Southern Machinery
Southern Machinery
SMT & THT PCB Assembly Automation for EMS Factories
Surface Mount Assembly Classifications
Three general classes for the intended end use of electronic assemblies have been established. As applications and functionality increase there may be overlap of equipment between classes. The owner of the application has the responsibility to determine the class that applies. Although a single class may be referenced, specific requirements defined in other classes may apply as well. If a class is not stated for a criterion then the single criterion applies to all classes.
Class 1: Consumer Products: This class of product includes non-critical applications which shall be reliable and cost effective but for which extended life is not the primary objective. Examples include products manufactured for general consumer applications.
Class 2 – General Industrial. This class includes high performance commercial and industrial products in which extended life if required but for which uninterrupted service is not critical. Application and environmental considerations should be taken into account.
Class 3 – High Reliability. Equipment in this class includes those equipment which continued performance is critical, equipment whose downtime cannot be tolerated, or equipment used as a life support item. Unless otherwise specified, Class 3 shall be used for soldering requirements on military electronic equipment.
Printed circuit assemblies are manufactured in a variety of ways, exclusively using smt devices or smt mixed with through-hole components. Boards which have both SMC’s and through-hole components are called mixed technology boards. Surface
mount components are conventionally attached to the substrate using the reflow or the wave soldering process. Typically PCBs are assembled in one of the following ways and categorized as:
Type 1:
SMC’s only are placed on one or both sides of a printed circuit board. The components are attached via the Reflow soldering process.
Type 2:
A combination of both surface mount and insertion mounted components on a printed circuit board. Both SMC’s and IMC’s are assembled on the top side of the board while SMC’s only are attached to the bottom of the board. Top side smt components are Reflow soldered, while the through hole and bottom side smt components are Wave soldered.
Type 3:
IMC’s are assembled on the top side of the board while SMC’s only are attached to the bottom of the board. The components are soldered in place via the Wave solder process.
The fast growth of these applications and advanced packages has led to the development of high density boards. As the industry increases the use of these boards and packages in its products, two of the greatest challenges that it will face are; establishing effective printing guidelines and utilizing equipment that can reliably produce a wide variety of assemblies.
A company’s success or failure in the surface mount industry will weigh heavily on its ability to adapt to automated manufacturing practices through innovative product design and development. Manufacturers can effectively compete in the electronics marketplace today only by utilizing automated equipment throughout the entire SMC assembly process. This includes addressing changes in the SMC production process from initial board printing to final inspection. The companies that do not act positively on these factors and successfully adapt to changing trends in the electronics market will find their business being lost to competitors and foreign ventures.
Type 1 – Single Sided SMT
SMT Components (Primary Side only)
Print Solder Paste Place SMT Components
Reflow Solder
Clean(if required) In Circuit Test/Rework
Surface Mount Process 1-13
Type 1 – Double Sided SMT
SMT Components (Primary & Secondary Side)
Print Solder Paste Place SMT Components
Reflow Solder
Clean(if required) Flip PCB
Print Solder Paste Place SMT Components
Reflow Solder
Clean(if required) In Circuit Test/Rework
Surface Mount Process 1-14
Surface Mount Process 1-15
Squeegee Aperture Paste
On Contact
Frame
Print Solder Paste Place SMT Components
Reflow Solder
Components
Flip PCB
Place SMT Components
Cure Adhesive Flip PCB Wave Solder Clean (If Needed) Test / Repair
Insert / Clinch Through-Hole
PCB
Apply Adhesive (secondary Side)
Flip PCB
Place Surface Mount Components
Surface Mount Process 1-16
Insert / Clinch Through-Hole Components (Primary Side)
Apply Adhesive (Secondary Side)
Cure Adhesive Flip PCB Wave Solder Clean (If Needed) Test / Repair
Procedures and Adjustments
CAUTION
The following procedures explain how to properly clean and test an ESD surface.
Clean an ESD Surface
Do not use abrasive or highly alkaline cleaners on polycarbonate. Never scrape polycarbonate with squeegees, razor blades, or other sharp instruments. Benzene, gasoline, acetone, or carbon tetra chloride should never be used on polycarbonate. Do not clean polycarbonate in the hot sun or at elevated temperatures.
