Solder paste typography for PCB's with BGA and leadless devices. How to avoid solder paste defects on SMT boards.

Here we look the many issues surrounding production faults of PCB assemblies during the SMT assembly process, and how best to avoid them.

If you are involved in the procurement or quality aspect of PCBA manufacturing, you'll of already seen a wide variety of solder defects and problems over the years. In fact, when you goggle 'solder paste defects' you'll be greeted with a wide range of forums, blogs, statistics and solutions for controlling the paste application process. 

Even with a top of the range stencil printer, along with all if its related cleaning and handling equipment comes a complicated set of rules to ensure that paste application is correct. At Gemini we use a completely different technology called solder jet printing. We are among a number of global based companies who are now adopting this process, to remove the many constraints of traditional stencils. In fact companies such as GE, Thales and BAE have chosen to adopt solder jet printing.

If you've previously had a problem with floating  QFN devices, or poor connections on BGA devices, its typically due to the volume of paste during the SMT process. Traditional stencils have a physical limit, for the distance between devices and the Z height.

Here we can see the the reasons why stencils have reached the limit of capability for high mix technology PCB assemblies. Stepped stencils that can cater for demanding PCB boards designs require a new set of design rules to be used. This is not the case with solder jet printing, due to the ability to land solder paste on any device, and pad at any size.

Here we have a picture of a typical QFN deposit, made with a solder jet printer.
 

As you can see the paste typography is unlike a stencil deposit, and is created with a unique construction for each pad type. With QFNs, the issue of floating after reflow is thus removed. The native paste deposit caters for the spread of paste. And even with stitching vias inside the pad, paste can be applied to fill the via holes, and avoid solder drain. Standard resistors and capacitors have a small deposit inside the heel to avoid tomb stoning during reflow. The dot is around 0.3 mm wide - a size that cant be pasted with repeatability with stencils, as the aperture hole gets blocked up)

When a PCB is reflowed the parts on the board required less remedial work to ensure they comply with IPC standards. Reworking complex parts can often lead to joint integrity problems or damaged devices, so being able to reflow first time is of course the optimum position for any CEM involved with SMT Assembly.

Fist pass rates at AOI (automated optical inspection) are much higher when the solder fillets and joints are correct. False calls are eliminated, when every joint on each board follows a uniform and consistent typography. Less re-work leads to a lower hidden costs for manufactures, that ultimately can be removed from the cost of manufacture.

 

Solder jet printing improves yields and reliability and drives out the out the hidden cost of PCB assembly. For complex PCB and SMT assembly nothing can rival the capability of jet printing.

Gemini Tec use 2 world-class jet printers for all its SMT assembly. Ensuring that we can avoids the common issues found with solder paste application using traditional stencils. Both jet printers provide a full AOI to paste deposits before placement to ensure do deviation on such a critical stage of the SMT assembly process.

In this video we can see within the MY600 jet printer. Filmed in slow motion, the advanced DSP electronics moves the head, with over 3g force, shooting solder paste deposits onto the PCB, through its unique ejector head. Small red lights are just visible showing the AOI process.
 

Here is a example of the latest XILINX Kintex-7 devices, being mounted to a production board built at Gemini during November 2014. Over 1000 solder connections on the FPGA, with the added complication of a mixture of devices that need differing paste volumes.

Complex PCB assembly with XILINX FPGA devices at Gemini Tec Ltd

If you would like to see more about jet printing and how its used to build complex SMT products, contact us at Gemini Tec for more help.

Resources:
A link to our supplier of jet printers and SMT placement equipment.
http://www.mycronic.com/

More details on our services. 
http://www.geminitec.co.uk/smt-production-service

Gemini Tec Ltd

1 The Brook Trading Estate

Deadbrook Lane

Aldershot

Hampshire

GU12 4XU

United Kingdom

+44 (0) 1252 333 444

www.geminitec.co.uk

Embedded Design Show 2014 - Press Release

Embedded Design Show - Press Release

Stand H30

Gemini Tec Ltd will once again be exhibiting at the Electronics and Embedded Design show in 2014, to talk about more leading edge technology being used for rapid and complex PCB hardware manufacturing.

The company has recently installed the UK’s first MY600 solder jet printer and is currently the only UK CEM operating with two Mycronic solder jet printers, enabling it to provide exceptionally high throughput for SMT boards that incorporate challenging components.

This latest investment brings extra production capacity to meet the needs of new customers who are designing PCB hardware using the latest array of components. Solder jet paste printing technology removes the limitations of screen printing with traditional stencils and delivers new levels of quality and reliability for flexible substrates, board cavities, package-on-package, QFNs and new components with small process windows.

One of the major advantages with the latest MY600 platform is the ability to increase paste printing speeds by up to 50%, allowing Gemini Tec to increase its ability to support higher volume orders to the same exacting standards as its current MY500 jet printer.

