the enhancing film.
4.3 Golden finger should not be scraped obviously; Any stain and foreign on the finger is unaccepted.
Vision inspection / Microscope
5. LCD screen 5.1 A protective plaster should be stuck to the screen based on the SPEC.
5.2 Any dust, fingermark, stain, or other foreign material on the screen surface that can not be got rid of with a soft cloth or air gun is unaccepted.
5.3 The Defect of no display is unaccepted.
5.4 Defect of lack of line or cross-talk is unaccepted.
5.5 Abnormal chroma, brightness, and contrast (compared with golden Sample and SPEC parameter) are unaccepted
5.6 Uneven backlight (compared with golden Sample) or dark area is unaccepted.
5.7 Response time of menu change must meet SPEC.
5.8The LCD screen shift amount should not be more than 0.2mm based on the SPEC.
5.9The criterion should be loosened in judging the defect in the area out of the screen.
Vision inspection
B. Visual failure
Inspection item Criterion Remark
Liner matter
Width (mm) Length (mm) QTY
W≤0.1 / Ignore
0.1/W≤0.2 L≤5 3
W>0.2 / 0
Width (mm) Length (mm) QTY
W≤0.03 / Ignore
0.03m/W≤0.05 L≤5 2
0.05m/W≤0.1 L≤2 2
W>0.1mm or L>2mm 0
As liner
Fisheye on film/Dent on film and Air bubble
Size (mm) QTY
D≤0.2 Ignore
0.2<D≤0.4 5
0.4<D≤0.5 2
D>0.5 0
Size (mm) QTY
D≤0.15 Ignore
0.15<D≤0.2 3
0.2<D≤0.3 1
D>0.3 0
As fish eye
Chip and crack Corner Chip X≤3mm Y≤3mm Z≤T
General Chip X≤3mm Y≤3mm Z≤T
X≤5mm Y≤1mm Z≤T
Crack 0
C. TFT bad dot matrix
Defect Mode Acceptable Judgment Criteria
Dot Type Quantity (ea)
Bright Dot Random (Red, Blue, Green) 1
2 or more adjacent dot defects 0
Dark Dot Dark dot 3
2 adjacent dots 1
3 or more adjacent dots 0
D. Reliability assurance
No. Items Specification
1 High Temp storage 70°C, 160hr
2 Low Temp storage -20°C, 160hr
3 High Temp operation 60°C, 160hr
4 Low Temp operation -20°C, 160hr
5 Humidity storage 60°C, 90%, 160hr
6 Humidity operation 60°C, 90%, 160hr
7 Thermal Shock -10°C (30min) ~60°C (30min) 20 cycle


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