By Terry Costlow, IPC online editor

Manufacturing processes  evolve as clever employees find ways to eliminate defects. Ball grid arrays (BGAs)  are a case in point: Some defects like solder ball voids were once considered a  major problem, but some researchers say they’re no longer an issue.

As ball sizes and  spacing have shrunk and processes have improved, voids in solder balls may no  longer be a problem. That’s a marked change from years past, and one that may  call for a standard revision.

For years, J-STD-001, Requirements  for Soldered Electrical and Electronic Assemblies, and IPC-A-610, Acceptability of Electronic Assemblies, had very specific  guidelines for BGA solder balls. The standards say BGAs are defective when  voids account for more than 25 percent of an X-ray image area. But many say  that as more industry investigations have been completed, that criterion is no  longer valid.

When those standards were  written, lead spacings were around 1.27 mm and ball diameters were around 30  mils. Now spacings are 0.5-0.8 mm and ball sizes are 10-20 mils.

“At those dimensions, if  you get a void in the solder ball, there is a high probability it’s going to be  greater than 25 percent of the X-ray image area,” said Dave Hillman, principal  materials and process engineer at Rockwell Collins.

Some say that voids  degrade the solder ball joint, while others have done research showing that  voids have little impact on reliability. Solder joints with voids of any size  likely have other problems that would cause failure.

“There may be some  confounding issues in test methodologies. When you’re seeing a wide diversity  in industry BGA void test results, it can mean test vehicles, test parameters  or testing condition setups are having an influence on the test results in  contrast to other industry tests,” Hillman said.

Hillman will provide  more detail at IPC APEX EXPO^® in San  Diego February 19-21. The title of his Wednesday morning technical conference session  lays out his views on the topic: “The Last Will and Testaments of  Tin/Lead and Lead-Free BGA Voids.”

Hillman, who has worked  closely with Hewlett Packard’s Chris Troxel and Linda Woody of Lockheed Martin  Missile and Fire Control on this issue, feels that it’s time to alter IPC standards  to eliminate the defect criteria on voids.

“If all of the industry  data is reviewed and BGA voids are determined to not be a defect, voids shouldn’t  be in the standards as a defect,” Hillman said.

Instead of focusing on defects,  manufacturers should tweak their processes when they see an increase of void occurrence  or size. Changes in the appearance, size or shape of solder contacts often suggest  that the process is beginning to go out of range. Monitoring the process can be  more effective than testing for defects.

“J-STD-001E and  IPC-A-610 use process control methodologies/protocols in a number of solder  process areas rather than 100 percent visual inspection,” Hillman said.

While noting that there  are many benefits to inspection with the broad range of tools now available,  Hillman commented that there can be cases where visual inspections are no  longer beneficial. That can be the case with solder voids, which aren’t visible  without advanced inspection equipment.

“One of the negative  aspects of X-ray inspection is that it lets you see things you couldn’t see  before. A process engineer now needs to make a determination if the things  being seen are a problem or an observation. Voids in BGAs are the poster child  for this issue,” Hillman said. “You get more immediate benefits by establishing  consistent solder processes than scanning for voids after the fact.”

Hillman feels that it’s  important to update standards as more knowledge is gained. When J-STD-001 and  IPC-A-610 were written, solder voids were thought to be a problem. But as  technology has advanced and new test data is accumulated, researchers have  found that they’re something of a red herring.

“A willingness to  change workmanship criteria shows the flexibility of the industry and IPC,”  Hillman said.

Verifier HR X-Ray Images
The Verifier HR is a high-resolution and high-magnification x-ray system designed for fast intuitive operation.
The Verifier HRs’ small 32 x 34″ footprint design, ease-of-use and high-quality imaging makes it well suited for virtually any quality inspection and defect detection application.

90kV, 5 micron microfocus no-maintenance x-ray source, provides more than enough power to penetrate challenging package types: Ceramic CGAs, BGAs with metal lids or heat sinks and RF shielding.
Sample handling: up to 16 x 18″ (406 x 457mm)
High-resolution imaging components provide ultra clear resolution and contrast.

