chipbonder basics
TRANSCRIPT
AE – Assembly – ChipbonderProductsa) Basic Chemistry / Technology• Surface mount adhesives in electronicsassemblyb) Performance Characteristics• Dot profile• Rheology• Dotting throughput
Application / Functiona) Industries / Segment• Introduction to surface mount adhesives inElectronics assembly covering process, productsand equipmentb) Application area• Surface mount adhesive application andintroductionc) Link to customer process, Equip. &Machinery• Process parameters optimisation for variouscustomer applications• Dispensing guidelines
d) Product Selection Criteria & ValueCalculation Process• Chipbonder product guidee) Product Handling• Storage condition and controlf) Success / Failure causes• Trouble shooting and ACHs (Application casehistory)
Testing & Certificationa) Type of Test• Push Testing• Hot strength shear testing
b) Standards / Certification• J -Standard, IPC Standard introduction
What Is A Surface Mount Adhesive?A glue used to bond planar electronics components on a printedcitcuit board temporarily prior to wave soldering operation
DISPENSEADHESIVE
PLACECHIP
HEATCURE
WAVESOLDER
Adhesive Key Characteristics
•Rheology or Dot Profile
•Wet Strength
•Cured Strength
•Hot Strength
•Moisture Absorption
Adhesive Rheology
Definition: Science of flow in materials
In chipbonder terms:To place a dot of adhesive on the substrate without “stringing” and toensure that the adhesive stays in place on the substrate with a predictabledot profile.
Dispensing Background
• Chip placement speeds ever increasing
• Adhesive dispense step increasingly becoming the bottle neck
• Machine manufacturers increasing dispense capability of machines
• Adhesives must keep pace
• High Speed Dispense Chipbonder
• > 40,000 dots per hour
• 3621 / 3609
Component Placement Speeds Increasing
0
10,000
20,000
30,000
40,000
50,000
Dis
pens
e S
peed
s, D
ots/
Hou
r
1987 1990 1994 1998
Fuji GL1 Fuji GL II Fuji GLV Fuji GL 541
Dot Profile
Dot profile produced by dispenser will be affected by:• Volume dispensed• Dispensing temperature• Needle diameter• Needle to board height• Needle movement
Green Strength
• The standard test for product wet or green strength is the Siemens SN59651Sliding Impact Test• This measures the displacement of components after impact down 300mmincline with 15° Angle
Glass Slide Moisture Absorption Test
Resistance In Molten Solder
IPC SM 817 4.5.13 Hot Solder Dip Test•C1206’s on FR4 board are held 12.7mm above a solder bath at 260°Cfor 60 seconds•They are then floated on the solder surface and agitated for a further10 seconds•Siemens spec for Shear Strength in Solder for these components is 1N
Hot Strength Testing
Solder temperaturecontroller
FR4 board movesdown into solder
Solder bath at 260C
FR4 with C1206chips in jig
Solder Bath at 260C
Jig fingers line up to push off C1206 chips
Jig fingers pulled with force gauge after
immersion in solder
Hot Strength Testing
Force Meter MeasuresPull Force in Newtons
Hot Strength Testing
Application Methods
Syringe Dispensing• Pneumatic• Positive displacement
Pin Transfer
Stencil Printing• Conventional metal• Mesh screen
Syringe Dispensing
Stencil Printing
Dispensing Method
Parameters:•Time
•Pressure
•Temperature
•Stand-off Height
•Nozzle size and pitch
Adhesive Quantity
AC
B
M E T A L L I Z A T I O N
S O L D E R L A N D
C > A + B
S M D
P C B
A D H E S I V E D O T
• Squashed dot must provide 80% coverage of surface bonding area of SMDbetween the copper pads
• Dot width to height ratio should be ideally 2:1 to 4:1
