IPC 4101
Lead Free Delamination
Tired of Printed Circuit Board Delamination?
IPC 4101/99 and /124 are the Answer
For some time now the Industry has had to deal with delamination in its Lead Free Boards as it waited for a solution, which would ideally get back to processing the way we did when everything was SnPb. Delamination has occurred primarily on boards made from phenolic laminates, which are used for lead-free and high temp PCBs. While these materials have great thermal properties (Tg > 170C° and Td > 340C°, and conforming to IPC 4101/126/129), they are extremely weak in the fundamental areas of moisture absorption and copper to laminate adhesion.
Moisture Absorption
Standard 130Tg FR4 materials typically have a moisture absorption rate of 0.20% when measured using a 0.028" core material. Phenolic materials often measure moisture absorption of up to 0.45% when measured using the same test vehicle.
Copper to Laminate Adhesion
Standard 130Tg FR4 materials generate peel strength results of 6-9 lbs. Holding all parameters equal, phenolic materials generate peel strength results of 3-4 lbs.
Vapor Escape
These material characteristics take on much more value when you consider the effects of lead-free assembly parameters. Any moisture trapped or absorbed into the PCB will escape during assembly in the form of water vapor, the force of which is measured in psi (pounds per square inch). The vapor will escape from the dielectric from the weakest point in the board, which is typically plated via holes. During standard SnPb assembly at 200C, the vapor pressure is 225 psi. At Pb-Free assembly temperatures (250C), however, the vapor pressure increases to 575 psi.
The Perfect Storm
Combining the increased vapor pressure with phenolic material characteristics of increased moisture absorption and lower adhesion strength gives you a perfect storm capable of ruining entire production runs. In fact, the forces here are so strong that often instead of just blowing vias, entire layers can separate from each other forming delamination areas of 1 square inch or greater.
The Saturn Solution
Our solution is move towards non-phenolic materials, many of which can be found under IPC 4101/99 and /124. To qualify under these IPC categories for lead-free materials, they must have 150Tg and 325Td. While the thermal properties are not as high as the /126 or /129 materials, the mechanical characteristics more than make up for this, as demonstrated by lab tests we commissioned on standard test vehicles.
For more detailed information, please view our webinar we had on this topic at http://www.saturnelectronics.com/webinar_leadfree.htm.
Other Modes/Issues that this improvement will address:
Processing Lead Times
Drill Quality
Total Cost of Ownership
Showing posts with label IPC 4101/124. Show all posts
Showing posts with label IPC 4101/124. Show all posts
Thursday, November 13, 2008
Tuesday, November 4, 2008
IPC 4101/99/124 and SN100CL – Lead Free HASL
Saturn Shines at PCB West
Bare Board Manufacturer Shows PCB Designers how to Control the Process
Saturn Electronics Corporation, a Bare Board Manufacturer, took its Lead Free Cost Reduction presentation to Santa Clara, CA for the PCB West 2008 from September 14-18. Yash Sutariya delivered the presentation, which claims that utilizing the right combination of materials, finishes, and solders through the IPC 4101/99/124 and SN100CL – Lead Free HASL can produce notable benefits, such as cutting the costs on lead free boards by up to 30% and increasing PCB reliability at the same time.
A crowd approaching close to 40 listened in as Sutariya advanced what he felt were the main reasons for the necessary implementations of the Saturn presentation. Sutariya mentioned the direct cost drivers in the fabrication of Lead Free Boards (high-temp laminates and final finishes) before asserting that the move to Pb-free had created a host of indirect cost drivers as well, which include pre-baking, storage & handling, and an increased scrap rate due to delamination and solderability.
IPC 4101/99/124
The presentation was broken into two sections. The first dealt with Capable Laminates for Lead Free Assembly corresponding to IPC 4101/99 and /124. Sutariya presented numerous effects of the current state of the common callouts. Suppliers lock customers into laminate brand names, and typically phenolic materials that have a moisture absorption up to .45% on 0.028” core; less mechanical strength (interlaminate adhesion); more prone to delamination during assembly; inclination to pad catering on BGA applications. Finally, there were the non-Pb Free capable materials such as FR4. Designers are commonly calling out FR-4 laminates with high Tg values, but without including appropriate Td callouts (time to decomposition at temperature). While FR4 is RoHS Compliant, it is not always capable and 180° Tg does not guarantee adequate Td.
Proposed Solution
Sutariya proposed mid-grade capable Lead Free laminates compliant to IPC 4101/99 or /124 at 150 Tg min. and 325 Td min. Utilizing this approach would lead to higher copper to laminate peel strength, higher inter-laminate adhesion, as well as lower moisture absorption. Also, a 10-20 percent cost saving on the raw materials was promised as a result of these implementations.
The first part of the presentation ended with a promotion for the new FR406HR that is going to address the delamination during the lead free bare board manufacturing process.
