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QUALITY A S S U R A N C E - - - - - - - - - - - - - - - - - - - -
3.3.1
Quality Control
of
Parts and Material.
As semiconductor devices tend towards higher per-
formance and higher reliability. the importance of
quality control of parts and materials becomes para-
mount. Items such as crystals. lead frames. fine wire
for wire bonding. packages. and materials needed in
manufacturing processes such as masks and chemi-
cals. are all subject to rigorous inspection and control.
Incoming inspection is performed based on the pur-
chase specification and drawing. The sampling is exe-
cuted based mainly on Mll-STD-105D.
The other activities of quality assurance are as
follows:
(1) Outside vendor technical information meeting.
(2) Approval and guidance of outside vendors.
(3) Chemical analysis and test.
The typical check points of parts and materials are
shown in Table 1.
Mlttrill.
Plrtl
Wlfer
Milk
Fine
Wirlfor
Wirl
Bonding
Pilltic
Impol'Ulnt
Control It,ml
Apptlr_
Dimension
ShtttRllilt_
D.ttct Denlity
Cryltll Axis
Appelrlnce
Dimension
Rlliltorllion
Grldltion
Appelrlnce
DimenSion
Purity
Elongltion Ratio
Appnr_
Dimenllon
PrOCllling
Accuracy
Pllting
Mounting
Chlrtcterilties
Appelr_
Dimension
L.ak Rlliltanee
Pllting
Mountiftg
Char_rilties
Eltctrical
Char_rilties
Mechanical
Strlngth
Composition
Electrical
Chartctariitici
Thermll
Chartcterilties
Molding
Performlnce
Mounting
Chlrtcttrilties
Point for Check
DIlNglInd Conttmlna·
tion on Surftct
Flit"...
RlliltlllCt
D.fect Numbers
Defect Numben. Scrltch
Dimenlion Level
Uniformity of ,Grldltion
Contlminltion. Scrltch.
Bend. Twilt
Purity Level
Mechanical Str.ngth
Contaminltion. Scratch
Dimenlion Level
Bondabilitv. Solderability
Helt RllilOtlnee
Contlminltion. Scratch
Dimenlion Level
Airtightn ...
BondlbilitV. Solderlbilitv
He.t Rlliltlnce
Mechlnical Strlngth
CharlCtirilties of
Pilitic Mlterill
Molding Performance
Mounting Char_risties
22
3.3.2
Inner Process Quality Control
Inner Process Quality Control performs very important
functions in quality assurance
of
semiconductor
devices. The manufacturing Inner Process Quality
Control is shown in Fig. 3.
(1) Quality Control
of
Semi-final Products and Final
Products
Potential failure factors
of
semiconductor
devices
are removed in the manufacturing process. To
achieve this. check points are set-up in each pro-
cess and products which have potential failure
factors are not moved to the next process step.
Manufacturing lines are rigidly selected and tight
inner process quality controls are executed-rigid
checks in each process and each lot. 100% inspec-
tion to remove failure factors caused by manufac-
turing variables and high temperature aging and
temperature cycling. Elements
of
inner process
quality control are as follows:
• Condition control
of
equipment and worker.
environment and random sampling
of
semi-
final products.
• Suggestion system for improvement
of
work.
• Education
of
workers.
• Maintenance and improvement
of
yield.
• Determining quality problems. and implement·
ing countermeasures.
• Transfer
of
quality information.
(2) Quality Control
of
Manufacturing Facilities and
Measuring Equipment
Manufacturing equipment is improving as higher
performance devices are
needed.
At Hitachi. the
automation
of
manufacturing equipment is en-
couraged. Maintenance Systems maintain opera-
tion
of
high performance equipment. There are
daily inSpections which are performed based on
related specifications. Inspection points are listed
in the specification and are checked one by one to
prevent any omission.
As
for adjustment and
maintenance
of
measuring equipment. specifica-
tions are checked one by one to maintain and
improve quality.
(3) Quality Control
of
Manufacturing Circumstances
and Sub-Materials
The quality and reliability
of
semiconductor
devices
are highly affected by the manufacturing process.
Therefore. controls
of
manufacturing circum-
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