In SMT PCB production, solder paste printing is a critical step. Since the solder paste is used to directly form the soldering joint, the quality of solder paste printing affects the performance and reliability of the surface mount assembly. Quality solder paste printing guarantees a quality solder joint and final product. Statistics demonstrate that 60% to 90% of soldering defects are related to solder paste printing defects. So it is very important to understand what causes defects in solder paste printing. ItemFactorsAnalysis1Solder PastePowder formationThe irregular shape of solder powder will easily clog stencil apertures. This will cause a big slump after printing. It can also cause solder ball and short bridge defects after reflow.
A spherical shape is best, especially for fine-pitch QFP printing.Particle SizeIf the particle size is too small, the results will be poor paste adhesion. It will have a high oxygen content and cause a solder ball after reflow.
The particle size should be controlled to about 25 ~ 45 μm in order to meet the requirements for fine-pitch QFP soldering, If the partical size desired is 25 to 30 μm, it should applied with less than 20 μm solder paste for an ultra fine-pitch IC.FluxFlux contains a thixotropic agent, which allows the solder paste to have pseudoplastic flow characteristics. Since the viscosity decreases when the paste passes through the stencil apertures, the paste can be applied to the PCB pads rapidly. When the external force stops, the viscosity will recover to ensure no deformation occurs.
The flux in the solder paste should be controlled to between 8 and 15 percent. A lower flux content will result in excess amount of solder paste applied. Conversely, a high flux content will result in an insufficient amount of solder applied.2StencilThicknessA stencil that is too thick will cause a solder bridge short.
A stencil that is too thin will cause an insufficient solder to be applied.Aperture sizeWhen the stencil aperature size is too big, a solder bridge short can occur.
When the stencil aperature size is too small, and insufficient solder paste will be applied.Aperture shapeIt is best to use a circular-shaped stencil aperture design. Its size should be slightly smaller than the PCB pad size, preventing a bridging defect during reflow.3Printing parametersBlade Angle Speed & PressureThe blade angle affects the vertical force applied on the solder paste. If the angle is too small, the solder paste will not be squeezed into the stencil apertures. The best blade angle should be set around 45 to 60 degrees.
A higher the printing speed means that less time will be spent in applying the solder paste through the stencil aperture surface. A higher printing speed will cause insufficient solder to be applied.
The speed should be controlled to around 20 ~ 40 mm/s.
When the blade pressure is too small, it will prevent the solder paste from being cleanly applied to the stencil.
When the blade pressure is too high, it will result in more paste leakage. The blade pressure is typically set at about 5N ~ 15N / 25mm.4Printing process controlPCB moistureIf the PCB moisture is too high, the water under the solder paste will quickly evaporate, causing the solder to splash and creating solder balls.
Dry the PCB if it was fabricated over 6 months ago. The recommended drying temperature is 125 degrees for 4 hours.Paste storageIf the solder paste is applied without a temperature recovery period, the water vapour in the surrounding environment will condense and penetrate the solder paste; this will cause the solder to splash.
Solder paste should be stored in a refrigerator at 0 to 5 degrees.Two to fours hours before use, place the paste in a normal temperature environment.
