Read KM_12_08_e_klein.pdf text version

Edition 2/2008

the Rehm customer magazine

T H E R M A L SYSTE M S

VisionXP with Pyrolysis!

Rehm goes for innovation

| | |

Successful start of Rehm China Pyrolysis Branding Light

Innovation for your success

Rehm on the move

Dear Rehm Friends, After being in the Rehm family now for acht months is my pleasure to update you on our great company and it actions. Reading the news the last weeks it seems that there are only negative news out in the market so it's good to update you on some positive news where the global Rehm team is working hard to continue to improve our products and company. As you will be able to read in more details in other sections in this magazine we are working on: Expansion Rehm Germany The finalization of our building expansion in Blaubeuren Germany adding over 3000 m² production area . This will allow our sister company Rehm Blech Tech who makes the parts of our products to move into their own building leaving the full current facility of over 8000 m² for Rehm Thermal Systems allowing us to give every product range the right size of production area and to expand our other areas to meet further growth planned. We hope to show you this full space difference during the upcoming technology days in Blaubeuren Germany March 26-27 2009. New facility Rehm Americas Our team in Atlanta has moved to a brand new facility that will enable us to integrate support office for all America including demo room, ­ Sales and Service organization and Parts supply from one central location. This will be the location that will support our further growth in the Americas. Recent successes included additional sales of Condensation Soldering systems for higher end accounts who are moving to Lead-Free soldering. Optimizing of the product mix in our facility in Dongguan China After flying start in 2008 this facility has proven to be big hit with accounts in and outside Asia. We are now working close between the global headquarters in Germany and this facility to further add new models to the machines made in China in order to expand our product lines offered. This will include all VXS Reflow models starting with heated lengths of 1850 mm so Rehm will be also able to supply our proven technology for users who require smaller systems. Successful release of the Pyrolysis Residue Management system After more then 20 beta sites, many of them running over 12 months we are proud to continue the release of the VXP Reflow platform using the Pyrolyse Residue Management system for the heating zones. This is another milestone in Rehm's ,innovation for your success program`, to make your future reflow process as clean as possible with minimum maintenance intervals and lowest operating costs. Rehm start in Japan We are please to announce our new cooperation in Japan with Techno Alpha that will result to show the Condenso Vacuum system on the Nepcon Japan (January 28-30 2009 Tokio Japan), this will be the fist time Rehm's technology is shown on this major show for the Japanese market. Techno Alpha is working on the Japanese market as trading company for close to 20 years and is experienced in Soldering technology. Further information: www.technoalpha.co.jp

EDITORIAL

CONTENT

First Condenso Vacuum shipped with full automatic loading ­ unloading handling In order to improve the productivity of our customers Rehm has added a fully automatic loading and unloading feature for the carriers used in the Condenso VP Soldering system. This will allow a higher productivity and throughput of the system due to the efficient use of the maximum loading space of the process chamber . More of these systems are already on order and will be shipped in Q 1 2009 Besides all this, the Condenso systems are now available with standard size process chamber for max. PCB size 530 mm x 530 mm x 100 mm and with a larger process chamber for max. PCB size 650 mm x 650 mm x 100 mm. Rise Selective Soldering system ready for your tests The upgraded Rise Selective Soldering system is now ready to test your applications in our technology center in Blaubeuren Germany We look forward to prove the capabilities of this flexible platform to you during visit. Please contact your regional sales contact to schedule a demonstration. Rehm in General As can be seen from above actions, Rehm is on the move to continue to improve our products and company. It's fun to be part of growing company that will continue to grow despite the current more challenging general conditions. We are investing in making the right connection for your future Soldering process. Best Regards Marc Dalderup C.C.O . Rehm Thermal Systems

Product information

VisionXP Pyrolysis - the world novelty .... .... 4 Voidfree Soldering with the Condenso ......................... 6 Bringing light into the darkness of the reflow oven ........................... 8

Rehm News

Rehm Thermal Systems Dongguan ..................................... 10 Leadfree Reflow Soldering SMT Forum China ......................... 12 Rehm USA ..................................... 16 Rehm Russia ................................ 16 Technology Day Hungary ...............17

Rehm Internal

FroheWeihnachtenFroheWeihnachtenFroheWeihnachtenFroheWeihnachtenFroherWeihnachtenFroheWeihnachtenFroheWeihnachte Feliz Navidad Feliz Navidad Feliz Navidad Feliz Navidad Feliz Navidad Feliz Navidad Feliz Navidad is growing! ....................19 Our team Feliz Navidad Feliz Merry Christmas Merry Christmas Merry Christmas Merry Christmas Merry Christmas Merry Christmas Merry Christ

