SMT Reflow

Solutions not known

Solutions not known at this time

Solutions need optimization

Current solutions need optimization

Solutions deployed or known

Solutions deployed or known today

Not determined

TBD

ROADMAP TIMEFRAME

TECHNOLOGY ISSUE

TODAY (2024)

3 YEARS (2027)

5 YEARS (2029)

10 YEARS (2034)

ISSUE #1

More AOI machines behind reflow machines so exit temperature for board from reflow oven has to be less than 50°C (actual temperature based on AOI equipment supplier requirements) (OSHA calls for 60°C) (Room temperature 25°C) (Cameras in automated optical inspection (AOI) cannot handle high temperatures) (This also covers double-sided boards)

NEED

More cooling capacity needed. (Need integration of cooling fans with oven). Increased number of cooling zones to 6 increases oven footprint by ~50%. Or allow higher allowable temperature into AOI.

Need to improve efficiency of cooling. Aim for 3°C/sec.

Need to improve efficiency of cooling Aim for 4°C/sec.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Most reflow ovens have a limited number of cooling zones (need more cooling zones) (Product size differences and conveyor speed requirements)

(Need to add external cooling units (fans) on top of oven behind reflow oven before AOI machines.)

Limited by the cooling rate of the components (<6°C/sec). Limited by the footprint of the oven in the factory  Current cooling rate for components on large boards is around 2°C/sec..

CHALLENGES

• If cooling capacity is increased then damage to component and boards occurs.

• Controlled length and time needed for cooling is difficult.

• Aggressive cooling rates could have a negative effect on the components for the product. (generally, component up to –6°C/sec) (Ceramic caps are limited to 3°C/sec)

ISSUE #2

Large boards with heavy fixtures.

NEED

Some ovens are vapor phase to address this concern. Have longer ovens to reduce this effect (increased preheat)

Longer ovens (up to 30% heating length)  to reduce this effect (increased preheat) Longer preheat or higher capacity heating capability.

Longer ovens  (up to 40% heating length) to reduce this effect (increased preheat) Longer preheat or higher capacity heating capability.

Longer ovens (up to 50% heating length) to reduce this effect (increased preheat) Longer preheat or higher capacity heating capability.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

-

-

-

-

CHALLENGE

Heating and cooling of large thermal mass product has effects on solder paste reflow and ovens (10 kg product plus fixture loads).

NEED

Cover small components so they will not go over temperature. Use of special fixture to cover small components and protect from hot air from oven (e.g., IBM work)

CURRENT TECHNOLOGY STATUS

Solutions not known

GAP

Lack of a better medium with a better heat transfer (for vapor phase reflow- smaller components are heated for too long (increased TAL- solder joint issue) even though not a very high temperature)

CHALLENGE

Challenge to heat big and small components at the same time and temperature that results in smaller components are overheated on board (flux charring).

ISSUE #3

Demand for higher throughput/ conveyor speed ovens (Longer ovens to meet process time/ throughput)

NEED

Higher throughput. Some 18-zone heating, 6-zone cooling ovens available

Higher throughput. Some 18-zone heating, 6-zone cooling ovens available.

More machines will have double 3 to 4 lanes to reduce floorspace.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Lack of optimum reflow oven setup for higher throughput with smaller footprint (increased use of conveyors)

CHALLENGE

Achieving a smaller oven with a smaller footprint, e.g., vertical reflow ovens (one option used in the past)

ISSUE #4

Confusion over the oven number of zones versus oven zone length for the user. Have a general guideline to define heated and cooling lengths.

NEED

Need to define the optimum ratio of the heated or cooling zone length in combination with the number of zones to make an accurate reflow profile.
Add the developed definitions into the relevant standard e.g., IPC 7530 and/or IPC 7801.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Lack of a standard and/or guideline definition of a required ratio for heating or cooling

CHALLENGE

None

ISSUE #5

Need low voiding during reflow, which will affect reflow oven throughput (e.g., for MOSFET type and bottom terminated components (BTC) components) (Look at types of heating zone methods to address this)

NEED

Lower voiding with vacuum ovens. (Could be vacuum in vapor phase oven and vacuum in convection ovens)

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Vacuum chamber size is small. Time to reach vacuum is very slow and affects product throughput.

CHALLENGE

• Challenging to ensure no leakage in vacuum chambers.

• Weekly maintenance required for vacuum chambers.

ISSUE #6

Vacuum/ Vapor (Formic acid/ Hydrogen atmosphere) phase oven contamination effect of flux chemistry on reflow oven - Maintenance requirements) (Vapor phase)

NEED

Improve flux collection system of oven

More efficient and robust collection system. Less Maintenance.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Lack of maintenance.  (Weekly maintenance is currently 10  to 12 hours maintenance). Chamber has to be opened to clean flux. Lack of efficient collection systems.

Development/ improvement of flux collection systems (improvement and re-design).

CHALLENGE

Mix of different pastes in vacuum/ vapor phase oven. Vacuum is used intermittently so flux is collected in chamber more when vacuum is off, which increases flux amount in chamber.

