Mike Fenner. Shipping solder paste. Paste vehicle and powder. Once made. Shipping and storing solder paste. Shipping and storing solder paste

Transcription

1 Shipping and storing solder Shipping and storing solder Mike Fenner Technical Manager Indium Europe August 2006 Slide 1 Slide 2 We ship world wide Shipping and storing solder In Europe we make several thousand movements a year We have ship to line status with nearly all our customers We have only 3 4 shipping incidences a year These are exclusively related to lost or damaged containers, not damage to product This is because of the precautions we and our customers observe on packing, shipping and storing This presentation explains and documents the key areas of our policy and recommendations to customers. Shipping solder Solder is an intimate combination of fine metal particles with a resin flux and rheology package: The vehicle Slide 3 Slide 4 Paste vehicle and powder Once made The powder has a very large surface area in contact with this mixture. The product is packed in a polymer container Once the product is made and packed, various things start to happen Some of these things are purely theoretical and of no practical concern. Example: solvents can given enough time - diffuse through the packaging and evaporate. [Neither we nor will live long enough to see the effects of this.] Slide 5 Slide 6 1

2 Once made What happens in storage Others are real. The flux has chemical activity, it can react with the metal powder, in particular with the small traces of oxide which will always be present, and are necessary with some alloys to maintain particle integrity. (oxide reduction is one of the functions of flux). We don t need to know all of the things in detail, Let s just say that whatever these changes are they represent a change from the original formulation. Eventually the sum of all these changes whatever they are - will be enough to affect the product in a measurable way. It won t be as formulated. In other words a loss of quality Slide 7 Slide 8 What happens Slowing down / speeding up change Slide 9 We can represent this graphically like this: Performance/Quality Unacceptable Time Slide 10 These events are slow. At ambient we do not expect to see anything for at least 3 months for an Sn62/Sn63 We can slow them further by cooling the product. Approximately: Refrigerating halves the rate of change. So we have at least 6 months What is unacceptable? Time and quality Slide 11 It will vary according the criticality and inspection levels/expectations of the user. To us it is when we can no longer guarantee - with a margin - that the product is to our as manufactured specifications. Slide 12 Shelf life cut-off Quality Unacceptable Time Shelf life Cut-off: 3 months weeks Ambient 6 months Refrigerated 2

3 Effect of heat Recap With increasing temperature the loss of quality is accelerated. However flux is a temperature activated product As the temperature continues to be increased the flux will begin to become more active more rapidly. At 220C, the flux will be completely activated and react in seconds Cooling the extends shelf life. 1x time at room temperature ~ 2x time in the fridge A few days removed from back end of refrigerated shelf life is irrelevant. Note: We actually say 6 months from end of month of manufacture, so there are always some free days. Refrigerated: 10C or less Major concern is excess temperature Slide 13 Slide 14 Effect of excess heat Effects of Over temperature 50 It is this very rapid change from months to seconds in speed of reaction which is the concern. somewhere above 40 C things really begin to happen, from about 70-80C the flux is starting a reflow cycle. We have made some measurements* *Indium Corporation America 2002 %Change SMQ92J: 16 hours exposure Viscosity Tack Slide 15 Slide 16 Temperature C Shipping procedures Above 40C, the shelf life transits from weeks/months to hours/days. Precautions include some or all: Insulated containers [refrigerant] Super cool before shipping Refrigerated transport Labelling Minimise time and number of transitions in shipping Measuring packaging efficiency We measured* the ability of our packaging to resist heat transfer. The time for to transit 35C whilst packed in our insulated container. Logger in container not probing To obtain constant (isothermal] conditions we actually put +25C in a -10C environment - an infinite heat sink This is somewhat more severe than real world Measurements were taken hourly till temperature stabilised Slide 17 Slide 18 *Re-verified by Indium Corporation Europe

4 Insulated Containers Time for over temperatures to affect Temperature C Hours Internal /ExternalTemperature Gradient C Paste at 25C will take 12 hours to warm to a 35C environment Hours to change Slide 19 Slide 20 Insulated Containers Employ Best practice Conclusions: hours 3 is a conservative number 2 for cooled transit 2 Internal /ExternalTemperature Gradient C 1 Over temperatures would have to be large and persist for some hours to effect 45 interior temperature Hours to change Wise precautions for critical applications Temperature logger till concerns are satisfied Use temperature strips Viscosity check if in doubt Coalescence test if in doubt Monitor Functionality Slide 21 Slide 22 Effects of over temperature If flux begins to react prematurely/incompletely effect is A rise in viscosity Poor coalescence as oxide reduction is impaired Functionality: Poor release, reduced out times, reduced tack, reduced wetting, Best Practice: SOP Over temperature procedures Goods-in to note concerns on receipt, move to cold storage. Set aside suspect material till viscosity and possibly coalescence checked. Add variances in properties above to SPC matrix If necessary identify product as On hold till tests concluded Slide 23 Slide 24 4

5 Best Practice: SOP Controlling on line Good FIFO Order and restocking frequency related to usage rate. Use cold [10 o C] long term storage and short term (1 week) ambient storage Control rate of issue to line (ambient store] Ensure a one way street Shipping and storing Paste We hope this has been useful in helping you understand the issues and so define your own procedures Slide 25 Slide 26 5