1 program composition 1) NC PROGRAM: Z-axis components are placed at X, Y positions at θ angle 2) PCB PROGRAM: substrate length, width, thickness and PIN spacing 3) ARRAY PROGRAM: Z specified components 4) PART LIBRARY: Component Information 5) MARK LIBRARY: tag information 2 NC PROGRAM 1) File name: P— [0-9, A-Z, +, -,.] 2) X, Y coordinates 3) Z No: ZA+ZB, K TYPE and Q TYPE, in single and double FEEDER at 8mm width The difference between K TYPE and Q TYPE: * PIN, no PIN * PITCH: K-21.5mm Q-20mm * ORG: FULL is 1, K-Z1, Q-Z2 when HALF FEEDER: HALF must be used when mixing single and double Z No: Single input K TYPE: Product number, Q TYPE: Even 4) θ angle: θ1, θ2 two, θ3 origin return Θ1:0° 90° 180° 270° Θ2: [set angle – θ1] + correction angle Reverse time is – 5) S&R: STEP REPEAT, PATTERN REPEAT On time is + 6) NO MOUNTING: 0-normal patch, 1-non-patch 7) SKIP BLOCK: 0 – unconditional execution, 1 to 9 – conditional jump, 7 – unconditional jump 8) MARK: 0 – no MARK, 1 – individual MARK, 2-PCB MARK, 3-PATTERN MARK 9) LAND TEACHING: 0-NO, 1-LAND TEACHING [Recommended for the second leg of each side] 10) BAD MARK: 0-NO, 1-BAD MARK [SENSOR] 2-BAD MARK [PCB CAMERA] 11) PROGRAM OFFSET: X=, Y=, move the first point of the patch to the camera center The machine automatically finds PROGRAM OFFSET 12) Z ORG is normally 1 and Z No can be set * NC PROGRAM sequence S&R->BAD MARK->MARK/PROGRAM->ROGRAM OFFSET->MARK 3 ARRAY PROGRAM 1) File name: P— [0-9, A-Z, +, -,.] 2) Z No: Fixed cannot be changed 3) SHAPE CODE: shape coding [machine] 4) PARTS NAME: component name [person] 5) VACUUM OFFSET: NOZZLE↑ +, NOZZLE↓ – [-3～3mm] 6) MASTER Z No.: master, slave Z axis 4 PCB PROGRAM 1) File name: P— [0-9, A-Z, +, -,.] 2) X: PCB length 3) Y: PCB width 4) T: PCB thickness [NO USED] 5) Whether the PIN is used: 0-not used, 1-automatic adjustment 6) Hole spacing: X-10 7) Conveyor speed: 1[H]~8[L] speed, X, Y table speed when fully automatic control 5 MARK LIBRARY 1) SHAPE CODE: shape coding, — X, Y: MARK size PCB material: 0-copper foil, 1-solder PATTERN: shape TYPE: 0-shade, 1-binarization 6 PARTS LIBRARY 1) Shape coding: SHAPE CODE [—, 0-9, A-Z, +, -,.] 2) Component type CLASS: 1 to 99 [1 to 19 transmission recognition, 20 to 99 reflection recognition] Reflection recognition: blue light is absorbed on the orange reflector, and the surface of the component is reflected [Figure A] By recognizing: the white light of the halogen lamp shines on the orange reflector, and the reflector reflects the light. Depending on the component, the edge of the component is reflected to the camera [Figure B] * High reflection recognition accuracy, high passability through recognition, LED off when used * For identification θ: CHIP angular deviation > 35° NG, QFP angular deviation > 25° NG TYPE: For component color, normal condition is 1 [black best] 3) SHUTTER [Shutter]: 0-on, 1-in [Generally open] Closed left and right to ensure component identification [Figure D] 4) Component dimensions SIZE: up, down, left, right Hand-drawn tape to see the reverse side of the component is the same as the camera [Figure C] 5) Component thickness THICKNESS: T-component body thickness 6) Thickness tolerance TOL: T<1 is 20% T≥1 is 15% 7) HEAD SPEED: 1[H]~8[L] X, Y TABLE SPEED: 1[H]~8[L] 8) NOZZLE SELECT: 1~5 9) CAMERA: 0-S, 1-L 10) Component feed direction FEED DIRECTION: 0 to 7, 45° interval 11) Packing method: 0-PAPER [including 32mmPEELING] 1-EMBOSS 2-BULK 12) PUSHPIN: 0-NO USE 1-USE only for 8mm bandwidth 13) Number of feeds FEED COUNT: 1~4 spacing 12mm 14) Auxiliary feed: NO USE 15) Component error correction RECOVERY: 0-NO, 1-YES, 2- large parts are sucking 16) CHIP STAND: 0-NO, 1-YES [Components stand up, thickness sensor is detected, LINE SENSOR application] 17) VACUUM OFFSET: absorbing, for components [-3mm~+3mm] 18) LEAD OUT SIZE: Up/Down Left/Right 19) LEAD PITCH: leg spacing 20) LEAD PITCH TOL: tube leg tolerance 21) LEAD COUNT: Up/Down Left/Right Legs 22) Electrode part ELECTROD: The length direction of the element is the length direction of the electrode [Fig. E] The width direction of the component is the width direction of the electrode 23) CUT LEAD: cut tube legs SIDE: 1~4, there are cut legs on the side COUNT: Cut off: POSTION: Position [Figure F]