CHALLENGE

Updating existing equipment will be a challenge.

ISSUE #7

Improve flux extraction and removal for convection ovens

NEED

Improving extraction and removal to reduce oven maintenance and machine downtime

Effective removal (60% removal) of reflowed flux fumes from the chamber to a collection system with no need to open the chamber. (Extraction and removal are two separate terms:
> 50% extraction of fumes,
80-90% removal of flux from the fumes)

Effective removal (80% removal) of reflowed flux fumes from the chamber to a collection system. No need to open the chamber.

The objective is to reduce oven maintenance and machine downtime.

Effective removal (90% removal) of reflowed flux fumes from the chamber to a collection system. No need to open the chamber.

The objective is to reduce oven maintenance and machine downtime.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAPS

• Lack of efficient flux extraction methods from chamber.

• Lack of  more efficient flux removal from gas atmosphere. (Air: flux is extracted out from the oven. Nitrogen: re-circulation of nitrogen with flux in oven.)

• Need to extract flux residues from air atmosphere in Europe based on legislation sustainability requirements.¹

How to extract flux from chamber without affecting the dynamics of the heating system and O2 level in nitrogen atmosphere if used.

CHALLENGE

Modes of extraction of flux residue from air atmosphere vary. Maintenance of the dynamics of the heating system.

ISSUE #8

Need to have different types of heating methods to reduce Delta T between small and large components. (Large Delta T implies overheating of small components.)

NEED

Reduce Delta T between small and large components (<5°C to <15°C Delta T and limited time over liquidus).  Explore different types of heating (Convection, radiation, conduction vapor)

Reduce Delta T between small and large components (<5°C to <15°C Delta T and limited time over liquidus). Explore different types of heating (Convection, radiation, conduction vapor) including hybrid technologies.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

Solutions not known

GAP

Development of different types of equipment is still in progress. Can not meet Delta T requirements for overall assembly or in some cases the smaller components have overheating.

CHALLENGE

Implementing low delta T equipment in production lines with no increased cost is a challenge. Some large board designs with large thermal mass are particularly challenging. Thermal modelling for DFM may help.  

CHALLENGE

For vapor phase preheating is a concern. Tendency for tombstoning of chip component with vapor phase.

N/A

ISSUE #9

Sustainability and energy consumption for reflow ovens (Less N2, power etc) (Lower carbon footprint)

NEED

Reduce power, N2 use and purity of N2 use and N2 leakage. Need more efficient heating and reduced temperature loss (insulation, etc.) through power/ N2 idle/ saving modes, reduced power motors.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

GAP

Inability to keeping power low while still needing to heat board in a sufficient time

CHALLENGE

Balance between lowering power consumption and maintaining production volumes is difficult when transitioning from a heavy product with hot program to a small product with lower heat. Changeover time is long.

ISSUE #10

Equipment and assembly materials compatibility (flux management system).

NEED

Equipment capable of managing the use of different flux materials, to reduce maintenance intervals and thereby reducing cleaning.

Equipment capable of managing the use of different flux materials to reduce maintenance intervals. Self-cleaning of the machine.

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

Condensation and catalysts to collect volatiles from flux.  Scrubbing is required for proper cleaning.

GAPS

• Lack of development of condensation and catalyst methods.

• Scrubbing.

• Advanced solder mask and flux chemistry.

• More development of condensation and catalyst methods.

• Scrubbing.

• Advanced solder mask and flux chemistry and better containment.

• More development of condensation and catalyst methods.

• Scrubbing.

• Advanced solder mask and flux chemistry and better containment.

Elimination of solder mask and flux management

CHALLENGES

• Solder mask and component and flux chemistry are needed to be collected which can change. This should be the dominant consideration when considering the equipment and the assembly material used. (Convection oven).

• Energy consumption and waste disposal is a challenge. In the development of the new types of solder masks and flux chemistries the environmental impact should be taken into account.

ISSUE #11

Standardization of oxygen level used in oven. Reduce N2 consumption to reduce operational cost.   Atmosphere control (maintaining O2 levels in a certain range in the oven) (ppm of O2 Levels: below 100 ppm- more tombstoning) (Target- 200-500 ppm O2) (Range varies by customer: some customers use 1000-2000 ppm O2).

NEED

Maintain O2 levels to customers’ requirements while  reducing N2 consumption. Provide industry guideline on N2 usage in terms of use and O2 ppm level guideline (e.g., place this information into IPC J-STD-001 handbook).  
For 1000 ppm O2- equivalent to 400 slpm (standard liters per minute).

Have a level of N2 and how much N2 flow is needed to maintain that level.

Maintain O2 levels to customer requirement. Provide industry guideline on N2 usage in terms of use and O2 ppm level guideline.

For 1000 ppm O2- equivalent to 350 slpm

Maintain O2 levels to customer requirement. Provide industry guideline on N2 usage in terms of use and O2 ppm level guideline.

