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Each surface finishing has specific characteristics, which mark pros and cons and, referring to cons, right tricks and precautions can be taken during PCB manufacturing.
Let’s go into detail of the most common surface finishes.
HASL Lead Free-HASL Sn/Pb Normative reference IPC-6012
PCB is immersed in a bath of molten tin and then hit by high-pressure hot air jets that flatten the thickness and remove the excess from holes and pads.
Thickness varies from 1 to 45 µm and is influenced by pad geometry, for this reason it is not particularly suggested for HDI PCB with VFP ( Very Fine Pitch) and BGA ( Ball Grid Array).
This finish is not suggested for flex and rigid-flex PCBs since thermic and mechanical stress coming from process air jets could damage the boards.
This type of finishing is particularly suggested for multiple soldering cycles and for long storages since tin alloy is characterized by longer Shelf Life.
ENIG Normative reference IPC-4552
Chemical process which plates the exposed copper with Nickel and Gold.
Nickel thicknesses are usually 3-6 µm, while for Gold the minimum thickness is 0.05 µm as provided in the normative reference.
This chemical finish, differently from HASL, is particularly suggested for HDI PCB with VFP and BGA, since coating planarity and homogeneity are granted.
These characteristics make this finish suitable also for press-fit technology for which it is really important holes’ diameter tolerance respect.
Immersion TIN Normative reference IPC-4554
Immersion Tin, more commonly named Chemical Tin, is a surface finishing, which has begun to be widely adopted from the beginning of year 2000, mainly sponsored in Automotive sector attracted to the chance to have an automatic horizontal process with tin planarity coating, differently from HASL.
This surface finishing results critical for the handling and is particularly sensitive to storage conditions; therefore, is strongly recommended to assemble PCB with this finishing within 3 months from manufacturing date to have an optimal operative window. Is not particularly indicated for multiple assembling given the thin copper thickness (0.8-1 µm) and given that at each soldering step the surface intermetallic layer increases, limiting the weldability.
For this kind of finishing is fundamental the vias treatment, is necessary to plug holes or to keep them completely open to avoid issue such as Acid Traps and consequent risk of delayed hole dismetallization.
IPC4761, guideline for vias treatment, suggests a Tenting double side or complete Pluggin ( Image 2) for this kind of finishing, to avoid that finishing residues could be trapped inside the holes ( Image 1) with the consequence to experience corrosion of hole walls through time.
Immersion Silver Normative reference IPC-4553
Realized by a chemical process of immersion through which a Silver layer with variable thickness between 0,2 and 0,4 µm would be deposited.
Silver finishing, due to thickness, is particularly suitable for technologies where planarity is fundamental such as VFP-BGA- Press-Fit.
Differently form Chemical Tin, it has longer Shelf Life, 6 months more or less, and finishing Rework process is easier.
An important feature of this finishing is packaging through which the manufacturer packs the PCBs; is very important that the paper inserted between PCBs is Sulphur free to avoid contamination of Silver on the surface.
OSP Normative reference IPC-6012
OSP is an organic compound that selectively bonds with copper so to plate copper itself, providing an organic-metallic layer. Thickness, measured in A° (angstrom), protects it until soldering.
OSP is the surface finishing most used in the world, particularly in white industry due to low costs and easy-to-use.
Shelf life is limited, therefore is suggested to assemble PCBs within one month, but the chance to redo finishing on stored pieces makes it suitable for long storage necessities.
Standard OSP process doesn’t fit multiple soldering while OSP HT could support it.
HARD GOLD Normative reference IPC-4552
Hard Gold finishing is composed by Nickel (3-6 µm) and Gold (0,8-1,2 µm), and it is realized through electrolytic galvanic process, that allows the finishing to plate copper.
Gold high thickness makes this selective finishing suitable for interference solutions (PCB with insertion connectors) but not suitable to soldering, even considering the high related costs.