Small footprint of 32×34″ | 813x864mm easily rolled to where ever needed.
715X magnification provides excellent imaging of semiconductor interconnections, to reveal wire-bonds, die shape/size, die-attach, delamination, voiding, etc.
Safe: CE certified and exceeds all CDRH and FDA safety and radiation requirements.

Sample Handling

The standard sample manipulator has eleven (11) angled set points, to provide angulations up to 180° depending on board size.
Angular viewing provides improved detection of opens, non-wetting and void position.
A motorized oblique view fixture provides up to 360° rotation and +/- 90 deg tilt limited only by the size of the sample.

The MiniV is an economical, multi-purpose bench top x-ray inspection tool; designed for fast 2-D solder quality inspection, component inspection and rework verification.
75kV, 33 micron Board Handling: up to 18Wx 21H” (432W x 533Hmm) Sample Door: 29(W) X 5.5(H)” (737W X 140Hmm) Footprint: 37(W) x 29(D) x 32(H)” (940W x 737D x 813Hmm)

Magnification: variable to 50X
Field-of-View: up to 2“ (50mm)
Safe: CE certified and exceeds all CDRH and FDA safety and radiation requirements.
Quality Inspection Applications
Solder quality and voiding inspection
SMT/PTH, CSP, BGA, QFN and connectors
Bare board mis-registration and drill offset
Rework Verification
Counterfeit Device Screening
Controls and Indicators
Optional Accessories
• Mobile stand (steel frame w/ casters).
*Safety Requirement: The Bench Top MiniV requires a heavy-duty bench capable of holding
600lbs. Intuitive controls and indicators allow operators to use the system efficiently with minimal training.
Emergency OFF switch
Safety Interlock Indicators
ESD Ground strap terminal
Keyed main power switch
X-ray on/off switch
X-ray: KV and mA controls
Camera: 2/4″ I.I., zoom and gain controls
Computer Workstation
Control Panel
• PC: Intel/ATX mini tower, printer, CDRW
• Flat Panel Display: 19” (480mm) LCD
• Network Ready: Ethernet 10/100 base-T
OS and Image Processor Software
• Operating System: Windows™ XP Pro
• Image Processor: Verifier VIP (standard)

The SEF Systec GmbH as successor of the SEF Robots GmbH continues this tradition. Fix Trade will take care for the BENELUX countries.

SEF offers its customers innovation in technology and expert services. The main principles of the company’s policy are closeness to our customers, expert knowledge and the highest quality.

Quins-easyInspect reliably, quick and „brilliantly simple“!
Quins-easy – a practical inspection system with many advantages for your quality protection.
Because of the simple useage it is possible to you to test units in least time, 100 % correct and without programming effort.
You do not need any extensive inspection programs. You save a lot of time and costs, and you win safety in the quality.

	Alternation image display The patented inspection procedure is based on the principle of the automatically trued alternation image display between the test- and the reference image. With this procedure you optimally support your physiological optics. Errors are uncovered immediately, fast and reliably. They could be documented and edited by a great number of automatized functions. At a solution up to 1200 dpi you receive the correct enlargement for every inspection.
	Auto – picture adjustment The position misalignment of the test unit to the reference becomes corrected with the automatic picture adjustment of QUINS – EASY. The automatic picture adjustment positioning both pictures exactly on top of each other. The typical wobbling during the refresh will be avoided.
	Auto – Segmentation The Automatic Segmentation partitions the images in single segments automatically. The user can inspect segment for segment by pressing space bar. Project oriented, segments can be switched off and the row can be defined individually. The guided tour guarantees that nothing is omitted or overlooked.
	Error Marking The advantage of the error marking and the automatic error image saving consists in being able to decollate inspection and repair of each other. The automatically saved error images include your markers. You can test whole lines of units. By using the saved error images it is possible to rework erroneous units at a separate place of work. All pictures are saved in jpg – format und can be displayed on every computer. The error identifications can be defined individually and preset for the user in a list.
	Statistic During the inspection all results and error markings are registered automatically. The statistic – function shows you your typical defects.. This is an essential advantage for the process optimization. You have at any time all dates of your inspection series at a glance and can carry out correspondingly improvements in the process of manufacture.
	Auto – Archivating Also positive pictures can be archivated automatically.
	Parallelscanning With the Parallel Scanning you scan the next unit while you are testing. That saves time!
	The difference image display The difference image display filters minimum image differences. Only essential differences are emphasized as error clearly. Through that the shimmering of the alternation image display becomes invisible, and a relaxed working is possible.