Dispensing Nozzle Geometry
0603
Component
0603 dot Size Ø 0.4-0.6 mm
cNozzle
• Diameter = (0.5 Dot Diameter) = 0.2-0.3 mm• Rule of thumb: Nozzle diameter should be x2.5-3 times larger than largestparticle to avoid blocking
Component Dimensions• 1206 - 3.0 mm length x 1.50 mm width• 0805 - 2.0 mm length x 1.25 mm width• 0603 - 1.5 mm length x 0.75 mm width• 0402 - 1.0 mm length x 0.50 mm width
Guideline For Adhesive Dot Size For 1206
0.25~0.5mm
Chip resistor or capacitorNeedle diameter = 0.4~0.5mmNeedle pitch = 1.0~1.3mm
Dot diameter = 0.8~1.0 mm
Guideline For Adhesive Dot Size For 0805
0.15~0.25mm
Chip resistor or capacitorNeedle diameter = 0.4mmNeedle pitch = 0.8~1.0mmDot Diameter = 0.6~0.8mm
Critical Parameters
Dot Profile
substrate
DOT PROFILE IS DETERMINED BY :
Thixotropic recovery rate, viscosity at zero shear rate
Development of Dot Profile
Chipbonder Dot Sizes For VariousComponent Sizes
SURFACE MOUNT ADHESIVEDOT SIZE FOR VARIOUS COMPONENTS
Imperial-Metric Conversion Table
Chipbonder Selector Guide
3611/3607Pin Transfer /
Stencil Printing
7360Chipbonder
Cleaner
348General Purpose
Syringe Dispensing
3609 /3610High Speed
Dispensing System
3615Diff to Bond Surface
3618Improved Humidity
Resistance and Low Ionic
3612 / 3614Varidot / MetalStencil Printing
3616 / 3617High Speed
Stencil Printing
3619 3620Low Temp. cure
High Speed
3621 3622
Ultra High Speed
3629Pb FreeLow Temp. cureHigh Speed
Dispensing Chipbonders
3609
• High Speed, Good Green Strength
• Color: Red
• DPH: 40,000+
• Dot Profile: Peaked
• Cure: 90 seconds @ 150 C
• Shelf life: 6 months DOM
• Recommend 3621if ultra high-speed
Ultra High Speed Dispensing Chipbonders
3621
•Ultra High Speed
•Excellent Green Strength
•Superior Humidity resistance
•Electrical Properties
•Room Temperature Storage
•Color: Red
•DPH: 47,000+ (Jettable)
•Dot Profile: Rounded
•Cure: 90 seconds @ 150 C
•Shelf Life: 10 months DOM
Low Temperature Cure Chipbonders
3619
• High Speed,
• Low Cure Temperature
• Color: Red
• DPH: 40,000+
• Dot Profile: Peaked
• Cure:90 seconds @ 100 C
• Shelf life: 6 months DOM
Stencil Printing
•Current Chipshooters place components at 80,000 chips/hour
•Current syringe dispenser rates are 40,000+ dots per hour
•A single board can be stencil printed in 10 second or less
Generic Printer Parameters
Stencil thickness: 250µStencil material: steelSqueegee material: steelSqueegee angle: 60°Squeegee pressure: 2.0 barSqueegee length: 200mmPrint speed: 30mm/sPrint strokes: single strokeSeparation speed: 1.0mm/sSnap Off: 0 = on contact
Stencil Printing
Key Parameters•Stencil Cleanliness – 7360,Acetone (hazard)•Stencil Pattern•Ambient Temp./Humidity•Printer Settings•Alignment Accuracy
3616•High Speed, Dek Proflow•Color: Red•Speed: 6.0” (150 mm) /second•Dot Profile: Rounded•Cure: 60 seconds @ 150C• 90 seconds @ 125 C•Shelf life : 6 months DOM
Pin Transfer
Key Parameters•Bath Life•Ambient Temp. &Humidity•Bath Temperature•Adhesive Level•Pin Configuration
3607•Low Moisture Pick Up•Color: Red•DPH: Pin Transfer•Dot Profile: Rounded•Cure: 150-180 seconds @ 150 C•Shelf life: 4 months DOM
General Process Recommendations
• Do not dispense adhesive completely from the syringe (allow at least2-3cc left in the syringe)
• Do not allow dispensed adhesive to remain on the board for morethan 1hr before component is placed
• Clean nozzles thoroughly in solvent or ultrasonic bath regularly.
• Change nozzle every shift if possible.
• Inspect nozzle after cleaning and replace worn or clogged nozzles.
• If downloading is done by customer, centrifuge the syringe.
