A common misconception about manufacturing (especially among the general public) is that there is no such thing as innovation. The fact is that new assembly technologies are constantly being developed and brought to the market. However, sometimes it is necessary to modify an innovation in order for it to become mainstream.
This is the case with the printed circuit board (PCB) assembly. From the early 1940s to the early 1990s, nearly all printed circuit board components were joined using one of three methods: point-to-point soldering, wave soldering, or reflow soldering.
Some components were assembled using press fit technology. Developed by the telecommunications industry in the late 1970s, this solderless method presses copper alloy pins (separately or preformed into plastic connectors) into through-holes to create a gas-tight electromechanical connection.
The process attracted little interest from other industries because the massive push pins used initially deformed the through-holes and caused microcracks in the circuit boards. That all changed in the late 1990s with the development of compatible press-fit pins, through-hole plating, and the introduction of servo-electric vises that offer precise control over the insertion process.
"Automotive suppliers of non-critical instrument clusters and switch assemblies began using press-fit technology more than 10 years ago," says Joe Lynch, director of Interplex Industries Inc. As these suppliers became more comfortable with reliability, they later used press-fit technology. technology for more critical functions, such as airbag sensors and crash-sensing control systems. Now the method is conventional because it also offers repeatability and ease of assembly.”
In recent years, a top-tier automotive company has used press-fit technology to assemble and test two types of PCB housings. One housing has a 16-pin molded connector with four power connections. The other case has two 16-pin connectors and four power pins.
Assembly and testing is done at a Schmidt Technology Corp. semi-automated workstation. A worker places each package (PCB on top) on a sliding table that transfers the package to a nesting fixture. The printed circuit board is positioned so that the connector pins line up correctly with the through-holes.
Once the cycle begins, a camera takes a picture of the case and circuit board, and a scanner reads the barcode on the circuit board. If the components are not compatible, a "not OK" message appears on an HMI and the device returns the casing to the sliding table. If the components are compatible, the case is loaded into a ServoPress 420 and its ram presses the circuit board onto the pins in 1.5 seconds.
After assembly, the camera performs a pin height check to verify accuracy to within 0.003 inches. The finished carcass is then transferred to a dump location. Total cycle time is 12 seconds. Barcode scanning allows full product traceability.
"Push-fit connections are at least 10 times more reliable than soldered connections according to the IEC1709 standard," says Glenn Nausley, president of Promess Inc. Sensitive components get hot, solder joints get cold, and jumpers of weld are cut.
Much better than soldering
Press fit technology offers many other advantages over solder paste and selective soldering. First, the solder is now lead-free and must reflow at high temperatures, which can damage the connectors and the board.
Press fit assembly can be easily automated, while secondary soldering processes are often manual, time consuming, expensive, and lack quality control. Also, no cleaning fumes, gases, or liquids are required for soldering, which often reduce contact reliability.
Lynch notes that compatible press-fit pins provide a direct contact connection with no metal fillers or voids in the connection. Pin compliance also offers some beneficial flex, including slight movement to compensate for high-vibration environments and temperature cycling.
The press fit pins are made from a copper alloy and each pin carries from three to 50 amps. Originally, the pins were solid with a rectangular cross section, which deformed the through hole when inserted. To counter the problem, vendors have developed compatible pins that are several thousandths of an inch larger than the PCB hole diameter, but compress when inserted.
Once inserted, the pin expands and presses against the rigid sides of the hole to form a gas-tight connection. In addition, the local high pressure in the joint creates a cold welding effect that ensures mechanical and electrical integrity.
The most popular compatible pen design is the "eye of the needle", which has flexible bars on each side. Other compatible designs include the C-section and the action pin. Profile C Pins are crescent shaped and taper to expand or contract to touch the perimeter of the through hole. Action pens feature a split beam design.
The compatible pins not only prevent damage to the circuit board, but also provide spring force to hold and allow connector repair. They also require less insertion force than solid pins and allow for multiple press fit cycles. Because of these advantages, compatible pins are generally preferred.
In certain high temperature applications (above 125°C), press fit pins must be coated for durability. Tin plating or electroless nickel plating is usually sufficient. However, the tin should be kept as thin as possible (1 micron) so it doesn't get scratched when the pins are inserted.