We expand! ....................................18

Pozdrevlyayu s prazdnikom Rozhdestva Pozdrevlyayu s prazdnikom Rozhdestva Pozdrevlyayu s prazdnikom Rozhd FroheWeihnachtenFroheWeihnachtenFroheWeihnachtenFroheWeihnachtenFroherWeihnachtenFroheWeihnachtenFroheWeihnacten

Joyeux Noël Joyeux Noël Joyeux Noël Joyeux Noël Joyeux Noël Joyeux Noël Joyeux Noël Joyeux Dates Shèng dàn jié Shèng dàn jié Shèng dàn jié Shèng dàn jié Shèng dàn jié Shèng dàn jié Shèng d

2008

2009

Coming together is a beginning; keeping together is progress; working together is success. (Henry Ford)

We would like to take this opportunity to thank you for the good cooperation and wish you and your family all the best for 2009. Your Rehm Thermal Systems Team

Overview dates ..............................20

CONTENT

Pyrolysis for the Reflow process

PRODUCT INFORMATION

The world novelty only for Rehm VisionXP Systems!

Cracking at 500 °C!

Pyrolysis (greek: pyro = fire, lysys = decomposition)

Condensable Residues before cracking The term Pyrolysis signifies thermal decomposition of organic compounds where a depreciation within big molecules is enforced through high temperatures (500-900°C). For the most part it takes place under the exclusion of oxygen (anaerobic) to avoid burning. With the new VisionXP Rehm Thermal Systems has extended his portfolio by a Premium-Reflow-Soldering System and makes use of the physical advantages of Pyrolysis to reduce the maintenance efforts. The VisionXP`s residue management system combines the pyrolysis action mechanisms in the preheating and peak range with cold condensation in the cooling zone. This way both the amount of liquid residues (drip formation in particular) and that of the crystalline residues can be drastically reduced. As a result the VisionXP achieves a higher efficiency as all available systems in the market until now using other techniques. Due to the effective elimination of residues, the maintenance intervals can be largely extended. The maintenance efforts are considerably reduced. The effect of the pyrolysis is the thermal splitting (cracking) of the long molecule chains into shorter ones thus reducing considerably the amount of condensable residues. The tendency to built drops declines. The remaining residues are taken up from a special granulate. The pyrolisis is nearly maintenance free. Eventually a yearly maintenance to exchange the granulate could be needed. Not condensable Residues after cracking The elimination system used for the cooling section is placed at the back side of the oven. It consists of filters and coolers where the remaining residues in the process gas condense. For maintenance only these units will be exchanged.

VXP is available in different system types

PRODUT INFORMATION

PRODUCT INFORMATION

Voidfree Soldering

with Condenso Batch or Condenso Inline-System

Profiling with vacuum

Condenso VP

Particularly the discussion about the introduction of lead free alloys on assemblies with big masses has stimulated the development of new soldering techniques. Condensation soldering offers the optimal solution to achieve best soldering results when simultaneously higher soldering temperatures and an amelioration of heat transfer but excluding the undesired overheating of the components are required. With CondensoXP you are on the right way. The positive characteristics of vacuum are taken advantage of in surface mount technology as well. In particular in power electronics and high reliability technology, void-free solder joints are being demanded to an ever greater extent. This is only possible if the solder is subjected to vacuum while it's still molten after the solder joint has been produced. Highly void-free solder joints with greater than 98% contact are achieved with underpressures of below 50 mbar. In order to achieve this goal, Rehm has combined condensation soldering technology (vapor phase soldering) with suitable vacuum technology. In Rehm's Condenso Vacuum systems, the soldering process is first of all controlled by injecting defined quantities of the utilized medium into the process chamber, thus generating a specified amount of heat. Soldering is immediately followed by a controllable vacuum process. Condensation-vacuum technology is available for process temperatures of up to 240° C. In order to ensure a higher throughput for High-End-Assemblies, an automatic loading handling was developed in cooperation with one of our customers. It works with two transport axes and thus allows an simultaneous cooling of soldered assembly groups on the first transport level, while on the second transport level the next workpiece carrier is in a resting position in the process chamber. Through this handling concept an almost double throughput can be achieved.

Voidfree Soldering without vacuum

with vacuum

Process

Vacuum

Cooler Overpressure compensation Cyclone Filter Tank

Heater

Pump

PRODUCT INFORMATION

Voidfree Soldering with automatic loading system

Bringing light into the darkness of the reflow oven.

New software tools make the soldering process transparent.