Vapour phase upcomming techniques are more and more needed for micro electronic manufacuring. Fix Trade introduces the new models vapor phase line from R&D.

DESCRIPTION:

R&D Technical Services offers a full line of Single Vapor Reflow Systems. The RD10 provides consistent, uniform and reliable heat transfer in a Belted Inline application for high quality reflow, curing and drying. The RD10 utilizes user friendly controls coupled with a fully automatic inline operation to deliver High Volume Reflow. This system uses a single fluid to generate precise temperature in the reflow chamber. This fluid is environmentally safe and contains NO CFC’s. The RD10 also integrates top and bottom ceramic preheats which allow the user to create the ideal thermal curve for their specific process.

APPLICATION: The RD10 was designed to accommodate high volume applications which are not sensitive to a slight incline at the vapor chamber.

DESCRIPTION: R&D Technical Services Inc. offers a full line of Single Vapor Batch Type Reflow Systems. The RD3 provides consistent, uniform and reliable heat transfer for high quality reflow, curing and drying.

The RD3 utilizes Programmable Logic Controls coupled with a Touch Screen Display to deliver user friendly operation and programming. The system uses a single fluid to generate precise temperature in the reflow chamber. This fluid is environmentally safe and contains NO CFC’s. The RD3 also integrates top and bottom ceramic preheats which allow the user to create the ideal thermal curve for their specific process.

APPLICATION: The RD3 was designed to accommodate high volume multi-shift production and larger sized products. This unit allows any company, regardless of size, to produce products of the highest quality.

SPECIFICATIONS:
Pallet Size:	24″ x 24″
Pallet Clearance Height:	2.5″ or 5″
Unit Size:	137″ long x 46″ wide x 50″ high
Power Required:	208 VAC, 3 Phase, 80 Amps, 60 Hz – Standard 380 VAC, 3 Phase, 1 Neutral, 80 Amps. 50 HZ – Optional
Main heater:	30 KW
Preheat:	6.5 KW
Operating Temperature:	175° to 260° Celsius depending on fluid used
Water Requirements:	4-6 GPM supplied, 25°C – 40°C
Inert Fluid Capacity:	7 gallons

DESCRIPTION: R&D Technical Services Inc. offers a full line of Single Vapor Batch Type Reflow Systems. The RD2 provides consistent, uniform and reliable heat transfer for high quality reflow, curing and drying.

The RD2 utilizes Programmable Logic Controls coupled with a Touch Screen Display to deliver user friendly operation and programming. The system uses a single fluid to generate precise temperature in the reflow chamber. This fluid is environmentally safe and contains NO CFC’s. The RD2 also integrates top and bottom ceramic preheats which allow the user to create the ideal thermal curve for their specific process.

APPLICATION: The RD2 was designed to accommodate medium volume multi-shift production and medium to large sized products. This unit allows any company, regardless of size, to produce products of the highest quality.

DESCRIPTION: R&D Technical Services Inc. offers a full line of Single Vapor Batch Type Reflow Systems. The RD1 provides consistent, uniform and reliable heat transfer for high quality reflow, curing and drying.

