To: AAA - Project Manager, BBB
CC: CCC - Engineer, BBB
Sid - Design Engineer, EEE |
| From: DDD �C IDAX Microelectronics |
| Subject: 15 mil Cap Proposal, GGG Card Assembly, FFF07.02.01 |
| Date: |
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| 1st Report: Proposal & Analysis |
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1. Object
2. Current way vs. Proposed way of Assembly
3. Glob Top Encapsulation vs. Metal cap Placement
4. Spec of Metal cap
5. Advantage of Metal cap
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1. Object: |
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1.1 Solve the difficulty of assembly process
on reaching "15 mil height above board surface" of JJJ card FFF07
1.2 Meet the product design requirement thru the proposed process
1.3 Save huge mfg cost & yield loss
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2. Current vs. Proposed Way of Assembly |
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| Procedures |
Statistic Height |
Current Way |
Proposed Way |
| Die attach |
epoxy |
0.8~ 1.5 mil |
0.8~ 1.5 mil |
Die, e.g.
U1, microcontroller;
U5, finger print sensor |
8.3 mil |
7.0 mil |
| Wire-bond |
above die surface |
3~7mil |
2~ 5 mil |
Glob top
Encapsulation
See Para3 |
Epoxy dome |
23~ 28 mil |
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Metal cap
placement,
Non-conductive
Cap,
See Para3 |
Flat cap |
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15 mil |
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3. Glob Top Encapsulation vs. Metal cap Placement |
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Glob Top Encapsulation w/epoxy |
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Metal Cap Placement, non-conductive |
| Assembling work-Procedures |
Assembling work-Procedures |
| Build dam, epoxy-1 |
Yes |
Place the metal cap |
Snap placement |
Height is cap thickness, or 15 mil |
| Dam height control |
manual |
Clamp the cap with Light force clip |
Snap |
| cure |
Yes |
Seal rim with epoxy |
manual |
| Trim or add the height of dam |
always |
cure |
Yes |
| Dispense the filling epoxy-2 |
manual |
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| Epoxy-2 volume control |
hard |
Height 23~28 mil |
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| Cure |
Yes |
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| Material |
2 kinds of epoxy |
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1 kind of epoxy |
| Metal caps, 4~5 ea/board |
| Equipment & Tools |
oven |
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Oven |
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Light force clip, 4~5 ea/ board |
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4. Spec of Metal Cap |
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| Material |
Alum 7075T7351 |
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(originally developed for aircraft frames) |
| stronger than |
that of feeler gauge (or shim gage) |
stainless steel #304 |
| high carbon steel 1045, 1065) |
| Material Source |
McMaster-Carr # 8885K11,
Ex. .032�� thk x 12�� x 12�� @$12.22 |
| Manufacturing process |
Chemical etching |
Not machined thru machine shop |
| Manufacturing cost |
Not expensive |
Min. labor time to load and unload |
| Chemicals perform the machining job |
| Surface treatment |
Standard Anodizing |
become
non-conductive skin |
| Black colorized |
Block UV & absorb optical random light |
| Configuration |
To be designed |
| 5 caps each board |
4 kinds of size each board |
| Cap top thickness |
2.2~2.5 mil |
| Cap rim width |
12 ~20 mil |
| Cap shape |
.38~.5�� Dia. or Rectangular |
| 15 mil th |
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5. Advantage of Metal Cap Placement |
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| Advantage |
Metal Cap Placement |
Glob Top Encapsulation (comparative base, current way) |
| assembly process |
simple |
Complicate |
| High Cpk, or high process capability |
Low Cpk |
| Assembly time |
short |
Long |
| Skill level |
low |
High |
| Assembly labor cost |
Low |
High |
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Save million dollars from mfg cost |
| Quality |
Stable |
Un-stable in height and Varies a lot |
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No disturb on wire-bond like CDIP, LCC package |
Disturb wire-bond like PDIP, SOIC |
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Meet the original design requirement |
feels thin |
Can��t never meet the requirement |
| Looks and feels smart |
| Wire-bond rework |
Just remove cap and do it |
Not possible |
| Quick & easy |
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Save huge yield or (save million dollars from process flexibility) |
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