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3. 2. Installation accessories, required energy and precautions
1) The source pressure is : 0.4Mpa~0.6Mpa
2)Taken the air over diameter for ?: 12mm, a quick joint is needed
3) The top of the equipment is designed ?: The 125mm exhaust port shall be connected to the outside by independent air duct
4) matters need attention: In order to ensure safe production, customers must ensure that the following security measures are installed in place. Otherwise, the company does not assume any responsibility for security
?It is at least 3 meters away from the electric equipment, away from fire source and heat source
?The ground wire must be connected, and the earth shall not be connected to any other electrified equipment
?The exhaust duct of this equipment shall not be connected to any equipment that can produce heat source. (such as reflow soldering wave soldering of SMT, etc.)
3.3 installation space
To facilitate the maintenance and replacement of spare parts for equipment operation, please leave more than one meter space around the equipment
4.0 Operations Guide
A Preparation before operation
4.1.1 connect the air source to the machine, the gas source is connected well, the display lamp is highlighted and the subsequent work can be continued
4.1.2 check if air pressure in the standard rating (04-0.6 MPa) range. Lower than 0.4mpa will affect the cleaning effect and reduce production efficiency (too low will not activate the machine).
Higher than 0.6mpa can result in damage to the mechanical gas system and all parts of the system.
Adjust the pressure method: pull upward gently to adjust the knob and rotate to the right————- Increase pressure
Go to the right ————– reduce stress
After reaching the required pressure, press the adjusting knob, air pressure lock and pressure to complete the gas connection, and the lamp is highlighted
4.1.3 check whether the top exhaust duct is unblocked or unblocked, which will result in damage to the environment and other consequences of the cleaning effect
4.1.4 check the glass viewport of the door panel through the liquid road to check the solvent reserves. The normal state is above the M position, and the machine can meet the various cleaning effects. The amount of liquid stored in this model is the maximum amount (40L).
4.1.5 if the solvent is not enough, please add adding method in time: see adding solvent method
4.1.6 the pump access panel is opened with a randomly attached triangle key to check whether the ball valves are in normal condition
Ball (the ball valve of pump outlet filter) A ball valve D (pump inlet connection of the reservoir fluid Xiang ball valve) opens, B ((the ball) of white PE tube pump discharge ball valve C (white PE tube pump inlet ball valve) closed
4.2 time setting
4.2.1The setting of the cleaning time (see figure below), gently rotate the timer protection cap to the left and pull up the cover.
General cleaning time is
Minutes, depending on the actual situation, will be different.
This timer is measured in seconds (S) with a range of 10-999 seconds (S).
It can be set to 0, otherwise the machine will not start and may damage the timer and other components.
4.2.2 setting of drying time
Operation method and cleaning time setting.
The general drying time is 4-6 minutes depending on the actual situation.There will be an elongation of the aqueous solvents.
4.2.3The cleaning and drying time are automatic reset.
That is, one set, multiple times (N times).
When the pressure is less than the required number, the timer can be reset and the device cannot be started.
At this point, the black reset button on the upper row of the timer can be reset manually.
4.2.4The counter’s use of this counter is the increment counter, each cleaning a steel net, automatically into the system,
One of them is going up.
The count range is 0-999999.
Mainly used for cleaning work statistics, timely replacement of consumables (filter element), etc.
The filter cartridge should be changed when cleaning up to 1500.
Specific visual cleaning products are different and different.
When the counter displays the number to reach the target number, press the 4.2.3 method to open the cover, then press the black reset button on the left of the timer and the counter is reset.
