Hot-Bump-Pull-Application-Note.pdf

Although these mechanical test methods test the entire assembly , it can howev er be dicult to dierentiate the types of failure modes occurring during the test. Common factors which contribute to dierent failure modes…

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Although these mechanical test methods test the entire
assembly, it can however be dicult to dierentiate
the types of failure modes occurring during the test.
Common factors which contribute to dierent failure
modes include:
• Solder metallurgy
• PBAmaterials
• Reowconditions
It is therefore important to isolate the failure modes
in order to identify any weaknesses in the assembly.
is is an important part of development and
production, as it ensures correct design of product,
manufacturing process control as well as quality of
product produced.
Hot Bump Pull/Hot Pin Pull
Application Note
e shift from tin-lead to lead-free materials has had
many aects on the surface mount technology
and printed circuit board industries. ese aects
continue to be a major focus of many sectors from
telecommunications, military, aerospace to consumer
electronics.
A common failure mode in lead-free assemblies is pad
cratering, where the contact pad on a PCB or package
substrate lifts away. ere are many factors that cause this
failure mode to be more prevalent in lead-free assemblies
compared to tin-lead assemblies, these include:
• Lead-free solders are mechanically stier than tin-lead
solders, hence it transfers more strain to the assembly.
• Lead-freesolderrequireshigherreowtemperaturesas
well as cooling rates compared to tin-lead. is can
lead to increased strains on the assembly.
Mechanical testing such as bend and shock testing are
common practices on surface mount assemblies and
printed circuit boards in order to verify product design,
ensure quality and ultimately to ensure product longevity.
e mechanical stresses applied, evaluate the susceptibility
of a product to failure.
Hot Bump Pull/Hot Pin Pull Application Note
What is Hot Bump Pull?
Hot Bump Pull load cartridge
e new Nordson DAGE 4000Plus HBP system is a totally
industry unique solution, conforming to IPC-9708 as well
as JEITA ET-7407A. It is fully integrated into a single load
cartridge on a standard 4000Plus system. Heating, cooling
stages and pin clamping mechanism are integrated into the
single load cartridge. e Paragon
™ software provides a user
friendly interface via temperature time proles to setup a test.
e new cartridge design allow simple straight test pins to
be used, allowing maximum force to be transferred as well as
providing a low cost consumable for testing. e new straight
pin design provides successful and consistent testing.
It is important to pull the pin vertically, directly by the
apparatus without imposing any bending moments.
e latest pad cratering standard, IPC-9708, denes hot bump pull as a method to evaluate the susceptibility of
printed board assembly materials and designs to cohesive dielectric failure underneath surface mount technology
attach pads. A method that can be used to rank order and compare dierent materials and parameters.
The Hot Bump Pull Test Procedure
e test procedure consists of two parts, set up of the test parameters and positioning of the pin over a solder bump.
Firstatemperatureproleiscreated,thisallowsausertoinputtemperatureandtimecriteriaforreowandtestconditions.
is simple interface only requires the desired temperature and the time to reach that temperature. e heating and cooling rates
as well as test execution are then automatically handled by the hardware and software.
A temperature time prole consists of the following stages.
Preheat
Soak
Rate of rise
Reflow/Liquidus
Cool down
Test execution
Close up of copper probe on BGA
Application Note Hot Bump Pull/Hot Pin Pull
Temperature-time profile in Paragon™
Test results in Paragon™
T1 is the preheat region, this is selected by dening the
temperature to reach and the time to achieve this heating period.
T1 to T2 is the soak period, the soak time can be selected.
T2 to T3 is the rate of rise.
A straight pin is vertically inserted into the cartridge, where it is held in place. e pin is then lowered onto the solder bump via motorised
horizontal and vertical stages. e pin is set so that it is touching the solder bump. e test is then executed, where the pin temperature
rampsupaccordingtothedenedtemperatureprolecreated.Atreowpointthepindropsdowntoadesiredlevel,ensuringagood
solder joint. e clamping mechanism then engages and clamps the pin so it is ready to be pulled. e cooling is handled internally by
pulsing compressed air past the pin and onto the test sample, cooling at the dened temperature prole.
Once the test temperature is reached, the test is automatically executed, recording the force-time,
force-distance and energy values.
T3toT4isthereowperiod,thereow
time period can be selected.
T4 to T5 is the cooling period.
T6 is the temperature where the test will be executed.
Close up of solder ball reflow