Standard Cure Profile
Typically, cure at 150 deg C > 90 sec
Low Temperature Cure Profile
For 3619, cure at 100 deg C > 90 secFor 3629, cure at 130 deg C > 110 sec
Handling Procedure
• 35 to 45 deg F (2 to 8 deg C)• Refrigerated NOT frozen• Requires thawing to dispense temperature prior to use (Thaw upright)• Thawing time depends on packaging size (1-2hrs)• Too cold is just as bad as too hot. Do not freeze!
• Prolonged low temperatures (below 0 deg C) can lead to the formationof freeze/thaw voiding in the product on bringing up to roomtemperature.• Repeated thermal cycling from refrigerated conditions to roomtemperature can cause an increase in viscosity and void formation.
• The rate of warming from cold to warm temperatures must be sufficientlyslow to avoid freeze/thaw voiding.
Typical Thaw Profile
• The CAMALOT brand name is synonymous with technology leadershipin dispensing systems for surface mount electronics and chip packagingand assembly applications.
• Available in stand-alone and inline configurations, CAMALOT’ssystems are ideal for dispensing underfill, encapsulants, solder paste,and adhesives with unmatched speed and accuracy.
• CAMALOT’s leadership position in dispense pump innovation ensuresthat the optimal technology is available for virtually any application.
• Jetting offers many advantages over traditionalneedle dispensing
• Speed: high flow rate up to 400 mg/second; highshot rate up to 200 dots per second; no Z-axismotion; jets "on the fly" - no stopping between dotsrequired; less height sensing required; no needlebacktracking to prevent fluid stringing.
• Quality: High wet-dispense accuracy; smallerwet-out areas; round, uniform dots;No bent needles; no chipped die; no dripping;reduced part interference; no effects fromwarpage; no corner buildup.
• Easy and quick to clean in 10 minutes or less;maintenance is tool-free; less waste of fluid due tosmall wetted path; consumable parts are lowercost.
• In operation, the jet "flies" over the part or substrate, shootsprecise volumes of fluid in dots, lines and patterns. Jetting multipleshots in the same location creates larger dots. Lines and complexshapes are constructed from adjacent dots.
Typical Thaw Profile
Troubleshooting - Stringing
• The adhesive must have the ability to breakquickly and cleanly from the nozzle as it isretracting.
• Older chipbonder grades will not have thisproperty adequately for the latest range ofhigh speed dispensers
• High speed chipbonder grades can still stringif the dispense volume of the adhesive is toosmall for the nozzle diameter and stand-offheight (resulting in a very tall, thin dot)
NOZZLE MOTION RELATIVE TO PCB
Troubleshooting - Stringing
• The solution is to use a smaller needlediameter/stand-off combination.
• Increasing the anti-string dwell timer (whereavailable) is another solution
• Adhesive may be too cold• Poor or aged adhesive• Increase nozzle temperature might help
TROUBLE SHOOTING -Low Bond Strength
• Adhesive dot size too small.• Insufficient cure conditions• Poor contact between components and PCB.
- Contamination or release agent oncomponents.
Recommend 3615 for difficult to bond componentsand packages.
- Adhesive quality
Troubleshooting -Inconsistent Dot Size
• The dot may be too small for the needlediameter, resulting in the poor wetting of thePCB.
• Temperature changes causing adhesiveviscosity variations. Use temperature controland vision system feedback control of dotquantity.
• Pressure variations due to changing volume andtemperature behind the piston. Use visionfeedback control of dot quantity. More recentdispensers enable the air to be vented back outof the syringe between “dispense-on” signals.
Troubleshooting -Inconsistent Dot Size
• Partial blockage or build up on the walls ofthe needle. Clean nozzles.
• Imbalance in flow through multiple needlenozzles. Clean nozzles, check for damage.
Troubleshooting -Missing Dots
• Missing Dots can occur for one of tworeasons:– Nozzle Blockage
• Due to foreign particle introduced either duringmanufacturing of the SMA or during nozzle attachment atthe customer’s site.
• One common source of blockage is old partially curedadhesive on unclean nozzles
– Air Bubbles• If not introduced in the SMA manufacturing process, then
air bubbles could be entrapped during the attachment ofnozzles and adapters to the syringe.
Troubleshooting -Adhesive on Solder Pad
– Adhesive dot quantity too much– Placement accuracy– Stringing– Adhesive slump or spread
QUESTIONS?