PRODUCT INFORMATION

Dr. H. Bell, Development & Technology and Matthias Kley, Processautomation Real-time monitoring of the manufacturing process is becoming more and more important for manufacturers of electronic products. And this applies not only to insertion, but rather to the soldering process in the reflow oven as well. Oven manufacturer Rehm Thermal Systems is supporting capability control and traceability in the reflow process with new tools. Electronics manufacturers who want to work efficiently and successfully must assure that only products which comply with the specified quality requirements are produced, and that costs for in-situ repairs are minimized. Beyond this, more and more customers are demanding documentation and objective substantiation of the quality and the stability of the manufacturing process, which provide them with reinsurance for their own final product ­ for example an automobile. It is thus essential to find competitive answers to questions concerning capability control and traceability. This encompasses the soldering process as well, which shares in the quality of the final electronics product to a great extent. For this reason, it's important for electronics manufacturers to be familiar with the capability coefficients of the soldering process and the key parameters of the reflow system. Capability indices Cp (process capability), Cm (machine capability), Cpk (critical process capability) and Cmk (critical machine capability) describe the potential capability of the soldering process of always producing the desired soldering profile in a uniform fashion within the specified tolerances for each PCB to be soldered. The capability indices are calculated using the following traditional formulas: The requirement which specifies a Cpk of greater than 1.5 is an old definition from Motorola, and is generally understood as 6 Sigma quality.

Monitoring the heat zones With its CCS Capability Control System, Rehm Thermal Systems offers an optional tool for the reflow system, by means of which process capability can be monitored during the production process. CCS is based upon the measurement of temperatures in all of the reflow oven's heat zones for each individual PCB, as well as measurement of conveyor speed. Machine capability coefficients Cm and Cmk are included in the report. They characterize the capability of the reflow oven to produce a high quality product with, to the greatest extent possible, identical specifications (reflow parameters). A Cmk of greater than 1.67 is generally required for reflow ovens. If Cmk drops to a value of less than 1.67, and alarm message is generated. The introduction of further PCBs to the oven can be stopped. Process disabling prevents defects In order to prevent products from being soldered with incorrect reflow parameters, the reflow system has to be equipped with process disabling. The inlet conveyor belt upstream from the reflow system is usually equipped with a scanner for the purpose of process disabling, which detects the identity of each PCB to be soldered. The included process disabling software determines whether or not the reflow oven's currently running soldering program matches the PCB to be soldered. In the case of a match, the software enables conveyance of the PCB into the oven. Otherwise, disabling is triggered and the operator is forced to load a matching soldering program. If desired, the software can also load the right program, further increasing the production line's degree of automation. Operating errors and the selection of incorrect soldering programs are practically eliminated.

Traceable soldering processes The scanner at the inlet of the reflow system is not only used for process disabling, it also serves as a basis for product traceability. Traceability means that when, where, by whom and how a product was manufactured, processed, stored and transported can be determined at any point in time. In order to assure process traceability, all of the reflow system's process-relevant information must be continuously monitored and recorded. Data logging is started as soon as the PCB passes the reflow system's inlet sensor. During its journey through the oven, each respective zone temperature is recorded with reference to the individual PCB. Conveyor speed and residual oxygen content, as well as other desired data, are also continuously logged for the PCB. When the PCB exits the oven, all of these data are written to an ASCII file along with the product ID (serial number), and made available to the production line controller for further evaluation. The data can be queried and retraced at any time by entering the product ID. On the one hand, these data serve as the basis for quality improvement measures and, on the other hand, substantiate compliance with warranted characteristics.

CCS software creates control charts at which momentary results and longterm trends are displayed as graphics (picture 2). All of the essential process data can be summarized in a CCS manufacturing report and printed out for the purpose of documentation for submission to the customer. This data sheet makes it possible for the PCB manufacturer to substantiate reflow soldering of the product in accordance with the specified quality requirements.

24.05.2007 08:36:28

Bild 2: Individual CCS values

Customer Switzerland AG

Customer Switzerland AG

P.O.BOX Bern 1230

Tel. +41 56/123 45 67 Fax. +41 56/123 45 68 [email protected] eMail www.kunde.com

Data sheet for CCS Quality capability

Product.:

Lot size.:

3BHB003154R0101

60

2,48

From:16.05.2007 11:06:56

Min Cpk

Manufacturing time

To: 16.05.2007 12:15:14

Transport speed:

Zones

Zone-1

1500

Frequency Top Bottom Specification limits Top Bottom

143.6

136.6

Set point Zone Top Bottom

150

Acceptance limits Top Bottom

142.4

Cp

3.19

Cpk

3.18

150

40 40 40 40

40 40 45 45 45

60 60 60 60 60

60 60 60 60

137.7 159.5 157.5 156.6 158.9 164.8 249.6 245.1 237.6

Zone-2

170

170

165.4

158.4

164.2

3.16

3.15

Zone-3

160

160

161.8

156.8

161.2

3.95

3.94

Zone-4

160

160

163.2

156.2

162.9

8.97

8.97

Zone-5

160

160

164.8

157.8

163.8

3.44

3.44

Zone-6

165

165

172.8

162.8

170.9

253.7 249.4

2.59

2.58

Peak-1

265

265

255.2

248.2

2.49

2.48

Peak-2

255

255

250.7

243.7

2.62

2.61

Peak-3

245

245

244.1

237.1

243.6

6.70

6.70

PRODUCT INFORMATION

Rehm Thermal Systems D

Successful Penetration of the Chinese Market

0

REHM NEWS

Dongguan

SMT China Forum Already during the first few months after company was founded, Rehm Thermal Systems Dongguan has been able to assert itself in the highly competitive Chinese electronics market. Since its festive inauguration in April 2008, Rehm Thermal Systems Dongguan has grown into a highly qualified manufacturer of reflow soldering systems at an astonishingly fast pace. Production facilities were set up within an extremely short period of time by the Chinese-German management team, which operate in accordance with the same quality standards and guidelines as Rehm Thermal Systems in Germany. Already today, 20% of the reflow systems from the Vision XS product range manufactured in China are shipped directly to customers in Europe and America. Compliance with EC directives and EU standards goes without saying for production management in China. Marketing of equipment produced in Dongguan for the Chinese market is handled by the sales office in Shanghai. Brisk activities carried out on-site by the sales team resulted in an exceptionally well frequented trade fair booth at Nepcon Shenzhen in August of this year. In order to provide customers and other interested parties with technological support, Rehm Thermal Systems Shanghai co-sponsored the "China SMT Forum 2008" which was held in Shanghai at the beginning of November. Dr. Hans Bell, director of R&D and technology at Rehm Thermal Systems in Germany, supplemented the conference with a technical presentation on the subject of "Lead-Free Reflow Soldering". More than 250 participants from various sectors of the Chinese SMT industry responded to an invitation to travel to Shanghai for the second "International Conference for Electronic Packaging and Assembly Technology ­ China SMT Forum". The conference, which was very well organized by Business Media China BMC and demonstrated a well balanced range of content, provided equal access to the presentations for all listeners thanks to simultaneous interpreting (English into Chinese). The talks were shown on two screens at the same time in English and Chinese. Selection of the Sheraton Grand Shanghai Tai Ping Yang Hotel as the event's venue assured highly professional organisation of the conference. During the breaks, participants had the opportunity of become better acquainted with some of the products offered by the exhibiting companies. Lively discussion amongst the participants, the speakers and company representatives substantiated the fact that the forum offerings met with a very good response. The two-day conference was subdivided into six sessions: reliability and testing, semiconductor packaging and power electronics, lead-free soldering and RoHS compliant technologies, PCB technologies ­ surface finishes and quality, assembly and soldering technologies. Planning of further events and participation at trade fairs in Asia in 2009 is currently in progress. Excitement continues with regard to seeing how growth in China and Asia will develop. In any case, Rehm Thermal Systems in China has created the best possible conditions for meeting future challenges.

SMT China Forum

View in to the Productionhall

Assembly

Assembly

Assembly

REHM NEWS

Lead-Free Reflow Soldering SMT Forum China

Dr. H. Bell, Manager Research and Development (Rehm Thermal Systems). In cooperation with Dipl.-Ing. R. Heinze and Dr.-Ing. H. Wohlrabe (TU Dresden), J. Pfülb (Beck GmbH), H. Yamada (7th Nakamura ELNA CO. LTD.), F. Oswald (Rehm Thermal Systems)

Introduction

In recent years, the production of RoHS compliant components has resulted in one of the most expansive material changeovers in the history of electronics. In particular for the utilized components, higher soldering temperatures cause additional stressing. Moisture sensitive IC packages and electrolytic capacitors are affected to an especially great extent. As yet, there are no standards for the component manufacturers which define reflow soldering in terms of practical temperature-time limits. Even in the new edition of IPC/JEDEC J-STD-020 D (Moisture/Reflow Sensitivity Classification ...), the following sentence appears: "Reflow profiles in this document are for classification/ preconditioning and are not meant to specify board assembly profiles". Only the specifications provided by the respective suppliers are available for the group of components consisting of electrolytic capacitors, which often do not take essential manufacturing conditions into consideration (e.g. vapor phase soldering). Additional knowledge is thus absolutely essential for the production of reliable components. The first part of this presentation introduces the results of several examinations regarding the thermal stability of a number of IC packages and electrolytic capacitors during the soldering process, and addresses the effects of interaction amongst various influencing factors on soldering results.