For 1000 ppm O2- equivalent to 325 slpm

Maintain O2 levels to customer requirement. Provide industry guideline on N2 usage in terms of use and O2 ppm level guideline.

For 1000 ppm O2- equivalent to < 300 slpm

CURRENT TECHNOLOGY STATUS

Solutions Need Optimization

Some machines have this capability but a majority of the system has a manual system of control. With manual system if production is stopped then the N2 level may go out of control as the machines have idle mode. If there is no production, fans may reduce in speed and N2 may be reduced.  The other method is reduction in N2 introduction. N2 flow/ consumption/ hour- CuM/ hr or liter/min-

GAPS

• Mainly manual control used today.

• Lack of equipment with automatic nitrogen control capability. 

• No calculation of minimum N2 quantity that is required in oven to maintain O2 ppm level.

CHALLENGES

• Cost/ benefit for use of N2.

• Flux chemistry, component, board surface finish, joint size dependencies.

2

TRL: 1 to 4

Levels involving research

6

TRL: 5 to 7

Levels involving development

9

TRL: 8 to 9

Levels involving deployment

EXPECTED TRL LEVEL*

TECHNOLOGY ISSUE

POTENTIAL SOLUTIONS

 TODAY

(2024)

3
YEARS

(2027)

5
YEARS

(2029)

10
YEARS (2034)

ISSUE #1

More AOI machines behind reflow machines so exit temperature for board from reflow oven has to be less than 50C (actual temperature based on AOI equipment supplier requirements) (OSHA calls for 60C) (Room temperature 25C) (Cameras in AOI cannot handle high temperatures) (This also covers double-sided boards)

More cooling capacity

5

6

7

8

Increased number of cooling zones (to 6 cooling zones)

5

6

7

8

Increased length

5

6

7

8

ISSUE #2

Large boards with heavy fixtures Smaller components are overheated on board (flux charring)

Fixtures with lower thermal mass and relatively cost (which would reduce the need for shielding of smaller components)

3

4

5

7

Improved ability of reflow oven to heat up and cool down (increased thermal and cooling capacity)

5

6

7

8

Better design of large boards so fixtures are limited in use

4

5

6

7

Better fixture design for large boards

4

5

6

7

ISSUE # 3

Demand for higher throughout/ conveyor speed ovens with smaller footprint (Longer ovens to meet process time/ throughput)

Horizontal integration ovens (multiple lanes or chambers)

6

7

7

8

Vertical integration ovens (curing applications)

8

8

8

8

Vertical integration ovens (soldering applications)

2

3

5

8

ISSUE # 4

Confusion over the oven number of zones versus oven zone length for the user. Have a general guideline to define heated and cooling lengths. 

Create standard definition/ guideline for the user

3

4

6

8

ISSUE #5

Need low voiding during reflow which will affect reflow oven throughput (e.g for MOSFET type and BTC components)

Improved vacuum oven throughput

6

6

7

8

Reduced vacuum oven size

7

7

8

8

Low maintenance/ reduced downtime of vacuum oven

5

6

7

8

Optimization of reflow profile to reduce voiding

6

6

7

8

ISSUE # 6

Vacuum/ Vapor (Formic acid/ Hydrogen atmosphere) phase oven contamination. Effect of flux chemistry on reflow oven - Maintenance requirements) (Vapor phase)

Improved flux collection system of oven

5

6

7

8

ISSUE # 7

Improve Flux extraction and removal for convection ovens

Fume extraction from chamber

5

6

7

8

Flux removal from the fume

5

6

7

8

ISSUE #8

Need to have different types of heating methods to reduce delta T between small and large components. Large delta T implies overheating of small components.

Development of hybrid heating solution (e.g., convection with, radiation, conduction with vapor technology)

1

3

5

7

ISSUE # 9

Sustainability and energy consumption for reflow ovens (Less N2, power etc) (Lower Carbon footprint)

Reduce N2 use and purity of N2 use and less N2 leakage.

5

6

7

8

Reduce power

4

5

6

7

ISSUE # 10

Equipment and assembly materials compatibility (flux management system). Lot of cleaning needed.

Equipment to be able to manage the use of different flux materials (including solder mask). (Convection reflow)

6

7

8

8

Reduce maintenance interval. Self-cleaning of the machine.

(Conventional reflow)

6

7

8

8

Equipment to be able to manage the use of different flux materials (including solder mask).  (Vapor phase reflow)

6

7

8

8

Reduce maintenance interval. Self-cleaning of the machine.

(Vapor phase reflow)

7

8

8

8

ISSUE #11

Standardization of oxygen level used in oven. Reduce N2 consumption to reduce operational cost.  Atmosphere control (maintaining O2 levels in a certain range in the oven) (ppm O2 Levels: below 100ppm- more tombstoning) (Target- 200-500ppm O2) (Range varies by customer: some customers use 1000-2000ppm O2).

Development of standard/ guideline (IPC or other organization) for recommended oxygen level in oven).

4

5

7

8