SN100CL – Lead Free HASL
The second section dealt with Pb-Free HASL, specifically SN100CL and the Industry misconceptions associated with the discipline such as the predictions of HASL’s inevitable demise, its solderability issues, and the short duration of its usage.
But Sutariya argued that the lower copper erosion on the PCB surface and in the vias was benefit to PCB reliability. Other benefits included: quick process, long shelf life, lower cost, forgiving in regards to humidity, handling and temperature, and finally, Solder Joint Strength.
According to the HALT Test Results (provided by Tim Murphy of Thomson Lab Services and Glenn Sikorcin of Florida CirTech), Lead-Free HASL, with all different solderpastes pooled together, required the most energy (G-force + thermo-cycling) to break the solder joints. Sutariya concluded that lead free HASL solder joints outperform all other surface finishes, including SnPb HASL.
Drawbacks
But there were drawbacks involved pertaining to its planar, which makes it problematic for extremely fine pitch applications. If you’re interested in Past Solderability Issues with SN100Cl, read HASL and Flow: A Lead-Free Alternative from the February 2008 issue of CircuiTree. Furthermore, the SN100CL requires a Thermal Cycle in addition to thermal cycles in the assembly process.
Finally, there still remains no Industry standard regarding the Thickness Acceptability Criteria for SN100CL. As a result, smaller pads receive thicker solder deposition as a result of a Generic Thickness requirement because it is not proper to have just one solder thickness for all pad geometries. Sutariya said the solution was to segregate the minimum alloy thickness by ranges of pad size. By implementing alloy control, lower copper content of alloy increases solderability and the standard drossing of the solder pot is not enough to keep copper below 0.90%.
Sutariya recommended a ¼ - 1/3 solder pot dump once weekly copper content measurement reaches 0.90%.
Specific Design Set-Up
Then Saturn turned its focus to the Design link in the PCB Supply Chain and addressed the need for a specific design set-up. In addition, adjustments would need to be made to air knife pressure, retract speed, and dwell time. In effect, since the operating window is smaller than the SnPB, it is vital for the top of the Supply Chain to take control of the process!
Saturn and Florida CirTech have been utilizing the SN100Cl for over a year and have had no solderability issues at any customer. He attributed this to the value of the Fab Notes that can specify the use of these coupons or range of solder thickness standards.
Sutariya concluded that by doing this, you’d take control of the process by forcing your supplier to meet these specs.
Conclusion
Saturn Electronics’ Corporation’s Lead Free Cost Reduction presentation concludes that through the implementation of one or both of these proposed solutions, one can save up to 30% on their bare board costs while increasing the performance of their products. Additionally, this makes it much easier to standardize fab notes to removable risk of non-performing products.
Sutariya opened the floor to questions from the crowd and attendees, mostly PCB Designers who had very positive feedbacks regarding the recipe Sutariya and Saturn had just shared with them.
During this past summer, Sutariya gave the same presentation through a webinar. Polling questions included:
Have you experienced delamination during Lead Free Assembly?
46% of attendees answered yes
Have you ever tried and subsequently abandoned SN100CL?
6% said yes
12% said no
82% had never even tried it
What is your primary Lead Free Finish?
38% said RoHS Compliant
31% said Immersion Silver
13% said ENIG
13% said Lead Free HASL
6% answered Immersion Tin
PCB West is for PCB engineers, designers, fabricators and managers and includes a five-day conference of more than 35 technical courses.
Saturn Electronics Corporation is a leading manufacturer of high-reliability, and technologically advanced printed circuit boards. Dedicated to quality since our inception, Saturn delivers steadfast manufacturing that ranges from quick-turning elaborate prototypes to scheduled principal volume-production.
Saturn’s adherence to quality resulted in being the first PCB Manufacturer in North America to achieve TS16949 certification.
To view the archived version of this presentation, please email jim@saturnelectronics.com
Bare Board Manufacturer Shows PCB Designers how to Control the Process
Saturn Electronics Corporation, a Bare Board Manufacturer, took its Lead Free Cost Reduction presentation to Santa Clara, CA for the PCB West 2008 from September 14-18. Yash Sutariya delivered the presentation, which claims that utilizing the right combination of materials, finishes, and solders through the IPC 4101/99/124 and SN100CL – Lead Free HASL can produce notable benefits, such as cutting the costs on lead free boards by up to 30% and increasing PCB reliability at the same time.
A crowd approaching close to 40 listened in as Sutariya advanced what he felt were the main reasons for the necessary implementations of the Saturn presentation. Sutariya mentioned the direct cost drivers in the fabrication of Lead Free Boards (high-temp laminates and final finishes) before asserting that the move to Pb-free had created a host of indirect cost drivers as well, which include pre-baking, storage & handling, and an increased scrap rate due to delamination and solderability.
