Medical Manufacturing & Outsourcing - Version A. April 2021 - 8

Medical Electronics PCBs

Figure 3 - If the thermal profile is too hot,
bridging results.

Z7 Z7

R9
Z6

R8
R1

J3
4

TP1
1

J5
1

R17
R27

C4
R20

Z3
Z2

R16

R14
C2

R3
R2

R18 1

R31

U1
C1
R13

Z5
Z4

R23
R24
R25

R21

R12

1
R22

R29

PCB

R26
R19

R10

SCANNER INTERFACE
625 - 6701- 9 REV

R30

R11

1
R15

R28

ASSEMBLY DWG TOP

NOTES :
1.
2.

ASSEMBLE IN ACCORDANCE WITH IPC - A - 610 CLASS II.
MARK THE DASH NUMBER AND REVISION OF BILL OF MATERIALS
USED FOR THE ASSEMBLY IN THE LOCATION INDICATED.

3.
4.

SMALLEST SMT PITCH IS .197 INCHES ( 0.5MM).
FOR SCHEMATIC SEE 101733 - SCH

An FAI system helps to create the first article
board by scanning the image of the whole
board, called a golden board. Images of other
boards are compared with the golden board
to ensure that all components are properly
placed on the board with correct orientation
and polarities.

Figure 4 - Example of a properly created assembly drawing. It can eliminate confusion, answer
questions, and reduce board defects.

images of all the other boards with
this golden board to ensure that all
the components are placed properly
on the board with correct orientation
and polarities. It is used as a process
verification and inspection tool to
significantly reduce the human interface
and make the inspection and QC
process more reliable, repeatable, and
faster by at least 30-50 percent.
During first article pre-reflow
inspection - when boards are about
to go for reflow - the process can be
stopped. It can be changed, however,
and a single board or set of two boards
as second articles can be run to correct
the process. If defects are not caught
during the process, they turn up at
the end of the process when it can be
too late to address them. A shipment
could be missed, or rework may be too
involved, thus adding time, resources,
and extra cost. Planning must also be
conducted to determine and document:

* Processes that need to be defined
* Machines needed
* ECOs
* Use of special equipment (e.g., an
arbor press for press fit connectors)
* Use of an AOI machine or
flying probe tester
Documentation is also important for
technicians in the field who need to
read and decipher ECO instructions,
which deviate from original build.
Likewise, rework instructions, if
any, need to clearly state solid
quantitative data for measurement
and verification purposes, in-
cluding illustrations, if possible.
At times, instructions can be issued
in an assembly drawing to avoid board
defects, which could be processrelated issues. Also, depending on
how progressive an EMS provider is,
post reflow x-ray inspection can be
specified as part of the process for
all BGAs, CSPs, and QFN devices,

8 APRIL 2021

rather than performing these steps as
part of the QC stage of the assembly
process. Early intervention enables
corrective actions to be taken to
prevent board defects such as improper
board reflow, poor orientation, wrong
thermal profile, and improper flux
activation, among other issues.
Lastly, it is essential that an EMS
provider or CM always maintains a
constant review of its assembly processes
and procedures. This ensures that
assembly is sustained at the highest levels
possible to efficiently produce quality
PCBs for ventilators or other medical
electronics. Repeatable processes also
minimize defects and issues at the
QC stage and in the marketplace.
This article was written by
Zulki Khan, President and Founder,
NexLogic Technologies, Inc. He
can be reached at zulki@nexlogic.com.
For more information, visit
http://info.hotims.com/76509-341.

MEDICAL MANUFACTURING AND OUTSOURCING SPECIAL REPORT

http://info.hotims.com/76509-341

Medical Manufacturing & Outsourcing - Version A. April 2021

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