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
Image
inspection criteria

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

Image
display area

LCD Inspection and Test Standard

Functional Test Standard

Acceptable Range

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
Image
segment missing
Reject Major
5 Dim Segment on Display
Image
segment dim
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
Image
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
Image
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)
 
Image
broken segments
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
Image
display spots
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

Cosmetic Standard - LCD Appearance

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
 
Image
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
 
Image
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
Image
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

Image
lcd scratch depth
(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

Cosmetic Standard - PCB / COB Appearance

2 PCB/COB Specification Description Standard Defect Type
2.1 PCB Deformity
Image
pcb deformity
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
Image
pcb convex 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
Image
scratched circuit
a ≦ 1/2w or b < w Accept  
a > 1/2w or b > w Reject  

Cosmetic Standard - Bezel Appearance

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  
Image
bezel tolerance
d1 - d2 ≦ tolerance Accept  
d1 - d2 > tolerance Reject Minor
3.8 Scratch on Bezel
Image
bezel scratch
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
Image
bezel twist
Accept  
3.10 Void Gap Between Bezel and PCB Reject Minor
3.11 Bezel Clip Incorrectly
Image
bezel clip
Reject Minor

Cosmetic Standard - Solder

4 Solder Specification Description Standard Defect Type
4.1 Wrong Component Reject Major
4.2 Broken Component Reject Major
4.3 Misalignment
Image
solder misalignment
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
Image
solder component offset
Solder legs offset distance L <  1/4W Accept  
Solder legs offset L > 1/4W Reject Minor
4.4 Component Assembly Defect
Image
solder component defect
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)
Image
solder pad tilt
Accept  
4.11 Excess Solder Above Components
Image
solder excess
Reject Minor
4.12 Insufficient Solder Below Components Height or less than Diameter
Image
solder insufficient
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)
Image
solder trimmed pin
Reject Minor

Packaging Standard

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