To ensure Gemini Tec can exceed the requirements of new customers, additional investment has been made into new placement and reflow equipment. A new fully automated SMT line with the latest MY200SX14 and MY200LX14 machines from Mycronic, provides more high mix SMT capability with a 40,000 components per hour capability. 

In its 37^th year, Gemini Tec provide rapid delivery prototypes and production orders for batch sizes of 1 to 1000 units. A full turnkey service includes a dedicated PCB Altium PCB layout service and contract manufacturing service, all conducted from its secure Hampshire based facility.  

Gemini Tec will be on stand H30, joined by its long-standing partner DSL, who provide hardware design services to the embedded computing market. Rory Dear of DSL will be on the stand to talk about their collaborative ‘Functional Building Block’ design approach, where we make the investment in designing and building an all-encompassing platform and our customers select the required ‘functional building blocks’ which are then transplanted into a preferred form factor – greatly reducing cost, risk and time to market.

Gemini Tec Ltd

1 The Brook Trading Estate

Deadbrook Lane

Aldershot

Hampshire

GU12 4XU

United Kingdom

+44 (0) 1252 333 444

www.geminitec.co.uk

DSL Ltd

Aylesford Court

Works Road

Letchworth Garden City

Hertfordshire

SG6 1LP

United Kingdom

+44 (0) 1462 675530

www.dsl-ltd.co.uk

Surface mount machine upgrades - first phase now complete...

Fully automated SMT line, including solder jet printing at Gemini Tec Ltd

The first phase of our SMT  upgrade has been completed this week. 2014 will see a major investment program to increase capacity and efficiency within the SMT production area.

With many new customer wins and increasing volumes of SMT assemblies from our loyal customer base, August sees the completion of the first phase. We have now installed our MY500 solder jet printer in-line with our MYCRONIC MY100 Synergy line, and added extra speed functionality to the placement lines, added additional Agilis feeders.

Blank boards are loaded via our Nutek loaders, along a conveyor into the MY500 solder jet printer. The solder jet printer places small dots of paste to make up the exact volume required, without the need to use a stencil. The process is quick, accurate and checked with on board cameras.

The solder jet printing really helps eliminate the problems with traditional screen printers, such as over paste, leading to shorts or blocked stencil aperture's which left open circuits. If you type 'solder paste defects' into goggle, you'll discover a high number of examples of this common problem.

Using stencils created us alot of solder paste defects, resulting in excessive SMT re-work. The effect of too many solder defects added a significant cost to the PCB assembly process - that ultimately needs to be recovered, setting aside the production delays and onward impact to customer's. Thankfully we are able to use solder jet printing to avoid such problems.

The boards are then run along more conveyors into the first SMT machine, where a selection of component parts are placed with 8 fast placement heads. Clever software works out which components should be loaded. to each machine in the Synergy line to balance the run time, thus by using 2 SMT machines simultaneously, we can half the placement time per board.When we are running NPI and prototype boards, we are able to use each machine as a stand alone placement machine, each building a different customer order.. very clever.

Both machines have electrical verification on-board, this has proved to be very useful when parts are supplied incorrectly, or if the wrong component value is ever presented to the machine, this avoids putting incorrect resistors and capacitors on to the board.

Once all the parts are machine placed, the boards then travel to a inspection conveyor, at this point we are able to add on any SMT parts. This is useful when building 1 or 2 offs, as we do not need to buy reels, tapes or take on large MOQ's etc.

The conveyor takes the PCBs directly into the oven. Our MYCRONIC Synergy 100 line uses a BTU VIP98, with 7 reflow zones. 7 zones allows us to create an accurate thermal profile, for any PCB, regardless of the types of components on board. We spend time engineering a profile for each board, using our knowledge and slim-kic technology.

The boards are automatically unloaded back onto a Nutek de-stacker, and can wait until cooled. The boards are then transferred into our AOI department for 100% inspection. Including 3D X-ray and ERSA camera inspection. This allows us to confirm our process is correct and detect any issues that may need further investigation. Our combination of solder jet printing, placement and reflow ensure the minimal amount of errors.

The process of how we get blank boards to fully populated assemblies is highly important for a contract manufacture to provide customers with high yield products and quick deliveries.We invested in MYRONIC technology, for its speed of set up and accuracy. The solder jet printing technology in amongst the best technologies available in the world.

We have been asked many times, 'why doesn't everyone have solder jet printing?'

The answer to this question has many points. Initially the investment deters traditional CEM's, who make higher volume or less product mix with more simple types of PCB assemblies. Gemini can produce complex boards, in low to medium volume.

Before the days of solder jet printing Gemini would order over 700 stencil's a year (due the the mix of assembly orders) so this made a substantial cost contribution, which has also been passed back to our customer's.

Managing the stencil process from procurements to storage and cleaning, added hidden costs. The quality problems that had risen from stencil printing often led to high amounts of re-work and un-happy customers! Gemini aim for a lean approach to its CEM business which helps optimise its costs to customer's.