ENEPIG Normative reference IPC-4556
ENEPIG finishing is composed by Nickel (3-7 µm), Palladium (0,05-0,25 µm) and Gold (0,02-0,05 µm), and it is realized through an immersion chemical process, that allows the finishing to plate copper.
ENEPIG was born as an updated version of ENIG, with the addition of a Palladium layer between Nickel and Gold.
Palladium layer plays the role of barrier to avoid Gold migration to Nickel layer, and of Nickel layer covering for the following Gold deposit reducing Nickel Spikes effect.
Moreover, ENEPIG offers high reliable Wire Bonding capacity.
HOT OIL REFLOW Normative reference ECSS
Hot Oil Reflow is a finishing usually used for SPACE products; it is indeed the only ESA (European Space Agency) approved surface finishing.
It consists in re-melting, with high-temperature oil bath, the Tin-Lead electrolytically deposited on surface.
This finishing grants good coating planarity, usually 5-7 µm tin on surface, and limited thermal shock to base material.
Hot Oil Reflow technology, largely diffuse in ‘80s/’90s, isn’t use anymore except from who, such as Cistelaier, works in Space Sector.
In surface finishing’ choice, you need to evaluate its Shelf Life, meaning the operative window which grants the finishing to have a complete PCB weldability.
Finishing Shelf Life is strongly influenced by PCBs packaging and storage.
Is really important to pursue the right storage methodology (suggested by IPC-1601 guidelines) to preserve weldability and reliability, because of the high hygroscopic nature of the base materials with which PCBs are manufactured.
For more details, call us to +39 059 269711 or send and e-mail to email@example.com.
Each sector has specific regulation requirements and each application field presents different technical necessities.
For this reason it is crucial to know not only regulations and be qualified in each industrial sector, but also to be able to answer practically to technical requirements, typical of each different application.
What makes Cistelaier a “unique” PCBs manufacturer, is to be accredited for the following sectors:
- Industrial: ISO 9001:2015
- Aerospace & Defence: UNI EN 9100:2016
- Automotive: IATF:2016
- Medical: ISO 13485
- Railway: ISO/TS 22163
and to handle the following standards
- IPC-A-600, class 2, 3 or class 3DS(A)
- IPC 6012 (Rigid), IPC 6013 (Rigid-Flex), IPC 6016 (HDI) and IPC 6018 (Microwave)
- MIL-P-55110 (Rigid) and MIL-P-50884 (Rigid-Flex)
- ESA-ECSS - Q – ST – 70 – 10C / 11C / 12C
- ESA-ECSS - Q – ST – 70 – 60C
that are are the basis of design and manufacturing of each electronic device.
This is the necessary premise to be able to realize PCBs in each sector.
Then, practically, electronic devices performances could be improved starting from the base materials choice.
The more-than-40-years know-how of production, together with its capability to use different materials to satisfy the more different requirements, allows Cistelaier to supply optimized PCBs for each possible application.
We can support our partners to reach the best performances from their electronic devices in each sector, for each application.
Do not hesitate to contact us, our technicians are at your disposal!
Make a call to +39 059 269711 or send and e-mail to firstname.lastname@example.org.
Sep 29 2020
Date: 29 September, 2020 10:00 PM
One of the main reasons for that is to have developed integrated production systems for the three companies of the PCB Division: Cistelaier in Italy, Techci-Rhône-Alpes in France and EPN Electroprint in Germany.
The aim of this integration process is to make the production systems of the three companies of the PCB Division more and more capable to interact and to replace each other, so that each one of them could offer its own production capacity completing and integrating the one of the others.
In Techci, this integration process has started in 2011 when Finmasi Group acquired it.
Since then, between the Italian plants of Cistelaier and the French plant of Techci has started an accurate technical evaluation and a deep exchange of experiences and technology knowledge.
Harmonic development logics has been carried out, such as base material’s standardization – the chemistry for production included, which is really important in PCBs manufacturing – and technologies's and machinery’s standardization.
The aim was, and still is, to get the best of each company of the PCB Division and to implement it at the PCB Division level so to make it a standard for the PCB Division itself.