Moisture Sensitive Components

Various packages rated MSL 3 and 4 were used for examining moisture sensitive ICs, namely SOT, SSOP, PQFP, MQFP and PFCM. All of the examined ICs were removed from their moisture resistant packages before soldering, and were placed into storage for 72 or 168 hours at a temperature of 30° C and a relative humidity of 60% in accordance with their moisture sensitive levels (MSL). The components were then subjected to different reflow stressing variants as shown in the table. Both before and after respective thermal stressing, the ICs were examined with an ultrasonic microscope using the pulse-echo technique (C-scan). Due to the fact that the transferred heat originates from phase change enthalpy (gaseous to liquid), 10 to 20 times more heat is transferred during the same period of time by means of this reflow process than with convection soldering, which works with hot nitrogen or hot air. Damaged components, for example delamination, are thus more likely with condensation soldering. Vacuum represents an additional stressing factor for moisture sensitive components. Residual moisture considerably increases internal pressure inside the package during reflow soldering, and the vacuum increases the relative pressure difference by an additional 1 bar. This is why emphasis was placed upon vacuum condensation soldering in our study. Subjecting the components to stressing three times was intended to demonstrate the ruggedness of the components, even in the case of multiple soldering. Maximum temperature was set to 260° C for convection stressing. This corresponds to the maximum temperature rating for moisture sensitive components in accordance with the JSTD IPC 20C standard (table 4-2). The condensation soldering system was filled with Galden® HS240, which means that the maximum temperature for this process did not exceed 240° C. During the course of adaptive vacuum stressing, a final pressure of 10 mbar was achieved for a period of approximately 30 seconds. The heat gradients were always £ 3 K/s. All of the components available to us had a moisture sensitive level of MSL3, except for one component which was rated MSL4 (in accordance with IPC 020C). The examined SSOP and SOT components have very rugged packages, which didn't demonstrate any delamination even after being subjected to reflow stressing several times. The MQFP80 and MQFP144 packages proved every bit as rugged as well. As opposed to this, the PQFP64 already demonstrated slight delamination after convection soldering, as well as after convection soldering without vacuum, although the bottom of the chip carrier did not demonstrate any changes at all. Delamination at the chip carrier / mold compound level increases as soldering stress becomes greater, and spreads out over the entire surface of the pad. 90% of all tested PQFP64 packages failed after being subjected to vacuum condensation soldering twice.

REHM NEWS

Table: Reflow Stressing Variants

Man

Training Requirements Knowledge & Experience

Machine

Maintenance / Service Heat Conveyor Controller Residue Management Atmosphere

PCB Design Solder Paste Components PCB Heat-Up Characteristics

Restsauerstoff Conveyor Speed Zone Temperatures Process Monitoring

Quality / Soldering Results

Electrolytic Capacitors

The following package types were used for examining thermal stability during the soldering process: D10x10L, D8x6.5L and D6.3x5.3. For these components, thermal stressing during reflow soldering was based upon the IPC J-STD 20C and IEC 60068-2-58 standards, as well as the ELNA specification. Due to the fact that electrolytic capacitors are also frequently exposed to the condensation soldering process, stressing under vapor phase as well as convection reflow conditions was carried out. The electrolytic capacitors were not specified for the vapor phase process. All of the process parameters were adjusted such that allowable temperatures in accordance with the standards were not exceeded. All of the electrolytic capacitors were examined by means of X-ray for possible mechanical defects after thermal stressing, and electrically measured. No mechanical defects could be detected at the capacitors after either convection soldering or condensation soldering. Neither fissures at the leads nor deformation of the housings occurred, as can be seen in the e-ray images. The electrical measurements revealed capacitance losses after each reflow process in all cases. Considerably greater thermal transfer in the case of vapor phase soldering also resulted in larger capacitance losses for all examined types of electrolytic capacitors. Several capacitors were subjected to stressing two and three times in the same convection reflow process. Subsequent measurements revealed that capacitance loss is further increased. When exposed to thermal stressing three times using the convection process, the same amount of capacitance loss occurs as is also the case after exposure to stressing only once with the condensation process.

Convection soldering demonstrates defect patterns which are similar to those of condensation soldering without vacuum. Very minimal, or no changes at all can be substantiated in the packages which were subjected to thermal stressing one time only. More complex packages may be destroyed when subjected to reflow stressing several times with vacuum. With regard to thermal stability during the soldering process, there was no difference between the PFCM100 with a moisture sensitive level of MSL4 and a PFCM128 of comparable design with a moisture sensitive level of MSL3. These results underscore the fact that thermal stability during the soldering process is not characterized by the degree of sensitivity to moisture. Charts 8 and 9 show ultrasonic images of several of the examined components.

X-Ray D10x10L

REHM NEWS

Sensitivity to reflow stressing also increases with more complex package designs, which has been substantiated, for example, by means of the examined PFCM128. The chips on the ICs are bonded to interposers, which in turn are mounted on the middle pad of the leadframe. Delamination at the interposer/leadframe level becomes apparent to an ever greater extent as reflow stressing increases.

