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

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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?