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LCD Module Inspection Standard

The purpose of the Displaytech LCD module inspection standard and criteria is to guarantee the quality of the LCD display module. This section covers the technical standards for Displaytech monochrome LCD modules.
 

Inspection Condition

  1. Put the display under a lamp (20w x 2) at a distance of 100mm
  2. Tilt upright at a 45 degree angle by the front to inspect the LCD appearance

Inspection Condition Example

AQL Inspection Level

Sample Method: MIL-STD-105D
Sampling Plan: Single
Major Defect: 0.65% (Major)
Minor Defect: 2.5% (Minor)
General Level: II / Normal


Display Area Definition

display area definition

 


LCD Inspection and Test Standard

 
Item Inspection Standard Description Standard Defect Type
1 LCD Has No Display Reject Major
2 LCM Display Does Not Change Reject Major
3 Display Has Wrong Pattern Reject Major
4 Missing Segment on Display
Reject Major
5 Dim Segment on Display
Dim Segment
Reject Major
6 Wrong LCD Viewing Direction Reject Major
7 Dim Display See Sample Major
8 LCD color variation See Sample Major
9 Pattern Parallelism
Acceptable Range    
L <a b    
≧ 20mm |0.43°| ≦ 0.15mm Accept  
≧ 30mm |0.38°| ≦ 0.2mm  
≧ 40mm |0.43°| ≦ 0.3mm  
≧ 50mm |0.40°| ≦ 0.35mm  
≧ 60mm |0.43°| ≦ 0.45mm  
≧ 70mm |0.41°| ≦ 0.50mm  
≧ 80mm |0.43°| ≦ 0.60mm  
≧ 90mm |0.41°| ≦ 0.65mm  
≧ 100mm |0.43°| ≦ 0.75mm  
10 LCD Display Pin Hole
lcd display pin hole
Standard    
Ø = (x + y) / 2 QTY    
Ø ≦ 0.25 1 Accept  
Ø > 0.25 1 Accept  
Ø < 1/4 W 1 Accept  
Ø > 1/4 W 1 Reject Minor
11 LCD Display Broken Segment (Dots)
broken lcd segment sample
Standard    
X y QTY    
≧ 1/4 b ≧ 1/4 a 1 Reject Minor
(X or y) ≧ 0.2mm 1 Reject Minor
≦ 1/4 b ≦ 1/4 a 1 Accept  
≦ 1/5 b ≦ 1/5 a 2 Accept  
12 LCD Display Black Spot or White Spot
lcd display spot
Ø = (x +y) / 2 QTY  
Ø < 0.10   Accept  
0.1 < Ø ≦ 0.20 2 Accept  
0.20 ≦ Ø < 0.25 1 Accept  
0.25 < Ø ≦ 0.4 0 Reject Minor
Ø > 0.4 0 Reject Major
13 LCD Display Excess Black Line or White Line Black Line / White Line (L x w) mm QTY  
(L ≦ 1.0) × (W ≦ 0.025) 2 Accept  
(1.0 < L ≦ 1.5) × (W ≦ 一 ‧ 0.025) 1 Accept  
(L > 1.5) × (W ≦ 0.025) 0 Reject Minor
(L > 2) × (W > 0.025) 0 Reject Major
14 Backlight Does Not Function Reject Major
15 LED Does Not Function or Dim Reject Minor
16 Backlight Defect (dirt or scratch) Reject Minor
1 LCD Inspection Description Standard Defect Type
1.1 LCD Color Variation See Sample Minor
1.2 LCD Broken Reject Major
1.3 Wrong Polarizer of LCD Reject Major
1.4 Spot on LCD Surface Reject Major
1.5 Scratch on LCD
lcd scratch
Ø = (x + y) / 2
Scratch = Ø QTY  
Ø < 0.1 Except Accept  
0.1 ≦ Ø ≦ 0.15 2 Accept  
0.15 < Ø ≦ 0.25 1 Accept  
Ø > 0.25 1 Reject Minor
1.6 LCD Scratch Depth
lcd scratch depth
Scratch = L Scratch = W QTY  
  W ≦ 0.015   Accept  
< 0.5 W ≦ 0.02 2 Accept  
< 1.0 W ≦ 0.03 1 Accept  
≧ 1.0 W ≧ 0.03 1 Reject Minor
1.7 White or Black Spot on LCD
display spots