The RD1 utilizes Programmable Logic Controls coupled with a Touch Screen Display to deliver user friendly operation and programming. The system uses a single fluid to generate precise temperature in the reflow chamber. This fluid is environmentally safe and contains NO CFC’s. The RD1 also integrates top and bottom ceramic preheats which allow the user to create the ideal thermal curve for their specific process.

APPLICATION: The RD1 was designed to accommodate low volume production and smaller sized products. This unit allows any company, regardless of size, to produce products of the highest quality.

Standard equipments

•Inlet Chain Conveyor

•Hot Air Pre-heater

•Double Wave

•Casting Iron Solder Pot

•Outlet Conveyor

•Finger Conveyor

•Control System

•Finger Cleaner Optional equipments

•Rapid Cooling System

•Center Bar for Solder Pot

•Touch Panel & PLC Control System •V/L type Titanium Finger

If you are considering automating your selective soldering process, then you need to consider the ESS Selective Soldering Machines.  The cost of entry into automated, batch, selective soldering has never been easier with the ESS Selective Soldering Machines. 

Designed for short run, mixed technology applications, the ESS310 & ESS500 Selective Soldering Machines will provide the throughput, accuracy, and reliability you are looking for to improve the productivity of your selective soldering process.

• All-inclusive system – Flux, Preheat, Solder
• Through-hole soldering flexibility – single point, drag, mini-wave, or dip soldering
• Reproducible, “zero defect” solder joints
• On-board, touch screen interface for easy instrument set-up, programming, and parameter control
• Save machine setup time and increase productivity with off-line programming with photoscan and Gerber software
• Flexibility with wettable and specialty nozzles

 View video of ESS Selective Soldering Machines

Get A Quote      View Literature      

Cleaning with plasma At the cleaning of surfaces using plasma, small remains of organic substances are removed. Normally a process of primary cleaning is applied before this cleaning. A sterile ultra pure cleaning with plasma is reached, if the parts which should be cleaned, are treated with oxygen plasma. The organic remains, which should be removed, react with the oxygen and the so produced gas is extracted with the vacuum pump. At some cases other process gases are used such as hydrogen or noble gases. That depends on the pollution or the properties of the substrates which should be cleaned.

Photo resist ashing The removal of photo resist layers is a process in the semi-conductor production, which is very often conducted. For this purpose our systems at micro wave basic have been proved particularly. They form a remarkably low priced and environmentally friendly alternative. Especially after etching of structures and at highly pressured varnishes this technology has proved itself. Even after implantation processes the benefits of micro waves can be used not only through high incineration rates. Mostly oxygen is used a process gas. Because of the high ionization grade and the properties of isotopes of micro wave plasma there is a particular gentle treatment of components and high removal rates. If your application needs a plasma activation using MHz, our systems are also available with MHz frequency. In the micro technology it is increasingly necessary to partly remove very thick varnish layers, which can be done successfully and notably low priced with our plasma equipment of series Q. For these applications our standard systems with silica glass chamber are available with a diameter of 150, 240 and 310 mm. Other dimensions are available on demand.

Afhankelijk van het soort atomen, de verhouding tussen de aantallen geïoniseerde en neutrale atomen en de energie van de deeltjes, zijn er veel soorten plasma te onderscheiden, met elk hun eigen karakteristieken. Doordat plasma elektriciteit geleidt, op veranderingen in elektrische en magnetische velden reageert en chemische reacties kan versnellen, zijn er veel toepassingsmogelijkheden. De tak van de natuurkunde waarin het dynamische gedrag van plasma’s wordt bestudeerd, heet plasmafysica.

Toepassing van plasma

De centrale elektrode van een plasmalamp, waarin blauwe plasma omhoog stroomt. De kleuren zijn het resultaat van de radiale herordening van de elektronen en ionen en de relaxatie van elektronen in aangeslagen toestanden, die terugvallen in lagere energieniveaus.

Een plasma, via twee kanalen van links in een vacuümkamer geblazen. Bovenste plaatje zonder magnetisch veld. Onderste plaatje met horizontaal magnetisch veld, waardoor de geladen deeltjes gedwongen worden zich via de richting van het veld te verplaatsen.