This process has allowed enhancing Cistelaier’s and Techci’s best practices maximising the overall results of the PCB Division.
Today the development of the PCB Division is continuing also with EPN Electroprint, a German PCB manufacturer based in Neustadt (Thuringia region) acquired by Finmasi Group in January 2019.
Only after a few months from the acquisition, EPN already qualified and adopted the same preferential materials of the PCB Division, the same chemistry for production and often also the same machineries.
Finmasi Group’s PCB Division integration continues, sure that this logic represents a concrete asset.
Integration activities very similar to those implemented throughout the companies of the PCB Division, have been developed and continue to be subject to improvement also with our Chinese partners for PCB manufacturing.
Indeed, the PCB Division takes advantage of the cooperation of the best Chinese manufacturers to complete its offer, especially for high volumes batches.
This integration allows to offer to our Customers a support wider than that which each one of the companies of the PCB Division could deliver by its own.
This is important, for example, when a higher production capacity is needed, as a result of an order income higher than the forecasted one or when a production breakdown occurs in one of the plants of the PCB Division.
Risk analysis and management are fundamental activities for leading companies in their own market sector such as those of the Finmasi Group’s PCB Division.
www.cistelaier.com - www.techci.fr - www.epn.de
Sep 17 2020
Date: 17 September, 2020 10:00 PM
To grant the quality of PCBs of increasing complexity and technological content all along their life cycle became a “must” for OEM active in all marketing sectors from Aerospace & Defence to Automotive and nevertheless in Rail, Medical and Industrial Automation sectors.
The process of miniaturization together with the new coming needs of PCB consumers in terms of performances of the finished electronic equipment had the cumulated effect to increase the complexity of PCBs and, as a consequence, forced to adopt the most advanced technologies to ascertain PCB conformity both, according to the international standards and according to specific requirements coming from the final customer.
The international standards, the IPC norms before all, suggest, in particular, to improve the interaction among the PCB designers – represented by the final customer in the most of the cases -, the PCB manufacturers and the PCB assembly service companies in order to reduce the criticalities of the PCBA (Assembled PCB) and, more in general, of the finished product.
The test methods to validate the conformity of PCBs are described by the IPC TM650 and by different and additional norms related to specific sectors like the MIL for the Military sector and the ESA ECSS for applications in the Space sector.
The way to prepare and to “read” cross sections are also described by the IPC.
Microsections are adopted to check the internal characteristics of PCBs (i.e copper plating thickness, quality of copper filling for blind vias, quality of resin filled vias in case of via in pad solutions in particular) and for the evaluation of the most critical points like the corners of PTH holes and vias or of the annular ring in where inner layers are drilled so to be connected to each other.
Another important aspect is the verification of correctness of the stack up, mainly, but not only, for PCBs with nets with controlled impedance. With microsections is possible to evaluate the presence and the thickness of each and every layer, and, even more, to evaluate thickness of base copper of the inner layers and of the successive platings with chemical copper and electrolytic copper.
The controlled impedance are calculated in the PCB design phase on the basis of the selected base material to produce it, and then will be rechecked and simulated in feasibility analysis and engineering phase by the PCB manufacturer on the basis of the definitive material agreed by the designer and the PCB manufacturer. The dielectric constant of the insulating material – pre-preg and core of inner layers - together with the section size of the nets determine the value of controlled impedance of nets.
Is possible to check the value of controlled impedance trough specific test coupons designed on the PCB production panel and therefore manufactured together with the PCB.
The necessity to reduce the PCB size forced the PCB designers to increase the number of internal interconnections between layers and to adopt more complex technological solutions like blind vias, single and sequential, stacked or staggered, blind vias and buried vias.
More complex structures with increased drill’s density make the internal structure of PCBs more sensible to thermal stresses related to the soldering process where two options, or a combination of them, are possible: wave soldering process for TH components or SMD soldering process for SMD components.
For this reason, the thermal stress tests are important to simulate the behaviours of PCBs and their robustness during the soldering process of the electronic components on them.
