▁be ▁generated ▁in ▁the ▁material ▁in ▁a ▁phenomen on ▁known ▁as ▁the ▁Se eb e ck ▁effect . ▁The ▁Se eb e ck ▁effect ▁is ▁essentially ▁the ▁reverse ▁of ▁the ▁P elt ier ▁effect . ▁In ▁this ▁mode , ▁elect rical ▁power ▁is ▁generated ▁from ▁the ▁flow ▁of ▁heat ▁in ▁the ▁TE ▁element . ▁The ▁structure ▁shown ▁in ▁Figure ▁ 3 ▁is ▁capable ▁of ▁operating ▁in ▁both ▁the ▁P elt ier ▁and ▁Se eb e ck ▁modes , ▁though ▁not ▁simultaneously . ▁ ▁Figure ▁ 4 ▁shows ▁a ▁sch ematic ▁of ▁a ▁typical ▁CP B ▁and ▁a ▁thermal ▁b ump ▁for ▁comparison . ▁ ▁These ▁structures ▁are ▁similar , ▁with ▁both ▁having ▁co pper ▁pill ars ▁and ▁sol der ▁connections . ▁ ▁The ▁primary ▁difference ▁between ▁the ▁two ▁is ▁the ▁introduction ▁of ▁either ▁a ▁P - ▁or ▁N - type ▁therm oe lect ric ▁layer ▁between ▁two ▁sol der ▁layers . ▁ ▁The ▁sold ers ▁used ▁with ▁CP B s ▁and ▁thermal ▁b umps ▁can ▁be ▁any ▁one ▁of ▁a ▁number ▁of ▁commonly ▁used ▁sold ers ▁including , ▁but ▁not ▁limited ▁to , ▁Sn , ▁Sn P b ▁e ut ect ic , ▁Sn Ag ▁or ▁Au S n . ▁ ▁Figure ▁ 5 ▁shows ▁a ▁device ▁equ ipped ▁with ▁a ▁thermal ▁b ump . ▁The ▁thermal ▁flow ▁is ▁shown ▁by ▁the ▁ar rows ▁l abeled ▁“ he at .” ▁Metal ▁traces , ▁which ▁can ▁be ▁several ▁mic rom et res ▁high , ▁can ▁be ▁stack ed ▁or ▁inter dig itated ▁to ▁provide