ISE 370 Industrial Automation Instructor Thomas Koon Camalot

ISE 370 Industrial Automation Instructor: Thomas Koon Camalot Dispensing System/Stencil Printer 9/16/2021 ISE 370 Industrial Automation 1

Introduction • The main purpose of the discussion is to provide a basic understanding of the Camalot dispensing system and the stencil printer, and the electronic manufacturing processes and systems they support. 9/16/2021 ISE 370 Industrial Automation 2

Topics of Discussion • Overview of the Electronic Manufacturing Processes. • Stencil Printing • Material Deposition • Electronic Manufacturing Terms. 9/16/2021 ISE 370 Industrial Automation 3

Electronic Manufacturing Process – Brief History 1950 -Present - Through Hole Technology. Axial lead 9/16/2021 Radial Lead Interconnect ISE 370 Industrial Automation 4

Electronic Manufacturing Process – Brief History 1980 -Present – SMT (Surface Mount Technology) • Passive Components Active Components • Resistors • Capacitors • Inductors 9/16/2021 Chip Carriers *Plastic *Ceramic ISE 370 Industrial Automation 5

Through Hole vs. SMT Through Hole Features: • Lowest cost assembly technique • 1 and 2 oz. Copper traces for high power applications • Solvent or aqueous based cleaning systems SMT Features: • Up to 10 times size reduction over Through-Hole assembly • Wide range of base materials available • Improved signal to noise ratio when using ceramic base material 9/16/2021 ISE 370 Industrial Automation 6

Type III Assembly Through hole on primary, SMT on secondary side of PCB 9/16/2021 ISE 370 Industrial Automation 7

Wave Solder 9/16/2021 ISE 370 Industrial Automation 8

Surface Mount Assembly 9/16/2021 ISE 370 Industrial Automation 9

Print 9/16/2021 ISE 370 Industrial Automation 10

Visual Inspect 9/16/2021 ISE 370 Industrial Automation 11

Place 9/16/2021 ISE 370 Industrial Automation 12

Reflow 9/16/2021 ISE 370 Industrial Automation 13

Reflow Oven Diagram 9/16/2021 ISE 370 Industrial Automation 14

Standard Reflow Profile 9/16/2021 ISE 370 Industrial Automation 15

Classification of Reflow Technologies Reflow oven types: TYPE A: Vapor Phase (heated solvent) TYPE B: Area Conduction (hot air) TYPE C: Hot Bar TYPE D: IR, Convection/IR and Convection Ovens TYPE E: Laser Reflow 9/16/2021 ISE 370 Industrial Automation 16

Nitrogen in Reflow Nitrogen is used in reflow soldering to drive out the oxygen from the soldering chamber. This prevents the solder pads and component terminals to oxidize during reflow of the solder paste. 9/16/2021 ISE 370 Industrial Automation 17

A Quick Review 1. What are the 2 basic types of PCB technologies? 2. What is at least one advantage of each type of technology? 3. How many of the 9 steps of a Type III PCB assembly process can you name? 4. What are the 2 types of components used in the manufacture of SMT PCB’s? 5. What are some types of reflow ovens? 9/16/2021 ISE 370 Industrial Automation 18

Fluxes *The purpose of flux is to clean surfaces that are going to be joined together to enhance wetting by solder in the molten state. Major Flux Categories: • Rosin based (Pine Tree Sap) • Organic Acid (Type OA). Water Soluble (the flux itself is not water soluble however the conductive residue left after soldering is). • Low Residue No-clean flux. “Leave on” flux 9/16/2021 ISE 370 Industrial Automation 19

Flux Activity *Flux Activity: The ability of materials (activators) in the flux to remove corrosion and make the surface solderable. 3 Types of rosin flux: • R (rosin only) • RMA (rosin mildly activated) • RA (rosin activated) 9/16/2021 ISE 370 Industrial Automation 20

The Solder Processes * Solder is a fusible metal alloy, consisting primarily of tin and lead, used for the purpose of joining together two or more metals at a temperature below their melting point. Two Major Processes: • Clean • No-Clean (no-clean solder requires no-clean flux) 9/16/2021 ISE 370 Industrial Automation 21

Solder Paste Functions Solder paste has to perform several functions: • It needs to be printable • It needs to transport flux and tin/lead to the joint • It needs to coalesce during reflow to form a permanent and reliable electrical connection. 9/16/2021 ISE 370 Industrial Automation 22

Solder Paste *Solder paste is a homogeneous combination of solder particles (ranging in diameter from about 20 to 75 microns), flux, solvent, and a suspension agent. • Solder (metal) particles (63 Sn/37 Pb) • This combination of materials is known as the 'vehicle system'. The vehicle system carries flux, solvent and thixotropic agents which are there to aid printing. 9/16/2021 ISE 370 Industrial Automation 23