“The most popular pin gauges are 0.64 and 0.81 millimeters to fit 1.016 and 1.486 millimeter holes, respectively,” Lynch explains. “Factors that determine the correct thickness include the spacing or density of the pins in a connector, as well as pin strength and current-carrying requirements. For example, applications that emphasize high mechanical resistance or performance, such as B. Hybrid cars, our macro pens (1 and 1.2 millimeters thick). But parts that require printed circuit boards to transfer data quickly are better off with our micro or mini pins (0.2 to 0.4 millimeters thick).”
Micropens are specifically designed to meet the needs of microwearable technology, including smartwatches, wrist-based monitors, and connected eyewear. Micro and mini pins are easily integrated into sensors, LEDs, and other specialized modules used in mobile medical monitoring devices. The Macro series is designed for industrial bus bars and other high current products with large heat sinks, multiple internal substrates, and complex control circuitry.
According to Frederick W. Grabau, vice president, Autosplice Inc. press-fit pins are available in two thicknesses (0.64 and 0.81 millimeters) and eight widths (0.64, 1, 1.5, 1.8 , 2.8, 6, 6.3 and 9.5 mm) available. global business development for autoempalmes. The insertion and retention forces for the 0.64-millimeter pin are 59.6 and 46.7 Newtons. For the 0.81 pin it is 132.1 and 88.1 Newtons.
All pins operating temperature is -40 to 125°C and can withstand 125°C for 1008 hours. Right angle pins (single and double row) are also available for connecting vertical circuit boards. All products are offered with RoHS lead free coating.
Connectors are molded of durable plastic with a wide range of pins. They can hold as few as three pens and up to 256 pens.
The trend is for increased density and more stringent requirements when used in harsh environment applications. As data rate requirements increase, the differential signal, power supply, and ESD grounding must be more firmly integrated into the connector.
According to Lynch, Interplex recently developed a unique connector for a car supplier. The connector is 1.2 inches wide with 120 pins, each bent at 90 degrees, and 1.6 inches long.
insert and check
Pressing a connector onto a PCB is a simple process that can be done manually, semi-automatically or fully automatically. After connecting the circuit board and placing and aligning the connector on it (or vice versa), the press is activated. Any type of press can be used (toggle, hydraulic, pneumatic and servoelectric) as long as it has the appropriate tools and its ram has the required force.
Pin insertion (one or more) is also easy and can be done manually, semi-automatically or fully automatically. Manual and semi-automatic insertion requires that the pins be placed in the correct holes and secured with a support piece (usually made of UHMW polyethylene) that will not damage the circuit board. The pins can also be placed in a spring-loaded top tool that releases them during insertion.
Fully automatic insertion is done with a sewing machine such as Lazpiur's LZ-Insert-2M, which presses each pin into a through-hole at high volume (up to six per second). An indicator under the circuit board verifies the correct insertion force for each pin, making sure it protrudes slightly from the bottom of the through-hole. Proper board design leaves room for bumps so performance isn't compromised.
At its Dayton, OH facility, Würth Elektronik ICS Inc. relies on various pneumatic and toggle presses from BalTec Corp. to insert push pins and connectors. On presses up to 56 kilonewtons, workers assemble printed circuit boards of all shapes and sizes for farm machinery, fire trucks, golf carts and buses.
According to Chuck Rupprecht, BalTec's vice president and general manager, the company's VK and L-VK series are commonly used for low-volume PCB assembly. Toggle presses offer force capacities from 5 to 12 kilonewtons. They also feature a square pusher to prevent rotation.
Connector vendors often specify top and bottom tooling for each of their plug or connector types. Most connectors, including right angle models, can be inserted with a flat top tool. The lower die supports the PCB during pressing.
Some vendors make connectors with holes in the top that expose the tips of the pins. Tool protrusions fit into these top holes to lock the connector and ensure that the same insertion force is applied to each pin during crimping.
To avoid deformation of the board, a distance of 0.5-1 millimeter should be maintained between the board and the bottom of the connector when pressing. The plastic casing of the connector must also be strong enough to withstand the force of pressure.