Thermal stresses are executed in order to check and validate the quality of copper plating of PTH holes according to two possible options: 3 thermal stresses at a 288°C (IPC TM 650 2.6) or 6 stress a 260°C (IPC TM650 2.6.27).
In addition to the destructive analysis, so those that force to destroy and waste the PCBs, that are often necessary to investigate the internal characteristics of the PCBs coming from the special processes involved in the PCB manufacturing process, not destructive analysis are performed like the X-Ray Fluorescence Spectroscopy (XRF) to determine the thickness of the PCB finishes (HASL, ENIG, ENEPIG, tin-lead Hot Oil reflow, Immersion Silver, Immersion Tin, iSiG,- Hard Gold).
The analysis of the thickness of the finishes, are not only important to control the process, but they are necessary to prove the conformity of the boards. Not conformity of the thickness of the finishes could, in fact, generate quality problems of electronic components soldering.
Through the contaminometer is also possible to determine the ionic contamination on the PCB surface, on the finishes and on soldermask. This method is known as Resistivity of Solvent Extract ( ROSE) and is performed with the aim to detect excess of halides on PCB surface that could generate soldering defects and weak adhesion of conformal coating.
Moreover, the most recent 3D microscope technologies for inspection allowed to substitute not destructive analysis to destructive ones i.e. to check surface roughness, dimple of filled holes, cavity depth, etching value for RF nets, and for quality verification of laser and mechanical drilled blind vias, back drilled vias included.
This technology allows to significantly reduce the time needed to test and validate the quality of PCBs.
The whole of the aforementioned analysis, together with some additional ones that will be the subject of another short tutorial, grant the conformity of the PCB and its stability during the time.
The results of these analysis are collected in the most common reports adopted to certificate the conformity of products like the FAI Report, the PPAP and the Test Report prepared and filled according to the EN9100, IATF, ISO13485, ISO TS 22163 and ESA ECSS standards and to different/additional requirements coming from customers.
Cistelaier, TECHCI and EPN Electroprint – the three companies of the PCB Division of the Finmasi Group – grant the quality of PCBs through the best available inspection and test technologies.
Higher heat resistance is needed for lead-free assembly processes: laminates that need to resist to high temperature must have a higher Decomposition Temperature (called Td).
Additional features important for the new laminates are:
- uniform glass distribution to get a better quality in laser drilling
- thinner glass fabrics to get better electrical properties
- thin dielectrics for distributed capacitance between power and ground
New laminates “designed” for high-performance PCBs have to be reviewed under thermal-mechanical and electrical aspects.
Here following a list of the typical characteristics to take under consideration during the base material choice.
- Thermal expansion in x, y and z-axis with special impact on the z-axis for the reliability of the vias (e.g. barrel cracking) and withstand multiple pressing processes.
- Parameters for signal integrity and impedance requirements.
- Uniform glass distribution helps to get a better quality in laser drilling.
- Thinner glass fabrics help to get better electrical properties.
- Thin dielectrics make it possible to get a better distribution of capacitance between power and ground.
Glass transition temperature Tg
- The temperature at which the material stops acting as a rigid material.
- Higher heat resistance is needed for lead-free assembly processes: laminates that need to resist to high temperature must have a higher Decomposition Temperature (called Td). This is the temperature that a laminate can withstand when it has lost 5% of its weight by thermal gravimetric analysis (TGA).
- mportant aspects may be the CAF Resistance and moisture absorption.
- Need of “Low Halogen” laminates for the green electronic.
