Reflow Wave Solder Pallets Matrix Fixture Adjust PCB Fixtures
FLEX CIRCUITS ARE A SPECIALTY AT CW
The demand for CW’s SMT Assembly Fixtures is growing as they are a
solution to solving many of the challenges associated with SMT
assembly. Our solid design capabilities are proven to handle even
thin PCBs as well as brands with unusual form factors. Some of
DMI’s design features include:
1. Optical grade composites to make it much easier for the PCB
present sensors to ‘see’ the fixture.
2. CW offers a unique design using a built-in spring-tension pin to
hold the PCB in place for ultra-precise applications or
interference fits. These sliding board tension locks secure PCB’s
(ranging in thickness from 0.005” to 0.125”).
3. CWs pallets are designed to set the PCB .005” ‘proud’ above the
fixture for optimal screen printing results.
IMPROVE YIELDS BY ENSURING CRUCIAL BOARD PLANARITY AND SOLID
ALIGNMENT ACCURACY DURING THE REFLOW PROCESS.
Print through & reflow pallets keep the PCB flat providing solid
stabilization for the stencil during the reflow process. DMI
developed a special pin for the purpose of holding
evenly-distributed tension on the PCB.
This innovative technique allows the operator to maintain both the
crucial planarity of the PCB and the critical alignment of the
stencil during the process of printing solder paste, component
pick-n-place, and the soldering of components.
CW’s implementation of this innovative pin design has eliminated
the need for Kapton tape, reducing materials waste and offering a
cleaner securing and releasing of the PCB from the pallet. This
quick and easy method is far less labor intensive and more
economical.
Because no tooling parts extend more than a few thousands of an
inch above the surface of the PCB, CW’s print through & reflow
pallets work exceptionally well for the stencil to print properly
on even thin PCBs with thicknesses under 0.010”.
FIDUCIALS FOR ALIGNMENT OF THIN PCBS (LESS THAN 0.040”)
For PCBs that can offer challenges during reflow operations, we
offer fiducials on the pallet to align the PCB to both the stencil
printer and pick-n-place machine.
Because the pallets hold the PCB flat, crucial planarity is
constantly maintained. This helps ensure accuracy throughout the
stencil paste application process and the component pick-n-place
process, ultimately improving yields.
TENSION PINS FOR THIN PCBS (LESS THAN 0.040”)
On flex PCBs, DMI offers tension fitting to provide secure and
accurate seating of PCBs against pallets. By using custom pins
mounted on spring leavers, PCB is stretched firmly into the recess
of the pallet to maintain proper orientation during stencil screen
printing and accurate pick-n-place. Fiducials are valuable on any
Print Through & Reflow pallet.
COMPRESSION FITTING FOR ALIGNMENT OF THICK PCBS (0.040” TO .240”)
On thicker PCBs,CW offers compression fitting to provide secure and
accurate seating of PCBs against pallets. By using edge tensioners,
the PCB is held firmly into the recess of the pallet to maintain
proper orientation during stencil screen printing and accurate
pick-n-place.
Specification:
| Model | DurostoneCHP760 | DurostoneCAS761 | DurostoneCAG762 |
| Grade | Standard | Anti-Static | Anti-static(Optical) |
| Colour | Blue | Black | Grey |
| Density(g/mm3) | 1.85 | 1.85 | 1.85 |
| Standard OperationTemperature | 260 | 260 | 260 |
| Maximum Operation Temperature(C) | 350 | 350 | 350 |
| Sheet Size(mm) | 2440×1220 | 2440×1220 | 2440×1220 |
| Tickness/weight(mm/kg) | 3/17, 4/22 | 5/28, 6/33, 8/44 | 10/55, 12/66 |
Our sales network
This estimation may be done in three ways
If a PCB is available (preferably populated) - our sales engineers
can rapidly evaluate your board.
If PCB design data is available we will process, analyse and
remotely assess it.
You can do it using the rules presented below - our customers
quickly find that the above two methods are easiest.
Gerber, Excellon and other data required
Pin Land to SMT pad clearance evaluation
The two figures below each show part of a CSWSC in plan and section
views. The right hand figure shows that more clearance
is required when the connector orientation is perpendicular to the
wave.
PTH Components Located Parallel to direction through wave
The clearance required between the pin land and SMT pad can be made
quite
small, as the solder does not have to flow "under" the component
pockets.
PCB Design Implications - for Board Designers - or respin
We are often called upon by our customers to help with identifying
design respin opportunities.
We will identify problem areas within a board and suggest
appropriate movements of components. (Ideally before the PCB is
fabricated)
However for board designers reading this, can you remember another
four "rules" (to compete with the hundred other rules you have to
have floating
around in your head).
Keep large (height) SMT components away from PTH areas.
Leave the leading and trailing areas around PTH components as clear
as possible.
DON'T put any SMT components within 3mm (0.12") of any PTH
components.
DON'T put all PTH components in line along one edge of a board -
leave some space to allow us to support the masking in the centre
of the board.