In de analytische scheikunde wordt bij atoomspectroscopie plasma gebruikt in de vorm van inductief gekoppeld plasma (ICP). Met deze techniek kunnen zeer lage concentraties van veel elementen worden bepaald. In een tokamak bevindt plasma zich in een torusvormig vat waarin kernfusie kan plaatsvinden. Met behulp van sterke magnetische velden wordt het plasma op zijn plaats gehouden. Sterren bestaan uit plasma en vermoed wordt dat bolbliksems uit plasma bestaan. Bij het terugkeren van ruimtevaartuigen in de aardatmosfeer wordt aan de voorkant van het hitteschild ook een plasma gegenereerd. Het noorderlicht of poollicht bestaat uit een plasma dat wordt opgewekt door invallende kosmische straling. Daarnaast vinden plasma’s een brede toepassing in de industrie, onder andere voor het bewerken van dunne films, voor de halfgeleiderindustrie en fabricage van dunne-film zonnecellen maar bijvoorbeeld ook voor het aanbrengen van de metaallaag in de binnenkant van chipszakken en de antireflectielaag op autoruiten. Verder worden ze ingezet voor het genereren van licht, zowel zichtbaar licht (o.a. TL-fluorescentielampen) als ook UV- en EUV-licht voor de lithografie. Ook worden plasma’s gebruikt voor de behandeling van textiel, het steriliseren van gereedschappen en het reinigen van gassen.

In de deeltjesfysica doet men volop onderzoek om plasma’s te gebruiken bij het versnellen van de elementaire deeltjes. Door de bijzondere eigenschappen van plasma’s en hun interacties met elektrische velden hoopt men ze ooit effectief te kunnen aanwenden om deeltjesversnellers te bouwen evenwaardig en zelfs beter aan deze in het CERN. Het voordeel van deze plasmaversnellers is dat ze veel kleiner zijn en fundamentele deeltjes tot een grotere snelheid kunnen brengen dan de huidige generatie versnellers, zoals de Large Hadron Collider.

• e.g. structuring of silicon
• Good adhesion of finish and glue on high temperature resistive plastics like PTFE, PFA and FEP.

	Silicon with etching mask before plasma treating Plasma treatment Afther the plasma treatment Example POM: Before plasma treating After plasma treating Example PTFE: Before plasma treating After plasma treating
	Applications: Structuring of Silicon Etching of PTFE For adhesion with paint and glue on plastics resistant to high temperatures, ie. PTFE, PFA, FEP Photoresist ashing Materials / Parts: Components (Semiconductors) Brackets (Dentistry) Pacemakers (Medical) Sensors Uses in Industry: Automobile Joint / sealant maufacturing Electronics Research Institutes Semiconductor technology Medical Technology Micromechanic manufacturing Sensor technology

• Cleaning surfaces of any residues, oils, or contamination
• Activation of various materials before gluing, painting, etc.
• Etching and partial removal of surfaces
• Coating of parts with several possible types of layers (PTFE-like, protective barriers, hydrophobic, hydrophilic, friction-reducing, etc.)

Plasma technology is establishing itself in all areas of industry, and new applications are constantly evolving.

Plasma Technology – Convincing Advantages
Compared to other methods, like flame treating or using chemicals to treat a surface, plasma technology exhibits many important advantages:

• Many surface properties can be obtained exclusively with this procedure
• Can be used in online production or operated independently
• nvironmentally friendly process
• Regardless of geometry you are able to treat powder, small parts, discs, fleece, textiles, tubing, bottles, circuit boards, etc.
• Fabricated parts will not be mechanically changed
• Heating of the parts is minimal
• Operating costs are very low
• Extremely safe to operate
• Process is extremely energy efficient