Standard FR4, high Tg Laminates also Halogen Free and specific for High Speed Digital:
- FR4 standard & Leadfree: Iteq IT140 & IT588; Isola Duraver ML104i - Tg 140 °C; Black FR4
- Mid Tg epoxy for Lead-free process: Iteq IT158 -Tg 160 °C; Isola IS400 -Tg 150 °C
- Mid Tg– Halogen Free: Iteq IT40G -Tg 140 °C, IT150G
- High Tg 180°C epoxy (without filler): Iteq IT180 (also No/Low flow Prepreg); Isola IS420& IS410; ARLON 45N
- High Tg 180°C epoxy (with filler): Iteq IT180A & IT180i; Isola PCL370HR; Nelco N4000-29; Hitachi 700GR; EMC 827 i
- High Tg 170°C epoxy – Halogen Free: Iteq IT170GRA1 & IT170G & IT180GN
- High speed application: Nelco N4000-13(Si) & N4800-20(Si); Isola Fr408HR, IS600(series), Astra and I-Tera; Iteq IT200DK and IT150DA(SE), IT-968 (SE), IT-988G, IT-988G SE; Panasonic Megtron6 and Megtron7
- Capacitance layer: OAK-Mitsui Faradflex
High-performances materials for avionic/military application:
- Polyimide Resin System: Arlon 33N, 35N, 84N, 85N, 85HP; Ventec VT901(also No/Low flow); Hitachi MCL-I-671; Isola 95P/96P; NELTEC N 7000VO
- Epoxy Resin System: Arlon® Kevlar 4NK (Tg 170 °C and 4.7 ppm/°C)
- Epoxy and Polyimide Thermount® & Para Aramid fiber: ARLON 55NT/85NT
- Copper/Invar/Copper: tipically 150 μm thick - 17/120/17 μm)
- Thick copper: up to 500 microns and over, for BusBar application and copper inlay&coin technology
- Flexible Laminates-Polyimide film based: DuPont PYRALUX LF; PYRALUX FR
- Flexible Laminates- Polyimide film based Adhesiveless: PYRALUX AP, PYRALUX AP-Plus & PYRALUX TK
- Flexible Laminates-Polyimide based Adhesiveless: UBE Upilex; Iteq IF-2LD; Panasonic Felios
- Emi shielding layer: Tatsuta SF-PC6000 and TATSUTA SF-PC 3300
- Rogers® / Arlon (also Copper/Brass supported): RT/Duroid Family; RO3000 Family; TMM Family; DiClad Family; Isoclad Family; Cuclad Family; AD Family; AR Family; TC Family
- Rogers® / Arlon®: RO4350 & RO4003 (Back up material for discontinued 25N & 25FR but partially applicable)
- Rogers®: ULTRALAM® 3850HT - Liquid Crystalline Polymer (LCP)
- Iteq “new generation” material for RF and Microvawe applications IT-88GMW, IT-8300GA, IT-8338G, IT-8338A, IT-8350G, IT-8350A, IT-8615G with Dk from 3,00 up to 6,15(,05)
- Taconic®: RF25A2, RF35, RF35A2, RF45, RF60, TSM-DS3, Cer10, FastRise, TACLAM Plus and all teflon family (TLX, TLY, TLE)
- Nelco: Mercurywave series, Meteorwave (1000 & 4000 Series) and all teflon family
- Foam: Rohacel HF51.
Jul 13 2020
Date: 13 July, 2020 10:00 PM
Cistelaier, established in 1998 merging the two industrial entities, Cistel S.r.l., established in Genoa in 1976 and Laier S.r.l., established in Modena in 1986, manufactures prototypes, small, medium and large series of a very wide range of printed circuit boards: double-sided, multilayer, rigid-flex, rigid and rigid-flex multilayer HDI PCBs and PCBs manufactured with special materials.
Given all its accreditations, produces all kind of PCBs for all market sectors with a very wide range of materials and almost all finishes.
Techci has been established in 1983 in Saint Genix Sur Guiers, France, their capabilities in PCB manufacturing in terms of technology and services are very similar to Cistelaier’ capabilities.
It is mostly focused in Aerospace, Defense and Civil avionic fields.
EPN has been established in 1988 in Neustadt, in Turingia Region in Germany and mainly devoted to production of PCBs for the industrial field.
VISION, MISSION AND BUSINESS MODEL
Our vision is to be leading manufacturer offering Global Services and Local Support to consumers mainly, but not only, on the European market.