Ø = (x + y) / 2
  QTY  
Ø < 0.1   Accept  
0.1 ≦ Ø < 0.2 2 Accept  
0.2 ≦ Ø ≦ 0.25 1 Accept  
Ø > 0.25 1 Reject Minor
Bevy point - Reject Minor
1.8 Black Line in LCD
line on lcd  
(L) (W) QTY  
L ≦ 1.0 W ≦ 0.025 2 Accept  
1.0 < 1 ≦ 1.5 W ≦ 0.025 1 Accept  
1.5 < L W > 0.025 1 Reject Minor
1.9 Round Air Bubble Size QTY  
Ø < 0.15 2 Accept  
0.15 ≦ Ø ≦ 0.25 1 Accept  
Ø > 0.25 0 Reject Minor
1.10 Line Defect (L) (W) QTY  
L < 0.5 W < 0.02 2 Accept  
L < 1.0 W < 0.03 1 Accept  
L ≧ 1.0 W ≧ 0.3 0 Reject Minor
1.11 Finger Print Reject Minor
2 PCB/COB Specification Description Standard Defect Type
2.1 PCB Deformity
pcb deformity drawing example
L H    
≦ 6.0mm ≦ 1.5mm Accept  
> 6.0mm ≦ 1.5mm Reject Minor
< 6.0mm > 1.5mm Reject Minor
> 6.0mm > 1.5mm Reject Minor
2.2 Deformity at PCB Edge, Damage Circuit Reject Major
2.3 Convex at PCB Edge
convex at pcb edge
L H    
≦ 6.0mm ≦ 1.5mm Accept  
> 6.0mm ≦ 1.5mm Reject Minor
< 6.0mm > 1.5mm Reject Minor
> 6.0mm > 1.5mm Reject Minor
2.4 Damage Excess 2 x 2mm at the PCB Corner Reject Minor
2.5 Scratch on PCB Surface See Sample Minor
2.6 Scratch on PCB Coat / Leakage Coat on PCB Surface Reject Major
2.7 Open Circuit Reject Major
2.8 PCB PTH Open Reject Major
2.9 Repair PCB PTH QTY ≦ 2PCS Accept  
QTY ≧ 3PCS Reject Major
2.10 Color Different from One Side to Another Side Reject Minor
2.11 Repaired Solder Mask Area ≦ 30mm2 Accept  
≧ 30mm2 Reject Minor
2.12 Scratch Circuit, Damage Circuit
scratched damaged circuit inspection
a ≦ 1/2w or b < w Accept  
a > 1/2w or b > w Reject  
3 Bezel Specification Description Standard Defect Type
3.1 Wrong Materials   Major
3.2 Incorrect Dimensions   Major
3.3 Bezel Broken   Major
3.4 Rust on Bezel   Major
3.5 Hole or Dirty on Oil Paint Surface   Size cm2/per    
Top Surface Ø ≦ 0.3 2 Accept  
0.3 < Ø ≦ 0.5 1 Accept  
Ø > 0.5 0 Reject Minor
Side Ø ≦ 0.5 2 Accept  
0.5 < Ø ≦ 0.8 1 Accept  
Ø > 0.8 0 Reject Minor
3.6 Bezel Bow or Twist h ≦ 0.01 mm/mm Accept  
h > 0.01 mm/mm Reject Minor
3.7 bezel tolerance d1 - d2 ≦ tolerance Accept  
d1 - d2 > tolerance Reject Minor
3.8 Scratch on Bezel
scratch on bezel
Face Accept QTY    
L W Not Defined See Sample  
- W ≦ 0.15  
L ≦ 3 W ≦ 0.20 2  
L ≦ 2 W ≦ 0.3 2  
- W > 0.3    
Side Accept QTY    
L W      
- W ≦ 0.2 except See Sample  
L ≦ 3 W ≦ 0.25 2  
L ≦ 2 W ≦ 0.3 2  
3.9 Twist Angle α = 45º + 5º
bezel twist example
Accept  
3.10 Void Gap Between Bezel and PCB Reject Minor
3.11 Bezel Clip Incorrectly
Reject Minor
4 Solder Specification Description Standard Defect Type
4.1 Wrong Component Reject Major
4.2 Broken Component Reject Major
4.3 Misalignment
solder misalignment example
Component legs extend beyond the pad and Legs > pad distance (w) on solder area > W2 Accept  
Component legs extend beyond the pad and Legs > pad distance (w) on solder area < W2 Reject Minor
Component Offset
solder component offset example
Solder legs offset distance L <  1/4W Accept  
Solder legs offset L > 1/4W Reject Minor
4.4 Component Assembly Defect
solder component assembly defect example
Reject Minor
4.5 CHIP Components Hoist ≦ 0.5mm Accept  
4.6 CHIP Components Hoist > 0.5mm Reject Minor
4.7 Components Hoist h ≦ 2.0mm Accept  
h > 2.0mm Reject Minor
4.8 Switch (socket) Hoist h ≦ 0.5mm Accept  
h > 0.5mm Reject Minor
4.9 Components Cold Solder or Incomplete Solder Reject Major
4.10 Solder PAD Tilted Up, but Height (h) is less than Solder PAD thickness (a)
solder pad tilt example
Accept  
4.11 Excess Solder Above Components
excess solder example
Reject Minor
4.12 Insufficient Solder Below Components Height or less than Diameter
insufficient solder below components example
Reject Minor
4.13 Solder Area less than Soldering PAD Area by 2/3 Reject Minor
4.14 Trimmed Pin Length Beyond 0.09 inch (2.3mm)
long pin length example
Reject Minor
5 Packaging Specification Description Standard Defect Type
5.1 Wrong Carton Mark Reject Major
5.2 Carton Mark Issue Reject Minor
5.3 Carton Damage Extends more than 150mm Reject Major
5.4 Carton Damage or Scratch is more than 50mm but less than 150mm Reject Minor