PCBs Printing and Assembly Process Quality

Material

Figure 1: Ishikawa Diagram of the Reflow Process

Process

Soldering Parameters

Effects of Reflow Parameters on Soldering Results

Numerous influencing factors effect the final quality of a PCB, some of which are depicted in figure 1 as an Ishikawa diagram. Due to this great variety, the user is frequently faced with the question of which combination of influencing factors results in ideal quality. During the last two years, systematic testing of reflow quality has been conducted at the Electronics Packaging Laboratory of the Dresden Technical University with vital support provided by Rehm Thermal Systems. The following quality characteristics were evaluated during the course of testing: · Wetting quality - Spreading of the solder from a previously round-shaped paste deposit after soldering; - Fillet height at the chips (the nonwetted area to be measured, i.e. the gap, should be as small as possible) · Number of tombstones per PCB · Number of solder balls at the chips (beading) · Void quota at BGA and surface solder joints

Wetting Quality

The surface of the PCB has a significant influence on wetting quality. Chart 16 shows the results of an evaluated test for which chemical tin demonstrates better wetting. In contrast to this, the expected results were obtained from the first test, i.e. nickelgold demonstrated better wetting. It is generally expected that tin reacts more sensitively to oxidation. The cause of these contradictory test results can be traced back to the differing levels of quality of the utilized PCBs. These results demonstrate the complexity of the various influences on reflow quality. Wetting quality at the chips was evaluated by means of AOI. A total of approximately 300,000 solder joints were recorded. The smaller the measured gap was, the better the wetting was. The graphic also shows the influence of the utilized peak temperature. At a higher peak temperature of 245° C, the gap becomes smaller. As temperature rises, chemical-metallurgical interaction increases and the surface tension of the molten solder is reduced, which promotes wetting on the whole.

Reflow Atmosphere / Nitrogen

The use of nitrogen in reflow soldering plainly has a favorable effect on wetting quality (see chart 18). During testing, residual oxygen content was varied from 100 to 1000 ppm instead of soldering in normal air. Nitrogen displaces atmospheric oxygen in the reflow atmosphere, and thus prevents oxidation of the surfaces to be wetted.

REHM NEWS

Tombstones

However, interactive influencing factors may lead to different quality results. For example, the number of tombstones rises as conveyor speed is increased in a nitrogen atmosphere, whereas it remains nearly constant in an air atmosphere. Oxidation processes acting upon the surfaces to be wetted and the solder paste in an air atmosphere increase wetting time and thus reduce delay time between the right and left connectors. Pastes with adequately good wetting characteristics are also capable of achieving equally low numbers of tombstones in a nitrogen atmosphere as is also the case in air. Whereas a nitrogen atmosphere may promote the occurrence of tombstones, it has a positive overall effect on wetting. With the help of nitrogen control, by means of which the selected residual oxygen level is held constant, and additional setting parameter is placed at our deposal for counteracting tombstones.

Figure: Tombstones Relative to the Utilized Solder Paste and Atmosphere

Solder Balls

Solder balls at the 0805 and 1206 chips were counted by means of AOI. The primary influencing factor for beading is the solder paste's grain size. The smaller the grain diameter, the more probable it becomes that grains will be displaced into the gap underneath the chip component. Due to the larger overall surface area of the metal contained in the fine grained solder paste, oxidation with residual oxygen also occurs to a greater extent, and beading is thus promoted. A higher peak temperature reduces the molten solder's surface tension, and the solder is thus even more easily forced into the gap. Furthermore, the chips drop down further during the soldering process when a higher peak temperature is used, which is confirmed by the standoff measurements. The size of the gap underneath the component is thus reduced, which enhances the capillary effect. Longer preheating times minimize beading. They promote more thorough drying out of the solder paste, thus reducing the flow of liquid (flux) underneath the component and the number of solder grains which can be displaced.

Voids

Void analyses were conducted at BGA and surface solder joints (QFN, Si chips). Test evaluation resulted in obvious contradictions. Ball and surface solder joints necessitate different reflow settings in order to achieve minimal void content (except for the solder paste's grain size). Only a small number of voids occur at the BGA with poor wetting quality. The reverse is true for the QFN: good wetting quality also results in a small number of voids. Solder paste grain size is here the exception. Furthermore, for both the BGA and the QFN, peak temperature has a greater influence on voids. For the QFN package, a higher peak temperature also results in a longer dwell time for the solder in its molten state, which means that gas bubbles have more time to escape. The viscosity of the molten solder is also reduced at higher temperatures, which also facilitates the escape of gas bubbles. In the case of the BGA, delayed wetting due to poorer wetting characteristics could facilitate the escape of gas bubbles. An oxide layer is formed on the surface of the molten balls due to the higher peak temperature, which impairs further escape of gas bubbles. If both types of components need to be soldered to the same PCB, there are no ideal settings which are capable of minimizing all voids ­ neither with regard to the utilized materials, nor concerning reflow parameters. The primary causes of contradictory performance are initially to be discovered in the geometric differences of the various components. A significant reduction in the number of voids can only be achieved with the help of vacuum soldering processes.