Our mission is to continue developing capabilities, services and know-how to offer our customers the widest range of PCBs in terms of technologies and services, from double-sided PCBs to HDI rigid and HDI rigid-flex PCBs of high and very-high technology level, in small, mid and high volumes, even with quick turnaround delivery, manufactured in our own plants in Europe. We complete our offer for high quantities through our fully controlled long standing sourcing-partnerships with highly qualified Asian manufacturers.
Our business model is to supply PCBs to our customers from the first prototype batch, with quick turn around service upon request, to the serial production. W e reserve our capacity and capability to manage QTA service only for our real partners who can share our business model thus contributing to build long-term partnerships that represent the basis to grant our continuity and growth.
ACCREDITATION AND STANDARDS
What makes the PCB Division unique, is to be certified to produce, not only for the industrial sector through ISO9001:2015 but also for critical sectors such as:
§ Aerospace & Defence: UNI EN 9100:2016 (Cistelaier & Techci)
§ Avionic : NADCAP (Techci)
§ Automotive: IATF:2016 (Cistelaier)
§ Medical: ISO 13485 (Cistelaier)
§ Railway: ISO/TS 22163 (Cistelaier & Techci)
Products are manufactured according to the following standards and specific control plans are agreed with customers if needed:
§ IPC-A-600, class 2, 3 or class 3DS(A)
§ IPC 6012 (Rigid), IPC 6013 (Rigid-Flex), IPC 6016 (HDI) and IPC 6018 (Microwave)
§ MIL-P-55110 (Rigid) and MIL-P-50884 (Rigid-Flex)
§ ESA-ECSS - Q – ST – 70 – 10C / 11C / 12C
§ ESA-ECSS - Q – ST – 70 – 60C
Cistelaier, Techci and EPN are also IPC Members and several employees are Qualified IPC Trainers and IPC Specialists. Thanks to their know-how and accreditations and to their flexible service they have been able to become technological partners of customers performing in almost all market sectors.
Cistelaier and Techci produce and sell all kinds of PCBs: double-sided PCBs, rigid multilayer boards up to 40 layers, rigid-flex boards up to 12 flex layers and HDI multilayer rigid and rigid-flex boards.
Cistelaier and Techci validated their processes to produce with more than 100 different base materials so as to deliver PCBs for all possible applications.
They produce with standard-performance materials and with high-performance materials (i.e. Hi Tg, Alogen Free, Hi-speed, epoxy and polyimidic resin materials, copper/invar/copper, HI frequency materials Teflon and not Teflon based, thick copper materials).
EPN produces PCBs of what we call standard technology from single-sided PCBs to 10 layers PCBs even with quick-turn delivery service.
The PCB Division could deliver PCBs with
- lines and spaces down to 75 microns width
- length / width combinations of the panel up to 860 mm x 470 mm
- thickness of the panel up to 5.5 mm
- copper thickness up to 500 microns
- copper coins and bas bars insertion
- mixed materials build up
- all finishes: ENIG, ENEPIG, chemical Tin, HAL Lead and Lead free, chemical Silver, OSP, electrolytic Nichel – Gold (Hard & Soft), tin-lead hot oil reflow
- all colours of solder mask: green, red, blue, black, white, grey and specific RAL on request.
Factories and Organizations of the PCB Division have been designed and implemented in order to be able to provide quick turnaround (QTA) service: this enables customers to get prototypes with short lead times so to improve their time-to-market and business performances.
All information related to products design coming from our customers are systematically verified in order to identify any risk factors through DFM, DFT and FMEA analysis.
Through our own mechanical and chemical LABs we can deliver all possible analysis results requested by PPAP Reports, CoC Reports or FAIR (First Article Inspection Reports) or by customized qualification processes for PCB conformity validation.
Our people, highly skilled in PCB design and manufacturing, are ready to support our partners at any time.
Let's celebrate with us over the next few months, following the footsteps of our history. Discover where we started and where we are today!