• Continuous width adjustment, handling boards
  up to 11.8″ (310mm)
• Durable “L” finger board handling for efficient, pallet-less transport
• Streamline design for easy maintenance and cleaning
• Welded steel frame for durablility and compact,
  space-saving footprint
• On-board profiler
• Lead or Lead-free compatible
• Quick change between lead and lead-free operation with solder pot trolley system
• Single or Double wave compatibility

Get A Quote      View Literature      Request Manual      Add To Product Inquiry Cart

Although a solder ball is present in Figure 1, it should have been referred to as a solder attachment rather than a ball. The solder has wet the track due to failure of the resist coating. The coating may have failed as it was applied over a tin/lead coating on the tracking or due to poor print thickness control. Care must be taken to ensure operators recognise the difference as any attempt to remove this type of ball manually will result in a damaged track.

Figure 1: Manual removal of this solder attachment will damage the track.

Solder balling can be caused by poor process conditions with gassing from the flux during wave contact or excessive turbulence as the solder flows back into the bath which causes spitting. Solder balls can be ejected from the joint area during soldering due to excessive outgassing of the PCB. In Figure 2 shown a solder ball is attached to the base of the board on the edge of the resist and must have attached itself to the resist as it separated from the pin.

Figure 2: This solder ball must have attached itself to the resist as it separated from the pin.

Solder balling can be caused by poor process conditions with gassing from the flux during wave contact or excessive turbulence as the solder flows back into the bath, which causes spitting. Solder balls can be ejected from the joint area during soldering due to excessive outgassing of the PCB. In Figure 3, a solder ball is attached to the base of the board on the edge of the resist and must have attached itself to the resist as it separated from the pin.

Figure 3: Another solderball attached to the edge of a resist.

Care should be taken with some solder balls. The example in Figure 4 is on a track and cannot be just knocked off. It is caused by squeeze out of the tin/lead from under the solder mask. or just simple adhesion. As the tin/lead becomes liquid during reflow or wave soldering, the tin/lead expands. The solder ball can form on a track. If the solder resist is thin, solder can wet during wave contact and leave a ball

Figure 4: Solder on a resist can wet during wave contact and leave a ball.

Solder balling during wave soldering has always been around, but the elimination of cleaning after the soldering operation has made it more visible as a process problem. In the past, the solder balls were washed off the board surface during cleaning, out of sight out of mind!

Solder balls are caused by a number of process parameters. In Figure 5, the position of the balls is random. This type of defect is normally caused by spitting from the surface of the wave, which is associated with wave soldering parameters. If the solder is falling a distance from the printed board as the wave separates, the solder can literally splash back from the bath. If the preheat is incorrectly set or the quantity of flux applied increases, the evaporation of the solvent from the flux may be affected. Using a glass plate over the wave should show up the gassing problem. Ideally there should be minimal bubbles visible below the glass when it contacts the wave. The compatibility of the resist and flux should be examined; often the mask can contribute to solder ball adhesion.

Figure 5: Solder balls on this board were caused by spitting from the surface of the wave.

The causes of solder balls are numerous, and they have always been present on the bottom side of printed boards. It has been the increase of the use of no clean low residue soldering that has focused more attention on the problem.

Regardless of the cause, if the solder balls do not adhere to the solder mask when leaving the solder wave, the problem is mostly eliminated. Selecting the best solder mask is the best solution to making a board design robust.

Solder balls are caused by gassing and spitting of the flux on the surface of the wave or by solder literally bouncing back from the solder wave. This is caused by excessive back flow in air or too high a drop in nitrogen environments.

Figure 6: More solder balls caused by spitting.

In Figure 7, the solder balling is random and more likely the result of solder balls spitting or bouncing up from the solder wave. This is caused by volatile materials still remaining from the flux or the height of the wave separation. Try using a piece of white card placed over the wave. Leave it there with the wave running but without boards being processed. Then try the same test with boards going through the machine. This will pinpoint the cause of the problem.

Figure 7: More solder balling caused by spitting. Place a white card over the wave to pinpoint the cause of the problem.