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TM4C1294KCPDT: Why no MCU reflow temperature ramp profile found in datasheet

Genatco
Guru 55913 points
Part Number: TM4C1294KCPDT

Where can TM4C129x MCU reflow profile information be found?

  • 0
    Guru 117855 points

    Is there "need" for such "profile info" when one "solders" w/"Combined, 200W - Wood-Working/Solder Pistol tool?" (understood is the "need" for such tool - when "removing" Power FETs - which have "LONG" met (never user caused) misfortune...)

    We await your next entry w/in the, (likely) "Toaster Oven" soldering sweepstakes...

    Is it not likely that (many) devices will be "reflow soldered" - in unison?     Broader survey (many devices) may "blip your radar."

  • 0
    TI__Guru**** 191256 points
    Hi BP101,
    Please take a look at this wiki page. Hopefully it will answer some of your questions about the reflow profile. processors.wiki.ti.com/.../Package_Reflow_Profiles
  • 0 in reply to Charles Tsai
    Guru 55913 points
    Hi Charles,

    Couple of things are not being answered by Wiki such as what is CBB/CBC package as TM4C1294 is an LQFP package?

    Wiki table describes a conveyor time and most IR type ovens have a static tray (no conveyer time), what then? The Wiki table seems to deviate from the typical ramp soak profiles available in many IR type ovens. Might there be an actual (static) ramp soak graph available for theTM4C129x LQFP package?
  • 0 in reply to Genatco
    Guru 55913 points
    >>The maximum allowed reflow temperature is stated on the Moisture Sensitivity Label (MSL).

    Will have to check package label again as that seems the key on determining the solder paste temperature range in the desired IR profile.
  • 0 in reply to Charles Tsai
    Guru 55913 points

    Hi Charles,

    Wouldn't you know the vendor omitted the maximum LQFP package temperature on the outer moisture bag but did write use within 187 days. Other TI devices same vendor have the maximum package temp marked on the bag 260*c. Note datasheet has No a reflow profile but a maximum package temperature vendor can write on the moisture barrier bag.

    CU NIPDAU Level-3-260C-168 HR

  • 0 in reply to cb1_mobile
    Guru 55913 points
    Thinking to reprogram lab oven for a different cake, like to know the maximum package temperature and the recommended seems to be 235*C. Ideally we paste/epoxy parts on back side PCB then ramp soak right side up and later 1 more cycle all top mount components.

    Considering a commercial IR oven with pre-programmed profiles - done with holding parts sharp bamboo stick while soldering with 3rd hand etc... : (
  • 0 in reply to Genatco
    Guru 117855 points
    There were (some) - who doubted my detection of your "conveyor-less" (i.e. likely toaster oven) method of reflow soldering. You appeared "uncertain" as to the value of the conveyor. It is intended to lessen and/or eliminate "thermal shock" - while enabling the best "board throughput."

    Our small firm acquired a used, 15' long, conveyor based system - hired experts to "refurbish/restore." (saved 70% of the price, new)

    Note that along w/reflow - you should employ a quality stencil. "Plastic" greatly challenges - saving "stencil cost" - by "risking the entire board" may not make, "Dollars & Sense."
  • 0 in reply to cb1_mobile
    Guru 55913 points

    cb1_mobile said:
    It is intended to lessen and/or eliminate "thermal shock" - while enabling the best "board throughput."

    Supposedly the pre-heat ramp of static convection (IR) profile produces the same bake cycle as the very costly conveyor system.

    cb1_mobile said:
    There were (some) - who doubted my detection of your "conveyor-less" (i.e. likely toaster oven)

     

    Actually a custom 1.2w' x 2.5h' x 1'd x 2" thick walled vermiculite oven with two 2KW 220VAC heat coils controlled by 2 SSR driven by programmable ramp soak controller. Had bad boy up to 750F/2Hr in 12 hour ramp soak cycle of metal parts hardening and later for high temp acrylic epoxy curing. Once chamber heats 1st cycle any moisture escapes via 3" long convection vent along top edge and pulls outside air in via slotted bottom edge vent side of heat strips. May remove ceramic bricks above strips for MCU ramp soak profile but those 2KW heat strip can rapidly rise chamber temp in controlled steps.   

    cb1_mobile said:
    Note that along w/reflow - you should employ a quality stencil.

    PCB shop will do the 1st reflow of bare copper and trust they have/use an OSP like coating (ENTEK® PLUS CU-106A). Such coating is a substituted benzimidazole that can preserve the solderability of Cu through multiple soldering operations. That might be a good advantage with so many dang parts both sides PCB populated in stages over time/months etc...

    Many folks simply apply 2nd reflow paste via needle type applicator (paste is costly) spread over & make stencil seemingly a difficult task. Good that solder mask MCU pins is .05mm removed circumference of pad. If a premade re-useable LQFP 128 pin stencil were available it might speed process of trying to apply even lines with needle under magnification lamp.

  • 0 in reply to Genatco
    Guru 117855 points

    May we assume the 2" thick walled vermiculite oven is "at home" in your basement? (along w/the custom BLDC Motor - clamped to the concrete floor!)

    I was unaware of your "oven upgrade" - the conveyor driven, oven system has long been judged superior - few would make that cost/size investment - w/out (very) identifiable advantages...

  • 0 in reply to cb1_mobile
    Guru 55913 points

    cb1_mobile said:
    the conveyor driven, oven system has long been judged superior

    Great for mass quantities yet smaller shops are commonly using low cost forced convection IR ovens with selectable pre-programmed ramp soak cycles. Especially prudent (pro) for double sided parts mounting there is no chance conveyor vibration to shake previous (side down) reflow and cause 2nd cycle paste migration between pins under force of gravity. 

    cb1_mobile said:
    I was unaware of your "oven upgrade" -

    It too may not hold weight against a forced air convection system yet oven still works great for curing high tem acrylic epoxy or resins.