REHM NEWS

Rehm USA

Rehm USA Rehm Thermal Systems LLC 3080 Northfield Place, Suite 109 Roswell, Georgia 30076 USA Telefon (770) 442-8911 Fax (770) 442-8914 www.rehm-group.com

REHM NEWS

Demo-Center ­ Rehm USA

The Sales Office Rehm USA in Atlanta managed by John Bashe moved into new premises in October 2008. Beside office premises and a spare parts stock a Demo-Center for trainings and solder tests is also available there. All sales and service activities in America are coordinated from Atlanta. The Demo Center is equipped with a VisionXS-system and CondesoBatch Vacuum. Especially, the field Condensation Soldering becomes increasingly important in America at present. The process window decreasing as a result of change-over to lead-free soldering processes is the reason why a lot of high-end customers switch to condensation soldering. In the new Demo-Center there is a possibility to compare both technologies and to select an adequate system for the required process . As the one manufacturer of Reflow Soldering Systems Rehm can offer both technologies convection and condensation soldering - to his customers.

New plant of Rehm in Russia

The manufacturing plant in Russia was already started in 2007 and could be finished in 2008. The Joint-Venture Rehm-Dial manufactures solely Reflow-Soldering Systems of the series VisionXS 422. The first five systems were delivered in Germany in October 2008. In a similar way as in the production facility in Dongguan, China Rehm is pursuing also here the same strategy. The production in Russia is organized similarly as in Germany or in China. Thus Rehm manufactures Reflow-Soldering Systems in the same way and at the highest quality level on three global markets .

Technology-Day Hungary ,,Practical assembly group manufacturing"

On 16. October 2008 over 100 interested participants followed the invitation of the companies Christian Koenen, Ekra, Kolb Cleaning Technology , Rehm Thermal Systems, Siemens, Zevac and Zollner to the first Technology-Day ,,Practical assembly group manufacturing" in Göd / Hungary. The tour in the afternoon through the manufacturing plant of Zollner in Vác was definitely the highlight of an overall interesting seminar day. The lectures from the morning were translated simultaneously into Hungarian, which found a positive welcome by the participants. The accompanying exposition in Pólus Palace Hotel enabled to become acquainted with the new technology and to discuss questions in more details. After the opening and welcome of the participants by Henning Obloch (Rehm), Dr. Hans Bell (Rehm) started the course of lectures with a presentation about the effect of reflow parameters on possible soldering defects. Without compromises and weighting of its own expectations on the defect distribution an optimization of a reflow process is hardly possible. Due to real soldering defects rework is still necessary in manufacturing. Lothar Pietrzak (Zevac) presented therefore a multitude of solutions. A high grade of automation ensures during the rework the reproducibility of processing parameters and reduces the stress for the affected assembly groups. The solder paste print has the most impact on the reflow quality . Thus the knowledge of the impact of print parameters and their optimization is of key-importance, as Uwe Schäfer (Ekra) reported. An adapted stencil design is therefore a condition sine-qua-non. Harald Grumm (Ch. Koenen) imparted in his lecture essential experiences and tips for aperture design. Stage stencils used to adapt the solder paste demand individually on the one and the same assembly group have experienced a considerable growth. No-Clean does not always apply to the whole assembly group. Due to highest demands, e.g. on the resistance to climatic conditions, the cleaning process after the soldering is necessary. Varied cleaning technologies, not only for the electronic assembly group, but also for stencils, misprints and machine parts were discussed by Jerome Clouet (Kolb). Highest flexibility and availability characterize the Pick and Place Systems of Siemens. The latest highlight in the Siplace-product family is the ,,Multi-Star" placing head, which increases considerably the speed and flexibility placing a wide spectrum of components. Furthermore Eszter Galantai (Siemens) reported on Siplace Quad Lane. Four (placing-) lanes with a width of 114,5 mm meet the demand for HighVolume-Assemblies.

Rehm Hungary

Rehm Hungária Kerekedelmi és Szolgáltató Kft. Váci út 0 Szendehely,Hungary Telefon: + (0) - 0 0 Telefax: + (0) - 0 [email protected]

In his short overview Mr. Ulrich Niklas introduced the company Zollner, a typical EMS-Provider (Electronic Manufacturing Services). Zollner was founded in 1965 and has today production sites in Germany, Hungary, Romania, China and Tunisia, with an overall staff of 6500 employees. From them over 2100 work at the site in Vác. As service provider in the electronics industry Zollner offers customized complete solutions along the entire value-added chain and beyond all supply stages. During the very well organized company tour, especially in some ranges of SMDproduction, the seminar participants could assure themselves of the high technological competence of the company Zollner. Qualified and motivated employees as well as latest technology are here the essential keys to corporate success. Zollner is a competent technological partner cultivating long-term customer and supplier connections. We thank the company Zollner and especially the staff of the plant Vác for the great support of the first TechnologyDay in Hungary!

