Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Eric Jenkins

#16011

Help... Need new or used SOIC-16 metal tubes | 4 May, 1998

Looking to buy used or new tubes, that will fit an SOIC-16 Need these tubes ASAP. We need to bake these parts and drypack. Please email or call if you can help. Eric Jenkins 801 956-0897

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Dave F

#16013

Re: Help... Need new or used SOIC-16 metal tubes | 4 May, 1998

| Looking to buy used or new tubes, that will fit an SOIC-16 | Need these tubes ASAP. We need to bake these parts and drypack. | Please email or call if you can help. | Eric Jenkins | 801 956-0897 Eric: A source for metal IC tubes is: Perfection Products 1320 S Indianapolis Ave Lebanon IN 46052 765.482.7786 fax 7792

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Dave F

#16012

Re: Help... Need new or used SOIC-16 metal tubes - Do You Really?? | 5 May, 1998

| Looking to buy used or new tubes, that will fit an SOIC-16 | Need these tubes ASAP. We need to bake these parts and drypack. | Please email or call if you can help. | Eric Jenkins | 801 956-0897 Eric I'm not sure of the manufacturer of the parts that you are baking, but many manufacturers have two bake profiles. 1. higher temperature and faster, but requires handling components and metal tubes and reels 2. Lower temperature and slower, but can be done with the supplers tubes and reels As an expample, page from Intel's "Packaging Databook," page 8-21 8.5.2 Rebaking of PSMCs � High Temp Bake. If the HIC indicates that the contents of the MBB have expired, then the components can be baked to desorb moisture. Two bake temperature profiles are recommended, High and Low temperature. The higher temperature bake is 125� C for 24 hours for thicker packages (� 2 mm) (for PQFP and QFP greater than 132 leads, bake units for 48 hours at 125� C). For packages less than 2mm thickness a 6 hour bake at 125� C is sufficient. This requires that the components be removed from plastic shipping tubes, trays or tape and reel and placed in metal or high temperature plastic containers. Components should be handled carefully to avoid lead coplanarity problems or any other type of damage. After this bake, the units may be exposed to an environment no more extreme than 30� C/60% RH for a maximum of the time specified on the label. � Low Temp Bake. Intel has also identified a low temperature bake profile. It allows component moisture desorption in the original plastic shipping containers and, thereby, avoids possible damage to component leads that might be introduced through additional handling. The low temperature bake is a 192 hour dwell at 40� C (+5� C, -0� C)/� 5% RH. Figure 8-24 shows the curves for moisture desorption in these conditions. After 192 hours, saturated components will desorb moisture down to a residual moisture content that will allow a maximum of 48 hours ambient exposure in environments not more extreme than 30� C/60% RH. The low % RH condition in the oven is critical. Longer bakes are required if the humidity exceeds 5% RH. Note that the temperature of the bake is limited by the thermal stability of the device shipping containers. The shipping containers will not hold dimension at bake temperatures higher than 45� C (40� C +5, -0 as indicated). It is not advisable to store PSMC units at the low bake temperature longer than the time required to dry out the units for use in the reflow. Lengthy storage times at elevated temperatures can lead to problems with intermetallic formation between the lead frame material and the lead finish, increased oxidation of the lead finish which can contribute to added reflow and wetting problems, and extended elevated temperatures can cause the antistatic properties of the shipping media (tubes/tape and reel) to deteriorate. � Solderability Considerations/Number of Rebakes. Solderability tests performed on PSMCs exposed to either bake cycle are the basis for Intel�s recommendations and limits on the number of allowable bake cycles. PSMCs should not be baked more than once by the customer if using the high temperature bake of 125� C for 24 hours. Following this guideline will limit the formation of Cu6Sn5 intermetallic and therefore, not promote solderability degradation. The low temperature bake of 40� C does not require this restriction.

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