- Using a sponge or soft cloth, wash the ESD-protected surface with either a mild detergent or Windex product and lukewarm water.
- After washing, rinse with water and dry thoroughly with a chamois or moist cellulose sponge to prevent water spots.
- To protect the ESD surface after rinsing and drying, recommends applying Kleenmaster Brillianize®. This application helps to maintain the static dissipative coating and reduce the accumulation of dust.
Test Static Dissipative Covers
Periodically and after maintenance, check the machine covers to determine if the dissipative qualities of the cover have changed. The following procedure ensures that static dissipative covers are in fact dissipative.
Tooling
Surface resistance meter (such as 3M 701 Surface Resistance meter and probe).
Comments
The surface resistance should be less than 109 ohms in all areas. If the cover package is no longer dissipative, contact you Universal Instruments Corporation sales representative.
Procedure
- Clean the static dissipative covers using the Clean ESD Surface procedure to ensure the accuracy of the test.
- Using the surface resistance meter, follow the instructions provided by the manufacturer to measure the surface resistance of both the inside and outside of the covers. Measure the resistance at all four corners and at several areas in the middle of the cover. This test checks the integrity of the ESD coating.
- Connect the ground path resistance probe to the meter and chassis ground.
The path to the ground should not be higher than the surface resistance. If it is, clean the frame connections, repair loose or corroded fasteners and ground straps, and check tracks for dirt and/or corrosion.
4. Measure the ground path from the covers to the chassis ground. Take this measurement from both surfaces and all four corners of each cover.
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Fill in “Green Areas” on Summary Sheet Below & Production Need Sheet |
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Calculations in “Blue” or “White” and should not be changed |
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| INPUTS | |||
| Financial | Machine Price | Depreciation Time (Years) |
Electricity Cost ($/kWHr) |
| US$ 205,000 |
5 |
US$ 0.1200 | |
| Machine Data | Configuration | Pass Thru / Non Pass Thru |
Spec Speed |
| Sm Triple Span (2.5/5.0/7.5) | Pass Thru (Automatic BDH) |
22,000 |
|
| Labor Rates / Hour | Machine Operator | Maintenance | |
| US$ 10.00 | US$ 15.00 | ||
| Factory Work Time |
Hours / Day |
Days / Week |
Weeks / Year |
|
20 |
6 |
50 |
|
| Hand Labor |
Hand Labor Rate |
Insertion Rate / Hour |
|
| US$ 6.00 |
250 |
||
| OUTPUTS | |||
| Production Data | |||
| Insertions Needed | 4,900,000 | Annual Component Insertion | |
| Machine Work Time | |||
| Machine Time |
613 |
Hours to MFG | |
| Hours in Year |
6000 |
||
| Machine Utilization |
10.22% |
||
| Machine Yearly Costs | |||
| Depreciation | US$ 41,000 | Straight Line Depreciation | |
| Utilities | US$ 155 | Electricity for Machine & Air | |
| Maintenance | US$ 900 | Parts & Labor for Machine | |
| Operator | US$ 6,132 | Operator Time @ machine | |
| Total Yearly Costs | US$ 48,186 | Sum of all costs | |
| Hand Labor Equivalents | |||
| Labor Hours | 19,600 | ||
| Labor Costs | US$ 117,600 | ||
| MACHINE DRIVEN SAVINGS | |||
| Hand Placement Cost | US$ 117,600 | Per Year | |
| Machine Placement Cost | US$ 48,186 | Per Year | |
| Annual Savings | US$ 69,414 | Per Year | |
|
Price |
Unit |
Notes |
|
|
Machine Cost |
US$ 205,000 |
$ |
Machine Costs |
|
Depreciation Time |
5 |
Years |
Straight Line Assumed |
|
Yearly Deprciation Expense |
US$ 41,000 |
Result |
|
|
Work Days per Week |
6 |
Days |
|
|
Hours Per Day |
20 |
Hours |
|
|
Weeks per year |
50 |
Weeks |
|
|
Hours per Year Available |
6,000 |
Hrs/Year |
Work Hours per Year |
|
PM Hours per 100 Hrs |
12 |
Hours |
Maintenance |
|
Machine Working Hours |
522 |
Hours |
Total Production Hours |
|
Maintenance Intervals |
5 |
Periods |
Maintenance Times |
|
Maintenance Time |
60 |
Hours |
Maintenance Times |
|
Maintenance Labor Cost |
