How to increase lifetime of electronic products (THT components): investigation and results

How to increase lifetime of electronic
products (THT components):
investigation and results
Soldering process platforms for THT
components
Delta Wave
6748
Present status for technology
6747
Inertec
ERSA
Svetlana Andersen
06-05-2014
Soldering methods
Svetlana Andersen
Present status for technology
Soldering of THT components
Soldering platforms:
• Wave soldering (one side SMD, same side THT).
Full nitrogen (ERSA) machine operates with less maintenance and less tin
consumption compared to Soltec. No limitation in quantity of product
variants.
• Selective soldering Soltec (2 sides SMD, one side THT).
6748 machine is used for module alignment and soldering at the same time.
Limited to 4 possible products.
6747 machine is used for hign volume, low mix production set up. Limited to
2 possible products.
• Selective soldering Inertec (2 sides SMD, 1 side THT).
Machine is used for soldering and accurate alignment of modules. Change
over between products is not complicated, but the technology is rather
expensive because of wear of tools.
06-05-2014
Svetlana Andersen
Test on representative products
5
Barrel fil, clinch-angle & hole size
Other findings:
•Simulation
•Test
Hulstørrelse er
vigtigere end
clinchning
Solder joint and Cycling Experience, 2007-04-27 JOJ
6
Simulation findings
Solder fill is very
important
Solder fill is much more
important than clinch
angle
Ranked order of importance:
1. Solder Fill
2. Size of hole
3. Solder
Clinch
Angle
joint and Cycling Experience, 2007-04-27 JOJ
7
Weak point candidates
8
What can impact flow-through (solder filling):
- Lack of adequate heat transfer up the lead and barrel. Both the barrel
and the lead must reach soldering temperature throughout the PWB
thickness, or solder flow up the barrel will be halted. Problems can be
caused by lack of lead protrusion, too many ground plane connections to
the PTH or insufficient thermal relief on ground connections, too low
solder temperature or too-short contact time.
- Slow or absent wetting. Both the lead surface and the hole wall must
be made wettable by a flux in order for a capillary force to be generated
that will cause the solder to flow up the hole. Wetting problems can be
caused by poorly-solderable surface finishes, lack of flux penetration, or
improper pre-heat (either too-aggressive or insufficient), or
contamination of hole walls or leads.
Proces parameters and output
Noise factors
Variation in raw material
Process variation (e.g. temperature, nozzle size, comp.placement inside the hole)
...
Factors
Flux material(??)
Flux amount
Borehole design
Diameter
Solder surface quality
(solderability)
Dimention of solder thermals
Cu thickness
Output
Filling degree
How to measure?
How to lower variation?
Selective soldering:
Saver on the existing
solder plate
Control parameter
Solder temperature
Contact time
Preheating temperature/time
Temperature
measurements
Temperature in nozzles (Saver 3ph)
No significant difference in temperature – no influence of nozzle size
Preliminary test with solder filling in wave soldering
process (test board used)
Picture of the test PCB
PCB manufactured with following
parameters:
- Cu in outerlayer (track 1+4)
- Cu in innerlayer (track 2+3)
- Cu in all 4 layers (track 1+2+3+4)
- Full flood in all layers
- thermal 0,4mm long in all layers
- thermal 1mm long in all layers
movement direction
Test results with pcb layout
Solder direction standard (9 PCB)
120
Solder filling %
100
80
Track layer 1+2+3+4
60
Full flood
Thermal 0,4/1,0
40
Thermal 1,0/1,0
20
0
0,8 0,9 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2 2,1 2,2 2,3
Solder direction changed 180 degr. (4 PCB)
120
100
Solder filling %
Process parameters:
1 reflow
Wave soldering
conveyor speed 110cm/min
Tin temp. 270oC
Preheating :280-200-200
flus: KOKI JS-EU-01
PCB nr.: 6-14
80
Track layer 1+2+3+4
60
Full flood
Thermal 0,4/1,0
40
Thermal 1,0/1,0
20
0
0,8 0,9 1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2 2,1 2,2 2,3
Test resultater
Ref 3ph
11-30600372
11-30600393
11-30701632
11-30701630
11-30701599
11-30701573
SaVer Reference Print
(til HMY layout)
HMY Trial Layout
C2.1
C2.2
C13.1
Barrel fill <75% (but
>50%)
C13.2
C16.1
C16.2
C19.1
Barrel fill <100%
(but >75%)
C19.2
C201.1
C201.2
C202.1
C202.2
C203.1
C203.2
C204.1
C204.2
C206.1
C206.2
C207.1
C207.2
C208.1
C208.2
C209.1
C209.2
C210.1
C210.2
C211.1
Find a
difference
Possible solution
Contacting top layer and
innerlayers by side of solder
hole with via holes
1
Selective soldering optimisation
Begge 2
løsninger
Indføres i DG
om lodning
2
There should be thin connection between solder pad and solder thieve.