Gemini Tec are among a range of leading suppliers in Europe, who have invested into solder jet printing to avoid traditional solder defects and gain many technical advantages, Companies who have also invested include Thales, Halin BV, Netherlands, Appel-Elektronik GmbH, Germany and Page (Belgium) to name a few.

UK & European customers can all benefit from rapid prototype to small and medium volume production with solder jet printing, which provides higher quality products at optimised prices points.

Next month we install the UK's first MY600 solder jet printer and new MY200 SX Synergy line, so more news to follow.

If you wish to know more about us, click our website or get in touch with us by phone.

http://www.geminitec.co.uk

Gemini Tec Ltd

1 The Brook Trading Estate

Deadbrook Lane

Aldershot

Hampshire

GU12 4XU

Tel: +44 (0) 1252 333 444

As seen in New Electronics

We are a UK based manufacture with the capability to help customers seeking time critical PCB layout and rapid PCB assembly services.

We are a respected supplier of technology manufacturing for PCB related hardware and have positioned our service help customers design PCBs with Altium layout tools and obtain entry to our rapid delivery PCB assembly facility.

We have been helping customers for over 37 years and conduct a wide range of PCB designs in Altium, including DDR3. applications. We have highly experienced layout engineers and understand the requirements of both the PCB manufacture and PCB assembly. Our experience allows customers to de-risk from both technical and time delays for challenging projects.

Our knowledge base ensures we implement the optimum PCB layout techniques and best practices. We work closely with our customers through the various stages of placement and routing to ensure all the requirements of the design are fully understood and implemented. Including full consideration for signal integrity (SI) and mechanical constraints with the generation of 3D models.

We offer the UK's fastest possible delivery for complex PCB hardware. With over 45 full time staff we have the resources to manufacture over 600 new products a year. Gemini currently manufactures over 90,000 PCB assemblies a year, ranging from rapid delivery prototypes to batch production orders of 10K.

We have made our reputation by providing complex SMT boards, on time critical orders. Our MYDATA surface mount lines can be set up quickly to build small orders from 1 to 50 units, with full capability for BGA and PoP (Package-on-Package) device technology. Even our skilled IPC technicians can hand solder devices at 0201 package sizes!

What makes us different ?
Our rapid SMT service offers unparalleled lead times due to the use of  'Solder Jet Printing' in our surface mount assembly department. The production of orders can commence immediately without the need to wait for stencils. As we no longer use stencils, we can remove the risk and delays, remove the cost of tooling and removes a number of known technical constraints associated with the use of traditional stencils.

What is 'Solder Jet Printing'?   
The application of the solder paste directly onto the PCB, during the surface mount assembly process.

This is completed entirely without the need to use any paste stencils, instead direct from a jet printing head.

See more here, including a video: http://www.geminitec.co.uk/advanced-smt-technology/solder-jet-printing

How does it work?
The printer shoots millions of small solder paste dots on the fly, at split-second speeds while moving above the blank PCB board. Just like an ink jet printer, it is completely non-contact technology. We can easily apply solder paste onto complex and challenging boards with high precision and repeatability. Thi smakes it suited to high technology boards using devices packages such as, BGA & PoP (package-on-package) devices.

Placing paste with such precision means we never have to compromise on the quality of the solder volume or position, unlike traditional stencils. Its even checked with on board AOI, in seconds. By removing the variables and constraints of stencils, we can ensure PCB assemblies are built to exacting standards. We no longer need to engineer, order, wait, set up and perfect the stencil process, giving rise to numerous advantages. The obvious cost savings mean we no longer need to charge customers for stencils.

Can we help your company?
In addition to our Altium PCB layout service and rapid PCB assembly service, Gemini Tec supports its customers with a full contract manufacturing service, inclusive of material procurement, product test and validation, through to a complete box build service.

Gemini Tec's facility has a wide range of manufacturing tools to build complex PCB products. In addition to our leading edge MYDATA printing and SMT placement technology, we use the very latest in multi camera AOI inspection tools, Ersascope cameras, real time X-Ray and even X- J-tag tools for product conformance.

Book a visit to our superbly equipped and ultra clean ESD facility. A visit to Gemini Tec will allow the full appreciation of the technology and resources in place to build your products and confirm our ability to support your outsourcing needs.

Call our friendly team on +44 (0) 1252 333 444, or mail us with any questions at sales@geminitec.co.uk

Rapid Prototype PCB Assemblies

We are the experts in rapid delivery of PCB assemblies, and have built a reputation for delivering high quality orders in a small time frame. We have the resources to engineer and manufacture over 600 new products a year, with our prototype services dedicated to orders of 1- 50 products. Find out more about our prototype services here: http://www.geminitec.co.uk/smt-prototype-service

Orders from 1 to 10000 pcs for SMT products