US$ 900 |
Costs |
Labor Hours x Rate |
|
Production Hours Needed |
522 |
Hours |
Machine Production Time |
|
Intrinsic Availability |
94.00% |
Uptime |
Downtime (Increased based on Age) |
|
Lost Hours |
31 |
Hours/Yr |
Downtime |
|
Machine Hours To Produce |
553 |
Hours |
Production Hours |
|
Guide Jaw / Clinch Costs |
US$3,000 |
Cost |
Per Unit |
|
Tooling Replacement |
6,000,000 |
Cycles |
Cycles per replacement |
|
Tooling Replacements / Yr |
0 |
Replacements |
Replacements Needed |
|
Yearly Replacement Costs |
US$0.00 |
Costs |
Total Yearly Tooling Costs |
|
Chain Clip Replacments |
US$780 |
Cost |
Cost Per Replacement |
|
Tooling Replacement |
15,000,000 |
Cycles |
Cycles per replacement |
|
Tooling Replacements / Yr |
0 |
Replacements |
Replacements in a Year |
|
Yearly Replacement Costs |
US$0.00 |
Costs |
Total Yearly Chain Costs |
Continuity Tube Life Expectancy
Applies to tubes used in Generation 8 clinch units.
The expected life span of a Continuity Tube is dependent upon a number of factors including:
- Lead Composition
A Continuity Tube that is subjected to steel leaded components will cause more stress between the cutter, the cutter Bushing, and the continuity Tube. Expect to experience a higher wear rate on a continuity tube that is subjected to stiffer lead material than a continuity tube that is subjected to softer leaded material.
- Lead Diameter
A larger lead diameter will cause more stress between the cutter, the cutter bushing, and the continuity tube. Larger leads being cut will accelerate the wear of a Continuity Tube.
- Tooling Maintenance
Worn Tooling (cutters and cutter bushings) will cause the scrap lead to ‘tear’ instead of cut with a sharp clean cut. This ‘tear’ in the lead will accelerate continuity tube on both the metal tube and the plastic surrounding the metal tube. The tooling should be changed at recommended intervals, sooner if tearing of leads is noticed.
- Working Environment (dust, humidity, temperature, etc.)
The continuity tube should be kept as clean as possible. Dust buildup caused as a result of the cut/form process and clinching process will grind into the metal tube and the plastic surrounding the metal tube possibly causing accelerated wear of the continuity tube.
There are too many variables associated with the performance of a continuity tube to allow Universal to list it as ‘consumable tooling’ and publish an estimated life span. The greatest life span will be generated by keeping the continuity tube as clean as possible, keeping the lead length within the middle of acceptable lead length range, and changing the cutters and cutter bushings on a regular basis.
Continuity Tubes and False Insertion Errors
Proper continuity lead sense is dependent upon the relationship between:
- the continuity tube
- the cutter
- the angle of the lead being cut
- the lead length as the leads are cut.
It is important the lead is bent and touches the continuity tube before the cut takes place, making the position where the lead enters the cut and clinch assembly very important.
As the cutter moves across to the cut position, the lead begins to bend in the direction of the continuity tube. However, once the lead is pinched between the cutter and the cutter bushing, the scrap portion of the lead will no longer be pushed toward the continuity tube. At this point the scrap portion of the lead will actually be forced in the opposite direction of the continuity tube as the cutter shears through the lead.
The following scenario describes what happens if the lead length is set too short. In other words, the lead entrance to the cutter bushing set so the lead is very close the cutter bushing shear point.
By setting the lead length too short, (the lead too close to the cut point of the cutter bushing), the scrap portion of the lead will not be bent far enough to reach the continuity tube as the cutter bends the lead, resulting in a false insertion error. In other words, if the lead reaches the cut point before it has been bent far enough to touch the continuity tube, a false continuity error may occur.