IPC 4101/99/124
The presentation was broken into two sections. The first dealt with Capable Laminates for Lead Free Assembly corresponding to IPC 4101/99 and /124. Sutariya presented numerous effects of the current state of the common callouts. Suppliers lock customers into laminate brand names, and typically phenolic materials that have a moisture absorption up to .45% on 0.028” core; less mechanical strength (interlaminate adhesion); more prone to delamination during assembly; inclination to pad catering on BGA applications. Finally, there were the non-Pb Free capable materials such as FR4. Designers are commonly calling out FR-4 laminates with high Tg values, but without including appropriate Td callouts (time to decomposition at temperature). While FR4 is RoHS Compliant, it is not always capable and 180° Tg does not guarantee adequate Td.
Proposed Solution
Sutariya proposed mid-grade capable Lead Free laminates compliant to IPC 4101/99 or /124 at 150 Tg min. and 325 Td min. Utilizing this approach would lead to higher copper to laminate peel strength, higher inter-laminate adhesion, as well as lower moisture absorption. Also, a 10-20 percent cost saving on the raw materials was promised as a result of these implementations.
The first part of the presentation ended with a promotion for the new FR406HR that is going to address the delamination during the lead free bare board manufacturing process.
SN100CL – Lead Free HASL
The second section dealt with Pb-Free HASL, specifically SN100CL and the Industry misconceptions associated with the discipline such as the predictions of HASL’s inevitable demise, its solderability issues, and the short duration of its usage.
But Sutariya argued that the lower copper erosion on the PCB surface and in the vias was benefit to PCB reliability. Other benefits included: quick process, long shelf life, lower cost, forgiving in regards to humidity, handling and temperature, and finally, Solder Joint Strength.
According to the HALT Test Results (provided by Tim Murphy of Thomson Lab Services and Glenn Sikorcin of Florida CirTech), Lead-Free HASL, with all different solderpastes pooled together, required the most energy (G-force + thermo-cycling) to break the solder joints. Sutariya concluded that lead free HASL solder joints outperform all other surface finishes, including SnPb HASL.
Drawbacks
But there were drawbacks involved pertaining to its planar, which makes it problematic for extremely fine pitch applications. If you’re interested in Past Solderability Issues with SN100Cl, read HASL and Flow: A Lead-Free Alternative from the February 2008 issue of CircuiTree. Furthermore, the SN100CL requires a Thermal Cycle in addition to thermal cycles in the assembly process.
Finally, there still remains no Industry standard regarding the Thickness Acceptability Criteria for SN100CL. As a result, smaller pads receive thicker solder deposition as a result of a Generic Thickness requirement because it is not proper to have just one solder thickness for all pad geometries. Sutariya said the solution was to segregate the minimum alloy thickness by ranges of pad size. By implementing alloy control, lower copper content of alloy increases solderability and the standard drossing of the solder pot is not enough to keep copper below 0.90%.
Sutariya recommended a ¼ - 1/3 solder pot dump once weekly copper content measurement reaches 0.90%.
Specific Design Set-Up
Then Saturn turned its focus to the Design link in the PCB Supply Chain and addressed the need for a specific design set-up. In addition, adjustments would need to be made to air knife pressure, retract speed, and dwell time. In effect, since the operating window is smaller than the SnPB, it is vital for the top of the Supply Chain to take control of the process!
Saturn and Florida CirTech have been utilizing the SN100Cl for over a year and have had no solderability issues at any customer. He attributed this to the value of the Fab Notes that can specify the use of these coupons or range of solder thickness standards.
Sutariya concluded that by doing this, you’d take control of the process by forcing your supplier to meet these specs.
Conclusion
Saturn Electronics’ Corporation’s Lead Free Cost Reduction presentation concludes that through the implementation of one or both of these proposed solutions, one can save up to 30% on their bare board costs while increasing the performance of their products. Additionally, this makes it much easier to standardize fab notes to removable risk of non-performing products.
Sutariya opened the floor to questions from the crowd and attendees, mostly PCB Designers who had very positive feedbacks regarding the recipe Sutariya and Saturn had just shared with them.
During this past summer, Sutariya gave the same presentation through a webinar. Polling questions included:
Have you experienced delamination during Lead Free Assembly?
46% of attendees answered yes
Have you ever tried and subsequently abandoned SN100CL?
6% said yes
12% said no
82% had never even tried it
What is your primary Lead Free Finish?
38% said RoHS Compliant
31% said Immersion Silver
13% said ENIG
13% said Lead Free HASL
6% answered Immersion Tin
PCB West is for PCB engineers, designers, fabricators and managers and includes a five-day conference of more than 35 technical courses.
Saturn Electronics Corporation is a leading manufacturer of high-reliability, and technologically advanced printed circuit boards. Dedicated to quality since our inception, Saturn delivers steadfast manufacturing that ranges from quick-turning elaborate prototypes to scheduled principal volume-production.
Saturn’s adherence to quality resulted in being the first PCB Manufacturer in North America to achieve TS16949 certification.
To view the archived version of this presentation, please email jim@saturnelectronics.com
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