"Always make sure the press can generate enough force for the job," recommends Rupprecht. “Let's assume that each pin only requires a few pounds of insertion force. But if a connector has more than 100 pins, you probably need around 500 pounds of force. And if the application requires multiple connectors to mate at once, you may need a 1,000 or 2,000 pound force press.”
Just as important, Nausley says, is making sure the connector and PCB fit together correctly the first time. Otherwise a good insertion is impossible.
“Many things can prevent proper engagement, including a slightly bent pin, using the wrong connector, imperfectly formed holes, and a machine malfunction that causes misalignment,” says Nausley. "If tampering occurs, the press typically damages the connector and circuit board to the point where they are unusable."
To prevent this problem, Promess has developed the Digital Signal Conditioner (DSC) for its electromechanical presses. The DSC has a built-in linearization algorithm that accurately measures the initial engagement force.
According to Nausley, the algorithm together with closed-loop position control ensures that the press stops mid-cycle if it detects a problem.
Most PCB manufacturers also rely on some form of press fit monitoring to ensure quality assembly. Simple load cells can be connected to a manual press to measure and record the pressing force. Semi-automatic and fully automatic devices are capable of documenting multiple variables for the board and connector and displaying them as a force displacement diagram.
“Beyond monitoring the press force, a secondary inspection is required,” says Dave Zabrosky, Schmidt's sales manager. "This inspection can be initiated with a simple pogo switch built into the top or bottom tool."
According to Zabrosky, the ServoPress and ElectricPress series are programmable and capable of checking for the presence of pins before and after crimping, the height of all pins relative to each other, the flatness of the printed circuit board, and the height of the board in relation to the printed circuit board case.
Jim is senior editor ofMOUNTINGand has more than 30 years of editorial experience. Before joining ASSEMBLY, Camillo was an editor atPM engineer,Magazine of the Facilities Engineering Association and Grinding Magazine. Jim has a degree in English from DePaul University.
Can you connect PEX to copper without soldering? ›
If you don't want to bother with soldering, opt for a SharkBite fitting. As described above, this fitting can accommodate a copper pipe on one side and a PEX pipe on the other. Just as the PEX pipe is pushed into the PEX end of the fitting, the copper pipe is pushed into the other end. That's it!Are ProPress fittings as good as solder? ›
Unlike soldering, ProPress fittings do not need a completely cleaned pipe to work. The force of the press creates a strong seal regardless. Unlike soldering, ProPress systems do not need an open flame to be completed. This creates a safer work environment and by not requiring a hot work permit, saves time.Why is soldering pipes going to be illegal? ›
Since the Safe Drinking Water Act Amendments of 1986 the use of lead-containing solders in potable water systems has effectively been banned nationwide. The major impact of the Act has been on solder containing 50% tin and 50% lead (50-50), until then the most widely used solder for drinking water systems.Are SharkBite fittings reliable? ›
SharkBites work better than plastic quick-connects on copper pipes because the lead-free brass body is rigid like the pipe and has a higher pressure tolerance. If you need to repair or replace copper plumbing in your home, a SharkBite fitting is an excellent choice.Do plumbers prefer PEX or copper? ›
Pex pipe is made of a flexible material. They are easy to bend and install in tricky areas, like crawlspaces and corners. Most plumbers prefer to work with pex pipes for this reason.Can I use SharkBite on PEX? ›
SharkBite brass push-to-connect fittings are compatible with PEX, copper, CPVC and HDPE pipe. They come with a PEX stiffener pre-loaded into the fitting for PEX and HDPE, and the stiffener doesn't need to be removed for copper or CPVC applications.How long do SharkBite fittings last on copper? ›
SharkBite fittings last a long time. In fact, SharkBite warrants the fittings for 25 years when used with SharkBite tubing.Why is there a green dot on ProPress fittings? ›
IMPORTANT NOTE: A GREEN DOT ON A VIEGA PROPRESS FITTING INDICATES SMART CONNECT TECHNOLOGY WITH AN EPDM SEALING ELEMENT. A YELLOW DOT ON A VIEGA PROPRESSG FITTING INDICATES SMART CONNECT TECHNOLOGY WITH AN HNBR SEALING ELEMENT.What is the life expectancy of a ProPress fitting? ›
Copper and PVC fittings can last 50 or more years. Even ProPress fittings have a warranty of 50 years (but who knows since they are so new).Are ProPress fittings permanent? ›
Pressing Upon identification, use the press tool to press the fitting, making a permanent leak-proof connection. Pressed ProPress connections are fast, flameless and reliable.