Eutectic Solder Eutectic solder is liquidous at 183 C (361 F) Eutectic. An alloy with a lower melting point lower than the melting points of its components. 63% tin and 37% lead (63 Sn/37 Pb) solder is referred to as eutectic solder. Eutectics change directly from liquid to solid, and the reverse, with no intermediate plastic states 9/16/2021 ISE 370 Industrial Automation 24

Stencils *Stencil: Is a thin sheet of brass or stainless steel with openings that match the land pattern of the printed circuit board. Aperture Shape: • Square is Preferred Over Round for Better Paste Release • Corners May be Rounded to Minimize Clogging • Positive Taper with Bottom Opening 25 to 50 microns Larger than the Top 9/16/2021 ISE 370 Industrial Automation 25

Solder Alloy • The alloy is formed to small particles with a diameter of 4 to 40 microns. • For fine pitch printing, meaning lead pitch on 0. 5 mm and below, the particles are typically 20 - 45 microns and for conventional printing 45 - 75 microns. 9/16/2021 ISE 370 Industrial Automation 26

A Quick Review? 1. What is the purpose of flux? 2. What are the 2 main components of solder? What temperature do the turn to a liquid state? 3. What are the 2 main soldering processes? 4. What is “Fine Pitch” ? (Size) 5. What is a stencil? 9/16/2021 ISE 370 Industrial Automation 27

Stencil Printer - Objectives • Name and/or identify the main operating components of the Camalot solder paste printer • Set-up and operate the solder paste printer in order to produce an acceptable electronic assembly (lab Exercise) • State the material requirements, process controls, set-up procedures and troubleshooting techniques regarding the solder paste printer 9/16/2021 ISE 370 Industrial Automation 28

Stencil Printer Outline • Machine Overview • Squeegee Materials & Selection • Solder Paste Printing • Set-up and Operation 9/16/2021 ISE 370 Industrial Automation 29

Stencil Printer Subassemblies • Print Head • Squeegee System • Stencil/Screen Frame • X, Y Table • Vision System 9/16/2021 ISE 370 Industrial Automation 30

Squeege Materials • Rubber • Metal 9/16/2021 ISE 370 Industrial Automation 31

(Screen) Stencil Function • Determines the pattern of solder paste • Solder paste is placed directly on the stencil then squeegees force the paste through the opening 9/16/2021 ISE 370 Industrial Automation 32

Metal Squeege • Work well with metal foil stencils • Minimal scooping of paste from apertures • Reduced print variability • Reduced set-up time • Reduced sensitivity to other printing variables • Higher manufacturing yields • Less Bleeding • More expensive than rubber • Easily damaged 9/16/2021 ISE 370 Industrial Automation 33

Rubber Squeege • Work well with screen printing and stencils • Compatible with non-wear resistant emulsions • More compatible with rough inner layer presented by • • wire mesh Sensitive to other printing variables Can be specified at different hardness levels High durometer reading 70 recommended for stencil printing Easily worn out 9/16/2021 ISE 370 Industrial Automation 34

Rubber Squeege 9/16/2021 ISE 370 Industrial Automation 35

Metal Stencil Types • Laser Cut Stainless Steel with Ni Plating– Standard Pitch= 0. 8 to 1. 0 mm. Fine pitch 0. 5 mm or less • Electroformed Co or Cr Hardened Ni Ultra-Fine pitch. < 0. 5 mm • Chem Etch – 1. 27 mm pitch and greater 9/16/2021 ISE 370 Industrial Automation 36

Wire Mesh Screens • • 9/16/2021 Patterned by polymer emulsion Emulsion carries the pattern and the mesh holds it together Generally woven from stainless steel, polyester or nylon Diameter of wire and size of opening in terms of mesh number 100 mesh screen has 100 openings per liner inch (mesh/inch) are varied depending on process requirements Screen is attached to an aluminum screen frame Limited to 50 mil pitch aperture range ISE 370 Industrial Automation 37

Wire Mesh Advantages • Low cost • Fast turnaround • Better surface conformance • Good gasket properties • Works well for prototype runs 9/16/2021 ISE 370 Industrial Automation 38

Wire Mesh Disadvantages • Easy to wear out • Higher squeegee wear • Potential clogging • Longer set-up time • More cleaning and maintenance • Susceptible to temperature 9/16/2021 ISE 370 Industrial Automation 39

Metal Foil Stencils • Apply solder paste in finer patterns • Usually made of stainless steel • Strong base with excellent stability • Thickness from 0. 004” to 0. 008” • Aperture size is determined by component pitch • Hundreds of openings can be etched through the foil with accuracy to +/- 0. 002” (laser cut to +/0. 0004”) • Paste flows freely and uniformly 9/16/2021 ISE 370 Industrial Automation 40