On the other hand, having the lead length too long may cause accelerated wear and damage to the continuity tubes. Forcing the lead into the continuity tube with too much force will cause denting of the continuity tube and wear of the plastic insulation, resulting in premature failure and false continuity errors over time.
Cutter Stroke Speed and false Continuity Errors
The length of time necessary to drive the Cutter from the home position, to the extended ‘cut’ position, can affect continuity sensing. If the cutter speed is set too slow, the cutter air pressure is insufficient, or a mechanical assembly used in the operation of the cutter stroke binds, the cutter will not reach the component lead in the ‘window’ of time necessary for continuity to be sensed. This will result in a false continuity error. Examples of cutter stroke speed problems:
- Pneumatic flow control for the cutters not properly set
- Poor air flow from the valve to the cutter
- Binding in the mechanical linkage from the cutter piston to the cutter
- Lack of sufficient lubrication in the mechanical linkage from the cutter piston to the cutter
- Incorrectly set cutter backstroke (the starting position for the cutter)
- A torn O-ring on the cutter piston which causes a bind in the cylinder
- Lack of sufficient lubrication on the O-ring for the cutter piston
END
PCB Stencil Cleaning Processes
Stencil Cleaning: Consider Your BEST Options
How many stencils are currently in use?
How do you currently clean stencils? Manually? Ultrasonic? Fully Pneumatic?
How much cleaning liquid do you use per month?
Can the process effectively clean fine and ultra fine- pitch apertures?
Does the process offer water and chemical reclamation/recycling?
Is the process fire safe? chemical safe?
Are there any health or safety hazards to consider?
What is the maintenance and potential downtime?
Does the machine consider current and future environmental regulations?
Is it cost Effective, High ROI?
Is there a built-in clean checking system?
Can the process clean dry as well as fresh paste?
Are there other objects to clean such as misprints?
What is the environmental impact?
What are the labor costs of each process?
What are the operating costs?
Is the machine fully automatic or semi-automatic? Programmable?
Does the machine free the operator from the cleaning process?
Does the machine require a specialized operator?
Does the machine require manual re-positioning?
What are the cleaning and drying times?
Does the drying process leave a film?
What size stencil does the process clean best?
Does the machine clean small stencils efficiently?
Does the machine handle large stencils?
Does the process recycle cleaning solution?
Lowers overall cleaning solution usage?
What is the electricity usage?
Overall Considerations:
Labor
Productivity
The Environment
Time
PCB Defects
Misprinted PCB
Solution Usage
If you would like more information or help, we are here to answer any questions you have. We know that the process takes time and there are many considerations. Allow us to help you in your consideration of all factors that can affect your BEST PCB operations! We are always here for any support you need.
Spare Parts:
Featuring Nozzles & Rotary Tables
Have you invested in one of our AI/SMT machines? Then you know that quality is our TOP priority. Our spare parts are of that same superior quality. We know first hand how important choosing the right spare parts are to the success of your factory, as it means higher productivity, efficiency, ultimately bringing you more business. We are dedicated to providing the lowest prices and the highest quality.
Check out our shop, and if you have any questions we are here to fill your needs with the highest quality advice, machines, and parts.
We provide Different Nozzle Brands:
Juki Nozzle, Fuji, Panasonic, YAMAHA, Samsung, odd form nozzle and MORE! Order at SMTHelp.com or contact us for more information!
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ON SALE: Rotary Table assy for Universal Axial Insertion machine
We are your one-stop shop for your accessories. Don’t miss our sales. We are currently offering Rotary Table assy for Universal Axial Insertion Machines for a discount. Visit SMThelp.com for more spare parts or click below to purchase this item!
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https://www.youtube.com/watch?v=Bh8eNgicR2Q
Attention PCB Design Engineers:
For a brief time, we will be giving away a FREE Gerber File.
For the first time, Southern Machinery is giving away a FREE Gerber File! If you need help with your design process, we are gladly here to help. Let us make your manufacturing set-up easy and efficient.
We at Southern Machinery know and understand what is needed for a successful PCB Assembly. If you need guidance with design, CAD, equipment configuration, training, just ask! Southern Machinery is not just a place to buy machines, but also a place to get your technical questions answered. So ask us! We want to help you find your PCBA solutions.