Can you connect copper to copper without soldering? ›
Connecting Copper Pipe with Push to Connect Fittings
However instead of having to solder, you can simply push the fitting onto the copper until it reaches your mark and snaps tight. The fitting will make a tight leak free connection in seconds.
Brazing and press fittings are both reliable and acceptable joining methods for copper pipe.Why do contractors steal copper pipes? ›
Costs change all the time and thieves can make a lot of money selling copper. Theft of copper pipes, tubing, and wiring has been on the rise in recent years due to the increased value for scrap copper. The US Department of Energy estimates that this once minor problem has exploded into $1 billion a year nightmare.Are soldered fittings being banned? ›
“We will take action against anyone who is found to be using lead solder on potable supplies.” Lead solder has been banned for use on domestic drinking supplies since 1987.When did plumbers stop using lead solder? ›
o Solders and flux were defined to be “lead-free” when they contained less than 0.2 percent lead. Before this ban took effect on June 19, 1986, solders used to join water pipes typically contained about 50 percent lead.Do professionals use SharkBite? ›
SharkBite push-to-connect fittings are compatible with a variety of pipe types including PEX, copper, CPVC, PE-RT and SDR-9 HDPE. Pros who use SharkBite tell us that, in addition to the versatility of SharkBite Universal, they find the fittings to be very easy to work with.Are SharkBite fittings a permanent fix? ›
Many professional plumbing technicians think that SharkBite fittings and other sort of push-fit fittings need to only be utilized as an emergency situation, temporary repair, and not for any enclosed or permanent plumbing system.Do SharkBite fittings ever leak? ›
A bad seal may be why your SharkBite fitting is leaking. SharkBite fittings are designed to create a leak-proof seal. When a SharkBite fitting does leak, the first thing you'll want to do is see if the pipe is correctly connected to the fitting. By disconnecting and reconnecting the pipe, you may fix the problem.When should you not use PEX? ›
PEX plumbing is fine inside the walls of a home, no matter the temperatures as it can be covered with insulation. However, one of the disadvantages of PEX plumbing is it cannot be used outdoors in cold climates as there is no way to cover them and protect them from freezing temperatures.What lasts longer copper or PEX? ›
Copper pipes can last anywhere from six months to the life of a building. But PEX tubing, when operating within its pressure and temperature ratings, has a predicted life expectancy of 50 years per PPI TR-3.
Are PEX pipes less likely to burst? ›
Thankfully, PEX pipes' ability to expand and resist breakage is a huge advantage compared to metal pipes, which could easily burst from drastic changes in temperature.Do rodents chew on PEX? ›
PEX Pipe Is Vulnerable
Rodents Chewing Through PEX Pipe is a common problem in our area. It doesn't matter how old your home is, if you have an attic, you need to watch for rodent damage to PEX Pipe or PVC. If you're hearing rustling noises coming from the attic, it's time to do an inspection.
Most professional plumbers believe that SharkBite fittings and other kinds of push-fit fittings should only be used as an emergency, temporary fix, and not for any enclosed or permanent plumbing system.How do you stop a push fit joint from leaking? ›
Using wire wool or similar, clean around copper pipe fitting by stop end/cap to remove dirt. Using pair of pliers or a wrench, push/force push end further into pipe. If leak does not stop, drain down, and replace. If all else fails, get a plumber in.Is SharkBite plumbing up to code? ›
Approved by the Uniform Plumbing Code, International Plumbing Code, and National Plumbing Code of Canada, properly installed SharkBite fittings offer permanent connections, says Product Manager Michael Kornegay.Should I sand copper pipe before SharkBite? ›
Do not sand the copper pipe – while it's the easiest way to smooth out the edge of the pipe, this practice should be avoided whenever possible since it disrupts the otherwise even pipe surface and may compromise the seal.Are SharkBite fittings good for hot water? ›
All SharkBite hot water heater connectors are approved for use on electric and gas water heaters with a flu vent.Can you ProPress steam lines? ›
However, ProPress copper fittings are better able to absorb the torsion and can even act as swing joints in the system. So ProPress copper fittings are a better option for steam systems than soldered copper fittings.Can ProPress be used on refrigeration? ›
Neither of the sealing elements are compatible with refrigerant gases, so Propress cannot be used in such appli- cations.Can you bury Viega ProPress? ›
It's one of the most common questions we get: can MegaPress, ProPress and other fittings be used underground? The answer is yes. Viega press fittings are approved for underground installations, per Uniform Code and International Code listings.