Foil Stencil Advantages • Complete open area • Low squeegee wear • Better print geometry • Easy cleaning and maintenance • Easy set-up 9/16/2021 ISE 370 Industrial Automation 41

Foil Stencil Disadvantages • High manufacturing cost • Less gasket properties • Etch Factor • Need good bonding at metal mask and flexible mesh border 9/16/2021 ISE 370 Industrial Automation 42

A Quick Review? Name the main operating components of the Camalot solder paste printer? 2. What are the 2 main types of Squeege’s? 3. What is the primary function of the Camalot Stencil Printer? 4. What are the 3 main metal stencil manufacturing processes? 1. 9/16/2021 ISE 370 Industrial Automation 43

Set-up & Operation • Printed wiring board registration • Squeegee pressure • Squeegee (print) speeds • Print stroke • Print gap (on/off contact) • Snap-off • Printing modes 9/16/2021 ISE 370 Industrial Automation 44

Liquid Dispensing System Objectives • Name and/or identify the main operating components of the Camalot liquid dispensing system • Set-up and operate the dispensing system • in order to produce an acceptable electronic assembly • State the material requirements, process controls, set-up procedures and troubleshooting techniques regarding the dispensing system 9/16/2021 ISE 370 Industrial Automation 45

Dispensing System Outline • Machine Overview • Solder Paste & Adhesive Selection • Set-up and Operation 9/16/2021 ISE 370 Industrial Automation 46

Dispensing System Subassemblies • X, Y, and Z Axis Gantry • Dispensing Assembly • Vision System • Work board Holder 9/16/2021 ISE 370 Industrial Automation 47

Dispensing Materials • Adhesives • Solder Paste 9/16/2021 ISE 370 Industrial Automation 48

Adhesives 2 Main Adhesives Types: • Thermosetting -Two-part epoxies - (typically thermally cured) • Acrylic –Silicones- (UV cure, Thermal cure, or both) Properties: • Electrically Conductive or Insulating • Thermally Conductive or Insulating 9/16/2021 ISE 370 Industrial Automation 49

Fluid Characteristics for Conductive Adhesives - Thixotropic (more fluid when stressed) - Viscosity ranging from 5, 000 cps to 100, 000 cps - “Stringy” (drawing out a long tail when pulling the needle away from dispensed fluid). - Viscosity sensitivity to temperature (except for silicones). - Sensitivity to moisture. 9/16/2021 ISE 370 Industrial Automation 50

Conductive Adhesive *Anisotropic Adhesive: An adhesive with a low concentration of metal particles to permit conduction in the z-axis only 9/16/2021 ISE 370 Industrial Automation 51

Solder Paste Review Solder pastes function is basically to supply solder material to the soldering spot, hold the components in place prior to soldering, clean the solder lands and component leads and finally to prevent further oxidation of the solder lands. 9/16/2021 ISE 370 Industrial Automation 52

Pumps(End Effectors) Time/Pressure (Air Pressure) 9/16/2021 Auger (Archimedes) Piston (Positive Displacement) ISE 370 Industrial Automation 53

Archimedes Metering Valve (AMV) Camalot uses this type of metering valve 9/16/2021 ISE 370 Industrial Automation 54

Dot Dispensing Sequence Increasing retract speed can have drawbacks: 9/16/2021 ISE 370 Industrial Automation 55

Choice of Needle For Camalot 670 & 680 Rotary Displacement Pumps 9/16/2021 ISE 370 Industrial Automation 56

A Quick Review? 1. Name the main components of the Camalot Liquid Dispensing System? 2. What are the 2 main liquids dispensed? 3. What type of fluid metering pump does the Camalot machine use? 4. What is the function of solder paste? 9/16/2021 ISE 370 Industrial Automation 57

ANSI/IPC-A-610 Rev. B Standards: • IPC is a United States-based trade association that everyone follows! 9/16/2021 ISE 370 Industrial Automation 58

Alloy Temperature Chart 9/16/2021 ISE 370 Industrial Automation 59

Soldering Considerations Solder Type 9/16/2021 ISE 370 Industrial Automation 60

Selector Guide 9/16/2021 ISE 370 Industrial Automation 61

Wire Bonding 9/16/2021 ISE 370 Industrial Automation 62

Type I Assembly 9/16/2021 ISE 370 Industrial Automation 63

Type I Assembly 9/16/2021 ISE 370 Industrial Automation 64

Type II Assembly 9/16/2021 ISE 370 Industrial Automation 65

Type II Assembly 9/16/2021 ISE 370 Industrial Automation 66

Type IIc Assembly 9/16/2021 ISE 370 Industrial Automation 67

Type III Assembly 9/16/2021 ISE 370 Industrial Automation 68