4.3 placement of steel mesh
4.3.1 press the inner door safety button to open the cleaning room
4.3.2 lift the steel net with http://topmednorx.com both hands, gently place the front in the cleaning room chute roller and push it gently forward to the sliding channel steel
Fixed fixture on the net.
The steel net is in the middle of the fixture and chute. The top of the steel net is at the top of the cleaning room
Steel mesh fixture middle.(see below.)
4.3.3 when placing the steel mesh, the steel mesh shall not be in contact with the door to avoid damaging the steel net and sealant
4.3.4After the steel net is placed, close the cleaning door.
The inner door should be kept in good condition, otherwise, the solvent will be expelled outside, causing machine damage or environmental damage, more likely to cause personal injury
4.3.5 after the inside door is closed, continue to close the outer security door.
The security door is closed and the light is on, so that the following operation can be continued.
If the security door is not closed, the lamp will be retracted and the machine will not be able to start.
After closing the door again, the machine can be started
For the last 20 years any odd-form components that did not come pre-packaged have been assembled BY HAND. Any PCB Assembly in today’s market can gain quick advantages by automating their assembly line. Huge costs are spent unnecessarily on labor and import fees.
If you are considering automation of odd-form components in your PCBA, consider these questions:
Does your desired component come available in a package?
Is your lead to hole ratio appropriate for automating?
Is the quality and repeatability of the component suitable for automation?
Does your component require lead preparation prior to insertion?
Does your process require that the component is clinched?
Need help with these questions? Let us know and we will help design your Odd-Form Assembly tailored to your needs!
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.
Surface resistance meter (such as 3M 701 Surface Resistance meter and probe).
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.
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.
While in attendance at the 2017 National Association of Music Merchants (NAMM) Show last month we found one thing to be true… THT Equipment is far from dead. The music industry continues to require robust and durable components for high quality and heavy duty gear. GEAR, GEAR, GEAR! And the better the gear the more likely THT was involved in the assembly. Proving that THT is not just surviving but thriving in our high-tech world.
But there are many missing links! Many of these specialty components are still placed by hand and many more are still IMPORTED. Opportunities abound for manufacturers to bring all assembly, quality control, and profits back home. Quality is the name of the game when it comes to being #1 in any product category but costs sometimes hold back some manufacturers. According to Joel Menchey, Menchey Music Service, import costs for audio manufacturers are the highest of all costs. This doesn’t have to be so.
We at Southern Machinery have the solutions to lower costs and improve your manufacturing assembly quality! Our S-600-OF Through-hole & Surface Mounting Multifunction Machine paves the way to incorporate THT with SMT technologies. We can help you design the exact machine for your needs, ordered to spec. It’s a simple conversation for a huge shift in ideology and savings.
Ensuring the Best Design for Final PCB Production Stage with Testing! Ensuring the Best Design for Final PCB Production Stage with Testing!
Avoiding Design Mistakes with Testing
Improve EMS Productivity by Testing Early
PC Board errors are a drain to EMS productivity. Through analysis and testing PCBs in the pilot stages, a smoother and more educated production set-up can be achieved. By performing automatic impedance measurements and testing of components (chip resistors and capacitors) early on, you can ensure the best design for production.
We recommend applying the best design logics when creating your PCB layout and Test, Test, Test for maximum efficiency and output. According to Circuits Assembly’s December 2016 Magazine, here is the list of 5 Most Common PCB Design Mistakes: “1. The components do not suit the production technology 2. Thermal imbalance 3. Incompatibility between fabrication and assembly technology 4. Component placement at PCB edge 5. Placing fiducials on the PCB’s edge.”
Once you have planned your PC Board with best practices, Southern Machinery’s High-Speed In-line Circuit Board Test Machine will help with testing by incorporating a visual inspection function which allows mounting status checks on each component (e.g.: typo descriptions in alphanumeric characters, orientation, size) on the operator’s monitor will serve to best analyze testing up close. As well as automatically generating test data from mounting data and component list.