Application Note

Light Emitting Diode

Reducing the Occurrence of Soldering
Failures for the Nichia 170 Series LEDs

Table of Contents
1. Overview ........................................................... 2
2. Applicable Part Numbers .................................. 2
3. Applying Non-Solder Mask Defined PCB(NSMD) ............................................................ 3
4. Reflow-Profile Optimization............................. 5
5. Summary ........................................................... 5

The Nichia part numbers NCSW170A, NC2W170A, NCSA170A, NC2A170A, NCSW170B,NC2W170B, NCSA170B, NJSW170C, NCSW170C, NC2W170C, NCSA170C and NC2A170C
within this document are merely Nichia’s part numbers for those Nichia products and are not related
nor bear resemblance to any other company’s product that might bear a trademark.

This document contains tentative information, Nichia may change the contents without notice.
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Application Note
1. Overview
When soldering Nichia 170 Series under reflow, there is possibility soldering problem may happen
due to solder-balls, solder-voids and poor-solderability if the conditions such as reflow-profile andPCB are not suitable for the right soldering process and conditions.
It is introduced the effective techniques for improving the soldering problem below.
･ Applying Non-Solder Mask Defined PCB (NSMD)1･ Reflow-Profile Optimization

Light Emitting Diode*Solder-ball means a part of overflowed solder out of soldering pad and being formed solid ballbeside the LED outline. (See Figure 1-Left)*Solder-void means a vacant-space in the soldering joint. (See Figure 1-Right)

Solder-void

Solder-ballFigure 1. Example of Solder-ball and Solder-void

2. Applicable Part Numbers
This application note applies to the LEDs shown in Table 1.
Table 1. Applicable LED Part Numbers

Part No.

NCSW170A

NCSW170B

NCSW170C

NC2W170A

NC2W170B

NC2W170C

NCSA170A

NCSA170B

NCSA170C

NC2A170A

NJSW170C

NC2A170C

Note:
1This PCB type is that Solder-Mask does not cover the copper layer around pads.
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Application Note
3. Applying Non-Solder Mask Defined PCB (NSMD)Standard PCB is SMD type as flat layer pattern. On the other hand, NSMD type is the one that
Solder-Mask does not cover the copper layer around pads. (See Table 2)
Table 2. Copper layer design comparison (SMD vs. NSMD)

Solder Resist Structure
PCB Populated with an LED
Appearance Overview of the Soldering Pad

Light Emitting Diode

SMD
Solder Mask

NSMD

Copper Layer

Solder Mask

Copper銅 箔 パLayer
ッドPCB

PCB

LEDLED
Solder

Solder

Solder Mask

Solder Mask
Copper Layer

Copper Layer

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Application Note

Light Emitting Diode

It is confirmed the PCB of NSMD type is effective to improve solder-ball and solder-void, applying
to Nichia 170 Series LEDs. (See Figure 2, Figure 3)

Solder-ball

No Solder-ball

SMD

NSMD

Figure 2. Appearance Observation

Solder-void

No Solder-void

SMD

NSMD
Figure 3. X-ray Observation

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Application Note
4. Reflow-Profile Optimization
When soldering Nichia 170 Series LEDs under reflow, it is important the set-up the profile. Thereis possibility solder-ball or solder-void happen if the reflow profile is not suitable for the parts
combination.
When soldering Nichia 170 Series LEDs under reflow with the paste type: Senju M705 (*SAC305),
the reflow profile set up below, referring the customized profile for M705 solder paste, made thegood results.

300

Reflow Conditions:

250

温度[℃]

Temperature (°C)

Light Emitting Diode0 ℃以上(およそ42 2(Approx.40
本加熱：≥ 220°Csec.) 0 秒)

Peak Temperature:
2 3 8 ℃ 238°C
ピーク温度：

Preheat
0 ℃～2 0 0 ℃(およそ6 0 秒)
予熱： 1 5Conditions:150~200°C (Approx.60sec.)

Ramp-down Rate:

冷却速度：
2~3°C per2 ～3sec.℃/ 秒

200

Ramp-up Rate:
1~3°C per1sec.
～3 ℃/ 秒
昇温速度：150100500050

100

150

200

250

300

350

400

時間[s]
Time[s]Time(s)Figure 4. Actual temperature measured profile as target set-up for M705 paste

5. Summary
The introduced items below in this document are influential factors for improving soldering problem.
- Applying Non-Solder Mask Defined PCB (NSMD)- Reflow-Profile Optimization
Please ensure to implement sufficient evaluations for the combination with PCB, considering
appropriate materials such as PCB, solder-paste.

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Application NoteDisclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide
technical information/data for reference purposes only. By using this application note, the user
agrees to the following:・ This application note has been prepared solely for reference on the subject matters incorporated
within it and Nichia makes no guarantee that customers will see the same results for their chosenapplication.

Light Emitting Diode・ The information/data contained herein are only typical examples of performances and/orapplications for the product. Nichia does not provide any guarantees or grant any license underor immunity from any intellectual property rights or other rights held by Nichia or third parties.
・ Nichia makes no representation or warranty, express or implied, as to the accuracy, completenessor usefulness of any information contained herein. In addition, Nichia shall not be liable for any
damages or losses arising out of exploiting, using, or downloading or otherwise this document,or any other acts associated with this document.
・ The content of this application note may be changed without any prior or subsequent notice.
・ Copyrights and all other rights regarding the content of this document are reserved by Nichia or
the right holders who have permitted Nichia to use the content. Without prior written consent of
Nichia, republication, reproduction, and/or redistribution of the content of this document in any
form or by any means, whether in whole or in part, including modifications or derivative workshereof, is strictly prohibited.

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TOKUSHIMA 774-8601, JAPAN
Phone: +81-884-22-2311 Fax: +81-884-21-0148

NICHIA CORPORATION
http://www.nichia.co.jp

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