Is press fit the future of plumbing? ›
It is becoming a popular method to connect pipes. For several reasons, press fittings make a better choice over conventional methods used to join pipes. Whether it's plumbing projects, HVAC work, or commercial mechanical projects, press fittings provide excellent benefits.How much pressure can a ProPress fitting take? ›
In tests conducted by NSF International, joints made by the ProPress System have rated test pressures of 600 psi, and working pressures of 200 psi within an operating temperature range of 0° to 250° F. The ProPress System has the following approvals and listings: NSF-61 approval for potable water.Can you ProPress soft copper? ›
Viega® ProPress fittings are for use with type K, L and M hard copper tubing from ½" to 4" and soft copper tubing in ½" to 1¼" diameters . All tubing must comply with the ASTM B88 standard . ProPress fittings are approved for installations in both above and below ground applications .What is the most common method of joining pipes? ›
A butt weld is the most common type of pipe joining welding method. Workers use this method to join two pipes of the same diameter. Generally, these joints are most prevalent in commercial or industrial pipe systems.What are the methods of connecting pipe? ›
Common joining methods include: Adhesive bonding, brazing, CSST, flanged, grooved, heat-fusion weld, hubless coupling, mechanical, PEX, press, quick connect, solder, solvent weld, SV gasket, threaded and welding.How do you connect two pipes together without welding? ›
Especially for pipe dimensions of single digit inches, several ways of connecting pipes without welding are possible. Let's have a look at the most popular alternatives: cuttings rings, flaring, radial press fittings and fipeing.How do you connect two pipes without threads? ›
You can take several approaches on how to connect unthreaded galvanized pipes. You can try to thread the pipe or use pipe thread tape to create a bond between the two pipes. Another alternative would involve welding the pipes or connecting them using coupling.What fittings can be used to join pipes permanently? ›
Coupling and Adapter Fittings - Pipe couplers slip over the outside of two pipes to connect them, usually permanently. A coupling can be a reducer, or reducing coupling, meaning they reduce flow by joining a larger pipe to a smaller size. Adapters are used when connecting two pipes of different types.Which material is used to join two pipes? ›
Brazed Joint in Pipe
Brazing is the process of jointing pipes using molten filler material at above 840oC. Brazing is generally used for joining copper pipes or copper alloy pipes. The filler material majorly consist tin which has great affinity towards copper.
A tee, the most common pipe fitting, combines or divides fluid flow. Tees can connect pipes of different diameters, change the direction of a pipe run, or both. Available in various materials, sizes and finishes, they may also be used to transport two-fluid mixtures.
How seamless pipes are joined? ›
Seamless pipe is formed from a cylindrical bar of steel. The bar is heated to a high temperature and then a probe is inserted to create a hole through the cylinder. The cylinder is then transferred to rollers which size the cylinder to the specified diameter and wall thickness.How do you connect metal pipes without welding? ›
Brazing: Brazing involves heating up a filler metal above 800 degrees Fahrenheit which connects the two metals together. The technique of brazing is similar to welding, but is less expensive. Also, brazing acts more like an adhesive as it bonds the two metals together with the filler metal.What happens if you don't use PVC primer and glue? ›
PVC primer maximizes the strength and longevity of the joint connection. A joint will still weld together without the primer, but the connection will not be as strong as the primer allows the cement itself to penetrate deeper into the material.