REHM NEWS

We expand!

REHM INTERNAL

Our subsidiary company RehmBlechTec ­ detached in 2003 ­ will be moving into the new 3000 m² production plant in March 2009. Within a short time the number of employees increased from 30 to now 70. We could also see a great increase in our regular customers. Due to the higher demand resulting in further investments we made the decision in 2007 to build a new production plant with 3000 m². This new production plant offers space for the welding shop, the steel construction and the laser cut work. Further, it is planned to have administration, storage, and common used areas. The move of RBT into the new premises offers Rehm Thermal Systems an additional production area of 1750 m². This will allow us to give every product range the right size. Further, it is planned to have several new conference rooms and training areas as well as a coffee shop. The finalization of the whole reconstruction is expected in 2010.

Our team is growing!

Günter Dieckmann takes over the quality management within Rehm Thermal Systems Since 1 September 2008 Günter Dieckmann is the Head of the Quality Assurance Department. He is responsible for the internal and external audit, the CIP management, job safety, quality assurance, quality management relating matters as well as the support of RBT in the quality management. Mr. Dieckmann has years of experience in the quality management and quality assurance. Before starting at Rehm he has been working as Head of Quality Assurance Department at Braas (Monier Group) for 8 years. Since July 00 Sonja Schleifer is our new Chief Financial Officer Jutta Dussler, the assistent of Marc Dalderup

Since 1992 Sonja Schleifer has been working within several a cco u n t a n t s . Before starting at Rehm Thermal Systems she has been working as Team Leader of the Financial Accounting Department, subsidiary companies at Müller in Ulm, Germany. Her main duties were the coordination of the accountings as well as the preparation of the annual balance sheets for the subsidiary companies in Austria, Switzerland, and Slovenia. She did it also for Spain the last time and she was additionally instructed to handle the staff provisions of the whole group of companies. In 2001 Ms. Schleifer finished her study to be a Chief Accountant followed in 2004 as an International Chief Accountant. Ms. Schleifer is a member of the management board with the following departments under her responsibility: Controlling, Purchase, Storage, Accounts Receivable, Accounts Payable and Dispatch. Further, she is responsible for the controlling of our plants outside Germany.

Since 1 July 2008 Jutta Dussler supports Marc Dalderup in his role as global C.C.O. for Rehm Thermal Systems. She also helps to support the communication between our new facility in RTS Dongguan and RTS Germany. Further, she helps with other tasks to support the global management team of Rehm Thermal Systems. She started her carrier at UTS Testsysteme in Ulm, Germany, in the purchase department for one year after having successfully finished her apprenticeship as an office manager. To get more familiar with the English language she decided to attend a one year private school for foreign language. After that she went to London, UK, for another 6 months to work and practice her language skills. Upon her return to Germany she started at Liebherr Ehingen, Germany, in the global sales team. In her 15 years in this job she was in contact with many areas of the world. Beside her last job she did a two year study on Saturdays for business administration.

Support for our engineering department We are welcoming Holger Volz, Michael Schubert and Christina Rühle in our engineering department.

New in Construction team

PERSONNEL

Don´t miss us....

Also in 2009 we are present on the most important scenes of the electronics industry. In addition, at our regional technology-seminars you get state of the art information about technological themes and our latest oven developments. In case you are interested in taking part in our seminars,please do not hesitate to contact us: [email protected]

DATES

We should be very pleased to see you on our next seminar!

NEPCON Japan 2009 28th till 30th January 2009, Tokyo www.nepconworld.jp

THERMAL SYSTEMS

Rehm Technology Days 2009 26th and 27th March 2009, Blaubeuren www.rehm-group.com

APEX 31st March ­ 2nd April 2009, Las Vegas www.goipcshows.org

NEPCON China 21st ­ 24th April 2009, Shanghai www.nepconchina.com

Seminar ,,Wir gehen in die Tiefe" 17th and 18th June 2009, Dresden www.wir-gehen-in-die-tiefe.eu

Masthead

review is a publication of Rehm Thermal Systems GmbH Leinenstrasse 7 D-89143 Blaubeuren-Seissen Telephon: +49 7344 96060 Telefax: +49 7344 960625 [email protected] www.rehm-group.com

SMT Hybrid Packaging 2009 5th ­ 7th May 2009, Nuremberg www.mesago.de

0

Information

20 pages

Report File (DMCA)

Our content is added by our users. We aim to remove reported files within 1 working day. Please use this link to notify us:

Report this file as copyright or inappropriate

617577


You might also be interested in

BETA