I am assuming that you are using common commercial tapes and reels. These can not withstand the commonly used 125 C baking temperatures that are listed are listed in IPC/JEDEC J-Std-033B.
The most frequently used drying approach is to:
This is usually done by a tape and reel sub-contractor. The process has several significant disadvantages.
- Have the moisture-sensitive packages removed from the tape.
- Discard the original tapes.
- Place them into high-temperature trays,
- Baked at 125 degrees C per J-Std-33B for 48-hours.
- Remove them from the trays.
- Placed the packages into new tapes.
There is a new moisture-sensitive surface-mount package drying process that allows your packages remain in their tape while baking. It uses a 70 C baking temperature for only 24-hour. Two years of independent testing shows that 50% or more of a packages expired floor-life can be restored by this method. This process fully conforms to IPC/JEDEC J-Std-033B. Normally, 50% of the package's floor-life is sufficient for mount and reflow soldering.
There are three cautions in implementing this 70 C process.
- It is expensive. It is not unusual to see contractor prices ranging 26-cents per package.
- It is time consuming. Delays of 96 hours or more in production are not uncommon.
- High temperature baking is detrimental to solder. It promotes intermetallic growth and the formation of surface oxides. Neither is good news for no-lead solders.
If you want more detailed information, visit our website.
- Precise temperature control is critical
- The oven chamber pressure should be reduced to 100 torr to reduce the relative humidity.
- The oven must provide proper tooling to prevent reel deformation.
Charles S. Leech Jr.
Director of Engineering
Innovative Drying Co.
Mr. Leech lead a successful 2 year long process development effort that identified the parameters required to rapidly dry moisture sensitive devices while they were encased in the tape and reel format. Mr. Leech has over thirty years of experience as a manufacturing engineering manager in the electronics industry.
NOTE: Mr. Leech is no longer working at Innovative Drying Co.
The recommended bake temperature for components in Tape and Reel is 40C. If you use a bake temperature higher than that, the cover tape and other elements of the packaging will degrade to the point that it becomes impossible to reliably use an automated tape feeder afterwards.
To determine the required bake duration for your specific application, refer to the industry standard for use and handling of Moisture Sensitive Devices, IPC/JEDEC Joint Standard 033B.1. Table 4-1 of this standard provides " Reference Conditions for Drying Mounted or Unmounted SMD Packages." Table 4-1 illustrates that required bake duration is dependent on the following variables:
If the 40C bake duration specified by Table 4-1 is unacceptably long, then your best bet is to remove the components from tape and reel and bake them in bulk at 125C. Bake durations at 125C are significantly shorter, and are also listed in Table 4-1. After baking in bulk you can have the components re-packaged into Tape and Reel, or Matrix Tray, or arrange to have them hand-placed. The most logical choice depends on the specific application, component body size, and quantity of components that you're dealing with.
Additional technical information about MSD related matters is available for download from the Knowledge Center at Cogiscan's Web Site, http://www.cogiscan.com/
- Moisture Sensitivity Level (MSL),
- Component Body Thickness,
- Length of time since component's Floor Life has expired (i.e. more or less than 72 hours?),
- Certain guidelines are different for BGAs and Stacked Die Packages, in comparison to other package types.
Sales Manager (Americas)
Mitch DeCaire, Sales Manager at Cogiscan, has served the electronics manufacturing industry since 1989. His prior experiences include process engineering, business development, and engineering management roles with Nortel Networks, Vansco Electronics, Universal Instruments and Siemens.
Please refer to IPC-JEDEC 033 from IPC or a pdf from MagnaB Eurostat. Also, for further enlightenment on MSD, take a look at Cogiscan's website as it is an excellent clearinghouse for articles on the subject.
Mr. Zarrow has been involved with PCB assembly for more than thirty years. He is recognized for his expertise in troubleshooting SMT manufacturing and lead-free implementation. He has extensive hands-on experience with set-up and troubleshooting through-hole and SMT processes throughout the world.